Research on the lack of alloying in the galvannealed coating of automotive sheet steel

Samples of the cross section microstructures of galvannealed steel sheets that lack alloying were analyzed. X-ray diffraction （XRD） tests were carried out. The study discovers that the deficit of alloying was higher on both sides of the steel sheet when compared to the center and the thickness of the coating on the sides was also higher than the center. The results of the XRD tests demonstrate that the microstructure of the coating with a lack of alloy is mainly composed of zinc,ζ and δ. They also indicate that the lack of alloying is mainly due to a lower galvannealing temperature and thicker coating. It is shown by the optical micrographs of coating that the δ phase forms first in a discontinuous manner at the interface and then rapidly pushes towards the coating and enlarges.

Experimental and finite element analysis for fracture of coating layer of galvannealed steel sheet

Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed to understand better the fracture of coating layer of GA steel sheet during plastic deformation. Yield strength of the coating layer was calculated by using a relative difference between hardness of coating layer measured from the nano-indentation test and that of substrate. To measure shearing strength at the interface between substrate and coating layer, shearing test with two specimens attached by an adhesive was carried out. Using the mechanical properties measured, a series of finite element analyses coupled with a failure model was performed. Results reveal that the fracture of coating layer occurs in an irregular manner at the region where compressive deformation is dominant. Meanwhile, a series of vertical cracks perpendicular to material surface are observed at the tensile stressed-region. It is found that 0.26-0.28 of local equivalent plastic strain exists at the coating and substrate at the beginning of failure. The fracture of coating layer depends on ductility of the coating layer considerably as well.

Effect of surface roughness on the surface lubrication performance of galvanized steel sheets with a self-lubricated coating

Four kinds of galvanized steel sheets having different surface roughness values were used to prepare the steel sheets with a self-lubricated coating. The effects of surface roughness on the surface lubrication performance of the steel sheets were examined using a friction coefficient tester. Results revealed large dynamic friction coefficients for the galvanized steel sheets, which increased remarkably with surface roughness. Once the self-lubricated coating was applied, significant drops in the dynamic friction coefficients were measured. After the first stage of the friction test,the coefficients were almost unchanged, which reflected a weak dependence on the surface roughness of the self-lubricated steel sheets. However, the dynamic friction coefficients gradually increased as the test progressed, where these increase clearly correlated with the surface roughness of the self-lubricated steel sheets.

Production and application of Baosteel inorganic-lubricant-coated galvannealed automobile steel sheet

The inorganic-lubricant-coated galvannealed automobile steel sheet is a new product that improves the press formability of automobile body panels.In this paper,the production process,physical and chemical properties,press formability,and corrosion resistance of this new automobile steel sheet were discussed.Test results show that this inorganic solid-lubricant galvannealed automobile steel sheet has good surface friction characteristics and press formability.This product also meets the automobile industry’s requirements for press formability,phosphate pro-perties,and corrosion resistance after coating.

Application of communication program between atomic absorption spectrometer and electronic balance for iron content determination of the galvanneal coating

At present,iron content in a galvanneal coating is determined by an atomic absorption spectrometer(AAS)in Baosteel.The mass of a sample is recorded by operators two times on paper,then the mass of the coating is manually calculated and input in a computer.With the aid of a communication program between an AAS and an electronic balance(EB),the above process can be modified.First,the mass of a sample is sent to a computer by the EB.Second,the mass of the coating is calculated by the computer automatically.Finally,the iron mass is uploaded to the communication program,and the iron content can also be calculated automatically.As such,the modified process is more efficient.

汽车用合金化热镀锌钢板的发展趋向

论述了国内外汽车用合金化热镀锌钢板的发展趋向。简要介绍了合金化热镀锌IF钢的传统强化方法和新强化技术的应用,并指出该钢种主要是在保证优良成型性能的前提下逐渐向高强化方向发展;详细介绍了340MPa级别合金化热镀锌烘烤硬化钢的开发情况,指出该钢种主要向易成型、抗粉化和抗时效方向发展;简要介绍了合金化热镀锌低碳当量型高强钢和双相钢的开发进展情况,指出该钢种主要向易成型方向发展。还简述了目前合金化热镀锌TRIP钢的开发进展情况,并指出我国应大力发展汽车用合金化热镀锌钢板,特别是高强度级别的合金化热镀锌钢板,以满足我国飞速发展的汽车工业需求。

基于平板滑动摩擦实验的镀锌板摩擦特性研究

利用平板滑动摩擦实验研究了模具粗糙度、正压力以及滑动速度对合金化热镀锌板表面摩擦系数的影响规律,结合摩擦学理论对摩擦系数变化的原因进行深入的分析,采用光镜观察钢板摩擦后的截面形貌,对比不同实验条件下的锌层截面失效情况,进而验证摩擦系数变化规律的正确性。结果表明,模具粗糙度在0.4μm^1.2μm范围时,摩擦系数随着模具粗糙度的增加先减小后增大,模具粗糙度约0.8μm时最佳,此时锌层发生少量粉化失效;摩擦系数随着正压力增加而减小,在较高压力范围内减小的趋势变缓,随着正压力增加,锌层粉化与剥落失效加重;摩擦系数随着滑动速度增加而减小,当滑动速度增加到一定值时,摩擦系数减小的趋势变慢并趋于稳定,随着滑动速度增加,锌层粉化与剥落失效情况转好。

IF钢合金化镀锌板镀层相结构对其性能影响研究的新进展

介绍了 IF钢合金化镀锌板镀层相结构对其性能影响的一些最新研究成果。内容包括 :相结构和铁含量对其冲压成型时的粉化性和剥离性的影响 ;对焊接性的影响 ;

汽车用合金化热镀锌IF钢表面摩擦系数

采用平板滑动实验研究了表面相组成、表面粗糙度、拉速、压力及涂油品种等因素对汽车用合金化热镀锌IF钢表面摩擦系数的影响。研究发现对于合金化热镀锌IF钢表面存在大量柱状ζ相的镀层表面,其表面摩擦系数通常大于以粒状δ1相为主的镀层表面;以柱状ζ相为主的镀层表面,当镀层表面存在大量尺寸较大的“火山口”状形貌时,其表面摩擦系数相对较小。

合金化热镀锌钢板抗粉化性能的研究进展

综述了合金化热镀锌钢板抗粉化性能的研究进展,重点论述了镀层相结构的形成机理和镀层相结构对镀层抗粉化性能的影响,同时介绍了镀层抗粉化性能的其它影响因素。

合金化热镀锌钢板冲压后表面小亮点的成因分析

简介了合金化热镀锌钢板在冲压后出现小亮点缺陷的试验研究 ,据此进行了调查、分析以及模拟冲压试验 ,找出形成小亮点缺陷的一个直接原因 。

汽车用锌铁合金和热镀锌板材涂装性能的比较

以热镀锌钢板代替锌铁合金镀层钢板可降低汽车生产成本而不影响汽车涂装性能。对2种钢板作系列前处理后,采用随车挂板和贴板方法进行涂装,对2种板材的涂装性能进行了研究。结果显示:相同工艺条件下,两者的整体涂装性能相近,电泳防腐蚀性能接近,涂层厚度相同;两者的耐高温性能和附着力性能相同;热镀锌板的磷化层晶体尺寸更为均一,其电泳层的粗糙度、喷涂层的桔皮质量和鲜映性略高于锌铁合金板。

国内外合金化热镀锌烘烤硬化钢板对比分析

对国内外生产的合金化热镀锌烘烤硬化钢板系统地进行了实物对比分析,主要从基板化学成分、力学性能、镀层粉化量、镀层质量、镀层铁含量、镀层铝含量、镀层主要元素分布、镀层表面形貌、镀层脆性断口形貌、镀层X射线物相组成和镀层表面粗糙度等方面进行了系统的对比分析。指出国内合金化热镀锌烘烤硬化钢板生产应在基板化学成分、镀层质量控制和镀后冷却速率控制等方面进行改进,以便生产出强度、镀层抗粉化性能等各项性能均优良的合金化热镀锌烘烤硬化钢板。

合金化热镀锌镀层组织中Γ_1相的有序结构

采用聚焦离子束(FIB)方法制备了合金化热镀锌IF钢横截面TEM试样,研究了镀层中Γ1相显微结构,得到了Γ1相选区电子衍射花样(SADPs)。结果表明:在Γ1相选区电子衍射花样中存在超点阵衍射,说明Γ1相是一种具有2倍周期结构的有序金属间化合物,这种结构不同于Γ1单相试样具有的6倍周期的有序结构。

自润滑合金化板的表面特性研究

对自润滑合金化板及普通合金化板的润滑性能、抗粉化性能、涂装性能、耐蚀性能等表面特性进行了分析和研究。结果表明,自润滑处理可以有效改善合金化板的摩擦特性,提高其润滑性能,从而显著提升合金化板的抗粉化性能。自润滑合金化板的耐蚀性能相比普通合金化板更加优良,两者的磷化性能无差异,经电泳后的耐腐蚀性能也在同等水平。

膜厚对自润滑合金化板性能的影响研究

对不同膜厚自润滑合金化板的润滑性能、成形性能、焊接性能、脱脂性能进行了研究。结果表明:随着膜厚增加,自润滑合金化板的润滑性能、成形性能提高,焊接性能、脱脂性能变差;膜厚小于300mg/m^2时,成形性能提高的不明显;膜厚大于500mg/m^2时,焊接性能及脱脂性能受到不良影响。为保证自润滑合金化板的性能,生产时应将自润滑膜厚控制在300mg/m^2~500mg/m^2。

合金化热镀锌钢板的抗粉化影响因素

从热镀锌板镀层的合金化机理着手,综述了镀锌基板、锌液成分、镀层结构、合金化温度和时间等方面对合金化热镀锌板镀层的抗粉化性能的影响。

宝钢无机润滑GA热镀锌汽车板的生产与应用

无机润滑GA汽车板是一种改善汽车用热镀锌板冲压成形性能的新型产品,概述了该产品的生产工艺,对该产品的主要理化性能、汽车厂实际冲压性能和耐蚀性能等进行对比分析,结果表明,无机润滑GA汽车板具有良好的表面摩擦特性和成形性,同时该产品满足汽车行业对冲压成形性能、磷化性能和涂装后的耐腐蚀性能等常规涂装工艺的生产要求。

预磷化板材电泳后出现印痕的问题及其解决方法

用预磷化板材制造的车身由于其表面的磷化膜在冲压、焊装的过程中不可避免地被划伤,因此在涂装磷化中往往成膜不均匀,电泳后容易产生印痕。就该问题出现的原因(如白车身状态、表调液粒径等)进行了探讨,并给出了一些解决方案。

三元磷酸盐体系无机预润滑试剂的研发及其在改善热镀锌汽车板成形方面的应用（英文）

目的旨在合成一种用于改善热镀锌汽车板材料成形性能的无机预润滑试剂,以期降低热镀锌板表面摩擦系数,进而减少冲压过程中开裂等缺陷的发生。方法以磷酸、金属硝酸盐等为主要试剂合成机预润滑试剂,在热镀锌汽车板材料表面得到均匀、连续的无机预润滑薄膜。采用扫面电子显微镜、辉光光谱仪等手段对材料表面所形成的无机预润滑薄膜的基本形貌、厚度等进行表征。采用平板摩擦、深冲实验对材料涂覆预润滑膜后的表面摩擦系数及冲压性能进行分析。同时,根据汽车板材料认证特点,对无机预润滑处理后的热镀锌汽车板材料的焊接/胶接、涂装性能进行分析。结果采用辊涂法在热镀锌汽车板材料表面可形成厚度为50～60 nm连续、均匀的薄膜。较之普通热镀锌材料,上述表面涂覆无机预润滑薄膜后的热镀锌材料表面摩擦系数可有效下降13%。,且伴随板面温度升高,无机预润滑热镀锌材料表面摩擦系数的下降愈发明显;同时,无机预润滑处理热镀锌材料的焊接性能(包括焊接窗口、焊接寿命)符合同等厚度汽车板材料的认证需求。涂覆无机预润滑薄膜热镀锌板表面与汽车结构胶具有良好的兼容性;此外,汽车主机厂挂片实验结果证实,现有的脱脂工艺可将材料表面无机预润滑膜彻底脱除,所得磷化膜厚度、晶粒大小与普通热镀锌板无异。结论当前所研发的无机预润滑试剂在热镀锌板表面形成薄膜,在不影响材料其他各项性能的前提下,可有效降低材料摩擦系数,为减少冲压缺陷的发生提供保证。