JP4781836B2 - Ultra-high strength steel sheet excellent in hydrogen embrittlement resistance, its manufacturing method, manufacturing method of ultra-high strength hot-dip galvanized steel sheet, and manufacturing method of ultra-high-strength galvannealed steel sheet - Google Patents
Ultra-high strength steel sheet excellent in hydrogen embrittlement resistance, its manufacturing method, manufacturing method of ultra-high strength hot-dip galvanized steel sheet, and manufacturing method of ultra-high-strength galvannealed steel sheet Download PDFInfo
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本発明は、自動車、建材、家電製品等に用いて好適な耐水素脆性に優れた超高強度鋼板とその製造方法及び超高強度溶融亜鉛めっき鋼板の製造方法並びに超高強度合金化溶融亜鉛めっき鋼板の製造方法に関するものである。 The present invention relates to an ultra-high-strength steel sheet excellent in hydrogen embrittlement resistance suitable for use in automobiles, building materials, home appliances, etc., a manufacturing method thereof, a manufacturing method of an ultra-high-strength hot-dip galvanized steel sheet, and an ultra-high-strength alloyed hot-dip galvanizing. The present invention relates to a method for manufacturing a steel sheet.
従来、ボルト、ＰＣ鋼線やラインパイプといった用途には高強度鋼が多く使われており、９８０ＭＰａ以上の強度になると、鋼中への水素の侵入により水素脆性が発生することが知られている。これに対し、（１）薄鋼板は板厚が薄いため水素が侵入しても短時間で放出されること、（２）加工性の点で９８０ＭＰａ以上の鋼板の利用がほとんどなかったこと等から、水素脆性に対しては、ほとんど問題とされていなかった。
近年、自動車の軽量化や衝突安全性の向上の必要性から、９８０ＭＰａ以上の超高強度薄鋼板をバンパーやインパクトビーム等の補強材に使用に供する場合が急速に増えてきており、耐水素脆性を備えた超高強度薄鋼板の開発が急務となっている。
この耐水素脆性を向上させる技術は、ほとんどがボルトや条鋼、厚板といった製品のままでかつ耐力または降伏応力以下で使用されることの多い鋼材に対して開発されてきている。
Conventionally, high-strength steel is often used for applications such as bolts, PC steel wires, and line pipes, and it is known that hydrogen embrittlement occurs due to hydrogen intrusion into steel when the strength becomes 980 MPa or more. . On the other hand, (1) the thin steel plate is thin, so that hydrogen is released in a short time even if hydrogen enters, and (2) there is almost no use of a steel plate of 980 MPa or more in terms of workability. The hydrogen embrittlement was hardly regarded as a problem.
In recent years, due to the need to reduce the weight of automobiles and improve collision safety, the use of ultra-high strength thin steel sheets of 980 MPa or higher for reinforcing materials such as bumpers and impact beams has been rapidly increasing. There is an urgent need to develop ultra-high-strength thin steel sheets equipped with.
The technology for improving the hydrogen embrittlement resistance has been developed for steel materials that are often used as products such as bolts, strips, and thick plates, and are often used below the yield strength or yield stress.
例えば、条鋼・ボルト用鋼においては、焼き戻しマルテンサイトを中心に開発が行われ、にＣｒ、Ｍｏや Ｖといった焼き戻し軟化抵抗性を示す添加元素が耐水素脆性性向上に有効であることが報告されている（非特許文献１）。これは、合金炭化物を析出させて、これを水素のトラップサイトに活用することで水素脆性形態を粒界から粒内破壊へと移行させる技術である。
また、Ｔｉ、Ｍｇを主体とする酸化物が水素性欠陥を防ぐことに効果があるという提案がなされている（特許文献１）。
For example, in steel bars and bolt steels, development has been centered on tempered martensite, and additive elements exhibiting temper softening resistance such as Cr, Mo and V are effective in improving hydrogen embrittlement resistance. It has been reported (Non-Patent Document 1). This is a technique for precipitating alloy carbides and using them as hydrogen trap sites to shift the hydrogen embrittlement form from grain boundaries to intragranular fracture.
There has also been a proposal that an oxide mainly composed of Ti and Mg is effective in preventing hydrogen defects (Patent Document 1).
一方、薄鋼板の水素脆性に関しては、例えば、残留オーステナイト量の加工誘起変態に起因した水素脆性の助長について報告されている（非特許文献２）。これは、薄鋼板の成型加工を考慮したものであるが、耐水素脆性性を劣化させない残留オーステナイト量の規制について報告がなされている。
また、水素トラップ能と成形性を考慮した薄鋼板として、耐つまとび性に優れたホウロウ容器用鋼板が提案されている（特許文献２）。これは、製造時に鋼板中に進入する水素を、鋼板内に含まれる酸化物でトラップすることで、ホウロウがけを行った後に発生するつまとびと呼ばれる表面欠陥を抑制しようとするものである。このことから、鋼板内部には多量の酸化物を含むこととなる。
In addition, as a thin steel plate considering hydrogen trapping ability and formability, a steel plate for a hollow container excellent in resistance to tearing has been proposed (Patent Document 2). This is intended to suppress a surface defect called a trap generated after enamelling by trapping hydrogen that enters the steel sheet during production with an oxide contained in the steel sheet. Therefore, a large amount of oxide is contained inside the steel plate.
ところで、従来の非特許文献１の鋼は、Ｃ量０．４％以上で合金元素も多く含むことから、薄鋼板で要求される加工性や溶接性が劣悪で、さらに、合金炭化物を析出させるために数時間以上熱処理する必要があるため、製造工程が非常に長くなり、製造コストが増大するという問題点があった。
また、特許文献１の鋼板は、対象が厚鋼板であり、特に大入熱の溶接後の水素脆性については考慮されているものの、薄鋼板に要求される高い成形性と耐水素脆性を両立させる点に関しては一切考慮されていない。
また、非特許文献２の薄鋼板は、特定の組織を持つ高強度薄鋼板であり、根本的な耐水素脆性を向上させる対策にはなっていない。
By the way, the conventional steel of Non-Patent Document 1 has a C content of 0.4% or more and contains a large amount of alloy elements, so that the workability and weldability required for a thin steel sheet are inferior, and alloy carbide is precipitated. Therefore, since it is necessary to heat-treat for several hours or more, there is a problem that the manufacturing process becomes very long and the manufacturing cost increases.
In addition, the steel plate of Patent Document 1 is a thick steel plate, and although hydrogen embrittlement after welding with particularly high heat input is taken into consideration, both high formability and hydrogen embrittlement required for a thin steel plate are achieved. No point is taken into account.
The thin steel sheet of Non-Patent Document 2 is a high-strength thin steel sheet having a specific structure, and is not a measure for improving the fundamental hydrogen embrittlement resistance.
また、特許文献２のホウロウ容器用鋼板は、つまとびと呼ばれる表面欠陥を抑制するために鋼板内部に多量の酸化物を含んだものであるから、これら酸化物を鋼板内に高密度に分散させると、成形性の劣化を招くこととなり、高い成形性が必要とされる自動車用鋼板への適用には問題がある。加えて、この鋼板は、高強度と耐水素脆性の両立を図ったものでもない。 Moreover, since the steel plate for enamel containers of patent document 2 contains a large amount of oxides in the steel plate in order to suppress the surface defect called the picking, these oxides are dispersed in the steel plate at high density. As a result, the formability is deteriorated, and there is a problem in application to automobile steel sheets that require high formability. In addition, this steel sheet is not intended to achieve both high strength and hydrogen embrittlement resistance.
このように、焼き戻しマルテンサイト鋼において遅れ破壊は、旧オーステナイト粒界等に水素が集積することによってボイド等が発生し、その部分が起点となって破壊を生じると考えられている。そこで、水素のトラップサイトを均等かつ微細に分散させて、その部分に水素をトラップさせると、拡散性水素濃度が下がり、遅れ破壊の感受性が下がる。既に述べたように、ＭｇおよびＴｉを複合添加した厚鋼板における酸化物の分散形態制御で、水素起因の耐遅れ破壊性が向上することが分かっている。これら酸化物は成形性に乏しく強加工を受ける際は、成形性を劣化させてしまう。その結果、優れた加工性が要求される薄鋼板においては、ＴｉやＭｇ等の酸化物を水素脆性が抑制可能なほど高密度に分散させ難い。
あるいは、Ｖ等の合金炭化物を鋼中への分散には長時間を有することから、薄鋼板の製造ラインである連続焼鈍ラインや連続めっきラインでの活用は行い難い。
Thus, delayed fracture in tempered martensitic steel is considered to be caused by the accumulation of hydrogen at the prior austenite grain boundaries and the like, resulting in fracture starting from that portion. Therefore, if the hydrogen trap sites are dispersed evenly and finely and hydrogen is trapped there, the concentration of diffusible hydrogen is lowered and the susceptibility to delayed fracture is lowered. As already described, it has been found that the delayed fracture resistance due to hydrogen is improved by controlling the oxide dispersion in the thick steel sheet to which Mg and Ti are added in combination. These oxides have poor moldability and deteriorate the moldability when subjected to strong processing. As a result, in thin steel sheets that require excellent workability, it is difficult to disperse oxides such as Ti and Mg at such a high density that hydrogen embrittlement can be suppressed.
Alternatively, since it takes a long time to disperse alloy carbides such as V in steel, it is difficult to utilize in continuous annealing lines and continuous plating lines, which are production lines for thin steel sheets.
本発明は、上記の事情に鑑みてなされたものであって、水素性欠陥を防止し、溶接部での耐水素脆性性に優れた超高強度鋼板とその製造方法及び超高強度溶融亜鉛めっき鋼板の製造方法並びに超高強度合金化溶融亜鉛めっき鋼板の製造方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, and is an ultra-high-strength steel sheet that prevents hydrogen defects and has excellent resistance to hydrogen embrittlement at welds, its manufacturing method, and ultra-high-strength hot-dip galvanizing. It aims at providing the manufacturing method of a steel plate, and the manufacturing method of an ultra-high-strength galvannealed steel plate.
本発明者等は、鋭意検討した結果、薄鋼板における使用環境を考慮して、耐水素脆性性を向上させる方法を見出すに至った。すなわち、鋼板にＳｉ、Ｍｎ、Ａｌ及びＣｒを添加し、かつ、連続焼鈍工程あるいは連続溶融亜鉛めっき工程における雰囲気を制御することで、鋼板の表面から１０μｍ以内の表層、めっき層中、あるいは鋼板と溶融亜鉛めっき層との界面から１０μｍ以内の表層における結晶粒界、または結晶粒内、もしくは結晶粒界及び結晶粒内に酸化物を形成させることにより、薄鋼板としての必要特性である成形性や耐食性を損なうことなく、耐水素脆性に優れる引張最大強度９８０以上の超高強度鋼板が得られることを見出した。
本発明は、上記の知見に基づいてなされたものであり、その要旨とするところは以下の通りである。
As a result of intensive studies, the present inventors have found a method for improving the hydrogen embrittlement resistance in consideration of the use environment in the thin steel sheet. That is, by adding Si, Mn, Al and Cr to the steel sheet and controlling the atmosphere in the continuous annealing process or the continuous hot dip galvanizing process, the surface layer within 10 μm from the surface of the steel sheet, in the plating layer, or with the steel sheet By forming an oxide in the crystal grain boundary in the surface layer within 10 μm from the interface with the hot dip galvanized layer, or in the crystal grain, or in the crystal grain boundary and the crystal grain, formability that is a necessary characteristic as a thin steel plate It has been found that an ultra-high strength steel sheet having a tensile maximum strength of 980 or more and excellent in hydrogen embrittlement resistance can be obtained without impairing corrosion resistance.
This invention is made | formed based on said knowledge, The place made into the summary is as follows.
（１） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。
(1) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total of each content is 0.3% or more, and any of crystal grain boundaries, crystal grains, crystal grain boundaries, and crystal grains in the surface layer within 10 μm from the surface of the steel plate, the balance being iron and inevitable impurities Or one or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO as the oxide , And Mn 2 SiO 4 and Cr 2 O 3 in total, an average content of 0.01 to 30 An ultra-high-strength steel sheet excellent in hydrogen embrittlement resistance, characterized by containing in mass% and having a maximum tensile strength of 980 MPa or more.
（２） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面に、Ｆｅを７質量％未満含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる溶融亜鉛めっき層を形成し、前記鋼板と前記溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。
(2) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total content of each is 0.3% or more, the balance is less than 7% by mass of Fe on the surface of the steel plate made of iron and inevitable impurities, and the remainder is made of Zn, Al and inevitable impurities. A galvanized layer is formed, and any one of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the steel sheet within 10 μm from the interface between the steel sheet and the hot dip galvanized layer, or in the hot dip galvanized layer. one kind or two or more, as oxides, SiO 2, FeSiO 3, Fe 2 SiO 4, nSiO 3, Al 2 O 3, MnAl 2 O 4, 1 or more kinds selected from the group of MnO, and a Mn 2 SiO 4 and Cr 2 O 3, a total average content 0.01 An ultra-high strength steel sheet excellent in hydrogen embrittlement resistance, characterized by being contained at 30% by mass and having a maximum tensile strength of 980 MPa or more.
（３） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面に、Ｆｅを７〜１５質量％含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる合金化溶融亜鉛めっき層を形成し、前記鋼板と前記合金化溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記合金化溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。
(3) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total content of each is 0.3% or more, and the balance of the steel sheet is made of iron and unavoidable impurities, and 7 to 15 mass% of Fe is contained, and the balance is made of Zn, Al and unavoidable impurities. Forming an alloyed hot-dip galvanized layer, and crystal grain boundaries within the steel plate within 10 μm from the interface between the steel sheet and the alloyed hot-dip galvanized layer; any one of the galvanized layer or two or more, as oxides, SiO 2, FeSiO 3 Fe 2 SiO 4, MnSiO 3, Al 2 O 3, MnAl 2 O 4, 1 or more kinds selected from the group of MnO, and a Mn 2 SiO 4 and Cr 2 O 3, in total, the average content An ultra-high strength steel sheet excellent in hydrogen embrittlement resistance, characterized by containing at a rate of 0.01 to 30% by mass and having a maximum tensile strength of 980 MPa or more.
（４） さらに、質量％で、Ｎｉ：０．０５〜１．０％、Ｃｕ：０．０５〜１．０％を含有してなることを特徴とする上記（１）ないし（３）のいずれかに記載の耐水素脆性に優れた超高強度鋼板。 (4) Any one of the above (1) to (3), further comprising Ni: 0.05 to 1.0% and Cu: 0.05 to 1.0% by mass% An ultra high strength steel plate with excellent hydrogen embrittlement resistance.
（５） さらに、質量％で、Ｎｂ：０．００５〜０．３％、Ｔｉ：０．００５〜０．３％、Ｖ：０．００５〜０．３％、Ｗ：０．００５〜０．３％の群から選択された１種または２種以上を含有してなることを特徴とする上記（１）ないし（４）のいずれかに記載の耐水素脆性に優れた超高強度鋼板。 (5) Further, by mass%, Nb: 0.005-0.3%, Ti: 0.005-0.3%, V: 0.005-0.3%, W: 0.005-0. The ultra-high strength steel sheet having excellent hydrogen embrittlement resistance according to any one of the above (1) to (4), comprising one or more selected from the group of 3%.
（６） さらに、質量％で、Ｂ：０．０００１〜０．１％を含有してなることを特徴とする上記（１）ないし（５）のいずれかに記載の耐水素脆性に優れた超高強度鋼板。 (6) Further, in the mass%, B: 0.0001 to 0.1% is contained, and the superb resistance to hydrogen embrittlement according to any one of the above (1) to (5) High strength steel plate.
（７） さらに、質量％で、Ｃａ：０．０００５〜０．０１％、Ｍｇ：０．０００５〜０．０１％、Ｌａ：０．０００５〜０．０１％、Ｃｅ：０．０００５〜０．０１％、Ｙ：０．０００５〜０．０１％の群から選択された１種または２種以上を含有してなることを特徴とする上記（１）ないし（６）のいずれかに記載の耐水素脆性に優れた超高強度鋼板。 (7) Further, in mass%, Ca: 0.0005 to 0.01%, Mg: 0.0005 to 0.01%, La: 0.0005 to 0.01%, Ce: 0.0005 to 0.00. 01%, Y: 1 type or 2 types or more selected from the group of 0.0005-0.01%, The resistance in any one of said (1) thru | or (6) characterized by the above-mentioned Super high strength steel sheet with excellent hydrogen embrittlement.
（８） 上記（１）ないし（７）のいずれかに記載の化学成分からなる高強度鋼板を熱処理する方法であって、Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなる雰囲気にて、この雰囲気中の水分圧ＰＨ２Ｏと水素分圧ＰＨ２を次式｛−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５｝を満足するように制御しつつ熱処理することにより、鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ ２ 、ＦｅＳｉＯ ３ 、Ｆｅ ２ ＳｉＯ ４ 、ＭｎＳｉＯ ３ 、Ａｌ ２ Ｏ ３ 、ＭｎＡｌ ２ Ｏ ４ 、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ ２ ＳｉＯ ４ 並びにＣｒ ２ Ｏ ３ を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度鋼板の製造方法。
(8) A method of heat treating a high strength steel sheet consisting of chemical components according to any one of (1) to (7), and H 2 contains 1 to 60 vol%, the remainder N 2, H 2 In an atmosphere composed of O, O 2 and inevitable impurities, the water pressure PH 2 O and the hydrogen partial pressure PH 2 in this atmosphere are expressed by the following formula { −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5 } Is controlled to satisfy any of the following, by oxidizing to one or more of grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the surface layer within 10 μm from the surface of the steel sheet. One or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, and Mn 2 SiO 4 and Cr 2 the O 3, a total average content Method for manufacturing ultra-high strength steel sheet excellent in embrittlement and controls to contain at .01～30 wt%.
（９） 上記（１）ないし（７）のいずれかに記載の化学成分からなる鋳造スラブを直接または一旦冷却した後１２００℃以上に加熱し、次いで、Ａｒ３変態点以上の温度にて熱間圧延を施し、次いで、６３０℃以下の温度域にて巻き取り、次いで、圧下率４０〜７０％の冷延を施し、その後、連続焼鈍する超高強度鋼板の製造方法であって、前記連続焼鈍するに際し、Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を次式｛−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５｝を満足するように制御する雰囲気下にて、５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、その後、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度４〜２００℃／秒で冷却して２００〜５００℃間の温度とし、この温度領域にて３０秒以上保持することにより、鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ ２ 、ＦｅＳｉＯ ３ 、Ｆｅ ２ ＳｉＯ ４ 、ＭｎＳｉＯ ３ 、Ａｌ ２ Ｏ ３ 、ＭｎＡｌ ２ Ｏ ４ 、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ ２ ＳｉＯ ４ 並びにＣｒ ２ Ｏ ３ を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度鋼板の製造方法。
( 9 ) The cast slab composed of the chemical component according to any one of (1) to (7) above is directly or once cooled and then heated to 1200 ° C or higher, and then hot-rolled at a temperature equal to or higher than the Ar3 transformation point. Next, it is wound up in a temperature range of 630 ° C. or less, then cold-rolled with a rolling reduction of 40 to 70%, and then subjected to continuous annealing, which is a continuous annealing method. At this time, 1 to 60% by volume of H 2 is contained, the balance is made of N 2 , H 2 O, O 2 and unavoidable impurities, and the water pressure PH 2 O and the hydrogen partial pressure PH 2 are expressed by the following formula { −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5 } In an atmosphere controlled to satisfy ≦ log (PH 2 O / PH 2 ) ≦ −0.5 } , heating is performed at an average heating rate of 0.7 ° C./second or more at 550 to 750 ° C. Above and at 900 ° C or lower, then up to 650 ° C Cooling is performed at a uniform cooling rate of 0.1 to 200 ° C./second, and a temperature between 650 ° C. and 500 ° C. is cooled at an average cooling rate of 4 to 200 ° C./second to obtain a temperature of 200 to 500 ° C. By holding for 2 seconds or more , any one or two or more kinds of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the surface layer within 10 μm from the surface of the steel sheet are used as oxides, SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , or one or more selected from the group of MnO, and Mn 2 SiO 4 and Cr 2 O 3 in total, The manufacturing method of the ultra high strength steel plate excellent in hydrogen embrittlement resistance characterized by controlling so that it may contain at an average content rate of 0.01-30 mass% .
（１０） 上記（１）ないし（７）のいずれかに記載の化学成分からなる鋳造スラブを直接または一旦冷却した後１２００℃以上に加熱し、次いで、Ａｒ３変態点以上の温度にて熱間圧延を施し、次いで、６３０℃以下の温度域にて巻き取り、次いで、圧下率４０〜７０％の冷延を施し、その後、溶融亜鉛めっきを施す超高強度溶融亜鉛めっき鋼板の製造方法であって、 前記溶融亜鉛めっきを施すに際し、Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を次式｛−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５｝を満足するように制御する雰囲気下にて、５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、次いで、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度３〜２００℃／秒で冷却して（亜鉛めっき浴温度−４０）℃〜（亜鉛めっき浴温度＋５０）℃間の温度とし、その後、亜鉛めっき浴に浸漬することにより、前記鋼板と前記溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ ２ 、ＦｅＳｉＯ ３ 、Ｆｅ ２ ＳｉＯ ４ 、ＭｎＳｉＯ ３ 、Ａｌ ２ Ｏ ３ 、ＭｎＡｌ ２ Ｏ ４ 、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ ２ ＳｉＯ ４ 並びにＣｒ ２ Ｏ ３ を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度溶融亜鉛めっき鋼板の製造方法。
( 10 ) The cast slab composed of the chemical component according to any one of (1) to (7) above is directly or once cooled and then heated to 1200 ° C. or higher, and then hot-rolled at a temperature equal to or higher than the Ar3 transformation point. Is then rolled in a temperature range of 630 ° C. or lower, then cold rolled at a rolling reduction of 40 to 70%, and then hot dip galvanized, followed by a method of manufacturing an ultra high strength hot dip galvanized steel sheet. In carrying out the hot dip galvanization, 1 to 60% by volume of H 2 is contained, the balance is made of N 2 , H 2 O, O 2 and unavoidable impurities, and water pressure PH 2 O and hydrogen partial pressure PH 2 is controlled so as to satisfy the following formula { −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5 } , an average heating rate of 0.7 ° C./second between 550 and 750 ° C. Heat above, 750 ℃ or more and 900 ℃ or less Then, it is cooled to 650 ° C. at an average cooling rate of 0.1 to 200 ° C./second, and is cooled between 650 ° C. and 500 ° C. at an average cooling rate of 3 to 200 ° C./second (zinc plating bath temperature). −40) to (temperature of galvanizing bath +50) ° C., and then immersed in a galvanizing bath to obtain crystal grains in the steel plate within 10 μm from the interface between the steel plate and the hot dip galvanized layer. Any one or more of the boundary, the crystal grain, the crystal grain boundary and the crystal grain, and the hot dip galvanized layer may be SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al as an oxide. One or two or more selected from the group of 2 O 3 , MnAl 2 O 4 and MnO, and Mn 2 SiO 4 and Cr 2 O 3 in total, the average content is 0.01 to 30% by mass To contain High-strength method for manufacturing a galvanized steel sheet having excellent resistance to hydrogen embrittlement, characterized by.
（１１） 上記（１）ないし（７）のいずれかに記載の化学成分からなる鋳造スラブを直接または一旦冷却した後１２００℃以上に加熱し、次いで、Ａｒ３変態点以上の温度にて熱間圧延を施し、次いで、６３０℃以下の温度域にて巻き取り、次いで、圧下率４０〜７０％の冷延を施し、その後、溶融亜鉛めっき及び合金化処理を施す超高強度合金化溶融亜鉛めっき鋼板の製造方法であって、前記溶融亜鉛めっきを施すに際し、Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を次式｛−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５｝を満足するように制御する雰囲気下にて、５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、次いで、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度３〜２００℃／秒で冷却して（亜鉛めっき浴温度−４０）℃〜（亜鉛めっき浴温度＋５０）℃間の温度とし、次いで、亜鉛めっき浴に浸漬し、さらに、４６０℃以上の温度にて合金化処理を施し、その後、室温まで冷却することにより、前記鋼板と前記合金化溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記合金化溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ ２ 、ＦｅＳｉＯ ３ 、Ｆｅ ２ ＳｉＯ ４ 、ＭｎＳｉＯ ３ 、Ａｌ ２ Ｏ ３ 、ＭｎＡｌ ２ Ｏ ４ 、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ ２ ＳｉＯ ４ 並びにＣｒ ２ Ｏ ３ を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度合金化溶融亜鉛めっき鋼板の製造方法。
( 11 ) The cast slab composed of the chemical component according to any one of (1) to (7) above is directly or once cooled and then heated to 1200 ° C or higher, and then hot-rolled at a temperature equal to or higher than the Ar3 transformation point. And then rolled up in a temperature range of 630 ° C. or lower, then cold rolled at a rolling reduction of 40 to 70%, and then subjected to hot dip galvanizing and alloying treatment. In the production method, the hot dip galvanizing is performed, the H 2 content is 1 to 60% by volume, the balance is N 2 , H 2 O, O 2 and unavoidable impurities, and the moisture pressure PH 2 An average heating rate between 550 and 750 ° C. in an atmosphere in which O and the hydrogen partial pressure PH 2 are controlled so as to satisfy the following formula { −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5 } Heat at 0.7 ° C / second or more, 750 More than this and annealing at 900 ° C. or less, and then cooling to 650 ° C. at an average cooling rate of 0.1 to 200 ° C./second, and cooling between 650 ° C. and 500 ° C. at an average cooling rate of 3 to 200 ° C./second ( Zinc plating bath temperature −40) ° C. to (Zinc plating bath temperature + 50) ° C., then immersed in a zinc plating bath, further subjected to alloying treatment at a temperature of 460 ° C. or higher, and then to room temperature By cooling , crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains within the steel sheet within 10 μm from the interface between the steel sheet and the alloyed hot dip galvanized layer, within the alloyed hot dip galvanized layer Any one or two or more of these may be selected from the group consisting of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , and MnO as an oxide. More than species, And Mn 2 SiO 4 and Cr 2 O 3 are controlled so as to contain an average content of 0.01 to 30% by mass in total, and an ultra-high strength alloy having excellent hydrogen embrittlement resistance is provided. Manufacturing method of hot dip galvanized steel sheet.
本発明の超高強度鋼板によれば、質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面から１０μｍ以内の表層、または、この鋼板と溶融亜鉛めっき層との界面から１０μｍ以内の鋼板内、あるいは、この鋼板と合金化溶融亜鉛めっき層との界面から１０μｍ以内の鋼板内の、結晶粒界、結晶粒内、結晶粒界及び結晶粒内、溶融亜鉛めっき層内または合金化溶融亜鉛めっき層内、のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有したので、自動車用の構造用部材、補強用部材、足廻り用部材に好適な成形性や耐食性を具備し、引張最大強度が９８０ＭＰａ以上であり、溶接部での耐水素脆性性に優れた超高強度鋼板を提供することができる。
According to the ultra high strength steel sheet of the present invention, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% or more and 3.0% or less, Al: 2 in mass%. 0.0% or less, Cr: 3.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and The total content of each of Si, Mn, Al and Cr is 0.3% or more, and the surface layer within 10 μm from the surface of the steel plate, the balance being iron and inevitable impurities, or this steel plate and hot dip galvanized layer In a steel plate within 10 μm from the interface with the steel, or in a steel plate within 10 μm from the interface between the steel plate and the alloyed hot dip galvanized layer, crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains, molten zinc In the plating layer or the alloyed hot-dip galvanized layer, any one or more of the oxide and One or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, and Mn 2 SiO 4 and Cr 2 Since O 3 is contained in an average content of 0.01 to 30% by mass in total, it has moldability and corrosion resistance suitable for structural members, reinforcing members, and suspension members for automobiles. It is possible to provide an ultra-high strength steel sheet having a maximum strength of 980 MPa or more and having excellent resistance to hydrogen embrittlement at a weld.
本発明の耐水素脆性に優れた超高強度鋼板とその製造方法及び超高強度溶融亜鉛めっき鋼板の製造方法並びに超高強度合金化溶融亜鉛めっき鋼板の製造方法の最良の形態について説明する。ここでは、延性が良好でありかつ引張強さ（ＴＳ）が７８０ＭＰａ級の高降伏比高強度冷延鋼板を例に取り説明する。
なお、この形態は、発明の趣旨をより良く理解させるために詳細に説明するものであるから、特に指定の無い限り、本発明を限定するものではない。
The best mode of the ultra high strength steel sheet excellent in hydrogen embrittlement resistance of the present invention, its manufacturing method, the manufacturing method of the ultra high strength hot dip galvanized steel sheet, and the manufacturing method of the ultra high strength alloyed hot dip galvanized steel sheet will be described. Here, a high yield ratio high strength cold-rolled steel sheet having good ductility and tensile strength (TS) of 780 MPa class will be described as an example.
In addition, since this form is demonstrated in detail in order to make the meaning of invention be better understood, unless otherwise specified, this invention is not limited.
本発明の超高強度鋼板は、次の（１）〜（３）のいずれかの鋼板である。
（１） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上のものである。
The ultra-high-strength steel sheet of the present invention is any one of the following steel sheets (1) to (3).
(1) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total of each content is 0.3% or more, and any of crystal grain boundaries, crystal grains, crystal grain boundaries, and crystal grains in the surface layer within 10 μm from the surface of the steel plate, the balance being iron and inevitable impurities Or one or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO as the oxide , And Mn 2 SiO 4 and Cr 2 O 3 in total, an average content of 0.01 to 30 It is contained in mass% and has a maximum tensile strength of 980 MPa or more.
（２） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面に、Ｆｅを７質量％未満含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる溶融亜鉛めっき層を形成し、前記鋼板と前記溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上のもので、超高強度溶融亜鉛めっき鋼板と称されるものである。
(2) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total content of each is 0.3% or more, the balance is less than 7% by mass of Fe on the surface of the steel plate made of iron and inevitable impurities, and the remainder is made of Zn, Al and inevitable impurities. A galvanized layer is formed, and any one of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the steel sheet within 10 μm from the interface between the steel sheet and the hot dip galvanized layer, or in the hot dip galvanized layer. one kind or two or more, as oxides, SiO 2, FeSiO 3, Fe 2 SiO 4, nSiO 3, Al 2 O 3, MnAl 2 O 4, 1 or more kinds selected from the group of MnO, and a Mn 2 SiO 4 and Cr 2 O 3, a total average content 0.01 It is contained at 30% by mass, has a maximum tensile strength of 980 MPa or more, and is called an ultra-high strength hot-dip galvanized steel sheet.
（３） 質量％で、Ｃ：０．０６〜０．２５％、Ｓｉ：２．０％以下、Ｍｎ：２．０２％以上３．０％以下、Ａｌ：２．０％以下、Ｃｒ：３．０％以下、Ｐ：０．０４％以下、Ｓ：０．０１％以下、Ｏ：０．０１％以下、Ｎ：０．０１％以下を含有し、かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、残部が鉄及び不可避的不純物からなる鋼板の表面に、Ｆｅを７〜１５質量％含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる合金化溶融亜鉛めっき層を形成し、前記鋼板と前記合金化溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記合金化溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上のもので、超高強度合金化溶融亜鉛めっき鋼板と称されるものである。 (3) By mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3 0.0% or less, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less, and the Si, Mn, Al and Cr The total content of each is 0.3% or more, and the balance of the steel sheet is made of iron and unavoidable impurities, and 7 to 15 mass% of Fe is contained, and the balance is made of Zn, Al and unavoidable impurities. Forming an alloyed hot-dip galvanized layer, and crystal grain boundaries within the steel plate within 10 μm from the interface between the steel sheet and the alloyed hot-dip galvanized layer; any one of the galvanized layer or two or more, as oxides, SiO 2, FeSiO 3 Fe 2 SiO 4, MnSiO 3, Al 2 O 3, MnAl 2 O 4, 1 or more kinds selected from the group of MnO, and a Mn 2 SiO 4 and Cr 2 O 3, in total, the average content It is contained at a rate of 0.01 to 30% by mass, has a maximum tensile strength of 980 MPa or more, and is called an ultra-high-strength galvannealed steel sheet.
ここで、鋼の組成を上記の様に限定した理由について説明する。ここでは、「％」は「質量％」を意味する。
Ｃは、鋼板の強度を上昇できる元素である。ここで、Ｃの含有量が０．０６％未満であると、引張最大強度を９８０ＭＰａ以上とすることが出来ない。そこで、下限を０．０６％とした。なお、含有量が０．０６％を下回った場合、引張最大強度を９８０ＭＰａ以上とすることは出来ないが、鋼板表層への酸化物形成の抑制による化成性の向上や溶融めっきの濡れ性および合金化促進等の効果は得られる。一方、Ｃの含有量が０．２５％を越えると、溶接部強度の確保が困難となる。そこで、上限を０．２５％に限定した。しかし、溶接部の強度を問題にしないのであれば、本発明の効果である耐水素脆性の向上効果を引き出すことはできる。
Here, the reason for limiting the steel composition as described above will be described. Here, “%” means “mass%”.
C is an element that can increase the strength of the steel sheet. Here, if the C content is less than 0.06%, the maximum tensile strength cannot be 980 MPa or more. Therefore, the lower limit was made 0.06%. In addition, when the content is less than 0.06%, the maximum tensile strength cannot be increased to 980 MPa or more. However, the improvement of chemical conversion by suppressing the formation of oxide on the steel sheet surface layer, the wettability of hot dipping, and the alloy Effects such as crystallization promotion can be obtained. On the other hand, if the C content exceeds 0.25%, it becomes difficult to ensure the strength of the weld. Therefore, the upper limit is limited to 0.25%. However, if the strength of the weld is not a problem, the effect of improving hydrogen embrittlement resistance, which is an effect of the present invention, can be brought out.
Ｓｉは、強化元素であり、鋼板の強度を上昇させることに有効である。加えて、酸化物とすることで耐水素脆性向上に寄与することから、添加することが望ましい。２．０％超の添加は成形性が低下することから、その上限を２．０％とした。下限は、特に限定しないが、０．０００５％以下とするのは困難であるので、これが実質的な下限である。
Ｍｎは、強化元素であり、鋼板の強度を上昇させることに有効である。しかしながら、３．０％超となると鋼板の成形性が低下することから、その上限を３．０％とした。下限は、特に限定しないが、０．０００５％以下とするのは困難であるので、これが実質的な下限である。
Si is a strengthening element and is effective in increasing the strength of the steel sheet. In addition, it is desirable to add the oxide because it contributes to the improvement of hydrogen embrittlement resistance. Since addition exceeding 2.0% lowers moldability, the upper limit was made 2.0%. The lower limit is not particularly limited, but it is difficult to set it to 0.0005% or less, so this is a substantial lower limit.
Mn is a strengthening element and is effective in increasing the strength of the steel sheet. However, if it exceeds 3.0%, the formability of the steel sheet is lowered, so the upper limit was made 3.0%. The lower limit is not particularly limited, but it is difficult to set it to 0.0005% or less, so this is a substantial lower limit.
Ａｌは、フェライト形成を促進し、延性を向上させるので添加しても良い。また、脱酸材としても活用可能である。加えて、酸化物とすることで耐水素脆性向上に寄与するので添加しても良い。ここで、過剰な添加は成形性を劣化させることから、その上限を２．０％とした。また、下限は、特に限定しないが、０．０００５％以下とするのは困難であるので、これが実質的な下限である。
Ｃｒは、酸化物とすることで耐水素脆性向上に寄与することから添加しても良い。ここで、３％超含有すると、製造時および熱延時の製造性に悪影響を及ぼすため、上限値を３％とした。また、下限は、特に限定しないが、Ｃｒ添加による耐水素脆化向上効果を活用するためには、０．０５％以上添加することが好ましい。加えて、高強度化のために添加しても良い。
Al may be added because it promotes ferrite formation and improves ductility. It can also be used as a deoxidizer. In addition, the oxide may contribute to the improvement of hydrogen embrittlement resistance and may be added. Here, excessive addition deteriorates moldability, so the upper limit was made 2.0%. Moreover, although a minimum is not specifically limited, Since it is difficult to set it as 0.0005% or less, this is a substantial minimum.
Cr may be added because it contributes to improvement of hydrogen embrittlement resistance by using an oxide. Here, if the content exceeds 3%, the manufacturability during production and hot rolling is adversely affected, so the upper limit was made 3%. Moreover, although a minimum is not specifically limited, In order to utilize the hydrogen embrittlement improvement effect by Cr addition, adding 0.05% or more is preferable. In addition, it may be added to increase the strength.
本発明の超高強度鋼板は、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独で含む酸化物、あるいは、これらの元素を複数種含む複合酸化物を鋼板表層に形成させることで、耐水素脆性の向上を図っていることから、Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計を０．３％以上とする必要がある。ここで、含有量の合計が０．３％未満であると、酸化物の含有量が少なすぎて顕著な耐水素脆性の向上が得られない。そこで、下限を０．３％とした。上限は特に定めないが、それぞれの含有量の上限を上回ると、成形性が劣化することから、それぞれの上限範囲内内とする必要がある。 The ultra-high-strength steel sheet of the present invention can improve hydrogen embrittlement resistance by forming an oxide containing Si, Mn, Al and Cr alone or a composite oxide containing a plurality of these elements on the surface of the steel sheet. Therefore, the total content of Si, Mn, Al and Cr needs to be 0.3% or more. Here, when the total content is less than 0.3%, the content of oxides is too small to significantly improve the hydrogen embrittlement resistance. Therefore, the lower limit was made 0.3%. The upper limit is not particularly defined, but if it exceeds the upper limit of each content, the moldability deteriorates, so it is necessary to be within the respective upper limit range.
Ｐは、鋼板の板厚中央部に偏析する傾向があり、溶接部を脆化させる。０．０４％を超えると溶接部の脆化が顕著になるため、その適正範囲を０．０４％以下に限定した。Ｐの下限値は特に定めないが、０．０００１％未満とすることは、経済的に不利であることからこの値を下限値とすることが好ましい。
Ｓは、溶接性ならびに鋳造時および熱延時の製造性に悪影響を及ぼす。そこで、その上限値を０．０１％とした。Ｓの下限値は特に定めないが、０．０００１％未満とすることは、経済的に不利であることからこの値を下限値とすることが好ましい。また、ＳはＭｎと結合して粗大なＭｎＳを形成し、穴拡げ性を低下させる。したがって、穴拡げ性向上のためには、出来るだけ少なくする必要がある。
P tends to segregate in the central part of the plate thickness of the steel sheet, causing the weld to become brittle. When the content exceeds 0.04%, the weld becomes brittle, so the appropriate range is limited to 0.04% or less. Although the lower limit value of P is not particularly defined, it is preferable to set this value as the lower limit value because it is economically disadvantageous to set it to less than 0.0001%.
S adversely affects weldability and manufacturability during casting and hot rolling. Therefore, the upper limit is set to 0.01%. Although the lower limit of S is not particularly defined, it is preferable to set this value as the lower limit because it is economically disadvantageous to make it less than 0.0001%. In addition, S combines with Mn to form coarse MnS, reducing the hole expandability. Therefore, it is necessary to reduce as much as possible in order to improve hole expandability.
Ｏは、酸化物を形成し、成形性を劣化させることから、添加量を抑える必要がある。特に、Ｏが０．０１％を超えると、この傾向が顕著となるので、Ｏの含有量の上限を０．０１％とした。また、０．００１％未満とすることは、過度のコスト高を招き経済的に好ましくないので、下限値としては０．００１％が好ましい。
ここで、Ｏの含有量とは、鋼板表層に含まれる内部酸化物、めっき層中に含まれる酸化物を除去した後の鋼板中に含まれるＯの含有量のことである。特に、本鋼板は鋼板表層、あるいは、めっき層中のいずれか一方、あるいは、両方に酸化物を含むことから、表層におけるＯの含有量は鋼板内部に比較して高くなる。しかし、これら酸化物は、めっき層中や鋼板表層に存在することから、成形性にほとんど悪影響を及ぼさない。
O forms an oxide and degrades the moldability, so the amount added must be suppressed. In particular, when O exceeds 0.01%, this tendency becomes remarkable. Therefore, the upper limit of the O content is set to 0.01%. Moreover, since making it less than 0.001% invites excessive cost and is not preferable economically, 0.001% is preferable as a lower limit.
Here, the content of O is the content of O contained in the steel sheet after removing the internal oxide contained in the steel sheet surface layer and the oxide contained in the plating layer. In particular, since the steel sheet contains an oxide in one or both of the steel sheet surface layer and the plating layer, the O content in the surface layer is higher than that in the steel sheet interior. However, since these oxides are present in the plating layer or on the surface layer of the steel sheet, the formability is hardly adversely affected.
Ｎは、粗大な窒化物を形成し、曲げ性や穴拡げ性を劣化させることから、添加量を抑える必要がある。これは、Ｎが０．０１％を超えると、この傾向が顕著となることから、Ｎの含有量の範囲を０．０１％以下とした。加えて、溶接時のブローホール発生の原因になることから少ない方が良い。下限は、特に定めることなく本発明の効果は発揮されるが、Ｎの含有量を０．０００５％未満とすることは、製造コストの大幅な増加を招くことから、これが実質的な下限である。 N forms coarse nitrides and degrades bendability and hole expansibility, so it is necessary to suppress the addition amount. This is because when N exceeds 0.01%, this tendency becomes remarkable. Therefore, the N content range is set to 0.01% or less. In addition, it is better to use less because it causes blowholes during welding. Although the lower limit is not particularly defined, the effect of the present invention is exhibited. However, if the N content is less than 0.0005%, the manufacturing cost is significantly increased, and this is a substantial lower limit. .
本発明の超高強度鋼板は、上記の組成に加えて、
さらに、質量％で、Ｎｉ：０．０５〜１．０％、Ｃｕ：０．０５〜１．０％を含有してなることが好ましい。
Ｎｉは、強化元素であるとともに焼入れ性の向上に重要である。しかし、０．０５％未満ではこれらの効果が得られないため、下限値を０．０５％とした。一方、１％を越えると、製造時および熱延時の製造性に悪影響を及ぼすため、上限値を１％とした。加えて、濡れ性の向上や合金化反応の促進をもたらすことから添加しても良い。
In addition to the above composition, the ultra high strength steel sheet of the present invention has
Furthermore, it is preferable to contain Ni: 0.05-1.0% and Cu: 0.05-1.0% by the mass%.
Ni is a strengthening element and is important for improving hardenability. However, since these effects cannot be obtained if the content is less than 0.05%, the lower limit is set to 0.05%. On the other hand, if it exceeds 1%, the manufacturability at the time of production and hot rolling will be adversely affected, so the upper limit was made 1%. In addition, it may be added because it improves wettability and promotes the alloying reaction.
Ｃｕは、強化元素であるとともに焼入れ性の向上に重要である。しかし、０．０５％未満ではこれらの効果が得られないため、下限値を０．０５％とした。一方、１％を越えると、製造時および熱延時の製造性に悪影響を及ぼすため、上限値を１％とした。加えて、濡れ性の向上や合金化反応の促進をもたらすことから添加しても良い。 Cu is a strengthening element and is important for improving hardenability. However, since these effects cannot be obtained if the content is less than 0.05%, the lower limit is set to 0.05%. On the other hand, if it exceeds 1%, the manufacturability at the time of production and hot rolling will be adversely affected, so the upper limit was made 1%. In addition, it may be added because it improves wettability and promotes the alloying reaction.
本発明の超高強度鋼板は、上記の組成に加えて、
さらに、質量％で、Ｎｂ：０．００５〜０．３％、Ｔｉ：０．００５〜０．３％、Ｖ：０．００５〜０．３％、Ｗ：０．００５〜０．３％の群から選択された１種または２種以上を含有してなることが好ましい。
Ｎｂは、強化元素である。析出物強化、フェライト結晶粒の成長抑制による細粒強化および再結晶の抑制を通じた転位強化にて、鋼板の強度上昇に寄与する。含有量が０．００５％未満では、これらの効果が得られないため、下限値を０．００５％とした。また、含有量が０．３％を越えると、炭窒化物の析出が多くなり成形性が劣化するため、上限値を０．３％とした。
In addition to the above composition, the ultra high strength steel sheet of the present invention has
Furthermore, by mass%, Nb: 0.005-0.3%, Ti: 0.005-0.3%, V: 0.005-0.3%, W: 0.005-0.3% It is preferable to contain 1 type (s) or 2 or more types selected from the group.
Nb is a strengthening element. It contributes to increasing the strength of steel sheets by strengthening precipitates, strengthening fine grains by suppressing the growth of ferrite crystal grains, and strengthening dislocations by suppressing recrystallization. If the content is less than 0.005%, these effects cannot be obtained, so the lower limit was made 0.005%. On the other hand, if the content exceeds 0.3%, precipitation of carbonitrides increases and the formability deteriorates, so the upper limit was made 0.3%.
Ｔｉは、強化元素である。析出物強化、フェライト結晶粒の成長抑制による細粒強化および再結晶の抑制を通じた転位強化にて、鋼板の強度上昇に寄与する。含有量が０．００５％未満では、これらの効果が得られないため、下限値を０．００５％とした。また、含有量が０．３％を越えると、炭窒化物の析出が多くなり成形性が劣化するため、上限値を０．３％とした。
Ｖは、強化元素である。析出物強化、フェライト結晶粒の成長抑制による細粒強化および再結晶の抑制を通じた転位強化にて、鋼板の強度上昇に寄与する。含有量が０．００５％未満では、これらの効果が得られないため、下限値を０．００５％とした。また、含有量が０．３％を越えると、炭窒化物の析出が多くなり成形性が劣化するため、上限値を０．３％とした。
Ti is a strengthening element. It contributes to increasing the strength of steel sheets by strengthening precipitates, strengthening fine grains by suppressing the growth of ferrite crystal grains, and strengthening dislocations by suppressing recrystallization. If the content is less than 0.005%, these effects cannot be obtained, so the lower limit was made 0.005%. On the other hand, if the content exceeds 0.3%, precipitation of carbonitrides increases and the formability deteriorates, so the upper limit was made 0.3%.
V is a strengthening element. It contributes to increasing the strength of steel sheets by strengthening precipitates, strengthening fine grains by suppressing the growth of ferrite crystal grains, and strengthening dislocations by suppressing recrystallization. If the content is less than 0.005%, these effects cannot be obtained, so the lower limit was made 0.005%. On the other hand, if the content exceeds 0.3%, precipitation of carbonitrides increases and the formability deteriorates, so the upper limit was made 0.3%.
Ｗは、強化元素である。析出物強化、フェライト結晶粒の成長抑制による細粒強化および再結晶の抑制を通じた転位強化にて、鋼板の強度上昇に寄与する。含有量が０．００５％未満ではこれらの効果が得られないため、下限値を０．００５％とした。また、含有量が０．３％を越えると、炭窒化物の析出が多くなり成形性が劣化するため、上限値を０．３％とした。
また、Ｔｉ、Ｎｂ、Ｖ及びＷを単独、あるいは、複合で含む炭化物、窒化物は、鋼板の母材の耐水素脆性を向上させることから、これらの元素を含有することで、耐水素脆性がさらに向上する。
W is a strengthening element. It contributes to increasing the strength of steel sheets by strengthening precipitates, strengthening fine grains by suppressing the growth of ferrite crystal grains, and strengthening dislocations by suppressing recrystallization. If the content is less than 0.005%, these effects cannot be obtained, so the lower limit was made 0.005%. On the other hand, if the content exceeds 0.3%, precipitation of carbonitrides increases and the formability deteriorates, so the upper limit was made 0.3%.
Further, since carbides and nitrides containing Ti, Nb, V and W alone or in combination improve the hydrogen embrittlement resistance of the base material of the steel sheet, by containing these elements, the hydrogen embrittlement resistance is improved. Further improve.
本発明の超高強度鋼板は、上記の組成に加えて、
さらに、質量％で、Ｂ：０．０００１〜０．１％を含有してなることが好ましい。
Ｂは、０．０００１質量％以上含有することで粒界の強化や鋼材の強度化に有効であるが、含有量が０．００４５質量％を超えると、その効果が飽和するばかりでなく、熱延時の製造製を低下させることから、その上限を０．００４５％とした。
In addition to the above composition, the ultra high strength steel sheet of the present invention has
Furthermore, it is preferable to contain B: 0.0001 to 0.1% by mass%.
B is effective for strengthening grain boundaries and strengthening steel by containing 0.0001% by mass or more, but when the content exceeds 0.0045% by mass, the effect is not only saturated but also heat The upper limit is set to 0.0045% because the production at the time of rolling is lowered.
本発明の超高強度鋼板は、上記の組成に加えて、
さらに、質量％で、Ｃａ：０．０００５〜０．０１％、Ｍｇ：０．０００５〜０．０１％、Ｌａ：０．０００５〜０．０１％、Ｃｅ：０．０００５〜０．０１％、Ｙ：０．０００５〜０．０１％の群から選択された１種または２種以上を含有してなることが好ましい。
これらＣａ、Ｍｇ、Ｌａ、Ｃｅ、Ｙの群から選択された１種または２種以上の含有量の合計は、０．０００５〜０．０４％が好ましい。
Ｃａ、Ｍｇ、Ｌａ、ＣｅおよびＹは、脱酸に用いる元素であり、１種または２種以上を合計で０．０００５％以上含有することが好ましい。しかしながら、含有量が合計で０．０４％を超えると、成形加工性の悪化の原因となる。そのため、含有量を合計で０．０００５〜０．０４％とした。
In addition to the above composition, the ultra high strength steel sheet of the present invention has
Furthermore, in mass%, Ca: 0.0005 to 0.01%, Mg: 0.0005 to 0.01%, La: 0.0005 to 0.01%, Ce: 0.0005 to 0.01%, It is preferable to contain 1 type (s) or 2 or more types selected from the group of Y: 0.0005-0.01%.
The total content of one or more selected from the group of Ca, Mg, La, Ce, and Y is preferably 0.0005 to 0.04%.
Ca, Mg, La, Ce, and Y are elements used for deoxidation, and it is preferable to contain one or more elements in total of 0.0005% or more. However, when the content exceeds 0.04% in total, it causes deterioration of molding processability. Therefore, the total content is set to 0.0005 to 0.04%.
なお、本発明においては、ＬａやＣｅを含有することで本発明の効果が発揮される。ＬａやＣｅはミッシュメタルにて添加されることが多く、ＬａやＣｅの他に、その他の希土類元素を複数種含有する場合がある。不可避不純物として、これらＬａやＣｅ以外の希土類元素を含んだとしても本発明の効果は発揮される。
ここで、鋼板強度を９８０ＭＰａ以上としたのは、９８０ＭＰａ未満の強度を有する鋼では、水素脆化の懸念が小さいためである。
鋼板表層、あるいは、めっき層中にＳｉ、Ｍｎ、Ａｌを単独あるいは複合で含む酸化物を含有させることで、溶接部の耐水素脆性を高めることが出来る。鋼板表層とは鋼板表面でなく、鋼板内部を意味し、めっき鋼板においては、めっき層と鋼板界面の鋼板側を意味する。ただし、当然酸化物の一部が鋼板表面に存在する場合もあるが、鋼板内部に酸化物が形成されているのであれば、鋼板表層に酸化物が形成されているとする。
In addition, in this invention, the effect of this invention is exhibited by containing La and Ce. La and Ce are often added by misch metal, and in addition to La and Ce, a plurality of other rare earth elements may be contained. Even if rare earth elements other than La and Ce are included as inevitable impurities, the effect of the present invention is exhibited.
Here, the steel sheet strength is set to 980 MPa or more because the steel having a strength of less than 980 MPa is less concerned with hydrogen embrittlement.
By including an oxide containing Si, Mn, and Al alone or in combination in the steel sheet surface layer or plating layer, the hydrogen embrittlement resistance of the welded portion can be enhanced. The steel sheet surface layer means not the steel sheet surface but the inside of the steel sheet. In the plated steel sheet, it means the steel sheet side at the interface between the plated layer and the steel sheet. Of course, a part of the oxide may be present on the surface of the steel sheet, but if the oxide is formed inside the steel sheet, it is assumed that the oxide is formed on the surface layer of the steel sheet.
Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は、焼鈍ラインあるいは連続めっきラインにおける加熱中の雰囲気を制御することで、鋼板中に含まれるＳｉ、Ｍｎ、Ａｌ及びＣｒは、鋼板表層、あるいは、めっき層中のいずれか一方、あるいは、両方に酸化物を形成させることが出来る。
ここで、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物を鋼板表層、あるいは、めっき層中としたのは、本発明の効果である薄鋼板の必要特性である成形性を損なわず、耐水素脆性を向上させるためである。
また、酸化物を鋼板表層、あるいは、めっき層中に形成させるとしたのは、成形性に乏しい酸化物を板厚中心にまで分散させると、薄鋼板としての必要特性である成形性を大幅に劣化させてしまうからである。鋼板表層やめっき層中のみであれば、成形性を損なうことなく耐水素脆性のみを向上可能である。
The oxide containing Si, Mn, Al and Cr alone or in combination is controlled by controlling the atmosphere during heating in the annealing line or the continuous plating line, so that Si, Mn, Al and Cr contained in the steel sheet Alternatively, an oxide can be formed on either one or both of the plating layers.
Here, the oxide containing Si, Mn, Al, and Cr alone or in combination is used in the steel sheet surface layer or plating layer, without impairing formability, which is a necessary characteristic of the thin steel sheet, which is an effect of the present invention. This is to improve hydrogen embrittlement resistance.
In addition, the oxide is formed in the surface layer or plating layer of the steel sheet. When the oxide with poor formability is dispersed to the center of the plate thickness, the formability, which is a necessary characteristic for a thin steel sheet, is greatly increased. It is because it will deteriorate. If it is only in the steel sheet surface layer or plating layer, only hydrogen embrittlement resistance can be improved without impairing formability.
加えて、これら酸化物は鋼板表層に存在することから、水素脆性抑制のための水素トラップサイトとしては、より効率的に働く。これは、水素脆化の割れの起点が、鋼板表層の応力集中部である点に起因すると推定される。すなわち、鋼板表層に酸化物を分散させることで、鋼板全体に含まれる酸化物の質量％が小さくとも、効果を発揮させることが可能である。加えて、水素が鋼板中に進入したとしても、鋼板表層で水素がトラップされることから、容易に放出される。
具体的には、腐食（水素発生と進入）−乾燥（水素放出）が連続的に起こる実環境下では、水素が進入したとしても鋼板表層でトラップされることから、鋼板表面までの拡散距離が短く、水素の放出が短時間で行われ、より効果的である。
In addition, since these oxides exist in the surface layer of the steel sheet, they function more efficiently as hydrogen trap sites for suppressing hydrogen embrittlement. This is presumed to be due to the fact that the starting point of hydrogen embrittlement cracking is the stress concentration part of the steel sheet surface layer. That is, by dispersing the oxide in the steel sheet surface layer, the effect can be exhibited even if the mass% of the oxide contained in the whole steel sheet is small. In addition, even if hydrogen enters the steel sheet, it is easily released because hydrogen is trapped in the steel sheet surface layer.
Specifically, in an actual environment where corrosion (hydrogen generation and entry) -drying (hydrogen release) occurs continuously, even if hydrogen enters, it is trapped on the steel sheet surface layer, so the diffusion distance to the steel sheet surface is It is short and the release of hydrogen takes place in a short time, which is more effective.
薄鋼板の要求特性として、耐食性が挙げられるが、冷延鋼板においては、鋼板表面に化成処理や塗装処理を行うことで、耐食性を向上させており、耐水素脆性を高めるのと同時にこれら特性を劣化させないことが求められる。
冷延鋼板の表面に存在するＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は、化成処理性を劣化させることが知られていることから、これら酸化物は鋼板内部に形成させる必要がある。加えて、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は電気を通し難いことから、これら酸化物が鋼板表面を覆うと、スポットやマッシュシーム溶接等の抵抗溶接が難しいという問題を有する。このことから、Ｓｉ、Ｍｎ、Ａｌを単独あるいは複合で含む酸化物は、鋼板表層に、内部酸化物として形成させる必要がある。
The required properties of thin steel sheets include corrosion resistance, but in cold-rolled steel sheets, the corrosion resistance is improved by subjecting the steel sheet surface to chemical conversion treatment and coating treatment. It is required not to deteriorate.
Since oxides containing Si, Mn, Al and Cr present on the surface of a cold-rolled steel sheet alone or in combination are known to degrade chemical conversion properties, these oxides must be formed inside the steel sheet. There is. In addition, since oxides containing Si, Mn, Al and Cr alone or in combination are difficult to conduct electricity, if these oxides cover the steel sheet surface, resistance welding such as spot or mash seam welding is difficult. Have. Therefore, an oxide containing Si, Mn, and Al alone or in combination needs to be formed as an internal oxide on the steel sheet surface layer.
また、めっき鋼板であれば、鋼板表面に、溶融亜鉛めっき処理、あるいは、溶融亜鉛めっき処理及び合金化処理を施すことで、耐食性を向上させており、これら溶融めっきの濡れ性の確保、あるいは、合金化溶融亜鉛めっき鋼板であれば、合金化の促進が必要である。ここで、めっき浴浸漬前に鋼板表面にＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含有する酸化物が存在すると、溶融めっきとの濡れ性が低下したり、合金化が遅延したりするために、溶融亜鉛めっき鋼板、あるいは、合金化溶融亜鉛めっき鋼板が得られない。このことから、めっき浴浸漬前での鋼板表面への酸化物形成を抑制する必要がある。 Moreover, if it is a plated steel plate, the corrosion resistance is improved by performing hot dip galvanizing treatment, or hot dip galvanizing treatment and alloying treatment on the surface of the steel plate, ensuring the wettability of these hot dip platings, or If it is an alloyed hot-dip galvanized steel sheet, it is necessary to promote alloying. Here, if there is an oxide containing Si, Mn, Al, and Cr alone or in combination before immersion in the plating bath, the wettability with hot-dip plating is reduced or alloying is delayed. Furthermore, a hot dip galvanized steel sheet or an alloyed hot dip galvanized steel sheet cannot be obtained. For this reason, it is necessary to suppress oxide formation on the steel sheet surface before immersion in the plating bath.
本発明では、加熱中の雰囲気を制御することで、加熱時の鋼板表面での酸化物形成を抑制し、鋼板内部での酸化物形成が可能となる。
酸化物は、鋼板内部であれば、めっき層中、あるいは鋼板表層の結晶粒内、または結晶粒界、あるいは結晶粒内及び結晶粒界、のいずれに形成してもめっき性は確保可能であり、特に、鋼板の表層から１０μｍ以内、あるいは鋼板と溶融亜鉛めっき層（または合金化溶融亜鉛めっき層）との界面から１０μｍ以内の鋼板内の結晶粒界、または結晶粒内、もしくは結晶粒界及び結晶粒内、あるいはめっき層内、のいずれかに形成することにより、めっき性を十分に確保することが可能である。
この結果、溶接部の耐水素脆性を具備した溶融亜鉛めっき鋼板、あるいは、合金化溶融亜鉛めっき鋼板の製造が可能となった。
In the present invention, by controlling the atmosphere during heating, oxide formation on the surface of the steel sheet during heating is suppressed, and oxide formation inside the steel sheet becomes possible.
As long as the oxide is inside the steel plate, plating properties can be secured even if it is formed in the plating layer, in the crystal grain of the steel plate surface layer, or in the crystal grain boundary, or in the crystal grain and crystal grain boundary. In particular, within 10 μm from the surface layer of the steel plate, or within 10 μm from the interface between the steel plate and the hot dip galvanized layer (or alloyed hot dip galvanized layer), By forming it in either the crystal grains or the plating layer, it is possible to sufficiently ensure the plating property.
As a result, it became possible to manufacture a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet having hydrogen embrittlement resistance at the weld.
ここで、めっき鋼板において、酸化物がめっき層中、鋼板表層のいずれに含まれても良いとしたのは、めっき浴浸漬前に鋼板内部に酸化物が存在していたとしても、めっき浴浸漬後、あるいは、合金化処理後にめっき層と鋼板の間で相互拡散が生じ、めっき層と鋼板との界面が鋼板側へ移動する場合があることから、めっき浴浸漬前に鋼板内部に形成された酸化物であっても、めっき層および鋼板内部のいずれにも存在する可能性がある。したがって、酸化物はめっき層中、鋼板表層のいずれに含まれても構わない。例えば、溶融亜鉛めっき鋼板では、合金化がほとんど進行していないことから、Ｓｉを含む酸化物は鋼板側に存在する割合が多い。一方、合金化溶融亜鉛めっき鋼板では、合金化が進行していることから、溶融亜鉛めっき鋼板に比較して、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物はめっき層中に存在する割合が多い。 Here, in the plated steel sheet, the oxide may be contained in either the plating layer or the surface layer of the steel sheet even if the oxide is present inside the steel sheet before immersion in the plating bath. After or after alloying treatment, interdiffusion occurs between the plating layer and the steel plate, and the interface between the plating layer and the steel plate may move to the steel plate side, so it was formed inside the steel plate before immersion in the plating bath. Even if it is an oxide, it may exist in both a plating layer and the inside of a steel plate. Therefore, the oxide may be contained in any of the plating layer and the steel sheet surface layer. For example, in a hot dip galvanized steel sheet, since alloying has hardly progressed, an oxide containing Si is often present on the steel sheet side. On the other hand, in the alloyed hot-dip galvanized steel sheet, since alloying has progressed, oxides containing Si, Mn, Al and Cr alone or in combination exist in the plated layer compared to hot-dip galvanized steel sheet. There are many ratios to do.
Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は、焼鈍ラインあるいは連続めっきラインにおける加熱中の雰囲気を制御することで、めっき層中、あるいは鋼板表層から１０μｍ以内の結晶粒内、または結晶粒界、もしくは結晶粒内及び結晶粒界に、容易に生成させることができる。
この効果は、冷延鋼板であれば、鋼板表層から１０μｍ以内の結晶粒界、もしくは、結晶粒内のいずれか一方、あるいは、両方に、Ｓｉ、Ｍｎ、Ａｌ及びＣｒの酸化物を平均含有率０．０１〜３０質量％含有させることで発揮される。
また、溶融亜鉛めっき鋼板、あるいは、合金化溶融亜鉛めっき鋼板であれば、鋼板とめっき層との界面から１０μｍ以内の鋼板側の結晶粒界、または結晶粒内、もしくは結晶粒界及び結晶粒内、あるいはめっき層中、のいずれか一方、あるいは両方に、酸化物が平均含有率０．０１〜３０質量％で含有させることで発揮される。
The oxide containing Si, Mn, Al, and Cr alone or in combination can be controlled by controlling the atmosphere during heating in the annealing line or continuous plating line, in the plating layer or in the crystal grains within 10 μm from the steel sheet surface layer, or It can be easily generated at the crystal grain boundary, or within the crystal grain and at the crystal grain boundary.
In the case of a cold-rolled steel sheet, the effect is that the average content of oxides of Si, Mn, Al, and Cr is either in the grain boundary within 10 μm from the steel sheet surface layer, or in the crystal grain, or both. It is exhibited by containing 0.01 to 30% by mass.
Further, in the case of a hot dip galvanized steel sheet or an alloyed hot dip galvanized steel sheet, the grain boundary on the steel sheet side within 10 μm from the interface between the steel sheet and the plating layer, or in the crystal grain, or in the crystal grain boundary and the crystal grain In addition, the oxide is exerted by adding an oxide at an average content of 0.01 to 30% by mass in either one or both of the plating layers.
ここで、鋼板表層から１０μｍ以内、あるいは、めっき層中としたのは、過度に鋼板内部まで酸化物を形成させることは、過度の熱処理を必要とし、経済的に好ましくないためである。
酸化物の含有量を０．０１〜３０質量％とすることで、耐水素脆化特性が大きく向上する。ここで、含有量を０．０１質量％以上としたのは、０．０１質量％未満では、耐水素脆化特性向上の効果が得られ難いためである。一方、含有量が３０質量％を超えると、溶融めっきとの濡れ性の低下、合金化の遅延等が生じる虞があり、また、酸化物を形成させるために長時間を要し、生産性に劣ることになるからである。
Here, the reason why it is within 10 μm from the surface layer of the steel sheet or in the plating layer is that excessively forming the oxide to the inside of the steel sheet requires excessive heat treatment and is not economically preferable.
By setting the content of the oxide to 0.01 to 30% by mass, the hydrogen embrittlement resistance is greatly improved. Here, the reason why the content is set to 0.01% by mass or more is that when the content is less than 0.01% by mass, it is difficult to obtain an effect of improving hydrogen embrittlement resistance. On the other hand, if the content exceeds 30% by mass, there is a possibility that the wettability with hot-dip plating is lowered, the alloying is delayed, etc., and it takes a long time to form an oxide, resulting in productivity. Because it will be inferior.
Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は、球状、糸状、紐状等の状態で鋼板中に存在するので、顕微鏡観察により明瞭に区別できる。
本発明において、酸化物を含有する層とは、顕微鏡観察において上記の酸化物が観察される層である。また、上記の酸化物の平均含有率とは、鋼層中に含まれるＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含有する酸化物の平均含有率のことである。また、内部酸化物を含有する鋼層の厚みとは、冷延鋼板においては鋼板表面から、めっき鋼板においては、鋼板とめっき層の界面からめっき層と鋼板界面からＳｉを含有する酸化物が観察される部分までの距離を示す。
酸化物の含有率の測定は、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物の質量％が測定できればどのような方法でも構わないが、酸化物を含有する層を酸で溶解し、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物を分離させた後、質量を測定する方法が確実である。また、酸化物の内部酸化物を含有する鋼層の厚みの測定も特に規定しないが、光学顕微鏡や走査型電子顕微鏡（ＳＥＭ）を用いて鋼板断面を観察する方法が確実である。
Oxides containing Si, Mn, Al and Cr alone or in combination exist in the steel sheet in a spherical, thread-like or string-like state, and therefore can be clearly distinguished by microscopic observation.
In the present invention, an oxide-containing layer is a layer in which the above oxide is observed by microscopic observation. The average oxide content is the average oxide content of Si, Mn, Al and Cr contained in the steel layer alone or in combination. In addition, the thickness of the steel layer containing the internal oxide is observed from the steel sheet surface in the case of cold-rolled steel sheet, and in the plated steel sheet, the oxide containing Si from the interface between the steel sheet and the plating layer is observed from the plating layer to the steel sheet interface. The distance to the part to be done is shown.
The oxide content may be measured by any method as long as the mass% of the oxide containing Si, Mn, Al, and Cr alone or in combination can be measured, but the oxide-containing layer is dissolved with an acid. After separating an oxide containing Si, Mn, Al and Cr alone or in combination, a method of measuring the mass is reliable. Moreover, although the measurement of the thickness of the steel layer containing the internal oxide of an oxide is not prescribed | regulated, the method of observing a steel plate cross section using an optical microscope or a scanning electron microscope (SEM) is reliable.
Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物であれば、酸化物の種類に依らず耐水素脆性は向上する。この酸化物としては、特に限定されるものではないが、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ｍｎ２ＳｉＯ４、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯ、Ｃｒ２Ｏ３の群から選択された１種または２種以上であることが好ましい。
ただし、ＳｉとＭｎ、あるいは、ＡｌとＭｎを複合で含む酸化物を形成した場合、耐水素脆性の向上効果が著しいことから、ＭｎＳｉＯ３、Ｍｎ２ＳｉＯ４、ＭｎＡｌ２Ｏ４を含有することが望ましい。
なお、鋼板中に存在する酸化物の同定は、ＴＥＭ、ＣＭＡ、ＥＰＭＡ、ＦＥ-ＳＥＭ等を用いて行うことができる。本実施形態では、抽出レプリカ試料を作成し、この試料中の酸化物をＴＥＭ、ＥＰＭＡを用いて同定した。また、このＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物は、他の原子を含む複合酸化物であったり、欠陥を多く含む場合があるが、元素分析及び構造同定からもっとも近いものを見つけて判別した。
If the oxide contains Si, Mn, Al, and Cr alone or in combination, the hydrogen embrittlement resistance is improved regardless of the type of oxide. As the oxide, it is not particularly limited, SiO 2, FeSiO 3, Fe 2 SiO 4, MnSiO 3, Mn 2 SiO 4, Al 2 O 3, MnAl 2 O 4, MnO, Cr 2 O 3 It is preferable that it is 1 type, or 2 or more types selected from the group of these.
However, when an oxide containing a composite of Si and Mn or Al and Mn is formed, the effect of improving hydrogen embrittlement resistance is remarkable, and therefore MnSiO 3 , Mn 2 SiO 4 , and MnAl 2 O 4 may be contained. desirable.
In addition, identification of the oxide which exists in a steel plate can be performed using TEM, CMA, EPMA, FE-SEM, etc. In this embodiment, an extracted replica sample was prepared, and the oxide in the sample was identified using TEM and EPMA. In addition, this oxide containing Si, Mn, Al and Cr alone or in combination may be a complex oxide containing other atoms or may contain many defects, but it is closest from elemental analysis and structural identification. I found and determined.
鋼板組織は、特に限定されることなく本発明の効果である優れた耐水素脆性は発揮されるが、９８０ＭＰａ以上の引張最大強度を得るためには、ベイナイト、マルテンサイト、あるいは、残留オーステナイトを単独あるいは複合で含むことが望ましい。必要に応じて、Ｔｉ、Ｎｂ、Ｖ等による析出強化を併用しても良い。
なお、上記ミクロ組織の各相、フェライト、マルテンサイト、ベイナイト、オーステナイトおよび残部組織の同定、存在位置の観察および面積率の測定は、ナイタール試薬、および特開昭５９−２１９４７３号公報に開示された試薬等を用いて鋼板圧延方向断面または圧延方向直角方向断面を腐食させ、この断面を、１０００倍の光学顕微鏡、または１０００〜１０００００倍の走査型電子顕微鏡（ＳＥＭ）、あるいは透過型電子顕微鏡（ＴＥＭ）を用いて観察することにより、定量化が可能である。各２０視野以上の観察を行い、ポイントカウント法や画像解析により各組織の面積率を求めることが出来る。
The steel sheet structure is not particularly limited and exhibits excellent hydrogen embrittlement resistance, which is an effect of the present invention. However, in order to obtain a maximum tensile strength of 980 MPa or more, bainite, martensite, or residual austenite is used alone. Alternatively, it is desirable to include a composite. If necessary, precipitation strengthening by Ti, Nb, V or the like may be used in combination.
Incidentally, identification of each phase of the above microstructure, ferrite, martensite, bainite, austenite and the remaining structure, observation of the existing position and measurement of the area ratio were disclosed in Nital reagent and Japanese Patent Application Laid-Open No. 59-219473. Using a reagent or the like, the steel sheet rolling direction cross section or the rolling direction perpendicular cross section is corroded, and this cross section is subjected to 1000 times optical microscope, 1000 to 100000 times scanning electron microscope (SEM), or transmission electron microscope (TEM). ) Can be used for quantification. It is possible to obtain an area ratio of each tissue by observing 20 fields of view or more and using a point counting method or image analysis.
次に、製造条件の限定理由について述べる。
鋼板中にＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合添加し、かつ、連続焼鈍ラインあるいは連続めっきラインの炉内の雰囲気を、Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなる雰囲気とし、かつ、この雰囲気中の水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御することで、耐水素脆性に優れた鋼板の製造が可能である。
ここで、雰囲気中のＨ２濃度を１〜６０体積％としたのは、６０体積％を超えるＨ２濃度の増加は、還元性が強くなり過ぎて鋼板中に生じた酸化物が還元される虞があり、また、Ｈ２の使用量の増大によるコスト高を招くことから好ましくなく、また、１体積％未満では、鋼板に含まれるＦｅが鋼板表面で酸化する虞があり、化成性、塗装性及び溶融めっきの濡れ性の劣化を避けることができないからである。これにより、雰囲気中のＨ２濃度の範囲を、１〜６０体積％とした。
Next, the reasons for limiting the manufacturing conditions will be described.
In the steel sheet, Si, Mn, Al and Cr are added alone or in combination, and the atmosphere in the furnace of the continuous annealing line or continuous plating line contains 1 to 60% by volume of H 2 , and the balance is N 2 , H The atmosphere is made of 2 O, O 2 and inevitable impurities, and the water pressure PH 2 O and the hydrogen partial pressure PH 2 in the atmosphere are expressed by the following formula: −3 ≦ log (PH 2 O / PH 2 ) ≦ −0. 5
It is possible to produce a steel sheet having excellent hydrogen embrittlement resistance by controlling so as to satisfy the above.
Here, the H 2 concentration in the atmosphere was set to 1 to 60% by volume because the increase in the H 2 concentration exceeding 60% by volume resulted in excessive reduction of the oxide generated in the steel sheet. In addition, there is a possibility that the cost is increased due to an increase in the amount of H 2 used, and less than 1% by volume, Fe contained in the steel sheet may be oxidized on the steel sheet surface, and there is a possibility of chemical conversion and coating. This is because deterioration of wettability and wettability of hot dip plating cannot be avoided. Thus, the concentration of H 2 in the range of atmosphere, and 1 to 60 vol%.
また、雰囲気中の水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御することで、Ｓｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含有する酸化物を鋼板表層、あるいは、めっき層中に含有させることが出来る。ここで、水分圧ＰＨ２Ｏと水素分圧ＰＨ２との比（ＰＨ２Ｏ／ＰＨ２）の対数の下限を−３以上としたのは、対数の値が−３未満では、鋼板表面にＳｉ、Ｍｎ、Ａｌ及びＣｒを含む酸化物が形成される割合が多くなり、濡れ性やめっき密着性を低下させる。そこで、下限を−３とした。一方、上限を−０．５としたのは、その効果が飽和するためである。
Further, the moisture pressure PH 2 O and the hydrogen partial pressure PH 2 in the atmosphere are expressed by the following formula: −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5
Thus, an oxide containing Si, Mn, Al and Cr alone or in combination can be contained in the steel sheet surface layer or the plating layer. Here, the lower limit of the logarithm of the moisture pressure PH 2 O to the hydrogen partial pressure PH 2 (PH 2 O / PH 2 ) is set to −3 or more. The ratio of oxides containing Si, Mn, Al, and Cr increases and wettability and plating adhesion are reduced. Therefore, the lower limit was set to -3. On the other hand, the upper limit is set to -0.5 because the effect is saturated.
このように、炉内の雰囲気を上記のように制御することで、Ｓｉ、Ｍｎ、Ａｌ及びＣｒが内部酸化する条件となる。内部酸化とは、鋼板内部に酸化物が形成される現象であり、鋼板内部に拡散したＯと、鋼板内部に含まれるＳｉ、Ｍｎ、Ａｌ及びＣｒが反応し鋼板内部で酸化物を形成する。この結果、化成性、塗装性、濡れ性及びめっき密着性を低下させることなく、耐水素脆性の向上が可能となる。
炉内の雰囲気を制御する手段として、本発明では、水分圧ＰＨ２Ｏと水素分圧ＰＨ２との比（ＰＨ２Ｏ／ＰＨ２）を制御したが、例えば、二酸化炭素と一酸化炭素、あるいは、二酸化窒素と一酸化窒素の分圧を制御する、あるいは、炉内に直接酸素を吹き込むことでも同様の効果は得られる。また、炉内の水分圧と水素分圧の比は、炉内に水蒸気を吹き込むことで調整する方法が簡便である。
In this way, by controlling the atmosphere in the furnace as described above, the conditions under which Si, Mn, Al, and Cr are internally oxidized are obtained. Internal oxidation is a phenomenon in which an oxide is formed inside a steel sheet, and O diffused inside the steel sheet reacts with Si, Mn, Al and Cr contained in the steel sheet to form an oxide inside the steel sheet. As a result, hydrogen embrittlement resistance can be improved without reducing chemical conversion, paintability, wettability, and plating adhesion.
As a means for controlling the atmosphere in the furnace, in the present invention, the ratio (PH 2 O / PH 2 ) between the moisture pressure PH 2 O and the hydrogen partial pressure PH 2 was controlled. For example, carbon dioxide and carbon monoxide, Alternatively, the same effect can be obtained by controlling the partial pressure of nitrogen dioxide and nitric oxide, or by blowing oxygen directly into the furnace. Moreover, the method of adjusting the ratio of the moisture pressure in the furnace and the hydrogen partial pressure by blowing water vapor into the furnace is simple.
また、冷延鋼板の化成性や塗装性を向上させるため、焼鈍後に鋼板にＮｉ、Ｃｕ、Ｃｏ、Ｆｅの単独あるいは複数より成るめっきを施しても本発明を逸脱するものではない。
あるいは、めっき鋼板のめっき密着性をさらに向上させるために、焼鈍前に鋼板に、Ｎｉ、Ｃｕ、Ｃｏ、Ｆｅの単独あるいは複数より成るめっきを施しても本発明を逸脱するものではない。
さらには、めっき鋼板の焼鈍については、「脱脂酸洗後、非酸化雰囲気にて加熱し、Ｈ２及びＮ２を含む還元性雰囲気にて焼鈍後、めっき浴温度近傍まで冷却し、めっき浴に侵漬」というゼンジマー法、「最初、焼鈍時の雰囲気を酸化性雰囲気に調整して鋼板表面を酸化させ、次いで、還元性雰囲気として還元することによりめっき前の清浄化を行い、その後、めっき浴に侵漬」という全還元炉方式、あるいは、「鋼板を脱脂酸洗した後、塩化アンモニウムなどを用いてフラックス処理を行って、めっき浴に侵漬」というフラックス法等があるが、いずれの条件で処理を行ったとしても本発明の効果は発揮できる。
Moreover, in order to improve the chemical conversion property and paintability of a cold-rolled steel sheet, it is not deviated from the present invention even if the steel sheet is plated with Ni, Cu, Co, or Fe alone or after annealing.
Alternatively, in order to further improve the plating adhesion of the plated steel sheet, the present invention does not depart from the present invention even if the steel sheet is plated with Ni, Cu, Co, or Fe alone or before the annealing.
Furthermore, regarding the annealing of the plated steel sheet, “after degreasing pickling, heating in a non-oxidizing atmosphere, annealing in a reducing atmosphere containing H 2 and N 2 , cooling to near the plating bath temperature, Senzimer method called “immersion”, “First, the atmosphere during annealing is adjusted to an oxidizing atmosphere to oxidize the steel sheet surface, and then reduced to a reducing atmosphere to clean before plating. There is an all-reduction furnace method called "Immersion" or a flux method such as "Immerse the plating bath after degreasing and pickling the steel plate and then using ammonium chloride etc. Even if it processes by, the effect of this invention can be exhibited.
熱間圧延に供するスラブは特に限定するものではない。すなわち、連続鋳造スラブや薄スラブキャスターなどで製造したものであればよい。また、鋳造後に直ちに熱間圧延を行う連続鋳造−直接圧延（ＣＣ−ＤＲ）のようなプロセスにも適合する。
熱延スラブの加熱温度は、特に定めることなく、本発明の効果は発揮されるが、加熱温度を過度に高温にすることは、経済上好ましくないことから、加熱温度の上限は１３００℃未満とすることが望ましい。また、過度に低温で加熱すると、仕上げ圧延温度をＡｒ３温度以上とすることが困難となることから、下限温度を１１００℃とすることが望ましい。
The slab used for hot rolling is not particularly limited. That is, what was manufactured with the continuous casting slab, the thin slab caster, etc. should just be used. It is also compatible with processes such as continuous casting-direct rolling (CC-DR) in which hot rolling is performed immediately after casting.
The heating temperature of the hot-rolled slab is not particularly defined, and the effect of the present invention is exhibited. However, since it is not economically preferable to make the heating temperature too high, the upper limit of the heating temperature is less than 1300 ° C. It is desirable to do. Moreover, since it will become difficult to make finishing rolling temperature more than Ar3 temperature if it heats too low temperature, it is desirable to make minimum temperature into 1100 degreeC.
仕上げ圧延温度はオーステナイト＋フェライトの２相域になると、鋼板内の組織不均一性が大きくなり、焼鈍後の成形性が劣化するので、Ａｒ３温度以上が望ましい。
なお、Ａｒ３温度は、次式により求めることができる。
Ａｒ３（℃）＝９０１−３２５×Ｃ＋３３×Ｓｉ−９２×（Ｍｎ＋Ｎｉ／２＋Ｃｒ／２＋Ｃｕ／２＋Ｍｏ／２）
When the finish rolling temperature is in the two-phase region of austenite + ferrite, the structure non-uniformity in the steel sheet increases and the formability after annealing deteriorates. Therefore, the Ar3 temperature or higher is desirable.
In addition, Ar3 temperature can be calculated | required by following Formula.
Ar3 (° C.) = 901-325 × C + 33 × Si-92 × (Mn + Ni / 2 + Cr / 2 + Cu / 2 + Mo / 2)
Ａｒ３温度以上で仕上げ圧延された鋳造スラブは、６３０℃以下の温度域にて巻き取られる。
この巻き取り温度は６３０℃以下かつ室温（２５℃）以上の温度範囲が好ましい。
ここで、６３０℃を超える温度で巻き取ることは、鋼板表面に形成する酸化物の厚さを過度に増大させるため、酸洗性が劣るので好ましくない。また、６３０℃を超えると、熱延組織中に粗大なフェライトやパーライト組織が存在するため、焼鈍後の組織不均一性が大きくなり、最終製品の穴拡げ性が劣化する。また、焼鈍後の組織を微細にして強度延性バランスを向上させる観点、更には、第二相を均一分散させ穴拡げ性を向上させる観点からは、６００℃以下で巻き取ることがより好ましい。下限については特に定めることなく本発明の効果は発揮されるが、室温以下の温度で巻き取ることは技術的に難しいので、これが実質の下限となる。
The cast slab finished and rolled at an Ar3 temperature or higher is wound up in a temperature range of 630 ° C or lower.
The winding temperature is preferably in the temperature range of 630 ° C. or lower and room temperature (25 ° C.) or higher.
Here, winding at a temperature exceeding 630 ° C. is not preferable because the thickness of the oxide formed on the surface of the steel sheet is excessively increased and the pickling property is poor. On the other hand, when the temperature exceeds 630 ° C., coarse ferrite or pearlite structure exists in the hot-rolled structure, so that the structure non-uniformity after annealing increases and the hole expandability of the final product deteriorates. From the viewpoint of making the microstructure after annealing fine and improving the strength ductility balance, and further from the viewpoint of uniformly dispersing the second phase and improving the hole expansibility, it is more preferable to wind up at 600 ° C. or lower. Although the lower limit is not particularly defined, the effect of the present invention is exhibited. However, since it is technically difficult to wind up at a temperature of room temperature or lower, this is the actual lower limit.
なお、熱延時に粗圧延板同士を接合して連続的に仕上げ圧延を行っても良い。また、粗圧延板を一旦巻き取った後、仕上げ圧延を行うこととしても構わない。
このようにして製造した熱延鋼板に、酸洗を行う。酸洗は鋼板表面の酸化物の除去が可能であることから、めっき性向上のためには重要である。また、一回の酸洗を行っても良いし、複数回に分けて酸洗を行っても良い。
酸洗した熱延鋼板を圧下率４０〜７０％、より好ましくは圧下率４５〜６５％で冷間圧延して、連続焼鈍ラインあるいは連続溶融亜鉛めっきラインを通板する。ここで、圧下率が４０％未満では、形状を平坦に保つことが困難であり、また、最終製品の延性が劣悪となるのでこれを下限とする。一方、７０％を越える冷延は、冷延荷重が大きくなりすぎてしまい冷延が困難となることから、これを上限とする。
圧延パスの回数、各パス毎の圧下率については特に規定することなく本発明の効果は発揮される。
Note that rough rolling sheets may be joined to each other during hot rolling to continuously perform finish rolling. Moreover, after winding a rough rolled plate once, it is good also as performing finish rolling.
The hot-rolled steel sheet thus manufactured is pickled. Pickling is important for improving plating properties because it can remove oxides on the surface of the steel sheet. Moreover, pickling may be performed once, or pickling may be performed in a plurality of times.
The pickled hot-rolled steel sheet is cold-rolled at a rolling reduction of 40 to 70%, more preferably a rolling reduction of 45 to 65%, and passed through a continuous annealing line or a continuous hot dip galvanizing line. Here, if the rolling reduction is less than 40%, it is difficult to keep the shape flat, and the ductility of the final product becomes poor, so this is the lower limit. On the other hand, cold rolling exceeding 70% makes the cold rolling difficult because the cold rolling load becomes too large.
The effect of the present invention is exhibited without particularly specifying the number of rolling passes and the rolling reduction for each pass.
なお、熱延板に直接めっきを行う場合は、冷間圧延を行わなくても良い。
連続焼鈍ラインを通板する場合の平均加熱速度は、０．７℃／秒以上とする必要がある。詳細な理由は不明なものの、０．７℃／秒未満で加熱を行うと、加熱中の水分圧と水素分圧の比を上記範囲にしたとしても、加熱中に鋼板表面にＳｉＯ２が形成されてしまいその後の内部酸化物の形成を抑制することから、本発明の効果である溶接部の耐水素脆性の向上が得られない他、冷延鋼板においては化成処理性、めっき鋼板においては溶融めっきとの濡れ性やめっき密着性が劣化してしまうことから、０．７℃／秒以上とすることが望ましい。一方、加熱速度を１００℃超とすることは、過度の設備投資を招き、経済的に好ましくないことから、これが実質的な上限である。
In addition, when directly plating a hot-rolled sheet, it is not necessary to perform cold rolling.
The average heating rate when passing through the continuous annealing line needs to be 0.7 ° C./second or more. Although the detailed reason is unknown, when heating is performed at a rate of less than 0.7 ° C./second, SiO 2 is formed on the surface of the steel plate during heating even if the ratio of the moisture pressure and the hydrogen partial pressure during heating is within the above range. In addition, since the formation of internal oxides is suppressed, the hydrogen embrittlement resistance of the welded portion, which is the effect of the present invention, cannot be obtained. The wettability and the plating adhesion are deteriorated, so that it is desirable that the temperature be 0.7 ° C./second or more. On the other hand, setting the heating rate to more than 100 ° C. results in excessive capital investment and is not economically preferable, so this is a practical upper limit.
最高加熱温度は、７５０〜９００℃の範囲が好ましい。その理由は、最高加熱温度が７５０℃未満になると、鋼板表層に水素脆性抑制可能な量のＳｉ、Ｍｎ、Ａｌ及びＣｒを単独あるいは複合で含む酸化物を形成させるのに長時間を要するからである。一方、過度の高温加熱は、製造コストの上昇を招くことから経済的に好ましくないばかりでなく、高温通板時の板形状が劣悪になったり、ロールの寿命を低下させたり等のトラブルを誘発することから、最高加熱温度の上限を９００℃とする。
この温度域での熱処理時間は特に限定しないが、十分な量の酸化物を形成させるためには、１０秒以上の熱処理が望ましい。一方、熱処理時間が６００秒超となると、コストの上昇を招くことから経済的に好ましくない。熱処理についても、最高加熱温度にて等温保持を行っても良いし、傾斜加熱を行い最高加熱温度に到達した後、直ちに、冷却を開始したとしても、本発明の効果は発揮される。
The maximum heating temperature is preferably in the range of 750 to 900 ° C. The reason is that when the maximum heating temperature is less than 750 ° C., it takes a long time to form an oxide containing a single amount or a combination of Si, Mn, Al, and Cr in an amount capable of suppressing hydrogen embrittlement on the steel sheet surface layer. is there. On the other hand, excessively high temperature heating not only is economically undesirable because it leads to an increase in manufacturing cost, but also induces troubles such as deterioration of the plate shape at the time of hot plate passing and reduction in roll life. Therefore, the upper limit of the maximum heating temperature is set to 900 ° C.
The heat treatment time in this temperature range is not particularly limited, but a heat treatment of 10 seconds or longer is desirable in order to form a sufficient amount of oxide. On the other hand, if the heat treatment time exceeds 600 seconds, the cost increases, which is not economically preferable. Regarding the heat treatment, the isothermal holding may be performed at the maximum heating temperature, or even if cooling is started immediately after the gradient heating is performed and the maximum heating temperature is reached, the effect of the present invention is exhibited.
焼鈍後の熱処理条件を特に定めることなく、本発明の溶接部の耐水素脆性に優れた鋼板を製造することが出来る。加えて、焼鈍後の熱処理条件を制御することで、耐水素脆性と成形性の両立を具備した鋼板の製造が可能となる。
上記焼鈍終了後、０．１〜２００℃／秒にて冷却することが望ましい。０．１℃未満での冷却は、生産性が大きく損なわれることから好ましくない。２００℃／秒を超えて冷却速度を上げる事は、製造コスト高を招くこととなるので、上限を２００℃／秒とすることが好ましい。
The steel plate excellent in hydrogen embrittlement resistance of the welded portion of the present invention can be produced without particularly setting the heat treatment conditions after annealing. In addition, by controlling the heat treatment conditions after annealing, it becomes possible to produce a steel sheet having both hydrogen embrittlement resistance and formability.
After completion of the annealing, it is desirable to cool at 0.1 to 200 ° C./second. Cooling below 0.1 ° C. is not preferable because productivity is greatly impaired. Increasing the cooling rate exceeding 200 ° C./second leads to an increase in production cost, and therefore the upper limit is preferably set to 200 ° C./second.
冷却方法については、ロール冷却、空冷、水冷およびこれらを併用したいずれの方法でも構わない。冷却速度を限定する冷却下限については、特に限定せず本発明の効果を発揮できるが、室温以下とすることは技術的に困難であることから、これが実質上の下限である。また、連続焼鈍ラインの場合、過時効帯を利用して、室温〜４５０℃の温度範囲で、３０秒以上の熱処理を行っても良い。過時効帯内における平均板温度が４５０℃超とすることは、製造コスト高を招くことになるので好ましくない。過時効帯の温度を室温以下とすることは困難であることから、これが実質上の下限である。ここで、保持時間とは、単なる等温保持だけでなく、室温〜４５０℃の温度範囲の滞留時間を意味し、この温度域での除冷や加熱も含まれる。 The cooling method may be roll cooling, air cooling, water cooling, or any combination of these methods. The cooling lower limit for limiting the cooling rate is not particularly limited, and the effect of the present invention can be exhibited. However, since it is technically difficult to set the cooling temperature to be room temperature or lower, this is a practical lower limit. Moreover, in the case of a continuous annealing line, you may heat-process for 30 seconds or more in the temperature range of room temperature-450 degreeC using an overaging zone. It is not preferable that the average plate temperature in the overaging zone be higher than 450 ° C. because this leads to high production costs. Since it is difficult to set the temperature of the overaging zone to room temperature or lower, this is a practical lower limit. Here, the holding time means not only mere isothermal holding but also a residence time in a temperature range of room temperature to 450 ° C., and includes cooling and heating in this temperature range.
熱処理後のスキンパス圧延の圧下率は、０．１〜１．５％の範囲が好ましい。０．１％未満では効果が小さく、制御も困難であることから、これが下限となる。また、１．５％を超えると、生産性が著しく低下するのでこれを上限とする。スキンパスは、インラインで行っても良いし、オフラインで行っても良い。また、一度に目的の圧下率のスキンパスを行っても良いし、数回に分けて行っても構わない。 The reduction ratio of the skin pass rolling after the heat treatment is preferably in the range of 0.1 to 1.5%. If it is less than 0.1%, the effect is small and control is difficult, so this is the lower limit. Moreover, since productivity will fall remarkably when it exceeds 1.5%, this is made an upper limit. The skin pass may be performed inline or offline. Further, a skin pass having a desired reduction rate may be performed at once, or may be performed in several steps.
また、化成性および塗装性をさらに向上させるために、焼鈍後に鋼板に、Ｎｉ、Ｃｕ、Ｃｏ、Ｆｅの単独あるいは複数より成るめっきを施しても本発明を逸脱するものではない。
また、箱焼鈍を行っても本発明の効果である溶接部の耐水素脆化に優れる高強度鋼板の製造は可能である。
連続溶融亜鉛めっきラインを通板する場合の加熱速度は、連続焼鈍ラインを通板する場合と同様の理由により、０．７〜１００℃／秒とすることが望ましい。 また、焼鈍温度は、連続焼鈍ラインを通板する場合と同様の理由により、７５０〜９００℃とする必要がある。焼鈍後のめっき浴浸漬までの冷却速度は、０．１〜２００℃／秒とすることが望ましい。
Further, in order to further improve the chemical conversion property and the paintability, it is not deviated from the present invention even if the steel sheet is plated with Ni, Cu, Co, or Fe alone or after annealing.
Moreover, even if box annealing is performed, it is possible to produce a high-strength steel sheet that is excellent in hydrogen embrittlement resistance of a welded portion, which is an effect of the present invention.
The heating rate when passing through the continuous hot dip galvanizing line is desirably 0.7 to 100 ° C./second for the same reason as when passing through the continuous annealing line. Moreover, the annealing temperature needs to be 750-900 degreeC for the same reason as the case where a continuous annealing line is passed. The cooling rate until immersion in the plating bath after annealing is preferably 0.1 to 200 ° C./second.
このめっき浴浸漬板温度は、溶融亜鉛めっき浴温度より４０℃低い温度「（亜鉛めっき浴温度−４０）℃」から溶融亜鉛めっき浴温度より５０℃高い温度「（亜鉛めっき浴温度＋５０）℃」までの温度範囲とすることが望ましい。
この浸漬板温度が（亜鉛めっき浴温度−４０）℃を下回ると、めっき浴浸漬進入時の抜熱が大きく、溶融亜鉛の一部が凝固してしまいめっき外観を劣化させる場合がある。そこで、下限を（溶融亜鉛めっき浴温度−４０）℃とする。
また、この浸漬板温度が（溶融亜鉛めっき浴温度＋５０）℃を超えると、めっき浴温度上昇に伴う操業上の問題を誘発するので、好ましくない。
This plating bath immersion plate temperature is 40 ° C. lower than the hot dip galvanizing bath temperature “(galvanizing bath temperature−40) ° C.”, 50 ° C. higher than the hot dip galvanizing bath temperature “(galvanizing bath temperature + 50) ° C.” It is desirable that the temperature range be up to.
When this immersion plate temperature is lower than (zinc plating bath temperature −40) ° C., the heat removal at the time of entering the plating bath is large, and a part of the molten zinc is solidified, which may deteriorate the appearance of plating. Therefore, the lower limit is set to (hot dip galvanizing bath temperature −40) ° C.
Moreover, when this immersion plate temperature exceeds (hot dip galvanizing bath temperature + 50) ° C., an operational problem accompanying an increase in the plating bath temperature is induced, which is not preferable.
ここで、浸漬前の板温度が（亜鉛めっき浴温度−４０）℃を下回った場合には、めっき浴浸漬前に再加熱を行って板温度を（亜鉛めっき浴温度−４０）℃以上とし、その後めっき浴に浸漬させればよい。
また、めっき浴は、純亜鉛に加え、Ｆｅ、Ａｌ、Ｍｇ、Ｍｎ、Ｓｉ、Ｃｒなどを含有しても構わない。
また、めっき層の合金化を行う場合には、４６０℃以上で合金化処理を施すのが好ましい。ここで、合金化処理温度が４６０℃未満であると、合金化の進行が遅く、生産性が悪いからである。また、上限は特に限定しないが、６００℃を超える高温での合金化は、経済的に好ましくない。また、めっき浴浸漬前に、５００〜２００℃の温度範囲にて、付加的な熱処理を行っても良い。また、溶融亜鉛めっき鋼板にスキンパス圧延を施しても構わない。
Here, when the plate temperature before immersion is lower than (zinc plating bath temperature −40) ° C., reheating is performed before immersion in the plating bath to set the plate temperature to (zinc plating bath temperature −40) ° C. or higher. Then, it may be immersed in a plating bath.
Further, the plating bath may contain Fe, Al, Mg, Mn, Si, Cr, etc. in addition to pure zinc.
Moreover, when alloying a plating layer, it is preferable to perform an alloying process at 460 degreeC or more. Here, when the alloying treatment temperature is less than 460 ° C., the progress of alloying is slow and the productivity is poor. The upper limit is not particularly limited, but alloying at a high temperature exceeding 600 ° C. is not economically preferable. Moreover, you may perform additional heat processing in the temperature range of 500-200 degreeC before plating bath immersion. Moreover, you may give a skin pass rolling to a hot-dip galvanized steel plate.
なお、本冷延鋼板に電気めっきを施しても鋼板の有する引張強度、成形性、耐水素脆性を何ら損なうことはない。すなわち、本発明鋼板は電気めっき用素材としても好適である。
また、本発明の溶接部の耐水素脆性に優れる高強度鋼板の素材は、通常の製鉄工程である精錬、製鋼、鋳造、熱延、冷延工程を経て製造されることを原則とするが、その一部あるいは全部を省略して製造されるものでも、本発明に係わる条件を満足する限り、本発明の効果を得ることができる。
In addition, even if this cold-rolled steel sheet is electroplated, the tensile strength, formability, and hydrogen embrittlement resistance of the steel sheet are not impaired at all. That is, the steel sheet of the present invention is also suitable as a material for electroplating.
In addition, the material of the high-strength steel plate excellent in hydrogen embrittlement resistance of the welded portion of the present invention is generally manufactured through refining, steelmaking, casting, hot rolling, and cold rolling processes, which are ordinary steelmaking processes, Even if manufactured by omitting some or all of them, the effects of the present invention can be obtained as long as the conditions according to the present invention are satisfied.
次に、本発明の鋼板を実施例及び比較例にて詳細に説明する。
表１に示す成分を有するスラブを、１２２０℃に加熱し、仕上げ熱延温度９００℃にて熱間圧延を行い、水冷帯にて水冷の後、表２に示す温度で巻き取り処理を行った。次いで、これらの熱延板を酸洗した後、厚み３ｍｍの熱延板を１．２ｍｍまで冷延を行い、冷延板とした。その後、これらの冷延板に表２に示す条件で熱処理を行った。最後に、得られた鋼板について０．３％の圧下率でスキンパス圧延を行った。
Next, the steel plate of this invention is demonstrated in detail in an Example and a comparative example.
A slab having the components shown in Table 1 was heated to 1220 ° C., hot-rolled at a finish hot rolling temperature of 900 ° C., water-cooled in a water-cooled zone, and then wound up at a temperature shown in Table 2. . Next, after pickling these hot-rolled sheets, a hot-rolled sheet having a thickness of 3 mm was cold-rolled to 1.2 mm to obtain cold-rolled sheets. Thereafter, these cold-rolled plates were heat-treated under the conditions shown in Table 2. Finally, skin pass rolling was performed on the obtained steel sheet at a rolling reduction of 0.3%.
一部の鋼板については、上記と同様の手法で冷延まで行い、連続合金化溶融亜鉛めっき設備にて、熱処理と溶融亜鉛めっき処理を施した。さらに、一部の鋼板については、めっき処理に引き続き合金化処理を行った。その際の目付け量としては、両面とも約５０ｇ／ｍ２とした。めっき後の鋼板に、０．３％スキンパス圧延を施した。 About some steel plates, it carried out to cold rolling by the method similar to the above, and performed the heat processing and the hot dip galvanization process in the continuous alloying hot dip galvanization equipment. Further, some steel sheets were subjected to an alloying treatment subsequent to the plating treatment. The basis weight at that time was about 50 g / m 2 on both sides. The plated steel sheet was subjected to 0.3% skin pass rolling.
得られた冷延鋼板あるいはめっき鋼板について、引張試験を行い、母材の引張特性であるＹＳ、ＴＳ、Ｅｌを測定した。なお、降伏応力は０．２％オフセット法により測定した。
引張試験は、１．２ｍｍ厚の鋼板から圧延方向と直角方向にＪＩＳ５号試験片を採取し、引張特性を評価した。
表３〜表６に、鋼板の水素脆化特性の評価結果を示す。
評価方法は、圧延方向と直角方向に切り出した１００ｍｍ×３０ｍｍの短冊試験片を曲げ加工し、表面に耐水性の歪みゲージを装着した後で０．５ｍｏｌ／Ｌの硫酸中に浸漬し、この試験片に通電することによって電解し、この試験片に水素を侵入させ、通電２時間後における割れの発生を評価した。ここでは、曲げ加工の半径を１０ｍｍとし、与える応力をそれぞれ６０ｋｇｆ／ｍｍ２及び９０ｋｇｆ／ｍｍ２とした。
測定した引張特性と耐水素脆性を表３に示す。
本発明の鋼板は、焼鈍中の雰囲気を制御することで、引張最大強度が高くとも、水素脆性抑制可能であることが解る。同時に、本鋼板は、Ｓｉを含む鋼板であっても、良好なめっき性が得られた。
The obtained cold-rolled steel sheet or plated steel sheet was subjected to a tensile test, and YS, TS, and El, which are tensile properties of the base material, were measured. The yield stress was measured by the 0.2% offset method.
In the tensile test, a JIS No. 5 test piece was taken from a 1.2 mm thick steel plate in a direction perpendicular to the rolling direction, and the tensile properties were evaluated.
Tables 3 to 6 show the evaluation results of the hydrogen embrittlement characteristics of the steel sheets.
The evaluation method is that a 100 mm × 30 mm strip test piece cut out in a direction perpendicular to the rolling direction is bent, and after mounting a water-resistant strain gauge on the surface, it is immersed in 0.5 mol / L sulfuric acid. Electrolysis was performed by energizing the piece, hydrogen was intruded into the test piece, and the occurrence of cracks after 2 hours of energization was evaluated. Here, the bending radius of the machining and 10 mm, and the stress applied to each 60 kgf / mm 2 and 90 kgf / mm 2.
Table 3 shows the measured tensile properties and hydrogen embrittlement resistance.
It can be seen that the steel sheet of the present invention can suppress hydrogen embrittlement by controlling the atmosphere during annealing even if the maximum tensile strength is high. At the same time, even if this steel plate was a steel plate containing Si, good plating properties were obtained.
本発明の超高強度鋼板は、引張最大強度（ＴＳ）が９８０ＭＰａ以上の高強度と優れた耐水素脆性を兼備した鋼板であり、しかも安価であるから、自動車用の構造用部材、補強用部材、足廻り用部材に適用することにより、自動車の軽量化に大きく貢献することが期待できるのはもちろんのこと、自動車以外の９８０ＭＰａ以上の高強度と優れた耐水素脆性が要求される分野に対しても適用可能であり、その産業上の利用価値は極めて大きい。 The ultra high strength steel sheet of the present invention is a steel sheet having both high strength with a tensile maximum strength (TS) of 980 MPa or more and excellent hydrogen embrittlement resistance, and is inexpensive, so structural members for automobiles and reinforcing members In addition, it can be expected to make a significant contribution to the weight reduction of automobiles by applying it to suspension members. For fields other than automobiles where high strength of 980 MPa or more and excellent hydrogen embrittlement resistance are required However, it is applicable, and its industrial utility value is extremely large.
Claims (11)
かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、
残部が鉄及び不可避的不純物からなる鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。 In mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3.0% Hereinafter, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less,
And the total content of each of the Si, Mn, Al and Cr is 0.3% or more,
Balance grain boundaries in the surface layer within 10μm from the surface of the steel sheet consisting of iron and unavoidable impurities, the crystal grains, any one of the crystal grain boundaries and in crystal grains or more, as oxides, SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, one or more selected from the group, and Mn 2 SiO 4 and Cr 2 O 3 in total An ultra-high strength steel sheet excellent in hydrogen embrittlement resistance, characterized by being contained at an average content of 0.01 to 30% by mass and having a maximum tensile strength of 980 MPa or more.
かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、
残部が鉄及び不可避的不純物からなる鋼板の表面に、
Ｆｅを７質量％未満含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる溶融亜鉛めっき層を形成し、
前記鋼板と前記溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。 In mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3.0% Hereinafter, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less,
And the total content of each of the Si, Mn, Al and Cr is 0.3% or more,
On the surface of the steel plate, the balance of which is iron and inevitable impurities,
Forming a hot-dip galvanized layer containing less than 7% by mass of Fe and the balance of Zn, Al and inevitable impurities;
Any one or more of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the steel plate within 10 μm from the interface between the steel plate and the hot dip galvanized layer, or in the hot dip galvanized layer In addition, as the oxide, one or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, and Mn 2 SiO 4 In addition, a super high strength steel sheet excellent in hydrogen embrittlement resistance, containing Cr 2 O 3 in an average content of 0.01 to 30% by mass and having a maximum tensile strength of 980 MPa or more.
かつ、前記Ｓｉ、Ｍｎ、Ａｌ及びＣｒ各々の含有量の合計が０．３％以上であり、
残部が鉄及び不可避的不純物からなる鋼板の表面に、
Ｆｅを７〜１５質量％含有し、残部がＺｎ、Ａｌおよび不可避的不純物からなる合金化溶融亜鉛めっき層を形成し、
前記鋼板と前記合金化溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記合金化溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有し、引張最大強度が９８０ＭＰａ以上であることを特徴とする耐水素脆性に優れた超高強度鋼板。 In mass%, C: 0.06 to 0.25%, Si: 2.0% or less, Mn: 2.02% to 3.0%, Al: 2.0% or less, Cr: 3.0% Hereinafter, P: 0.04% or less, S: 0.01% or less, O: 0.01% or less, N: 0.01% or less,
And the total content of each of the Si, Mn, Al and Cr is 0.3% or more,
On the surface of the steel plate, the balance of which is iron and inevitable impurities,
Forming an alloyed hot-dip galvanized layer containing 7 to 15% by mass of Fe and the balance of Zn, Al and inevitable impurities;
Any one of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the steel sheet within 10 μm from the interface between the steel sheet and the alloyed hot-dip galvanized layer, and the alloyed hot-dip galvanized layer. Or, as the oxide, as the oxide, one or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, and Mn 2 SiO 4 and Cr 2 O 3 are contained in total at an average content of 0.01 to 30% by mass, and the tensile maximum strength is 980 MPa or more, which is excellent in hydrogen brittleness resistance. Strength steel plate.
Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなる雰囲気にて、この雰囲気中の水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御しつつ熱処理することにより、鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度鋼板の製造方法。 A method for heat-treating a high-strength steel plate comprising the chemical component according to any one of claims 1 to 7,
In the atmosphere containing 1 to 60% by volume of H 2 and the balance being N 2 , H 2 O, O 2 and unavoidable impurities, the water pressure PH 2 O and the hydrogen partial pressure PH 2 in this atmosphere are expressed by the following formula: −3 ≦ log (PH 2 O / PH 2 ) ≦ −0.5
By controlling the heat treatment so as to satisfy the requirements, the surface grain within 10 μm from the surface of the steel sheet, within the crystal grain boundary, within the crystal grain, the crystal grain boundary, and within the crystal grain, an oxide As one or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO, and Mn 2 SiO 4 and Cr 2 O 3 is controlled so as to contain a total content of 0.01 to 30% by mass in total, and a method for producing an ultra-high strength steel sheet having excellent hydrogen embrittlement resistance.
前記連続焼鈍するに際し、
Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御する雰囲気下にて、
５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、その後、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度４〜２００℃／秒で冷却して２００〜５００℃間の温度とし、この温度領域にて３０秒以上保持することにより、鋼板の表面から１０μｍ以内の表層の結晶粒界、結晶粒内、結晶粒界及び結晶粒内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度鋼板の製造方法。 A cast slab composed of the chemical component according to any one of claims 1 to 7 is directly or once cooled and then heated to 1200 ° C or higher, then hot-rolled at a temperature not lower than the Ar3 transformation point, and then Winding in a temperature range of 630 ° C. or lower, then cold rolling with a rolling reduction of 40 to 70%, and thereafter producing a super high strength steel sheet that is continuously annealed,
During the continuous annealing,
H 2 is contained in an amount of 1 to 60% by volume, the balance is composed of N 2 , H 2 O, O 2 and unavoidable impurities, and the water pressure PH 2 O and the hydrogen partial pressure PH 2 are expressed by the following formula −3 ≦ log ( PH 2 O / PH 2 ) ≦ −0.5
In an atmosphere controlled to satisfy
Heat between 550 and 750 ° C. at an average heating rate of 0.7 ° C./second or more, anneal at 750 ° C. or more and 900 ° C. or less, and then cool to 650 ° C. at an average cooling rate of 0.1 to 200 ° C./second. The temperature between 650 ° C. and 500 ° C. is cooled at an average cooling rate of 4 to 200 ° C./second to a temperature between 200 and 500 ° C., and is kept within this temperature range for 30 seconds or more, and within 10 μm from the surface of the steel sheet. Any one or more of crystal grain boundaries, crystal grains, crystal grain boundaries, and crystal grains in the surface layer may be used as oxides such as SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3. , MnAl 2 O 4 , one or more selected from the group of MnO, and Mn 2 SiO 4 and Cr 2 O 3 in total, with an average content of 0.01 to 30% by mass To control Method for manufacturing ultra-high strength steel sheet excellent in resistance to hydrogen embrittlement to symptoms.
Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御する雰囲気下にて、
５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、次いで、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度３〜２００℃／秒で冷却して（亜鉛めっき浴温度−４０）℃〜（亜鉛めっき浴温度＋５０）℃間の温度とし、その後、亜鉛めっき浴に浸漬することにより、前記鋼板と前記溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度溶融亜鉛めっき鋼板の製造方法。 A cast slab composed of the chemical component according to any one of claims 1 to 7 is directly or once cooled and then heated to 1200 ° C or higher, then hot-rolled at a temperature not lower than the Ar3 transformation point, and then A method for producing an ultra-high-strength hot-dip galvanized steel sheet that is wound in a temperature range of 630 ° C. or lower, then cold-rolled at a rolling reduction of 40 to 70%, and then hot-dip galvanized, When applying
H 2 is contained in an amount of 1 to 60% by volume, the balance is composed of N 2 , H 2 O, O 2 and unavoidable impurities, and the water pressure PH 2 O and the hydrogen partial pressure PH 2 are expressed by the following formula −3 ≦ log ( PH 2 O / PH 2 ) ≦ −0.5
In an atmosphere controlled to satisfy
Heat between 550 and 750 ° C. at an average heating rate of 0.7 ° C./second or more, anneal at 750 ° C. or more and 900 ° C. or less, and then cool to 650 ° C. at an average cooling rate of 0.1 to 200 ° C./second. Then, the temperature between 650 ° C. and 500 ° C. is cooled at an average cooling rate of 3 to 200 ° C./second to obtain a temperature between (zinc plating bath temperature−40) ° C. and (zinc plating bath temperature + 50) ° C. By immersing, any one of crystal grain boundaries, crystal grains, crystal grain boundaries and crystal grains in the steel sheet within 10 μm from the interface between the steel sheet and the hot dip galvanized layer, or the hot dip galvanized layer. One or more selected from the group of SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 , Al 2 O 3 , MnAl 2 O 4 , MnO as the oxide or two or more species, and , Mn 2 SiO 4 and Cr 2 O 3 are controlled so as to contain a total content of 0.01 to 30% by mass in total, and a method for producing an ultrahigh strength hot-dip galvanized steel sheet excellent in hydrogen embrittlement resistance .
前記溶融亜鉛めっきを施すに際し、
Ｈ２を１〜６０体積％含有し、残部をＮ２、Ｈ２Ｏ、Ｏ２および不可避的不純物からなり、かつ、水分圧ＰＨ２Ｏと水素分圧ＰＨ２を下記式
−３≦ｌｏｇ（ＰＨ２Ｏ／ＰＨ２）≦−０．５
を満足するように制御する雰囲気下にて、
５５０〜７５０℃間を平均加熱速度０．７℃／秒以上で加熱し、７５０℃以上かつ９００℃以下で焼鈍し、次いで、６５０℃まで平均冷却速度０．１〜２００℃／秒で冷却し、６５０℃〜５００℃間を平均冷却速度３〜２００℃／秒で冷却して（亜鉛めっき浴温度−４０）℃〜（亜鉛めっき浴温度＋５０）℃間の温度とし、次いで、亜鉛めっき浴に浸漬し、さらに、４６０℃以上の温度にて合金化処理を施し、その後、室温まで冷却することにより、前記鋼板と前記合金化溶融亜鉛めっき層との界面から１０μｍ以内の前記鋼板内の結晶粒界、結晶粒内、結晶粒界及び結晶粒内、前記合金化溶融亜鉛めっき層内のいずれか１種または２種以上に、酸化物として、ＳｉＯ２、ＦｅＳｉＯ３、Ｆｅ２ＳｉＯ４、ＭｎＳｉＯ３、Ａｌ２Ｏ３、ＭｎＡｌ２Ｏ４、ＭｎＯの群から選択された１種または２種以上、及び、Ｍｎ２ＳｉＯ４並びにＣｒ２Ｏ３を、合計で、平均含有率０．０１〜３０質量％にて含有するように制御することを特徴とする耐水素脆性に優れた超高強度合金化溶融亜鉛めっき鋼板の製造方法。 A cast slab composed of the chemical component according to any one of claims 1 to 7 is directly or once cooled and then heated to 1200 ° C or higher, then hot-rolled at a temperature not lower than the Ar3 transformation point, and then It is a method for producing an ultra-high-strength galvannealed steel sheet that is wound in a temperature range of 630 ° C. or lower, then cold-rolled at a rolling reduction of 40 to 70%, and then subjected to hot dip galvanizing and alloying treatment. And
When performing the hot dip galvanizing,
H 2 is contained in an amount of 1 to 60% by volume, the balance is composed of N 2 , H 2 O, O 2 and unavoidable impurities, and the water pressure PH 2 O and the hydrogen partial pressure PH 2 are expressed by the following formula −3 ≦ log ( PH 2 O / PH 2 ) ≦ −0.5
In an atmosphere controlled to satisfy
Heat between 550 and 750 ° C. at an average heating rate of 0.7 ° C./second or more, anneal at 750 ° C. or more and 900 ° C. or less, and then cool to 650 ° C. at an average cooling rate of 0.1 to 200 ° C./second. , The temperature between 650 ° C. and 500 ° C. is cooled at an average cooling rate of 3 to 200 ° C./second to obtain a temperature between (zinc plating bath temperature−40) ° C. and (zinc plating bath temperature + 50) ° C. Immersion is further performed at a temperature of 460 ° C. or higher, and then cooled to room temperature, whereby crystal grains within the steel sheet within 10 μm from the interface between the steel sheet and the alloyed hot-dip galvanized layer. SiO 2 , FeSiO 3 , Fe 2 SiO 4 , MnSiO 3 as oxides in any one or more of the boundaries, crystal grains, crystal grain boundaries and crystal grains, and the alloyed hot-dip galvanized layer , Al 2 O 3 , MnAl 2 O 4 , one or more selected from the group of MnO, and Mn 2 SiO 4 and Cr 2 O 3 in total, with an average content of 0.01 to 30% by mass A method for producing an ultra-high-strength galvannealed steel sheet excellent in hydrogen embrittlement resistance, characterized by being controlled as described above.
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Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3887308B2 (en) * | 2002-12-27 | 2007-02-28 | 新日本製鐵株式会社 | High strength and high ductility hot dip galvanized steel sheet and its manufacturing method |
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| JP4464720B2 (en) * | 2003-04-10 | 2010-05-19 | 新日本製鐵株式会社 | High-strength hot-dip galvanized steel sheet and manufacturing method thereof |
| JP4119804B2 (en) * | 2003-08-19 | 2008-07-16 | 新日本製鐵株式会社 | High-strength galvannealed steel sheet with excellent adhesion and method for producing the same |
| JP4529549B2 (en) * | 2004-06-15 | 2010-08-25 | Ｊｆｅスチール株式会社 | Manufacturing method of high-strength cold-rolled steel sheets with excellent ductility and hole-expansion workability |
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| RU2485203C1 (en) * | 2012-04-28 | 2013-06-20 | Открытое акционерное общество Научно-производственное объединение "Центральный научно-исследовательский институт технологии машиностроения" (ОАО НПО "ЦНИИТМАШ") | Wear-resistant metastable austenitic steel |
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