JP5589269B2 - Alloyed hot-dip galvanized steel sheet and method for producing alloyed hot-dip galvanized steel sheet - Google Patents
Alloyed hot-dip galvanized steel sheet and method for producing alloyed hot-dip galvanized steel sheet Download PDFInfo
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本発明は合金化溶融亜鉛めっき鋼板およびその製造方法に係り、さらに詳しくは耐溶接スパッタ付着性に格段に優れると同時に優れた加工性を得ることができる合金化溶融亜鉛めっき鋼板およびその製造方法に関する。 The present invention relates to an alloyed hot-dip galvanized steel sheet and a method for producing the same, and more particularly to an alloyed hot-dip galvanized steel sheet capable of obtaining excellent workability at the same time as being excellent in weld spatter resistance and a method for producing the same .
合金化溶融亜鉛めっき鋼板は、塗装密着性、塗装耐食性、溶接性などの点に優れることから、自動車用をはじめとして、家電、建材等に非常に多用されている。合金化溶融亜鉛めっき鋼板は鋼板表面に溶融亜鉛をめっきした後、直ちに亜鉛の融点以上の温度に加熱保持して、鋼板中からＦｅを亜鉛中に拡散させることで、Ｚｎ−Ｆｅ合金を形成させるものであるが、鋼板の組成や組織によって合金化速度が大きく異なるため、その制御はかなり高度な技術を要する。一方、複雑な形状にプレスされる自動車用鋼板には、非常に高い成形性が要求されるとともに、近年では自動車の防錆性能への要求が高まったことによって、合金化溶融亜鉛めっきが適用されるケースが増加している。 Alloyed hot-dip galvanized steel sheets are extremely used in automobiles, home appliances, building materials and the like because they are excellent in coating adhesion, coating corrosion resistance, weldability, and the like. An alloyed hot-dip galvanized steel sheet forms a Zn-Fe alloy by coating hot-dip zinc on the surface of the steel sheet and immediately holding it at a temperature equal to or higher than the melting point of zinc and diffusing Fe from the steel sheet into the zinc. However, since the alloying speed varies greatly depending on the composition and structure of the steel sheet, the control thereof requires a considerably advanced technique. On the other hand, steel sheets for automobiles that are pressed into complex shapes are required to have very high formability, and in recent years, alloyed hot dip galvanizing has been applied due to an increase in demand for rust prevention performance of automobiles. Increasing cases.
自動車車体形状が一段と複雑になるのに従って、鋼板の成形性に対する要求も一段と厳しくなっており、従来にもまして深絞り性等の成形性の優れた鋼板が、合金化溶融亜鉛めっき鋼板にも要求されている。こうした加工性を得るためには、鋼板の成分として、Ｃを極めて低いレベルにまで低減した上でＴｉを添加する、あるいはＴｉとＮｂを複合添加するＴｉ添加極低炭素ＩＦ鋼、あるいはＴｉ−Ｎｂ添加極低炭素ＩＦ鋼を使用することが一般的である。 As the car body shape becomes more complex, the demands on formability of steel sheets have become more severe, and steel sheets with excellent formability such as deep drawability are also required for galvannealed steel sheets. Has been. In order to obtain such workability, Ti is added as a component of the steel sheet after Ti is reduced to a very low level, or Ti-added ultra-low carbon IF steel in which Ti and Nb are added together, or Ti-Nb. It is common to use added extra low carbon IF steel.
例えば、特許文献１や特許文献２においては、鋼板の成分、熱延条件、焼鈍条件を規定し、高延性、高ｒ値を持つ鋼板を製造し、その表面に溶融めっきを行う製造方法が開示されている。
For example,
ただし、成形性向上を目的として固溶Ｃ、Ｎ量を低下させたこれらの鋼は、溶融亜鉛めっきの合金化における合金化速度が非常に速いために、合金化が進みすぎてΓ相が厚く成長し、パウダリング性能が低下しやすいという課題がある。 However, these steels, in which the amount of solid solution C and N is reduced for the purpose of improving formability, have a very high alloying speed in the alloying of hot dip galvanizing, so that alloying proceeds too much and the Γ phase becomes thick. There is a problem that it grows and the powdering performance tends to decrease.
また、自動車の組み立てにはスポット溶接が多く使用されているが、このスポット溶接を行う際に発生するスパッタが鋼板に付着し、外観不良の原因となるという課題もある。このため自動車の外板等では、溶接工程の後にスパッタ除去工程を設けて付着したスパッタの除去を行っている。また、溶接に先立って溶接部位に塗布することによりスパッタの付着を防止するスパッタ付着防止剤も知られており、特許文献３においては、この防止剤を塗布するスパッタ付着防止剤噴霧装置が提案されている。 Further, spot welding is often used for assembling automobiles, but there is also a problem that spatter generated when spot welding adheres to the steel sheet, causing appearance defects. For this reason, on the outer plate of an automobile, a spatter removal step is provided after the welding step to remove the adhering spatter. Also known is a spatter adhesion preventive agent that prevents spatter adhesion by applying it to the welded part prior to welding, and Patent Document 3 proposes a spatter adhesion preventive spraying apparatus that applies this inhibitor. ing.
しかしながら、スパッタ付着防止剤噴霧装置は、設置スペースが無い場合には採用できず、また、スパッタ付着防止剤噴霧装置による生産コスト上昇は避けられない。一方、作業員によるスパッタ付着防止剤の塗布作業は大きな労力を必要とするだけでなく、溶接部位に均一にスパッタ付着防止剤を塗布するには熟練を要し、塗布が不均一であるとスパッタの付着が避けられないという課題がある。 However, the spatter adhesion preventing agent spraying device cannot be employed when there is no installation space, and the production cost rise due to the spatter adhesion preventing agent spraying device is unavoidable. On the other hand, the application of the spatter adhesion preventive agent by the worker is not only labor intensive, but also requires skill to apply the spatter adhesion preventive agent uniformly to the welded part. There is a problem that adhesion of unavoidable.
しかし、上記及びその他これまで開示された合金化溶融亜鉛めっき鋼板は、加工性の向上が重視されてきており、耐スパッタ付着性については十分検討されていない。 However, the alloyed hot-dip galvanized steel sheet described above and others have been emphasized in improving workability, and the sputter resistance is not sufficiently studied.
本発明は上記の現状に鑑みて、耐溶接スパッタ付着性に格段に優れると同時に優れた加工性を得ることができる合金化溶融亜鉛めっき鋼板およびその製造方法を提供することを目的としている。 An object of the present invention is to provide an alloyed hot-dip galvanized steel sheet which can remarkably improve weld spatter resistance and at the same time have excellent workability, and a method for producing the same.
本発明者は溶融亜鉛めっきラインの生産性および加工性を低下させずに耐スパッタ付着性を向上させる手段を種々検討した結果、めっき表面の平坦部の面積率を最適化することにより、耐スパッタ付着性を著しく向上させることを見出して本発明に至った。さらに、Ｃ、Ｐ、Ｎ等を低減しためっき鋼板のめっき層の相構造を制御し、δ1k相を主体とすることによって、加工性を低下させずに耐スパッタ付着性を著しく向上できることを見出して本発明に至った。 As a result of studying various means for improving the spatter resistance without reducing the productivity and workability of the hot dip galvanizing line, the present inventor has optimized the area ratio of the flat portion of the plating surface, thereby improving the spatter resistance. The inventors have found that the adhesion is remarkably improved and have reached the present invention. Furthermore, it has been found that by controlling the phase structure of the plated layer of the plated steel sheet with reduced C, P, N, etc. and mainly using the δ 1k phase, it is possible to remarkably improve the spatter resistance without decreasing the workability. To the present invention.
すなわち、本発明の要旨とするところは、以下のとおりである。 That is, the gist of the present invention is as follows.
（１） 鋼板の片面または両面にＡｌ：０．０５〜０．５質量％、Ｆｅ：１０超〜１７質量％、残部がＺｎおよび不可避的不純物からなり、めっき表面の平坦部の面積率が４０〜６０％、めっき表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相の平均厚さが０．１〜０．５μｍとなることを特徴とする合金化溶融亜鉛めっき層を形成させた加工性および耐スパッタ付着性に優れた合金化溶融亜鉛めっき鋼板。
(1) On one or both sides of the steel sheet, Al: 0.05 to 0.5 mass%, Fe: more than 10 to 17 mass%, the balance is made of Zn and inevitable impurities, and the area ratio of the flat portion of the plating surface is 40 ~ 60%, the ratio 50 to 100% of the [delta] 1k phase occupying the plating surface, plating / alloying average thickness of the steel sheet interface Γ phase is characterized by comprising a 0.1 to 0.5 [mu] m galvanized An alloyed hot-dip galvanized steel sheet with excellent workability and spatter resistance.
（２）鋼板が質量％で、
Ｃ：０．０００１〜０．０１５％、
Ｓｉ：０．００１〜０．４５％、
Ｍｎ：０．０１〜２．８％、
Ｐ：０．００１〜０．１％、
Ｓ：０．０１５％以下、
Ａｌ：０．０００５〜０．０５％、
Ｔｉ：０．００２〜０．１０％、
Ｎ：０．０００５〜０．００４％、
を含有し、残部がＦｅおよび不可避不純物からなることを特徴とする（１）に記載の合金化溶融亜鉛めっき鋼板。
(2) The steel sheet is mass%,
C: 0.0001 to 0.015%,
Si: 0.001 to 0.45%,
Mn: 0.01 to 2.8%,
P: 0.001 to 0.1%,
S: 0.015% or less,
Al: 0.0005 to 0.05%,
Ti: 0.002 to 0.10%,
N: 0.0005 to 0.004%,
The alloyed hot-dip galvanized steel sheet according to (1), wherein the balance is Fe and inevitable impurities.
（３）鋼板が付加成分としてさらに、質量％で、Ｎｂ：０．００２〜０．１０％を含有することを特徴とする深絞り性に優れた（２）に記載の合金化溶融亜鉛めっき鋼板。
(3) The alloyed hot-dip galvanized steel sheet according to (2), which is excellent in deep drawability , characterized in that the steel sheet further contains Nb: 0.002 to 0.10% by mass as an additional component. .
（４）鋼板が付加成分としてさらに、質量％で、Ｂ：０．０００２〜０．００３％を含有することを特徴とする（２）または（３）に記載の合金化溶融亜鉛めっき鋼板。
(4) The alloyed hot-dip galvanized steel sheet according to (2) or (3), wherein the steel sheet further contains B: 0.0002 to 0.003% by mass% as an additional component .
（５）鋼板が付加成分としてさらに、質量％で、Ｃｅ、Ｌａ、Ｎｄ、Ｐｒ、Ｓｍの一種または二種以上を合計で０．０００１〜０．０１％を含有することを特徴とする（２）乃至（４）のいずれか１つに記載の合金化溶融亜鉛めっき鋼板。
(5) The steel sheet is further characterized by containing 0.0001 to 0.01% in total of one or more of Ce, La, Nd, Pr, and Sm as an additional component in mass% (2 The alloyed hot-dip galvanized steel sheet according to any one of ( 1 ) to (4).
（６）鋼板を溶融亜鉛めっき浴でめっき後、加熱炉出側の板温が５３０℃超、６００℃以下となるように加熱し、１０秒以内に４００℃まで冷却する合金化処理工程と、合金化処理後のめっき鋼板をワークロール径３００〜７００ｍｍのロールで伸長率０．５〜２．０％の調質圧延を行う調質圧延工程を有することを特徴とする（１）乃至（５）のいずれか１つに記載の合金化溶融亜鉛めっき鋼板の製造方法。
(6) An alloying treatment step of heating the steel plate so that the plate temperature on the heating furnace exit side is over 530 ° C. and 600 ° C. or lower after being plated with a hot dip galvanizing bath, and cooling to 400 ° C. within 10 seconds; (1) to (5) characterized by comprising a temper rolling step of subjecting the plated steel sheet after the alloying treatment to temper rolling with a work roll diameter of 300 to 700 mm and an elongation of 0.5 to 2.0%. The manufacturing method of the galvannealed steel plate as described in any one of 1 ).
本発明は耐溶接スパッタ付着性と加工性のいずれにも優れる合金化溶融亜鉛めっき鋼板を提供することを可能としたものであり、産業の発展に貢献するところが極めて大である。 The present invention makes it possible to provide an alloyed hot-dip galvanized steel sheet that is excellent in both weld spatter resistance and workability, and greatly contributes to industrial development.
以下、本発明を詳細に説明する。なお、本発明において％は、特に明記しない限り、質量％を意味する。 Hereinafter, the present invention will be described in detail. In the present invention, “%” means “% by mass” unless otherwise specified.
本発明は、鋼板の片面または両面にＡｌ：０．０５〜０．５％、Ｆｅ：１０超〜１７％、残部がＺｎおよび不可避的不純物からなり、めっき表面の平坦部の面積率が４０〜７０％、めっき表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相厚さが０．１〜０．８μｍとなることを特徴とする合金化溶融亜鉛めっき層を形成させた合金化溶融亜鉛めっき鋼板である。 In the present invention, Al: 0.05 to 0.5%, Fe: more than 10 to 17% on one side or both sides of a steel plate, the balance is made of Zn and inevitable impurities, and the area ratio of the flat portion of the plating surface is 40 to 40%. An alloyed hot-dip galvanized layer is formed, characterized in that the ratio of δ 1k phase to the plating surface is 50% to 100% and the Γ phase thickness at the plating / steel interface is 0.1 to 0.8 μm. An alloyed hot-dip galvanized steel sheet.
本発明において合金化溶融亜鉛めっき層のＡｌ組成を０．０５〜０．５％に限定した理由は、０．０５％未満では合金化処理時においてＺｎ―Ｆｅ合金化が進みすぎ、地鉄界面に脆い合金層が発達しすぎてめっき密着性が劣化するためであり、０．５％を超えるとＦｅ−Ａｌ−Ｚｎ系バリア層が厚く形成され過ぎ合金化処理時において合金化が進まないため目的とする鉄含有量のめっきが得られないためである。 In the present invention, the reason why the Al composition of the alloyed hot-dip galvanized layer is limited to 0.05 to 0.5% is that if it is less than 0.05%, Zn-Fe alloying has progressed too much during the alloying treatment, and the interface between the iron and steel This is because an excessively brittle alloy layer develops and plating adhesion deteriorates, and when it exceeds 0.5%, an Fe-Al-Zn-based barrier layer is formed too thick and alloying does not progress during alloying treatment. This is because the desired iron content plating cannot be obtained.
また、Ｆｅ組成を１０超〜１７％に限定した理由は、１０％以下だとめっき表面に柔らかいＺｎ−Ｆｅ合金が形成されプレス成形性を劣化させるためであり、１７％を超えるとめっき／鋼板界面に脆い合金層が発達し過ぎてめっき密着性が劣化するためである。望ましくは、１０．５％以上である。 Further, the reason why the Fe composition is limited to more than 10 to 17% is that if it is 10% or less, a soft Zn—Fe alloy is formed on the plating surface and press formability is deteriorated. This is because a brittle alloy layer develops too much at the interface and the plating adhesion deteriorates. Desirably, it is 10.5% or more.
さらに本発明においては、合金化溶融亜鉛めっき鋼板の耐スパッタ付着性を向上させることを目的として、めっき表面の平坦部の面積率を４０〜７０％とする。溶接スパッタは、接触面積が大きいほど抜熱が早く、付着し難くなるため、平坦部の面積率が大きいほど耐スパッタ付着性が向上する。めっき表面の平坦部の面積率を４０％以上とする理由は、平坦部の面積率が４０％未満では、接触面積が小さい部分が多くなり、付着するスパッタの数が多くなるためである。平坦部の面積率が大きいほど付着するスパッタの数は少なくなり、耐スパッタ付着性は良好となるが、平坦部の面積率が大きくなると、めっき表面の凹凸が減少するため、油保持性が低下し、摺動性が低下する。従って、加工性を低下させずに耐スパッタ付着性を向上させるため、めっき表面の平坦部の面積率を７０％以下とする。特にプレス成形性が厳しい部品に使う場合には、めっき表面の平坦部の面積率を６０％以下とすることが望ましい。 Furthermore, in this invention, the area ratio of the flat part of a plating surface shall be 40 to 70% for the purpose of improving the sputter | spatter resistance of an galvannealed steel plate. As the welding spatter has a larger contact area, heat removal is quicker and is less likely to adhere. Therefore, as the area ratio of the flat portion is larger, the sputter resistance is improved. The reason why the area ratio of the flat portion on the plating surface is 40% or more is that when the area ratio of the flat portion is less than 40%, the portion with a small contact area increases and the number of spatters adhering increases. The larger the area ratio of the flat part, the less the number of spatters that adheres and the better the spatter resistance, but the larger the flat part area ratio, the less the unevenness of the plating surface, so the oil retention decreases. In addition, the slidability decreases. Therefore, in order to improve the spatter resistance without decreasing the workability, the area ratio of the flat portion of the plating surface is set to 70% or less. In particular, when used for parts with severe press formability, it is desirable that the area ratio of the flat portion of the plating surface be 60% or less.
さらに、めっき層中のＡｌ組成とＦｅ組成を限定するだけでは、加工性、めっき密着性共不十分であり、プレス成形性、特に深絞り性を向上させることを目的として、めっき層表面に占めるδ1k相の割合を５０〜１００％とする。 Furthermore, the workability and plating adhesion are insufficient only by limiting the Al composition and the Fe composition in the plating layer, and occupy the surface of the plating layer for the purpose of improving press formability, particularly deep drawability. The proportion of the δ 1k phase is 50 to 100%.
本発明において、合金化溶融亜鉛めっき層とは、合金化反応によってＺｎめっき中に鋼中のＦｅが拡散しできたＦｅ−Ｚｎ合金を主体としためっき層のことである。このめっき層は、これまでＦｅの含有率の違いにより、ζ相、δ1相、Γ１相、Γ相と呼ばれる合金層が形成されることが知られていたが、最近の研究により、δ1相にはさらにδ1p相とδ1k相の２相が存在することが明らかになってきている。 In the present invention, the alloyed hot dip galvanized layer is a plated layer mainly composed of an Fe—Zn alloy in which Fe in steel can diffuse during Zn plating by an alloying reaction. The plating layer, the difference in content of Fe far, zeta phase, [delta] 1 phase, .GAMMA.1 phase, but that the alloy layer is formed called Γ phase was known, recent studies, [delta] 1 It has become clear that the phase further includes two phases of δ 1p phase and δ 1k phase.
本発明においてζ相とは、単斜晶で格子定数がａ＝１３．４Å、ｂ＝７．６Å、ｃ＝５．０６Å、β＝１２７．３である金属間化合物を示す。ζ相の組成は、ＦｅＺｎ13であると考えられる。また、本発明においてδ1p相とは、六方晶で格子定数がａ＝１２．８Å、ｃ＝５７．４Åである金属間化合物を、δ1k相とは、δ1p相の３倍周期の格子定数を持つ金属間化合物を示す。いずれの金属間化合物も組成はＦｅＺｎ7であると考えられる。また、本発明においてΓ１相とは、面心立方晶で格子定数がａ＝１７．９６Åである金属間化合物を示す。Γ１相の組成は、Ｆｅ5Ｚｎ21またはＦｅＺｎ4であると考えられる。また、本発明においてΓ相とは、体心立方晶で格子定数がａ＝８．９７Åである金属間化合物を示す。Γ相の組成は、Ｆｅ3Ｚｎ10であると考えられる。 In the present invention, the ζ phase refers to an intermetallic compound having a monoclinic structure and lattice constants of a = 13.4Å, b = 7.6Å, c = 0.06Å, and β = 127.3. The composition of the ζ phase is considered to be FeZn 13 . In the present invention, the δ 1p phase is an intermetallic compound having a hexagonal crystal lattice constant of a = 12.8１２ and c = 57.4Å, and the δ 1k phase is a lattice having a period three times that of the δ 1p phase. An intermetallic compound having a constant is shown. The composition of any intermetallic compound is considered to be FeZn 7 . In the present invention, the Γ1 phase refers to an intermetallic compound having a face-centered cubic crystal and a lattice constant of a = 17.96Å. The composition of the Γ1 phase is considered to be Fe 5 Zn 21 or FeZn 4 . In the present invention, the Γ phase refers to an intermetallic compound having a body-centered cubic crystal and a lattice constant of a = 8.97. The composition of the Γ phase is considered to be Fe 3 Zn 10 .
合金化溶融亜鉛めっき鋼板の相構造は、鋼板側から、Γ相、Γ１相、δ1k相、δ1p相、ζ相の順にＦｅ−Ｚｎ金属間化合物が形成されるが、後述するように合金化条件によっては、δ1p相やζ相ができないこともある。 The phase structure of the alloyed hot-dip galvanized steel sheet consists of Fe-Zn intermetallic compounds in the order of Γ phase, Γ1 phase, δ 1k phase, δ 1p phase, and ζ phase from the steel plate side. Depending on the conversion conditions, the δ 1p phase and the ζ phase may not be possible.
このうち、δ1k相は合金化溶融亜鉛めっき鋼板の深絞り性を著しく向上させるため、合金化溶融亜鉛めっき鋼板の深絞り性向上を目的として、めっき層表面に占めるδ1k相の割合を５０〜１００％とする。めっき層表面に占めるδ1k相の割合を５０〜１００％に限定した理由は、５０％以上で深絞り性を向上させる効果が顕著であるためである。 Among these, since the δ 1k phase significantly improves the deep drawability of the galvannealed steel sheet, the proportion of the δ 1k phase in the surface of the plating layer is 50 for the purpose of improving the deep drawability of the galvannealed steel sheet. ~ 100%. The reason why the ratio of the δ 1k phase in the plating layer surface is limited to 50 to 100% is that the effect of improving deep drawability is remarkable at 50% or more.
めっき層の相構造をδ1k相とすることで深絞り性が向上する理由は、めっきの硬度が高くなることにより、しわ抑え部から縦壁部への流入抵抗が小さくなるためであると考えられる。めっき層の相構造をδ1k相とすることで深絞り性は１０〜２０％向上するため、深絞り性の良好な鋼板のめっき層をδ1k相とすると、その相乗効果で合金化溶融亜鉛めっき鋼板の深絞り性は著しく向上する。そのため、ｒ値が高い鋼板にδ1k相を主体とした合金化溶融亜鉛めっきを生成させることが好ましい。 The reason why the deep drawability is improved by setting the phase structure of the plating layer to the δ 1k phase is considered to be that the inflow resistance from the wrinkle suppressing portion to the vertical wall portion is reduced by increasing the hardness of the plating. It is done. By making the phase structure of the plating layer a δ 1k phase, the deep drawability is improved by 10 to 20%. Therefore, if the plating layer of a steel plate having a good deep drawability is a δ 1k phase, the synergistic effect of the alloyed molten zinc The deep drawability of the plated steel sheet is remarkably improved. Therefore, it is preferable to produce alloyed hot dip galvanizing mainly having a δ 1k phase on a steel plate having a high r value.
さらに、δ1k相はδ1p相、ζ相より融点が高く、スパッタ付着時にめっきの溶解が起こり難いため、深絞り性の向上だけでなく、耐スパッタ付着性向上に対しても相乗効果が得られる。 Furthermore, the δ 1k phase has a higher melting point than the δ 1p phase and ζ phase, and it is difficult for the plating to dissolve at the time of sputter deposition. Therefore, it has a synergistic effect not only for deep drawability but also for improving spatter resistance. It is done.
ただし、このような深絞り性の良好な鋼板は、溶融亜鉛めっきの合金化における合金化速度が非常に速いために、合金化が進みすぎてΓ相が厚く成長し、パウダリング性能が低下しやすいという課題がある。これを防止する目的で、めっき／鋼板界面のΓ相厚さを０．８μｍ以下とする。Γ相厚さは薄いほどめっき密着性は良好ではあるが、めっき層の相構造をδ1k相としたままΓ相厚さを０．１μｍ未満に低減するためにはコストが多大になるため、下限厚さは０．１μｍとする。特に成形の厳しい部品では、Γ相厚さは０．１〜０．５μｍが好ましい。 However, such a steel sheet with good deep drawability has a very high alloying speed in the alloying of hot dip galvanizing, so that the alloying progresses too much and the Γ phase grows thick, and the powdering performance decreases. There is a problem that it is easy. In order to prevent this, the thickness of the Γ phase at the plating / steel plate interface is set to 0.8 μm or less. The thinner the Γ phase thickness is, the better the plating adhesion is. However, in order to reduce the Γ phase thickness to less than 0.1 μm while maintaining the phase structure of the plating layer as δ 1k phase, the cost becomes great. The lower limit thickness is 0.1 μm. Particularly for parts that are severely molded, the Γ phase thickness is preferably 0.1 to 0.5 μm.
下地の鋼板としては、熱延鋼板、冷延鋼板共に使用でき、何れの鋼板においてもめっき表面の平坦部の面積率を４０〜７０％とすることにより、耐スパッタ付着性を向上でき、さらにめっき層表面に占めるδ1k相の割合高いめっき層を形成させることにより深絞り性を向上させることができるが、特に自動車用外板に使用する場合、プレス成形性の良好な極低炭素鋼板を使用することが望ましい。 As the base steel plate, both hot-rolled steel plates and cold-rolled steel plates can be used, and in any steel plate, by setting the area ratio of the flat portion of the plating surface to 40 to 70%, it is possible to improve the spatter resistance, and further plating Deep drawability can be improved by forming a plating layer with a high proportion of δ 1k phase on the surface of the layer, but when using for automotive outer plates, use ultra-low carbon steel plates with good press formability It is desirable to do.
具体的には、質量％で、Ｃ：０．０００１〜０．０１５％、Ｓｉ：０．００１〜０．４５％、Ｍｎ：０．０１〜２．８％、Ｐ：０．００１〜０．１％、Ｓ：０．０１５％以下、Ａｌ：０．０００５〜０．０５％、Ｔｉ：０．００２〜０．１０％、Ｎ：０．０００５〜０．００４％を含有し、残部Ｆｅおよび不可避不純物からなる鋼板である。 Specifically, by mass%, C: 0.0001 to 0.015%, Si: 0.001 to 0.45%, Mn: 0.01 to 2.8%, P: 0.001 to 0.8. 1%, S: 0.015% or less, Al: 0.0005 to 0.05%, Ti: 0.002 to 0.10%, N: 0.0005 to 0.004%, the balance Fe and It is a steel plate made of inevitable impurities.
本発明において各成分の範囲を限定した理由は以下の通りである。 The reason why the range of each component is limited in the present invention is as follows.
Ｃ：Ｃは鋼の強度を高める元素であって、過剰に含有すると強度が上昇しすぎて加工性が低下するので上限含有量は０．０１５％とする。Ｃが少ないほど加工性は良好であるが、０．０００１％未満とするためには精練コストが多大となるので下限含有量は０．０００１％とする。 C: C is an element that increases the strength of steel. If it is excessively contained, the strength increases excessively and the workability decreases, so the upper limit content is made 0.015%. The smaller the C, the better the workability, but in order to make it less than 0.0001%, the scouring cost becomes large, so the lower limit content is made 0.0001%.
Ｓｉ：Ｓｉも鋼の強度を向上させる元素であって、過剰に含有すると加工性および溶融亜鉛めっき性を損なうので、上限は０．４５％とする。ただし、０．００１％以上未満とするためには精練コストが多大となるので下限含有量は０．００１％とする。 Si: Si is also an element for improving the strength of steel, and if contained excessively, workability and hot dip galvanizing properties are impaired, so the upper limit is made 0.45%. However, in order to make it less than 0.001% or more, the scouring cost becomes great, so the lower limit content is made 0.001%.
Ｍｎ：Ｍｎも鋼の強度を高める一方で加工性を低下させる元素であるので、上限含有量は２．８％とする。Ｍｎが少ないほど加工性は良好であるが、０．０１％以下とするためには精練コストが多大となるので下限含有量は０．０１％とする。 Mn: Since Mn is an element that increases the strength of steel while reducing workability, the upper limit content is 2.8%. The smaller the Mn, the better the workability, but in order to make it 0.01% or less, the scouring cost becomes large, so the lower limit content is made 0.01%.
Ｐ：Ｐも鋼の強度を高める一方で加工性を低下させる元素であるので、上限含有量は０．１％とする。一方、Ｐ含有量を０．００１％未満に低減するためには精練コストが多大となるので、下限含有量は０．００１％とする。 P: P is an element that increases the strength of the steel while decreasing the workability, so the upper limit content is 0.1%. On the other hand, in order to reduce the P content to less than 0.001%, the scouring cost becomes large, so the lower limit content is made 0.001%.
Ｓ：Ｓは鋼の熱間加工性、耐食性を低下させる元素であるから少ないほど好ましく、上限含有量は０．０１５％とし、より好ましくは０．０１０％以下とする。但し、本発明のような極低炭素鋼のＳ量を低減するためにはコストがかかるので、加工性およびめっき密着性の観点からはＳを過度に低減する必要はなく、熱間加工性、耐食性等から必要なレベルにまでＳを低減すれば良い。 S: Since S is an element that decreases the hot workability and corrosion resistance of steel, it is preferably as small as possible. The upper limit content is 0.015%, and more preferably 0.010% or less. However, since it takes cost to reduce the amount of S of the ultra-low carbon steel as in the present invention, it is not necessary to excessively reduce S from the viewpoint of workability and plating adhesion, What is necessary is just to reduce S to the required level from corrosion resistance etc.
Ａｌ：Ａｌは鋼の脱酸元素として０．０００５％以上を含有させることが必要であるが、過剰に含有させると粗大な金属間化合物を生成して加工性を損なうので、上限含有量は０．０５％とする。 Al: Al needs to contain 0.0005% or more as a deoxidizing element of steel. However, if excessively contained, a coarse intermetallic compound is formed and workability is impaired, so the upper limit content is 0. .05%.
Ｔｉ：鋼中のＣおよびＮを炭化物、窒化物として固定するために、０．００２％以上の添加が必要であり、０．０１０％以上含有させるとより好ましい。一方、０．１０％を超えて添加してももはやその効果は飽和しているのに対して、いたずらに合金添加コストが上昇するだけであるので、上限含有量は０．１０％とする。過剰な固溶Ｔｉは鋼板の加工性および表面品質を損なう場合があるので、０．０５０％以下とするとより好ましい。 Ti: In order to fix C and N in steel as carbides and nitrides, 0.002% or more of addition is necessary, and it is more preferable to contain 0.010% or more. On the other hand, even if added over 0.10%, the effect is no longer saturated, but the alloy addition cost only increases unnecessarily, so the upper limit content is 0.10%. Since excessive solute Ti may impair the workability and surface quality of the steel sheet, it is more preferably 0.050% or less.
Ｎ：Ｎは鋼の強度を上昇させる一方で加工性を低下させるので上限は０．００４％とし、特に高い加工性を必要とする場合には０．００３％以下とすることがより好ましく、０．００２％以下とするとさらに好ましい。Ｎはより少ないほど好ましいが、０．０００５％未満に低減することは過剰なコストを要するので、下限含有量は０．０００５％とする。 N: N increases the strength of the steel while lowering the workability, so the upper limit is made 0.004%, and when high workability is particularly required, it is more preferably 0.003% or less. More preferably, the content is 0.002% or less. N is preferably as little as possible, but reducing it to less than 0.0005% requires excessive cost, so the lower limit content is made 0.0005%.
本発明では上記に加えて、さらに付加成分として、鋼中のＣおよびＮを炭化物、窒化物として固定するために、前記のＴｉ添加のもとでＮｂを添加することができるが、Ｎｂ添加によるＣ、Ｎ固定効果を充分発揮させるためには０．００２％以上の添加が必要であり、０．００５％以上とするとより好ましい。Ｎｂを、０．１０％を超えて添加しても、もはやその効果は飽和している一方、いたずらにコストが上昇するだけであるので、上限含有量は０．１０％とする。過剰なＮｂ添加は鋼板の再結晶温度を上昇させ、溶融亜鉛めっきラインの生産性を低下させるので、０．０５０％以下とするとより好ましい。 In the present invention, in addition to the above, as an additional component, Nb can be added under the above Ti addition in order to fix C and N in the steel as carbides and nitrides. In order to fully exhibit the C and N fixing effect, addition of 0.002% or more is necessary, and more preferably 0.005% or more. Even if Nb is added in excess of 0.10%, the effect is no longer saturated, but the cost is increased unnecessarily, so the upper limit content is 0.10%. Excessive Nb addition raises the recrystallization temperature of the steel sheet and lowers the productivity of the hot dip galvanizing line.
本発明においてはさらに、鋼板に付加成分として、Ｂを０．０００２〜０．００３％含有させることができるが、これは２次加工性の改善を目的としている。Ｂの含有量が０．０００２％未満では２次加工性改善効果が充分ではなく、０．００３％を超えて添加してももはやその効果は飽和しているのに加えて、成形性が低下するので、Ｂを添加する場合にはその範囲は０．０００２〜０．００３％とする。特に高い深絞り性を必要とする場合には、Ｂの添加量は０．００１５％以下とするとより好ましい。 In the present invention, the steel sheet may further contain 0.0002 to 0.003% of B as an additional component, and this is intended to improve secondary workability. If the B content is less than 0.0002%, the secondary workability improvement effect is not sufficient, and even if added over 0.003%, the effect is no longer saturated, and the moldability is reduced. Therefore, when adding B, the range is made 0.0002 to 0.003%. In particular, when high deep drawability is required, the amount of B added is more preferably 0.0015% or less.
本発明においてはさらに、鋼板に付加成分として、Ｃｅ、Ｌａ、Ｎｄ、Ｐｒ、Ｓｍの一種または二種以上を合計で０．０００１〜０．０１％添加することができる。これは、筋模様等の表面欠陥の発生を抑制し、良好な外観を有する合金化溶融亜鉛めっき鋼板を得ることを目的としている。Ｃｅ、Ｌａ、Ｎｄ、Ｐｒ、Ｓｍの一種または二種以上の添加量は、筋模様欠陥の発生を抑制する目的から０．０００１％以上必要である。ただし、０．０１％を超えるとコスト高となるばかりか、これらの金属の酸化物が鋼板中の介在物となり、プレス加工後の表面欠陥の原因となりやすくなるため添加量は合計で０．０１％以下とする。 In the present invention, one or more of Ce, La, Nd, Pr, and Sm can be added to the steel sheet as an additional component in a total amount of 0.0001 to 0.01%. The purpose of this is to obtain an alloyed hot-dip galvanized steel sheet having a good appearance by suppressing the occurrence of surface defects such as streaks. The addition amount of one or more of Ce, La, Nd, Pr and Sm is required to be 0.0001% or more for the purpose of suppressing the generation of streak defects. However, if it exceeds 0.01%, not only will the cost be increased, but the oxides of these metals become inclusions in the steel sheet, which tends to cause surface defects after press working, so the amount added is 0.01% in total. % Or less.
なお、特に加工性が必要な場合は、Ｃ：０．０００１〜０．００４％、Ｓｉ：０．００１〜０．１０％、Ｍｎ：０．０１〜０．５０％、Ｐ：０．００１〜０．０１５％とすることが望ましい。 In particular, when workability is required, C: 0.0001 to 0.004%, Si: 0.001 to 0.10%, Mn: 0.01 to 0.50%, P: 0.001 to It is desirable that the content be 0.015%.
本発明においては、さらに鋼板の成形性、加工性を一段と高くする場合には、Ｔｉの含有量が下記（１）式を満足する範囲とする。
［％Ｔｉ］≧４［％Ｃ］＋３．４［％Ｎ］＋１．５［％Ｓ］ ・ ・ ・ （１）
In the present invention, when the formability and workability of the steel sheet are further increased, the Ti content is set in a range satisfying the following expression (1).
[% Ti] ≧ 4 [% C] +3.4 [% N] +1.5 [% S] (1)
これは、Ｔｉ含有量を上記の範囲とすると、加工性を阻害する元素であるＣおよびＮをＴｉで有効に固定し、鋼板の加工性を高めることができるからである。あるいは、ＴｉおよびＮｂの含有量を下記（２）式および（３）式を満足する範囲とする。
（［％Ｔｉ］＋０．５２［％Ｎｂ］）≧４［％Ｃ］＋３．４［％Ｎ］＋１．５［％Ｓ］
・ ・ ・ （２）
［％Ｔｉ］≧０．００９％ ・ ・ ・ （３）
This is because when the Ti content is in the above range, C and N, which are elements that hinder workability, are effectively fixed with Ti, and the workability of the steel sheet can be improved. Or let content of Ti and Nb be the range which satisfies the following (2) Formula and (3) Formula.
([% Ti] +0.52 [% Nb]) ≧ 4 [% C] +3.4 [% N] +1.5 [% S]
(2)
[% Ti] ≧ 0.009% (3)
これは、ＴｉおよびＮｂの含有量を上記の範囲とすると、加工性を阻害する元素であるＣおよびＮをＴｉとＮｂの複合効果で有効に固定し、鋼板の加工性を高めることができるからであるが、Ｎｂ単独の添加ではかかる加工性向上効果は充分ではなく、Ｔｉ含有量が０．００９％以上である場合にＴｉとＮｂの複合添加効果が顕著となり、この場合においてＴｉおよびＮｂの含有量が（２）式を満足すると、ＣおよびＮをＴｉとＮｂとで有効に固定することができる。 This is because, if the content of Ti and Nb is in the above range, C and N, which are elements inhibiting workability, can be effectively fixed by the combined effect of Ti and Nb, and the workability of the steel sheet can be improved. However, when Nb alone is added, the effect of improving the workability is not sufficient, and when Ti content is 0.009% or more, the combined effect of Ti and Nb becomes remarkable. When the content satisfies the formula (2), C and N can be effectively fixed with Ti and Nb.
一方、高い加工性を保持しつつ、３００ＭＰａ以上の引張強度を付与するためには、Ｃ：０．０００１〜０．０１５％、Ｓｉ：０．００１〜０．４５％、Ｍｎ：０．２０％以上、Ｐ：０．０２％以上とすることが望ましい。 On the other hand, C: 0.0001 to 0.015%, Si: 0.001 to 0.45%, Mn: 0.20% for imparting a tensile strength of 300 MPa or more while maintaining high workability. As mentioned above, it is desirable to set it as P: 0.02% or more.
Ｍｎの含有量を０．２％以上とする理由は、Ｍｎが０．２％未満では必要とする引張強さの確保が困難であるためである。更に望ましくは、強度、加工性とコストのバランスから０．２〜１．５％である。 The reason why the Mn content is 0.2% or more is that if Mn is less than 0.2%, it is difficult to ensure the required tensile strength. More preferably, it is 0.2 to 1.5% from the balance of strength, workability and cost.
Ｐの含有量を０．０２％以上とする理由は、Ｐが０．０２％未満では必要とする引張強さの確保が困難であるためである。更に望ましくは、強度、加工性とコストのバランスから０．０２〜０．１％である。 The reason why the P content is 0.02% or more is that it is difficult to ensure the required tensile strength when P is less than 0.02%. More preferably, it is 0.02 to 0.1% from the balance of strength, workability and cost.
次に、製造条件の限定理由について述べる。本発明において、Ａｌ：０．０５〜０．５質量％、Ｆｅ：１０〜１７質量％、残部がＺｎおよび不可避的不純物からなり、表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相厚さが０．１〜０．８μｍとなることを特徴とする合金化溶融亜鉛めっき層を形成させるためには、めっき後、加熱炉出側の板温が５３０℃超、６００℃以下となるように加熱し、１０秒以内に４００℃まで冷却する方法が有効である。 Next, the reasons for limiting the manufacturing conditions will be described. In the present invention, Al: 0.05 to 0.5% by mass, Fe: 10 to 17% by mass, the balance is made of Zn and inevitable impurities, the proportion of δ 1k phase in the surface is 50 to 100%, plating / In order to form an alloyed hot-dip galvanized layer characterized in that the Γ phase thickness at the steel plate interface is 0.1 to 0.8 μm, after plating, the plate temperature on the heating furnace exit side exceeds 530 ° C., A method of heating to 600 ° C. or lower and cooling to 400 ° C. within 10 seconds is effective.
深絞り性の良好な鋼板は、溶融亜鉛めっきの合金化における合金化速度が非常に速いために、合金化は、これまで５３０℃以下の低温で行われてきた。しかし、めっき層表面をδ1k相とするためには、図１に示す状態図から解るように合金化温度を５３０℃超とし、δ1k＋Ｌの２相域で合金化する必要がある。５３０℃以下で合金化すると合金層はζ相またはδ1p相が初晶となる。初晶がζ相またはδ1p相であってもそのまま高温で保持を続けると鋼中からＦｅが拡散し、いずれはδ1k相へ変態するが、同時にΓ相も成長するため、パウダリング性能が著しく低下する。従って、５３０℃以下で合金化した場合、表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相厚さが０．１〜０．８μｍとなることを両立することができない。 A steel sheet with good deep drawability has a very high alloying speed in alloying of hot dip galvanizing, and thus alloying has been performed at a low temperature of 530 ° C. or lower. However, in order to set the plating layer surface to the δ 1k phase, it is necessary to make the alloying temperature higher than 530 ° C. and to alloy in the two-phase region of δ 1k + L as can be seen from the phase diagram shown in FIG. When alloyed at 530 ° C. or lower, the alloy layer becomes primary crystal in ζ phase or δ 1p phase. Even if the primary crystal is a ζ phase or δ 1p phase, if it is kept at a high temperature as it is, Fe diffuses from the steel and eventually transforms into the δ 1k phase, but at the same time the Γ phase grows, so that the powdering performance is improved. It drops significantly. Therefore, when alloying at 530 ° C. or lower, it is possible to achieve both a proportion of the δ 1k phase in the surface of 50 to 100% and a Γ phase thickness of the plating / steel interface of 0.1 to 0.8 μm. Can not.
また、δ1k＋Ｌの２相域は５３０〜６６５℃であるが、合金化温度が高すぎるとδ1k相形成後すぐにめっき／鋼板界面にΓ相が成長し、パウダリング性能が低下するため、合金化温度の上限は６００℃とする。 The two-phase region of δ 1k + L is 530 to 665 ° C., but if the alloying temperature is too high, the Γ phase grows immediately after the formation of the δ 1k phase and the powdering performance deteriorates. The upper limit of the alloying temperature is 600 ° C.
さらに、合金化後、高温で保持を続けると鋼中からＦｅが拡散し、Γ相が成長して、パウダリング性能が著しく低下するため、合金化温度が５３０〜６００℃に到達後、１０秒以内に４００℃まで冷却する。 Furthermore, if the alloy is kept at a high temperature after the alloying, Fe diffuses from the steel, the Γ phase grows, and the powdering performance is remarkably lowered. Therefore, after the alloying temperature reaches 530 to 600 ° C., 10 seconds. Within 400 ° C.
つまり、めっき後、加熱炉出側の板温が５３０℃超、６００℃以下となるように加熱し、１０秒以内に４００℃まで冷却することにより、表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相厚さが０．１〜０．８μｍとなることを両立することが可能となる。特に成形の厳しい部品では、Γ相厚さが０．１〜０．５μｍとするために、加熱炉出側の板温が５３０℃超、５７０℃以下となるように加熱し、１０秒以内に４００℃まで冷却することが好ましい。 That is, after plating, heating is performed so that the plate temperature on the exit side of the heating furnace is higher than 530 ° C. and 600 ° C. or lower, and cooled to 400 ° C. within 10 seconds, whereby the ratio of δ 1k phase to the surface is 50 to It is possible to achieve both 100% and a Γ phase thickness of 0.1 to 0.8 μm at the plating / steel plate interface. Especially for parts with severe molding, in order to set the Γ phase thickness to 0.1 to 0.5 μm, heating is performed so that the plate temperature on the exit side of the heating furnace is over 530 ° C. and 570 ° C. or less, and within 10 seconds. It is preferable to cool to 400 ° C.
また、本発明の合金化溶融亜鉛めっき鋼板の製造において、用いる溶融亜鉛めっき浴はＡｌ濃度が浴中有効Ａｌ濃度で０．１０〜０．１５ｍａｓｓ％に調整することが好ましい。ここでめっき浴中の有効Ａｌ濃度とは、浴中Ａｌ濃度から浴中Ｆｅ濃度を差し引いた値である。 In the production of the alloyed hot-dip galvanized steel sheet of the present invention, the hot dip galvanizing bath used preferably has an Al concentration adjusted to 0.10 to 0.15 mass% as an effective Al concentration in the bath. Here, the effective Al concentration in the plating bath is a value obtained by subtracting the Fe concentration in the bath from the Al concentration in the bath.
有効Ａｌ濃度が０．１０％よりも低い場合には、めっき初期の合金化バリアとなるＦｅ−Ａｌ−Ｚｎ相の形成が不十分となり、合金化温度が５３０℃に達する前に合金化が終了するため、表面に占めるδ1k相の割合が５０〜１００％、めっき／鋼板界面のΓ相厚さが０．１〜０．８μｍとなることを両立することができない。一方、有効Ａｌ濃度が０．１５％よりも高い場合には、高温長時間の合金化が必要となるため、ライン速度を低下させる等、めっきラインの生産性を低下させ、コストを上昇させる必要が生じる。 When the effective Al concentration is lower than 0.10%, the formation of the Fe—Al—Zn phase that becomes an alloying barrier at the initial stage of plating becomes insufficient, and the alloying is completed before the alloying temperature reaches 530 ° C. Therefore, it is impossible to satisfy both the ratio of the δ 1k phase in the surface to 50 to 100% and the Γ phase thickness at the plating / steel sheet interface to 0.1 to 0.8 μm. On the other hand, when the effective Al concentration is higher than 0.15%, high temperature and long time alloying is required. Therefore, it is necessary to decrease the productivity of the plating line and increase the cost, such as decreasing the line speed. Occurs.
また、本発明において、めっき表面の平坦部の面積率が４０〜７０％となることを特徴とする合金化溶融亜鉛めっき層を形成させるためには、合金化処理後、ワークロール径３００〜７００ｍｍのロールで伸長率０．５〜２．０％の調質圧延を行う方法が有効である。 In the present invention, in order to form an alloyed hot-dip galvanized layer characterized in that the area ratio of the flat portion of the plating surface is 40 to 70%, the work roll diameter is 300 to 700 mm after the alloying treatment. A method of performing temper rolling with an elongation of 0.5 to 2.0% with a roll of 2 is effective.
合金化溶融亜鉛めっき鋼板では、ストレッチャーストレインの発生を抑制する目的で、調質圧延が行われる。この調質圧延時、めっき表面は圧延ロールによる圧縮変形を受け、平坦部が形成される。めっき表面の平坦部の面積率を４０％以上とするためには、ワークロール径７００ｍｍ以下のロールで伸長率０．５％以上の調質圧延を行うことが望ましい。 In the galvannealed steel sheet, temper rolling is performed for the purpose of suppressing the occurrence of stretcher strain. During this temper rolling, the plating surface is subjected to compressive deformation by a rolling roll to form a flat portion. In order to make the area ratio of the flat part of the plating surface 40% or more, it is desirable to perform temper rolling with an elongation of 0.5% or more with a roll having a work roll diameter of 700 mm or less.
平坦部の面積率は、単位面積あたりの圧下量で決まるため、ワークロール径が７００ｍｍを超えると目的とする面積率を得られない。ワークロール径が小さくなるほど、単位面積あたりの圧下量が大きくなり、同じ圧下率でもより大きな面積率が得られるようになるため、ワークロール径は小さいほど望ましく、６００ｍｍ以下だとさらに望ましい。 Since the area ratio of the flat portion is determined by the amount of reduction per unit area, the target area ratio cannot be obtained when the work roll diameter exceeds 700 mm. The smaller the work roll diameter, the larger the amount of reduction per unit area, and a larger area ratio can be obtained even with the same reduction ratio. Therefore, the smaller the work roll diameter, the more desirable, and even more preferably 600 mm or less.
同様に伸長率（調質圧延では、板厚の精度を良くするため圧下率の変わりに伸長率を加工度として使用する）は、平坦部の面積率を４０％以上とする目的で、０．５％以上とする。 Similarly, the elongation ratio (in temper rolling, the elongation ratio is used as the degree of processing instead of the reduction ratio in order to improve the accuracy of the plate thickness) is 0. 5% or more.
一方、ワークロール径（２Ｒ）と鋼帯の板厚（ｔ）との比２Ｒ／ｔが４００未満では、十分な形状が得られないため、ワークロール径は３００ｍｍ以上とする。 On the other hand, if the ratio 2R / t between the work roll diameter (2R) and the plate thickness (t) of the steel strip is less than 400, a sufficient shape cannot be obtained, so the work roll diameter is set to 300 mm or more.
また、伸長率が高すぎると、材質が悪化するため、伸長率は２．０％以下とする。 Moreover, since a material will deteriorate if the elongation rate is too high, the elongation rate is set to 2.0% or less.
その他の製造方法は、目的に応じて公知の製造方法と同様の方法を使用すれば良い。 Other manufacturing methods may be similar to known manufacturing methods depending on the purpose.
本発明では鋼板中のＯは特に限定しないが、Ｏは酸化物系介在物を生成して鋼の加工性や耐食性を損なうので、０．００４％以下とすることが望ましく、少ないほど好ましい。 In the present invention, O in the steel sheet is not particularly limited, but O generates oxide inclusions and impairs the workability and corrosion resistance of the steel. Therefore, the O content is desirably 0.004% or less, and the smaller the better.
本発明の鋼板には上記の成分の他に、鋼板自体の耐食性や熱間加工性を一段と改善する目的で、あるいはスクラップ等副原料からの不可避不純物として、他の合金元素を含有することも可能であり、他の合金元素を含有したとしても本発明の範囲を逸脱するものではない。かかる合金元素として、Ｃｕ、Ｎｉ、Ｃｒ、Ｍｏ、Ｗ、Ｃｏ、Ｃａ、希土類元素（Ｙを含む）、Ｖ、Ｚｒ、Ｔａ、Ｈｆ、Ｐｂ、Ｓｎ、Ｚｎ、Ｍｇ、Ｔａ、Ａｓ、Ｓｂ、Ｂｉが挙げられる。 In addition to the above components, the steel sheet of the present invention may contain other alloy elements for the purpose of further improving the corrosion resistance and hot workability of the steel sheet itself, or as an inevitable impurity from secondary materials such as scrap. Even if other alloy elements are contained, it does not depart from the scope of the present invention. Such alloy elements include Cu, Ni, Cr, Mo, W, Co, Ca, rare earth elements (including Y), V, Zr, Ta, Hf, Pb, Sn, Zn, Mg, Ta, As, Sb, Bi. Is mentioned.
本発明鋼板は、通常の溶融亜鉛めっき鋼板製造ラインに適用して、加工性・成形性とめっき密着性の優れた合金化溶融亜鉛めっき鋼板を得ることができるので、製造プロセスに対する制約は特に無い．コスト、生産性を考慮して、適宜プロセスを選択すれば良い。 Since the steel sheet of the present invention can be applied to a normal hot dip galvanized steel sheet production line to obtain an alloyed hot dip galvanized steel sheet having excellent workability, formability and plating adhesion, there is no particular restriction on the manufacturing process. . A process may be selected as appropriate in consideration of cost and productivity.
本発明鋼板は、溶融亜鉛めっき浴中あるいは亜鉛めっき中にＰｂ、Ｓｂ、Ｓｉ、Ｆｅ、Ｓｎ、Ｍｇ、Ｍｎ、Ｎｉ、Ｃｒ、Ｃｏ、Ｃａ、Ｃｕ、Ｌｉ、Ｔｉ、Ｂｅ、Ｂｉ、希土類元素の１種または２種以上を含有、あるいは混入してあっても本発明の効果を損なわず、その量によっては耐食性が改善される等好ましい場合もある。合金化溶融亜鉛めっきの付着量については特に制約は設けないが、耐食性の観点から２０ｇ／ｍ2以上、経済性の観点から１５０ｇ／ｍ2以下で有ることが望ましい。また、合金化溶融亜鉛めっき鋼板の粗度についても特に制約は設けないが、油保持性の観点から、中心線平均粗さＲａ（ＪＩＳ Ｂ０６０１規格）が０．５〜１．５μｍ、ＰＰＩ（１インチあたりに含まれる１．２７μｍ以上の大きさのピークの数、ＳＡＥ、Ｊ９１１規格）が１５０〜３００で有ることが望ましい。 The steel sheet of the present invention is made of Pb, Sb, Si, Fe, Sn, Mg, Mn, Ni, Cr, Co, Ca, Cu, Li, Ti, Be, Bi, rare earth elements during hot dip galvanizing bath or during galvanizing. Even if one kind or two or more kinds are contained or mixed, the effects of the present invention are not impaired, and depending on the amount, the corrosion resistance may be improved. There are no particular restrictions on the amount of galvannealed coating, but it is preferably 20 g / m 2 or more from the viewpoint of corrosion resistance and 150 g / m 2 or less from the viewpoint of economy. The roughness of the galvannealed steel sheet is not particularly limited, but from the viewpoint of oil retention, the center line average roughness Ra (JIS B0601 standard) is 0.5 to 1.5 μm, PPI (1 It is desirable that the number of peaks having a size of 1.27 μm or more included per inch (SAE, J911 standard) is 150 to 300.
本発明において、めっき鋼板の製造方法については特に限定するところはなく、通常の無酸化炉方式やオールラジアント方式の溶融めっき法が適用できる。 In the present invention, the method for producing the plated steel sheet is not particularly limited, and a normal non-oxidizing furnace type or all-radiant type hot dipping method can be applied.
また、本発明において鋼板の板厚は本発明に何ら制約をもたらすものではなく、通常用いられている板厚であれば本発明を適用することが可能である。さらに、本発明鋼板は通常のプロセスで製造される冷延鋼板、熱延鋼板のいずれであってもその効果は充分に発揮されるものであり、鋼板の履歴によって効果が大きく変化するものではない。また、熱間圧延条件、冷間圧延条件、焼鈍条件等は鋼板の寸法、必要とする強度に応じて所定の条件を選択すれば良く、熱間圧延条件、冷間圧延条件、焼鈍条件等によって本発明鋼板の効果が損なわれるものではない。 In the present invention, the thickness of the steel sheet does not impose any restrictions on the present invention, and the present invention can be applied as long as it is a commonly used sheet thickness. Furthermore, the steel sheet of the present invention is sufficiently effective whether it is a cold-rolled steel sheet or a hot-rolled steel sheet manufactured by a normal process, and the effect does not change greatly depending on the history of the steel sheet. . Moreover, the hot rolling conditions, the cold rolling conditions, the annealing conditions, etc. may be selected according to the dimensions of the steel sheet and the required strength, depending on the hot rolling conditions, the cold rolling conditions, the annealing conditions, etc. The effect of the steel sheet of the present invention is not impaired.
以下、実施例により本発明を具体的に説明する。
（実施例１）
Hereinafter, the present invention will be described specifically by way of examples.
Example 1
表１の組成からなるスラブを１１５０℃に加熱し、仕上温度９１０〜９３０℃で４ｍｍの熱間圧延鋼帯とし、６８０〜７２０℃で巻き取った。酸洗後、冷間圧延を施して０．８ｍｍの冷間圧延鋼帯とした後、ライン内焼鈍方式の連続溶融亜鉛めっき設備を用い、合金化溶融亜鉛めっき鋼板を製造した。めっきに際しては、焼鈍雰囲気は５％水素＋９５％窒素混合ガスとし、焼鈍温度は８００〜８４０℃、焼鈍時間は９０秒とした。溶融亜鉛浴は浴中有効Ａｌ濃度０．１０２％のめっき浴を使用し、ガスワイパーで亜鉛の目付量を５０ｇ／ｍ2に調整した。合金化の加熱は誘導加熱方式の加熱設備を使用し、５３０〜５５０℃で合金化を行った。調質圧延は、ワークロール径４８０ｍｍのロールを使用し、表２に示す伸長率で圧延を行った。 A slab having the composition shown in Table 1 was heated to 1150 ° C. to form a 4 mm hot-rolled steel strip at a finishing temperature of 910 to 930 ° C. and wound at 680 to 720 ° C. After pickling and cold rolling to obtain a 0.8 mm cold rolled steel strip, an alloyed hot dip galvanized steel sheet was produced using an in-line annealing continuous hot dip galvanizing facility. In plating, the annealing atmosphere was 5% hydrogen + 95% nitrogen mixed gas, the annealing temperature was 800 to 840 ° C., and the annealing time was 90 seconds. As the molten zinc bath, a plating bath having an effective Al concentration of 0.102% in the bath was used, and the basis weight of zinc was adjusted to 50 g / m 2 with a gas wiper. The alloying was heated at 530 to 550 ° C. using induction heating type heating equipment. For temper rolling, a roll having a work roll diameter of 480 mm was used, and rolling was performed at the elongation shown in Table 2.
めっき中のＦｅ％、Ａｌ％は、めっきをインヒビター入りの塩酸で溶解し、ＩＣＰにより測定して求めた。 Fe% and Al% during plating were obtained by dissolving the plating with hydrochloric acid containing an inhibitor and measuring by ICP.
めっき層表面の各合金相の割合は、ＦＩＢμ−サンプリング法を用いて断面試料を作製し、ＦＥ−ＴＥＭで電子線回折パターン解析を行い測定した。断面試料は任意の場所から５点サンプリングした。各試料のめっき表層からそれぞれ２点の相構造を測定し、計１０点の測定データを使用してめっき層表面の各合金相の割合を求めた。相構造の同定解析は、単斜晶で格子定数がａ＝１３．４Å、ｂ＝７．６Å、ｃ＝５．０６Å、β＝１２７．３であったものをζ相、六方晶で格子定数がａ＝１２．８Å、ｃ＝５７．４Åであったものをδ1p相、δ1p相の３倍周期が観察されるものをδ1k相として行った。 The ratio of each alloy phase on the surface of the plating layer was measured by preparing a cross-sectional sample using the FIB μ-sampling method and analyzing the electron diffraction pattern with FE-TEM. The cross-sectional sample was sampled at five points from an arbitrary location. Two-point phase structures were measured from the plating surface layer of each sample, and the ratio of each alloy phase on the plating layer surface was determined using a total of ten measurement data. The identification analysis of the phase structure shows that the monoclinic crystal lattice constants are a = 13.4１３, b = 7.6Å, c = 0.06Å, β = 127.3 and the lattice constant is ζ phase and hexagonal crystal. there was conducted a = 12.8Å, c = 57.4Å and a thing to [delta] 1p phase, those three times the period of the [delta] 1p phase is observed as [delta] 1k phase.
めっき層中のΓ相の厚さは、埋め込み研磨した断面試料のΓ相をナイタールでエッチングし、ＳＥＭを使用して測定した。Γ相厚みの測定は、任意の場所から５点行い、その値を平均した。 The thickness of the Γ phase in the plating layer was measured by etching the Γ phase of the embedded and polished cross-sectional sample with nital and using SEM. The thickness of the Γ phase was measured at five points from an arbitrary place, and the values were averaged.
めっき表面の平坦部の面積率は、めっき表面をＳＥＭで撮影し、画像処理装置により、調質圧延で平坦となった部分の面積率を測定して求めた。ＳＥＭは任意の場所から５００×４００μｍの範囲を５ヶ所撮影し、その面積率の平均値を代表値とした。 The area ratio of the flat portion of the plating surface was obtained by photographing the plating surface with an SEM and measuring the area ratio of the portion flattened by temper rolling with an image processing apparatus. The SEM photographed five areas of 500 × 400 μm from an arbitrary place, and the average value of the area ratio was used as a representative value.
耐溶接スパッタ付着性は、以下の溶接条件でスポット溶接を行った試験片からサンプルに向かって溶接スパッタを飛散させ、付着したスパッタの状態を評価した。サンプルは他の要因を廃するため、試験前にアルカリ脱脂を行って使用した。溶接スパッタを発生させる試験片には、板厚０．８ｍｍの軟鋼を使用した。スポット溶接は、試験片端面から２ｍｍ内側に電極の円周部が当たるように試験片をセットすることによって、スパッタが狙った方向へ発生するようにした。
溶接条件
加圧力：２００ｋｇｆ
通電時間：１０ｃｙｃ
初期加圧時間：３５ｃｙｃ
保持時間：１ｃｙｃ
電流値：スパッタ発生限界電流＋１ｋＡ
電極−サンプル間距離：１５０ｍｍ
The welding spatter resistance was evaluated by scattering welding spatter from a specimen subjected to spot welding under the following welding conditions toward the sample, and evaluating the state of adhering spatter. In order to eliminate other factors, the sample was used after alkaline degreasing before the test. A mild steel having a thickness of 0.8 mm was used as a test piece for generating welding spatter. Spot welding was made to occur in the direction in which sputtering was aimed by setting the test piece so that the circumference of the electrode hits 2 mm inside from the end face of the test piece.
Welding conditions Pressure: 200kgf
Energizing time: 10 cyc
Initial pressurization time: 35 cyc
Retention time: 1 cyc
Current value: Sputter generation limit current + 1 kA
Electrode-sample distance: 150mm
耐溶接スパッタ付着性は、冷延鋼板のスパッタ付着量を基準にし、以下の分類で評価し、×を不合格とした。
◎：スパッタ付着量が冷延鋼板の２倍以下のもの
○：スパッタ付着量が冷延鋼板の２倍を超え、６倍以下のもの
△：スパッタ付着量が冷延鋼板の６倍を超え、１６倍以下のもの
×：スパッタ付着量が冷延鋼板の１６倍を超えるもの
The welding spatter resistance was evaluated according to the following classification based on the spatter adhesion amount of the cold rolled steel sheet, and x was rejected.
◎: Spatter adherence is less than twice that of cold-rolled steel sheet ○: Spatter adherence is more than twice that of cold-rolled steel sheet, and less than 6 times Less than 16 times x: Spatter adhesion amount exceeds 16 times that of cold-rolled steel sheet
摺動性は、肩Ｒが１ｍｍＲの角ビード（凸部は４×４ｍｍ）を使用して引き抜き試験を行い、その時の見かけの摩擦係数を使用して評価した。引き抜き試験は、防錆油を１ｇ／ｍ2塗油した、幅３０ｍｍ長さ３００ｍｍのサンプルをビード金型で挟んだ後、１０〜１５ｋＮで押し付け加重を変化させて引き抜き、その時の引き抜き荷重を測定した。測定した押し付け加重と引き抜き荷重をそれぞれ横軸と縦軸にとったときの一次関数の比（Δ引き抜き荷重／Δ押し付け加重）を見かけの摩擦係数とし、見かけの摩擦係数が０．３以下のものを合格とした。 The slidability was evaluated using a pull-out test using a square bead with a shoulder R of 1 mmR (the convex part is 4 × 4 mm) and using the apparent friction coefficient at that time. In the pull-out test, a sample with a width of 30 mm and a length of 300 mm, coated with 1 g / m 2 of rust-preventive oil, was sandwiched between bead molds, pulled out by changing the pressing load at 10 to 15 kN, and the pulling load at that time was measured. did. A ratio of linear functions when the measured pressing load and pull-out load are plotted on the horizontal and vertical axes (Δ pull-out load / Δ push load), respectively, with an apparent friction coefficient and an apparent friction coefficient of 0.3 or less Was passed.
結果を表２−１および表２−２にあわせて示す。番号１、７、１３、１９、２５、３１、３７、４３、４９、５５、６１、６７、７３、７９は平坦部の面積率が本発明の範囲外であるため、耐溶接スパッタ付着性が本発明の鋼板より劣っていた。番号６、１２、１８、２４、３０、３６、４２、４８、５４、６０、６６、７２、７８、８４は平坦部の面積率が本発明の範囲外であるため、摺動性が本発明の鋼板より劣っていた。また、番号６、１２、１８、２４、３０、３６、４２、４８、５４、６０、６６、７２、７８、８４は伸長率が大きすぎるためＹＳ／ＴＳが０．６６以上となり、材質が低下していた。 The results are shown in Table 2-1 and Table 2-2. Nos. 1, 7, 13, 19, 25, 31, 37, 43, 49, 55, 61, 67, 73, and 79 have an area ratio of the flat portion outside the range of the present invention. It was inferior to the steel plate of the present invention. Nos. 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, and 84 have flat areas outside the scope of the present invention. It was inferior to the steel plate. In addition, the numbers 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, and 84 have a YS / TS of 0.66 or more because the elongation rate is too large, and the material is deteriorated. Was.
これら以外の本発明品は、優れた耐溶接スパッタ付着性と加工性が両立し、自動車用外板として使用可能な合金化溶融亜鉛めっき鋼板であった。
（実施例２）
The products of the present invention other than these were alloyed hot-dip galvanized steel sheets that had both excellent weld spatter resistance and workability and could be used as automotive outer panels.
(Example 2)
表１の組成からなるスラブを１１５０℃に加熱し、仕上温度９１０〜９３０℃で４ｍｍの熱間圧延鋼帯とし、６８０〜７２０℃で巻き取った。酸洗後、冷間圧延を施して０．８ｍｍの冷間圧延鋼帯とした後、ライン内焼鈍方式の連続溶融亜鉛めっき設備を用い、合金化溶融亜鉛めっき鋼板を製造した。めっきに際しては、焼鈍雰囲気は５％水素＋９５％窒素混合ガスとし、焼鈍温度は８００〜８４０℃、焼鈍時間は９０秒とした。溶融亜鉛浴は浴中有効Ａｌ濃度０．１０２％のめっき浴を使用し、ガスワイパーで亜鉛の目付量を５０ｇ／ｍ2に調整した。合金化の加熱は誘導加熱方式の加熱設備を使用し、表３に示す条件で合金化を行った。調質圧延は、ワークロール径４８０ｍｍのロールを使用し、伸長率０．８％で圧延を行った。 A slab having the composition shown in Table 1 was heated to 1150 ° C. to form a 4 mm hot-rolled steel strip at a finishing temperature of 910 to 930 ° C. and wound at 680 to 720 ° C. After pickling and cold rolling to obtain a 0.8 mm cold rolled steel strip, an alloyed hot dip galvanized steel sheet was produced using an in-line annealing continuous hot dip galvanizing facility. In plating, the annealing atmosphere was 5% hydrogen + 95% nitrogen mixed gas, the annealing temperature was 800 to 840 ° C., and the annealing time was 90 seconds. As the molten zinc bath, a plating bath having an effective Al concentration of 0.102% in the bath was used, and the basis weight of zinc was adjusted to 50 g / m 2 with a gas wiper. The alloying was heated using induction heating type heating equipment under the conditions shown in Table 3. In the temper rolling, a roll having a work roll diameter of 480 mm was used, and rolling was performed at an elongation rate of 0.8%.
めっき中のＦｅ％、Ａｌ％は、めっきをインヒビター入りの塩酸で溶解し、ＩＣＰにより測定して求めた。 Fe% and Al% during plating were obtained by dissolving the plating with hydrochloric acid containing an inhibitor and measuring by ICP.
めっき層表面の各合金相の割合は、ＦＩＢμ−サンプリング法を用いて断面試料を作製し、ＦＥ−ＴＥＭで電子線回折パターン解析を行い測定した。断面試料は任意の場所から５点サンプリングした。各試料のめっき表層からそれぞれ２点の相構造を測定し、計１０点の測定データを使用してめっき層表面の各合金相の割合を求めた。相構造の同定解析は、単斜晶で格子定数がａ＝１３．４Å、ｂ＝７．６Å、ｃ＝５．０６Å、β＝１２７．３であったものをζ相、六方晶で格子定数がａ＝１２．８Å、ｃ＝５７．４Åであったものをδ1p相、δ1p相の３倍周期が観察されるものをδ1k相として行った。 The ratio of each alloy phase on the surface of the plating layer was measured by preparing a cross-sectional sample using the FIB μ-sampling method and analyzing the electron diffraction pattern with FE-TEM. The cross-sectional sample was sampled at five points from an arbitrary location. Two-point phase structures were measured from the plating surface layer of each sample, and the ratio of each alloy phase on the plating layer surface was determined using a total of ten measurement data. The identification analysis of the phase structure shows that the monoclinic crystal lattice constants are a = 13.4１３, b = 7.6Å, c = 0.06Å, β = 127.3 and the lattice constant is ζ phase and hexagonal crystal. there was conducted a = 12.8Å, c = 57.4Å and a thing to [delta] 1p phase, those three times the period of the [delta] 1p phase is observed as [delta] 1k phase.
めっき層中のΓ相の厚さは、埋め込み研磨した断面試料のΓ相をナイタールでエッチングし、ＳＥＭを使用して測定した。Γ相厚みの測定は、任意の場所から５点行い、その値を平均した。 The thickness of the Γ phase in the plating layer was measured by etching the Γ phase of the embedded and polished cross-sectional sample with nital and using SEM. The thickness of the Γ phase was measured at five points from an arbitrary place, and the values were averaged.
また、加工性の指標として、各合金化溶融亜鉛めっき用鋼板の引張試験を行ない、強度、伸び、及びランクフォード値（ｒ値；０゜、４５゜、９０゜の平均ｒ値）を測定した。 In addition, as an index of workability, tensile tests were performed on each alloyed hot-dip galvanized steel sheet, and the strength, elongation, and rankford value (r values; average r values of 0 °, 45 °, and 90 °) were measured. .
深絞り性は、以下の条件のＴＺＰ試験を行い、Ｔ値が０となるブランク径を限界絞り比（ＬＤＲ）として評価した。
ブランク径（Ｄ0）：φ９０ 〜φ１２５ｍｍ
工具サイズ：
ポンチ径（Ｄ0）φ５０ｍｍ、肩ｒ：５ｍｍ
ダイ穴径 φ５１．６ｍｍ、肩ｒ：５ｍｍ
ＢＨＦ：
成形荷重（Ｐ）測定時 ５ｋＮ
破断荷重（Ｐf）測定時 １００ｋＮ
潤滑油 ： 防錆油
評価値 成形余裕度 Ｔ値＝（Ｐf−Ｐ）／Ｐf
For deep drawability, a TZP test was performed under the following conditions, and a blank diameter with a T value of 0 was evaluated as a limit draw ratio (LDR).
Blank diameter (D 0 ): φ90 to φ125 mm
Tool size:
Punch diameter (D 0 ) φ50mm, shoulder r: 5mm
Die hole diameter φ51.6mm, shoulder r: 5mm
BHF:
5kN when measuring molding load (P)
100kN when measuring breaking load (P f )
Lubricating oil: Evaluation value of rust preventive oil Molding margin T value = (P f -P) / P f
めっき密着性は、以下の条件の角筒絞り試験を行い、試験前後の質量差から剥離しためっきの質量を測定し評価した。
角筒絞り試験条件
ブランクサイズ：１５０×１１０ｍｍ
ポンチ寸法：８０×４０ｍｍ
ポンチ肩ｒ：５ｍｍ
ダイス肩ｒ：５ｍｍ
成形深さ：２５ｍｍ
The plating adhesion was evaluated by performing a square tube drawing test under the following conditions, and measuring the mass of the plating peeled from the mass difference before and after the test.
Square tube drawing test condition blank size: 150 × 110mm
Punch size: 80 × 40mm
Punch shoulder r: 5mm
Dice shoulder r: 5mm
Molding depth: 25mm
密着性は、以下の分類で評価し、×を不合格とした。
◎：めっき層の剥離量が５０ｍｇ以下のもの
○：めっき層の剥離量が５０ｍｇを超え、１５０ｍｇ以下のもの
△：めっき層の剥離量が１５０ｍｇを超え、３００ｍｇ以下のもの
×：めっき層の剥離量が３００ｍｇを超えるもの
Adhesion was evaluated according to the following classification, and x was rejected.
：: Plating layer peeling amount of 50 mg or less ○: Plating layer peeling amount of more than 50 mg and 150 mg or less Δ: Plating layer peeling amount of more than 150 mg and 300 mg or less ×: Plating layer peeling Amount exceeding 300mg
めっき表面の平坦部の面積率は、めっき表面をＳＥＭで撮影し、画像処理装置により、調質圧延で平坦となった部分の面積率を測定して求めた。ＳＥＭは任意の場所から５００×４００μｍの範囲を５ヶ所撮影し、その面積率の平均値を代表値とした。 The area ratio of the flat portion of the plating surface was obtained by photographing the plating surface with an SEM and measuring the area ratio of the portion flattened by temper rolling with an image processing apparatus. The SEM photographed five areas of 500 × 400 μm from an arbitrary place, and the average value of the area ratio was used as a representative value.
耐溶接スパッタ付着性は、以下の溶接条件でスポット溶接を行った試験片からサンプルに向かって溶接スパッタを飛散させ、付着したスパッタの状態を評価した。サンプルは他の要因を廃するため、試験前にアルカリ脱脂を行って使用した。溶接スパッタを発生させる試験片には、板厚０．８ｍｍの軟鋼を使用した。スポット溶接は、試験片端面から２ｍｍ内側に電極の円周部が当たるように試験片をセットすることによって、スパッタが狙った方向へ発生するようにした。
溶接条件
加圧力：２００ｋｇｆ
通電時間：１０ｃｙｃ
初期加圧時間：３５ｃｙｃ
保持時間：１ｃｙｃ
電流値：スパッタ発生限界電流＋１ｋＡ
電極−サンプル間距離：１５０ｍｍ
The welding spatter resistance was evaluated by scattering welding spatter from a specimen subjected to spot welding under the following welding conditions toward the sample, and evaluating the state of adhering spatter. In order to eliminate other factors, the sample was used after alkaline degreasing before the test. A mild steel having a thickness of 0.8 mm was used as a test piece for generating welding spatter. Spot welding was made to occur in the direction in which sputtering was aimed by setting the test piece so that the circumference of the electrode hits 2 mm inside from the end face of the test piece.
Welding conditions Pressure: 200kgf
Energizing time: 10 cyc
Initial pressurization time: 35 cyc
Retention time: 1 cyc
Current value: Sputter generation limit current + 1 kA
Electrode-sample distance: 150mm
耐溶接スパッタ付着性は、冷延鋼板のスパッタ付着量を基準にし、以下の分類で評価し、×を不合格とした。
◎：スパッタ付着量が冷延鋼板の２倍以下のもの
○：スパッタ付着量が冷延鋼板の２倍を超え、６倍以下のもの
△：スパッタ付着量が冷延鋼板の６倍を超え、１６倍以下のもの
×：スパッタ付着量が冷延鋼板の１６倍を超えるもの
The welding spatter resistance was evaluated according to the following classification based on the spatter adhesion amount of the cold rolled steel sheet, and x was rejected.
◎: Spatter adherence is less than twice that of cold-rolled steel sheet ○: Spatter adherence is more than twice that of cold-rolled steel sheet, and less than 6 times Less than 16 times x: Spatter adhesion amount exceeds 16 times that of cold-rolled steel sheet
結果を表３にあわせて示す。番号１、２、９、１０、１７、１８、２５、２６は合金化温度が低いため、めっき表層にδ1k相が形成されていない合金化溶融亜鉛めっき用鋼板の例である。番号３、１１、１９、２７は、めっき表層にδ1k相を形成することを目的に、低温長時間合金化したため、Γ相厚が本発明の範囲外となり、めっき密着性が不合格となった。番号６、１４、２２、３０は、合金化温度到達後４００℃となるまでの時間が長いため、Γ相厚が本発明の範囲外となり、めっき密着性が不合格となった。 The results are shown in Table 3. Nos. 1, 2, 9, 10, 17, 18, 25, and 26 are examples of steel plates for alloying hot dip galvanization in which the δ 1k phase is not formed on the plating surface layer because the alloying temperature is low. Nos. 3, 11, 19, and 27 were alloyed at low temperatures for a long time for the purpose of forming a δ 1k phase on the plating surface layer, so the Γ phase thickness was outside the scope of the present invention, and the plating adhesion was rejected. It was. Nos. 6, 14, 22, and 30 had a long time until reaching 400 ° C. after reaching the alloying temperature, so the Γ phase thickness was out of the range of the present invention, and the plating adhesion was unacceptable.
これら以外の本発明品は、優れた深絞り性と高いめっき密着性が両立し、自動車用外板として使用可能な合金化溶融亜鉛めっき鋼板であった。めっき層表面に占めるδ1k相の割合を５０〜１００％とした本発明品は、めっき表層にδ1k相が形成されていない比較例に比べ、ＬＤＲの値が０．１〜０．２向上する。表３の結果を比較して解るように、これは、ｒ値を０．２〜０．４向上させたことと同等の深絞り性向上効果であった。 The products of the present invention other than these were alloyed hot-dip galvanized steel sheets that have both excellent deep drawability and high plating adhesion and can be used as automotive outer plates. The product of the present invention in which the ratio of the δ 1k phase occupying the surface of the plating layer is 50 to 100% improves the LDR value by 0.1 to 0.2 compared to the comparative example in which the δ 1k phase is not formed on the plating surface layer. To do. As can be seen by comparing the results in Table 3, this was an effect of improving the deep drawability equivalent to increasing the r value by 0.2 to 0.4.
Claims (6)
On one or both sides of the steel plate, Al: 0.05 to 0.5% by mass, Fe: more than 10 to 17% by mass, the balance is made of Zn and inevitable impurities, and the area ratio of the flat part of the plating surface is 40 to 60%. An alloyed hot-dip galvanized layer is formed in which the ratio of the δ 1k phase to the plating surface is 50 to 100% and the average thickness of the Γ phase at the plating / steel interface is 0.1 to 0.5 μm. Alloyed hot-dip galvanized steel sheet with excellent workability and spatter resistance.
Ｃ：０．０００１〜０．０１５％、
Ｓｉ：０．００１〜０．４５％、
Ｍｎ：０．０１〜２．８％、
Ｐ：０．００１〜０．１％、
Ｓ：０．０１５％以下、
Ａｌ：０．０００５〜０．０５％、
Ｔｉ：０．００２〜０．１０％、
Ｎ：０．０００５〜０．００４％、
を含有し、残部がＦｅおよび不可避不純物からなることを特徴とする請求項１に記載の合金化溶融亜鉛めっき鋼板。 The steel plate is mass%,
C: 0.0001 to 0.015%,
Si: 0.001 to 0.45%,
Mn: 0.01 to 2.8%,
P: 0.001 to 0.1%,
S: 0.015% or less,
Al: 0.0005 to 0.05%,
Ti: 0.002 to 0.10%,
N: 0.0005 to 0.004%,
The alloyed hot-dip galvanized steel sheet according to claim 1, wherein the balance is made of Fe and inevitable impurities.
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| JP5906633B2 (en) | 2011-09-26 | 2016-04-20 | Ｊｆｅスチール株式会社 | Alloyed hot-dip galvanized steel sheet with excellent corrosion resistance after painting |
| PL3204530T3 (en) | 2014-10-09 | 2019-07-31 | Thyssenkrupp Steel Europe Ag | Cold rolled steel sheet and recrystallisation-annealed steel flat product and method for producing the same |
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