Effect of Galvannealed Coating Evolution during Press Hardening on RSW Weldability

IF 2.2 3区 材料科学 Q2 METALLURGY & METALLURGICAL ENGINEERING
Xu Han, M. H. Razmpoosh, E. Biro, Y. Zhou, A. Macwan
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引用次数: 2

Abstract

Press-hardening steels (PHSs) are used in modern passenger vehicles to increase part strength while reducing vehicle weight to meet both environmental and safety regulations. To prevent oxidization and decarburization during heat treatment, some PHSs are coated with Zn (galvanized or galvannealed). Heating during the press-hardening process drives interdiffusion of Zn from the coating and the Fe from the steel substrate, forming a diffusion layer composed of -Fe phase (a Zn-Fe solid solution). The electrical resistance of the diffusion layer is a function of its thickness and Zn-Fe composition. Both the diffusion layer thickness and the Zn-Fe composition are dependent on the initial coating thickness and heat-treatment time/temperature conditions. Changes to the heat-treatment process shift the resistance spot welding process window by altering the resistance behavior of the material. If the shift in the process window is not accounted for during assembly welding, the welds produced may either be too small or exhibit expulsion, both of which will reduce the strength of the weld. This study showed increasing heattreatment time shifted the process window toward lower current. A final combined processing window of 1.5 kA, which is suitable for industrial application, was obtained when taking into account the variation in heat-treatment time. The tensile shear performance was not affected by the heat treatment, as increased softening in the heat-affected zone at longer heat-treatment time canceled the strength gain from increas-
压淬过程中电镀层演变对RSW可焊性的影响
压淬钢(PHS)用于现代乘用车,以提高零件强度,同时减轻车辆重量,从而满足环境和安全法规的要求。为了防止热处理过程中的氧化和脱碳,一些PHS涂有锌(镀锌或镀锌)。加压硬化过程中的加热驱动Zn从涂层和Fe从钢基体的相互扩散,形成由以下组成的扩散层-Fe相(Zn-Fe固溶体)。扩散层的电阻是其厚度和Zn-Fe成分的函数。扩散层厚度和Zn-Fe成分都取决于初始涂层厚度和热处理时间/温度条件。热处理工艺的变化通过改变材料的电阻行为来改变电阻点焊工艺窗口。如果在组装焊接过程中没有考虑工艺窗口的变化,则产生的焊缝可能太小或出现脱落,这两种情况都会降低焊缝的强度。这项研究表明,增加热处理时间会使工艺窗口朝着较低的电流移动。当考虑到热处理时间的变化时,获得了适用于工业应用的1.5kA的最终组合处理窗口。拉伸剪切性能不受热处理的影响,因为在较长的热处理时间内,热影响区软化程度的增加抵消了热处理后强度的增加-
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来源期刊
Welding Journal
Welding Journal 工程技术-冶金工程
CiteScore
3.00
自引率
0.00%
发文量
23
审稿时长
3 months
期刊介绍: The Welding Journal has been published continually since 1922 — an unmatched link to all issues and advancements concerning metal fabrication and construction. Each month the Welding Journal delivers news of the welding and metal fabricating industry. Stay informed on the latest products, trends, technology and events via in-depth articles, full-color photos and illustrations, and timely, cost-saving advice. Also featured are articles and supplements on related activities, such as testing and inspection, maintenance and repair, design, training, personal safety, and brazing and soldering.
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