JP4564207B2 - Hot-pressed hot-dip aluminized steel sheet that is heated to 800 ° C or higher - Google Patents
Hot-pressed hot-dip aluminized steel sheet that is heated to 800 ° C or higher Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、高温でのプレス成形性に優れ、かつ極めて高い機械強度を有し、良好な耐食性、外観を有する溶融アルミめっき鋼板に関するものである。
【０００２】
【従来の技術】
近年、環境保護と地球温暖化を防止するため化石燃料の消費を抑制する動きが強まっており、移動手段として我々の生活に欠かせない自動車においても車体の軽量化が強く求められている。この軽量化を達成するためには、従来に比べ高い機械強度を有する材料を使用することが必要になるが、一般に高い強度を有する材料は曲げ加工などの成形加工において形状凍結性が低下する傾向にあり、また複雑な形状のものに対しては成形そのものが困難である。
【０００３】
これらの問題を解決する方法の一つとして、８００℃以上の高温に加熱し、プレス加工を行った後冷却するいわゆる高温プレスによる方法が有望である。この手法によれば、一旦高温に加熱して軟化した状態にすれば容易にプレス成形でき、さらに成形後の冷却時の焼入れ効果により高強度化を可能にしたもので、良好な形状凍結性と高強度を有した成形品が得られる。しかし、鋼板を８００℃程度の高温に加熱するため表面に酸化物（スケール）が発生し、それを取り除くための工程が発生する。また、耐食性を必要とする部材などでは、表面に防錆処理や金属被覆する必要があり、表面洗浄化工程、表面処理工程が必要となる。
【０００４】
これらの欠点を克服する方法として、特開２０００−３８６４０号公報に開示されているように、所定の鋼成分を有する鋼にＡｌ系の金属被覆を施した鋼板を用いる知見が示されている。しかしながら、この知見では目的とする材料強度は得られるものの、プレス前の予備加熱条件によっては、鋼板のＦｅとめっき層のＡｌによる合金層が成長しすぎて表面が荒れ、外観を損ねると共に、耐食性が低下するおそれがある、という欠点がある。
【０００５】
【発明が解決しようとする課題】
本発明は、加熱時における上記のＡｌ−Ｆｅ合金層の成長を抑制することで美麗な外観を有し、かつ優れた耐食性を有した高強度成形品を可能とする８００℃以上に加熱しプレス加工する高温プレス用の溶融アルミめっき鋼板を提供するものである。
【０００６】
【課題を解決するための手段】
本発明者らは、鋼板成分およびめっき浴組成が高温プレス成形性に及ぼす諸因子を詳細に検討した結果、特定の元素を含有する鋼板を使用し、かつめっき浴成分を制御することで合金層成長を制御でき、高い強度を有する外観良好な成形品を得ることができることを見いだした。すなわち、鋼板の高強度化にはＣ、Ｍｎ、Ｂの添加と、Ｓｉ、Ｐ、Ｓ、Ａｌ、Ｔｉ、Ｃｒをある量に制限することが有効であり、冷却時に十分な焼入れ効果が得られ１０００〜２０００ＭＰａの高い強度が得られること、かつ鋼板の酸化を防止し美麗な外観を得るためには、Ａｌ、Ｓｉ、Ｃｒを主成分とするめっき金属の被覆が有効であり、特にＳｉとＣｒの働きによって、加熱時のＡｌ−Ｆｅ合金化反応が抑制されることを見出した。
【０００７】
本発明によれば、
（１）質量％で、Ｃ：０．１％以上０．６％以下を含み、残部Ｆｅ及び不可避的不純物からなる鋼板に、Ｓｉ：３％以上１５％以下、Ｃｒ：０．０１％以上２％以下を含み、残部Ａｌ及び不可避的不純物からなるアルミめっき被覆層を施したことを特徴とする８００℃以上に加熱しプレス加工する高温プレス用の溶融アルミめっき鋼板。
（２）質量％で、Ｃ：０．１％以上０．６％以下、Ｍｎ：０．１％以上３．０％以下を含み、残部Ｆｅ及び不可避的不純物からなる鋼板に、Ｓｉ：３％以上１５％以下、Ｃｒ：０．０１％以上２％以下を含み、残部Ａｌ及び不可避的不純物からなるアルミめっき被覆層を施したことを特徴とする８００℃以上に加熱しプレス加工する高温プレス用の溶融アルミめっき鋼板。
【０００８】
（３）Ｃ：０．１％以上０．６％以下、Ｍｎ：０．１％以上３．０％以下、Ｂ：０．０００２％以上０．０１％以下を含み、残部Ｆｅ及び不可避的不純物からなる鋼板に、Ｓｉ：３％以上１５％以下、Ｃｒ：０．０１％以上２％以下を含み、残部Ａｌ及び不可避的不純物からなるアルミめっき被覆層を施したことを特徴とする８００℃以上に加熱しプレス加工する高温プレス用の溶融アルミめっき鋼板。
（４）鋼板中のＳｉ含有量が、質量％でＳｉ：０．０１％以上０．５％以下であることを特徴とする、前記（１）〜（３）に記載の溶融アルミめっき鋼板。
【０００９】
（５）鋼板中のＰ、Ｓ、Ａｌ含有量が、質量％でＰ：０．１％以下、Ｓ：０．０２％以下、Ａｌ：０．００５％以上０．１％以下であることを特徴とする前記（４）に記載の溶融アルミめっき鋼板。
（６）鋼板中にＴｉ、Ｃｒを少なくとも１種以上含み、その（Ｔｉ＋Ｃｒ）含有量が０．００５％以上で、上限がそれぞれＴｉ：０．２％以下、Ｃｒ：１．０％以下であることを特徴とする前記（５）に記載の溶融アルミめっき鋼板を提供する。
【００１０】
【発明の実施の形態】
本発明の成分及び含有量の限定理由を次に述べる。
Ｃは目的とする強度を確保するために添加する。Ｃが０．１％未満だと十分な強度が得られず効果に乏しい。一方、０．６％を超えるとさらに高強度化するものの溶接割れが生じやすくなるため、上限を０．６％以下とした。
Ｍｎは強化元素であり、焼入れ性を高める元素でもある。かつ、不純物であるＳによる熱間脆性を防止するのに有効である。Ｍｎが０．１％以上においてそれらの効果が発現する。一方、３．０％を超えると残留γ相が多くなりすぎ強度が低下する。そのため、Ｍｎ濃度は０．１％以上３．０％以下とした。
【００１１】
Ｂは焼入れ時に作用し強度を向上させる効果をもつ。０．０００２％以上の添加で作用するが、０．０１％超では介在物を形成して脆化し疲労強度を低下させるため、０．０００２％以上０．０１％以下とする。
Ｓｉは強度向上元素として有効であるが、易酸化性元素でもあり、溶融アルミめっきを行う際、鋼中のＳｉ濃度が０．５％を超えると濡れ性が低下し不めっきが生じる。従って、Ｓｉは０．５％以下とする。
Ｐは強度強化元素であるが０．１％を超える添加は靱性を低下させる。従って、０．１％以下とする。
【００１２】
Ｓは硫化物系介在物による成形性低下のため少ないほど好ましいが、０．０２％まで許容できる。従って、Ｓは０．０２％以下とする。
Ａｌは脱酸剤として作用する。この目的のためには０．００５％以上が必要であるが、０．１％を超えると効果は飽和し、かえって介在物を形成して脆化させるため、上限値を０．１％とした。従って、Ａｌは０．００５％以上０．１％以下とする。
【００１３】
Ｔｉは強度強化元素であり、また、アルミめっきの耐熱性を向上させる元素でもあるが、あまり添加しすぎると炭化物、窒化物を形成して軟質化してしまう恐れがある。０．００５％以上の添加で強度向上効果、耐酸化性向上効果が現れるが、０．２％より多く添加すると目的とする強度が得られない可能性がある。また、Ｃｒも強度強化元素であり、かつ耐食性も向上するが、その効果を得るには０．００５％以上添加する必要がある。ＴｉとＣｒを同時に添加する場合には、Ｔｉ＋Ｃｒで０．００５％以上あれば強度向上効果が得られる。一方、Ｃｒを１．０％より多量に添加しても強度の向上効果は少なく、コストが増大するため、Ｃｒの上限値を１．０％とした。
その他の成分については特に制限していないが、Ｃｕ，Ｎｉ，Ｃｒ，Ｓｎ，Ｖ，Ｗ，Ｚｒ，Ｍｏ，Ａｓ等のスクラップから混入する元素が存在しても、本発明の鋼の特性には全く影響しない。
【００１４】
次に、アルミめっき層成分及び含有量の限定理由について述べる。
Ｓｉは溶融めっき金属被覆時に生成する合金層の制御が目的で添加する。このＳｉの含有量は、３％以上１５％以下が好適である。３％未満だとＦｅ−Ａｌ合金層がめっき段階で厚く成長し、加工時にめっき層割れを助長して耐食性に悪影響を及ぼす。一方、１５％超ではめっき層の加工性、耐食性が低下するため、Ｓｉ含有量は３％以上１５％以下とした。
【００１５】
本発明ではめっき浴中にＣｒを少量添加することを特徴とする。Ｃｒを添加すると、Ｃｒはめっき層と鋼板の間に形成されるＦｅ−Ａｌ−Ｓｉ合金層に含有される。これが高温プレス時のＦｅの拡散を抑制し、合金層の成長を抑制する。そのため加工後も美麗な外観を得られ、また、耐食性も完全に合金化した場合に比較して格段に優れている。この効果を得るためにはＣｒは０．０１％以上の添加が必要である。より発揮させるためには０．０２％以上の添加が望ましい。一方、２％以上添加すると浴の融点が高くなりすぎて操業に支障をきたす。従って、Ｃｒ添加量は０．０１％以上２％未満とする。
【００１６】
また、めっき層中には主成分のＡｌ，Ｓｉ，Ｃｒ以外に、通常約２％のＦｅが含まれることが多いが、Ｆｅは浴中の機器やストリップから供給される不可避のものであり、本発明のめっき層の特性には影響しない。
その他、めっき金属インゴット、浴中機器、ストリップから混入する不純物、例えば、Ｚｎ、Ｎｉ、Ｃｕ，Ｍｇ、Ｍｎ、Ｃｏ、Ｐｂ、Ｓｎ、Ａｓ、Ｓｂなどの元素が微量存在しても、本発明のめっき特性には全く影響しない。
めっき層の厚みについては本発明では特に制限を設けない。実使用上は片側あたり合金層まで含めて厚み８〜４０μｍで何ら問題なく使用可能である。
【００１７】
また、溶融めっき後の後処理として、クロメート処理皮膜、Ｃｒ、Ｓｉ、Ｐ、Ｚｎの化合物及びアクリル樹脂の少なくとも１種以上よりなる皮膜、有機皮膜処理のほかに、溶融めっき後の外観均一化処理であるゼロスパングル処理（ｍｉｎｉｍｉｚｅｄ ｓｐａｎｇｌｉｎｇ）、めっき層の加工性改善処理である焼鈍処理等があり得るが、本発明においては特にこれらを限定せず、適用することも可能である。
溶融アルミめっき鋼板の製造工程についても何ら限定するものではなく、通常の製鋼、熱延、冷延、焼鈍条件が適用可能である。また、Ｎｉ，Ｆｅプレめっき等もありうるが、これも適用可能である。
次に実施例により本発明を更に詳細に説明する。
【００１８】
【実施例】
表１に示す成分の鋼を転炉−真空脱ガス処理により溶製し、鋼片とした後、熱間圧延、冷間圧延を経て板厚１．２ｍｍの冷延鋼板、板厚１．８ｍｍの酸洗後の熱延鋼板を得た。鋼種Ａ〜Ｈが冷延鋼板、鋼種Ｉ、Ｊが熱延鋼板である。これらの鋼板を無酸化炉−還元炉方式のラインを使用して還元−焼鈍を行った後、表２に示すアルミめっき浴に浸漬して溶融めっきを行った。めっき後ガスワイピングでめっき付着量を片面あたり２５μｍに調節した。このときのめっき組成は、主成分のＡｌ以外に表中のＳｉ、Ｃｒ、それに２％のＦｅが含まれていたが、Ｆｅは浴中の機器やストリップから供給される不可避のものである。こうして製造しためっき鋼板について、熱処理後の強度と耐食性を評価した。
【００１９】
評価方法は以下によった。
（１）熱処理後の強度
９００℃の温度で５ｍｉｎ熱処理し、鋼板にはさんで冷却した後、ＪＩＳ５号引張り試験片にて引張り試験を実施し、引張り強度（ＴＳ）を測定した。
（２）高温プレス成形性評価
９００℃の温度で５ｍｉｎ加熱した後、５０ｍｍφの円筒プレス試験により表面の外観を観察した。
○：成形可能で、表面外観に変化無し
△：成形可能で、表面外観わずかに黒化
×：成形可能で、全面黒化もしくはスケール発生
【００２０】
（３）耐食性評価
（２）で作製した円筒プレス成形品について湿度９５％以上、温度４０℃にて湿潤試験を２４ｈ実施し、外観を観察した。
○：赤錆発生無し
△：わずかに赤錆発生
×：前面赤錆発生
【００２１】
【表１】
【表２】
Ｎｏ．１１は目的とする高強度は得られたものの、めっき層中のＣｒが無かったため、プレス成形後の外観が良くなかった。Ｎｏ．１２も目的とする高強度は得られたものの、めっき層中のＳｉが高すぎたため、プレス成形後の外観が良くなかった。また、Ｎｏ．１３、１５は、Ｃの量が少なく、必要な焼入れ性が得られずに目的とする高強度が得られなかった。Ｎｏ．１４ではＭｎの量が高すぎ、目的の強度が得られなかった。Ｎｏ．１〜１０については、強度、外観、耐食性とも良好な特性が得られた。特に、Ｎｏ．１〜３においては、Ｃだけでなく、Ｍｎ、さらにはＢを添加すると強度が向上する傾向である。また、Ｎｏ．２とＮｏ．９はＴｉ，Ｃｒの添加も強度が向上する傾向がある。
【００２４】
【発明の効果】
以上述べたように、本発明は、高温プレス時の課題であった外観を改善し、かつ必要な耐食性を兼備した高強度プレス品用溶融アルミめっき鋼板を提供するもので、今後材料の軽量化が求められたときの新しい材料として非常に有望であり、産業上の寄与も大きい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hot dip galvanized steel sheet having excellent press formability at high temperature, extremely high mechanical strength, good corrosion resistance and appearance.
[0002]
[Prior art]
In recent years, there has been an increasing movement to reduce fossil fuel consumption in order to protect the environment and prevent global warming, and there is a strong demand for weight reduction in automobiles that are indispensable for our daily lives as a means of transportation. In order to achieve this weight reduction, it is necessary to use a material having a higher mechanical strength than before, but generally a material having a higher strength tends to have a lower shape freezing property in a molding process such as bending. In addition, it is difficult to form a complicated shape.
[0003]
As a method for solving these problems, a so-called high-temperature press method in which heating is performed at a high temperature of 800 ° C. or higher, press-processing, and cooling is promising. According to this method, once it is heated to a high temperature and softened, it can be easily press-molded, and it can be strengthened by the quenching effect at the time of cooling after molding. A molded product having high strength is obtained. However, since the steel sheet is heated to a high temperature of about 800 ° C., oxide (scale) is generated on the surface, and a process for removing it is generated. Moreover, in the member etc. which require corrosion resistance, it is necessary to carry out a rust prevention process or metal coating on the surface, and a surface cleaning process and a surface treatment process are needed.
[0004]
As a method for overcoming these drawbacks, as disclosed in Japanese Patent Application Laid-Open No. 2000-38640, there has been shown knowledge of using a steel plate having a predetermined steel component and an Al-based metal coating. However, with this knowledge, the desired material strength can be obtained, but depending on the preheating conditions before pressing, the alloy layer of Fe of the steel sheet and Al of the plating layer grows too much, the surface becomes rough, the appearance is impaired, and the corrosion resistance There is a drawback in that there is a risk of lowering.
[0005]
[Problems to be solved by the invention]
The present invention has a beautiful appearance by suppressing the growth of the Al—Fe alloy layer during heating and is heated to 800 ° C. or higher to enable a high-strength molded product having excellent corrosion resistance. The present invention provides a hot-dip pressed aluminum-plated steel sheet for processing .
[0006]
[Means for Solving the Problems]
As a result of detailed examination of various factors that the steel plate component and the plating bath composition have on the high temperature press formability, the present inventors have used a steel plate containing a specific element and controlled the plating bath component to obtain an alloy layer. It has been found that it is possible to control the growth and obtain a molded article having high strength and good appearance. That is, to increase the strength of the steel sheet, it is effective to add C, Mn, B and limit Si, P, S, Al, Ti, Cr to a certain amount, and a sufficient quenching effect can be obtained during cooling. In order to obtain a high strength of 1000 to 2000 MPa, and to prevent the oxidation of the steel sheet and obtain a beautiful appearance, it is effective to coat a plated metal mainly composed of Al, Si, and Cr, particularly Si and Cr. It was found that the Al—Fe alloying reaction during heating is suppressed by the action of.
[0007]
According to the present invention,
(1) In steel plates containing C: 0.1% or more and 0.6% or less, and the balance Fe and unavoidable impurities, Si: 3% or more and 15% or less, Cr: 0.01% or more 2 A hot-pressed hot-dip galvanized steel sheet that is heated to 800 ° C. or higher and press-worked, wherein an aluminum plating coating layer comprising the remaining Al and the inevitable impurities is applied.
(2) By mass%, C: 0.1% or more and 0.6% or less, Mn: 0.1% or more and 3.0% or less, and the balance Fe and unavoidable impurities are added to the steel sheet, Si: 3% 15% or less, Cr: 0.01% or more and 2% or less, with an aluminum plating coating layer composed of the remaining Al and inevitable impurities, and for high-temperature presses that are heated to 800 ° C or higher and are pressed the molten aluminum-plated steel sheet.
[0008]
(3) C: 0.1% to 0.6%, Mn: 0.1% to 3.0%, B: 0.0002% to 0.01%, the remainder Fe and inevitable impurities 800 ° C. or higher , characterized in that an aluminum plating coating layer comprising Si: 3% or more and 15% or less, Cr: 0.01% or more and 2% or less, and the balance Al and inevitable impurities is applied to the steel plate made of Hot-pressed hot-dip aluminized steel sheet that is heated and pressed .
(4) Si content in the steel sheet, Si by mass%: is characterized in that 0.01% to 0.5% or less, the (1) to molten aluminum-plated steel sheet according to (3) .
[0009]
(5) The P, S, and Al contents in the steel sheet are P: 0.1% or less, S: 0.02% or less, and Al: 0.005% or more and 0.1% or less in mass%. molten aluminum-plated steel sheet according to (4), characterized.
(6) The steel sheet contains at least one kind of Ti and Cr, the (Ti + Cr) content is 0.005% or more, and the upper limit is Ti: 0.2% or less and Cr: 1.0% or less, respectively. providing molten aluminum-plated steel sheet according to (5), characterized in that.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The reasons for limiting the components and contents of the present invention will be described below.
C is added to ensure the desired strength. If C is less than 0.1%, sufficient strength cannot be obtained and the effect is poor. On the other hand, if it exceeds 0.6%, the strength is further increased, but weld cracking tends to occur, so the upper limit was made 0.6% or less.
Mn is a strengthening element and also an element that enhances hardenability. Moreover, it is effective in preventing hot brittleness due to the impurity S. These effects are manifested when Mn is 0.1% or more. On the other hand, if it exceeds 3.0%, the residual γ phase becomes too much and the strength decreases. Therefore, the Mn concentration is set to 0.1% or more and 3.0% or less.
[0011]
B acts during quenching and has the effect of improving strength. Addition of 0.0002% or more acts, but if it exceeds 0.01%, inclusions are formed and become brittle and reduce fatigue strength. Therefore, the content is made 0.0002% or more and 0.01% or less.
Si is effective as a strength improving element, but is also an easily oxidizable element. When performing hot dip aluminum plating, if the Si concentration in the steel exceeds 0.5%, wettability is reduced and non-plating occurs. Therefore, Si is 0.5% or less.
P is a strength enhancing element, but addition exceeding 0.1% lowers toughness. Therefore, it is made 0.1% or less.
[0012]
S is preferably as small as possible because of the decrease in moldability due to sulfide inclusions, but it is acceptable up to 0.02%. Accordingly, S is set to 0.02% or less.
Al acts as a deoxidizer. For this purpose, 0.005% or more is necessary, but if it exceeds 0.1%, the effect is saturated, and on the other hand, inclusions are formed and embrittled, so the upper limit was made 0.1%. . Therefore, Al is made 0.005% or more and 0.1% or less.
[0013]
Ti is a strength-enhancing element and is also an element that improves the heat resistance of aluminum plating. However, if it is added too much, it may form carbides and nitrides and soften. When 0.005% or more is added, the effect of improving the strength and the effect of improving the oxidation resistance appear, but if it is added more than 0.2%, the intended strength may not be obtained. Cr is also a strength-enhancing element and improves corrosion resistance. However, to obtain the effect, it is necessary to add 0.005% or more. In the case where Ti and Cr are added at the same time, an effect of improving the strength can be obtained if Ti + Cr is 0.005% or more. On the other hand, even if Cr is added in a larger amount than 1.0%, the effect of improving the strength is small and the cost increases. Therefore, the upper limit value of Cr is set to 1.0%.
The other components are not particularly limited. However, even if elements mixed from scrap such as Cu, Ni, Cr, Sn, V, W, Zr, Mo, As are present, the characteristics of the steel of the present invention are not limited. No effect at all.
[0014]
Next, the reasons for limiting the components of the aluminum plating layer and the content will be described.
Si is added for the purpose of controlling the alloy layer produced during hot-dip metal coating. The Si content is preferably 3% or more and 15% or less. If it is less than 3%, the Fe—Al alloy layer grows thick at the plating stage, promotes cracking of the plating layer during processing, and adversely affects the corrosion resistance. On the other hand, if it exceeds 15%, the workability and corrosion resistance of the plating layer deteriorate, so the Si content is 3% or more and 15% or less.
[0015]
The present invention is characterized in that a small amount of Cr is added to the plating bath. When Cr is added, Cr is contained in the Fe—Al—Si alloy layer formed between the plating layer and the steel plate. This suppresses the diffusion of Fe during high-temperature pressing and suppresses the growth of the alloy layer. Therefore, a beautiful appearance can be obtained even after processing, and the corrosion resistance is remarkably excellent as compared with the case where it is completely alloyed. In order to obtain this effect, Cr needs to be added in an amount of 0.01% or more. In order to exhibit more, addition of 0.02% or more is desirable. On the other hand, if 2% or more is added, the melting point of the bath becomes too high, which hinders operation. Therefore, the Cr addition amount is 0.01% or more and less than 2%.
[0016]
The plating layer usually contains about 2% Fe in addition to the main components Al, Si, Cr, but Fe is inevitable supplied from equipment and strips in the bath, It does not affect the characteristics of the plating layer of the present invention.
In addition, even if a trace amount of impurities such as Zn, Ni, Cu, Mg, Mn, Co, Pb, Sn, As, and Sb is present in the metal plating ingot, the equipment in the bath, and the strip, the present invention It does not affect the plating characteristics at all.
The thickness of the plating layer is not particularly limited in the present invention. In practical use, it can be used without any problem with a thickness of 8 to 40 μm including the alloy layer per side.
[0017]
Moreover, as post-treatment after hot dipping, in addition to chromate treatment film, Cr, Si, P, Zn compound and film made of at least one of acrylic resin, organic film treatment, appearance homogenization after hot dipping However, in the present invention, these are not particularly limited, and can be applied.
The manufacturing process of the hot-dip aluminum-plated steel sheet is not limited at all, and normal steelmaking, hot rolling, cold rolling, and annealing conditions can be applied. Ni, Fe pre-plating, etc. can also be used, but this is also applicable.
Next, the present invention will be described in more detail with reference to examples.
[0018]
【Example】
Steel of the components shown in Table 1 is melted by a converter-vacuum degassing treatment to form a steel slab, which is then subjected to hot rolling and cold rolling to obtain a cold rolled steel sheet having a thickness of 1.2 mm, a thickness of 1.8 mm. A hot-rolled steel sheet after pickling was obtained. Steel types A to H are cold-rolled steel plates, and steel types I and J are hot-rolled steel plates. These steel sheets were subjected to reduction-annealing using a non-oxidation furnace-reduction furnace type line, and then immersed in an aluminum plating bath shown in Table 2 to perform hot dipping. After plating, the amount of plating adhered was adjusted to 25 μm per side by gas wiping. The plating composition at this time contained Si, Cr, and 2% Fe in the table in addition to Al as the main component, but Fe is inevitable supplied from equipment and strips in the bath. The plated steel sheet thus manufactured was evaluated for strength and corrosion resistance after heat treatment.
[0019]
The evaluation method was as follows.
(1) Strength after heat treatment After heat treatment at a temperature of 900 ° C. for 5 minutes and cooling between steel plates, a tensile test was performed with a JIS No. 5 tensile test piece, and the tensile strength (TS) was measured.
(2) Evaluation of high-temperature press formability After heating at 900 ° C. for 5 minutes, the appearance of the surface was observed by a cylindrical press test of 50 mmφ.
○: Moldable, no change in surface appearance △: Moldable, slightly blackened surface appearance ×: Moldable, entire surface blackened or scale generated [0020]
(3) Evaluation of corrosion resistance The cylindrical press-molded product produced in (2) was subjected to a wet test at a humidity of 95% or more and a temperature of 40 ° C. for 24 hours, and the appearance was observed.
○: No red rust △: Slight red rust ×: Front red rust [0021]
[Table 1]
[Table 2]
No. No. 11 had the desired high strength, but had no Cr in the plating layer, so the appearance after press molding was not good. No. Although the intended high strength of No. 12 was obtained, the appearance after press molding was not good because Si in the plating layer was too high. No. In Nos. 13 and 15, the amount of C was small, and the required hardenability could not be obtained, and the intended high strength could not be obtained. No. In No. 14, the amount of Mn was too high, and the desired strength was not obtained. No. About 1-10, the characteristic with favorable intensity | strength, external appearance, and corrosion resistance was acquired. In particular, no. In 1-3, when not only C but Mn and also B are added, it exists in the tendency for an intensity | strength to improve. No. 2 and No. In No. 9, the addition of Ti and Cr tends to improve the strength.
[0024]
【The invention's effect】
As described above, the present invention provides a hot-dip galvanized steel sheet for high-strength press products that improves the appearance, which was a problem during high-temperature pressing, and also has the necessary corrosion resistance. It is very promising as a new material when demanded for, and has a great industrial contribution.
Claims (6)
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001190709A JP4564207B2 (en) | 2001-06-25 | 2001-06-25 | Hot-pressed hot-dip aluminized steel sheet that is heated to 800 ° C or higher |
| KR1020037016351A KR100836282B1 (en) | 2001-06-15 | 2002-06-14 | High-strength alloyed aluminum-system palted steel sheet |
| AU2002309283A AU2002309283B2 (en) | 2001-06-15 | 2002-06-14 | High-strength Alloyed Aluminum-system Plated Steel Sheet and High-strength Automotive Part Excellent in Heat Resistance and After-painting Corrosion Resistance |
| PCT/JP2002/005978 WO2002103073A2 (en) | 2001-06-15 | 2002-06-14 | High-strength alloyed aluminum-system plated steel sheet and high-strength automotive part excellent in heat resistance and after-painting corrosion resistance |
| KR1020077017549A KR20070087240A (en) | 2001-06-15 | 2002-06-14 | Hot press method of high-strength alloyed aluminum-system palted steel sheet |
| KR1020087029007A KR20080108163A (en) | 2001-06-15 | 2002-06-14 | Hot press method of high-strength alloyed aluminum-system palted steel sheet |
| CNB028120361A CN100370054C (en) | 2001-06-15 | 2002-06-14 | High-strength alloyed aluminum-system plated steel sheet and high-strength automotive part excellent in heat resistance and after-painting corrosion resistance |
| TW091113018A TWI317383B (en) | 2001-06-15 | 2002-06-14 | High-strength alloyed aluminum-system plated steel sheet and high-strength automotive part excellent in heat resistance and after-painting corrosion resistance |
| KR1020077027723A KR20070119096A (en) | 2001-06-15 | 2002-06-14 | High-strength alloyed aluminum-system palted steel sheet |
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| JP2001190709A JP4564207B2 (en) | 2001-06-25 | 2001-06-25 | Hot-pressed hot-dip aluminized steel sheet that is heated to 800 ° C or higher |
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| JP4564207B2 true JP4564207B2 (en) | 2010-10-20 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080286603A1 (en) | 2005-12-01 | 2008-11-20 | Posco | Steel Sheet for Hot Press Forming Having Excellent Heat Treatment and Impact Property, Hot Press Parts Made of It and the Method for Manufacturing Thereof |
| KR101008042B1 (en) | 2009-01-09 | 2011-01-13 | 주식회사 포스코 | Aluminum Coated Steel Sheet with Excellent Corrosion Resistance and Hot Press Formed Article Using The Same and Manufacturing Method Thereof |
| KR101253893B1 (en) | 2010-12-27 | 2013-04-16 | 포스코강판 주식회사 | Aluminium coated steel sheet having excellent in oxidization resistence and heat resistence |
| KR101988724B1 (en) * | 2017-06-01 | 2019-06-12 | 주식회사 포스코 | Steel sheet for hot press formed member having excellent coating adhesion and manufacturing method for the same |
| JP7230448B2 (en) * | 2018-11-16 | 2023-03-01 | 日本製鉄株式会社 | Hot-dip Al-plated steel sheet |
| JP2020084223A (en) * | 2018-11-16 | 2020-06-04 | 日鉄日新製鋼株式会社 | HOT-DIP Al-BASED STEEL SHEET, AND MANUFACTURING METHOD OF HOT-DIP Al-BASED STEEL SHEET |
| WO2021210114A1 (en) * | 2020-04-16 | 2021-10-21 | 日本製鉄株式会社 | Hot-dip al-based-material-coated steel plate, and method for manufacturing hot-dip al-based-material-coated steel plate |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0288754A (en) * | 1988-09-27 | 1990-03-28 | Nippon Steel Corp | Hot-dip aluminized steel sheet excellent in corrosion resistance |
| JPH06299370A (en) * | 1993-04-13 | 1994-10-25 | Nisshin Steel Co Ltd | Hot dip al plated steel sheet and its production |
| JPH08104964A (en) * | 1994-10-03 | 1996-04-23 | Nisshin Steel Co Ltd | Production of hot-dip aluminum plated steel sheet for fire-resistant structure excellent in corrosion resistance |
| JPH10158784A (en) * | 1996-11-27 | 1998-06-16 | Kawasaki Steel Corp | High strength hot rolled steel sheet |
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2001
- 2001-06-25 JP JP2001190709A patent/JP4564207B2/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0288754A (en) * | 1988-09-27 | 1990-03-28 | Nippon Steel Corp | Hot-dip aluminized steel sheet excellent in corrosion resistance |
| JPH06299370A (en) * | 1993-04-13 | 1994-10-25 | Nisshin Steel Co Ltd | Hot dip al plated steel sheet and its production |
| JPH08104964A (en) * | 1994-10-03 | 1996-04-23 | Nisshin Steel Co Ltd | Production of hot-dip aluminum plated steel sheet for fire-resistant structure excellent in corrosion resistance |
| JPH10158784A (en) * | 1996-11-27 | 1998-06-16 | Kawasaki Steel Corp | High strength hot rolled steel sheet |
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