Abstract The yield-point phenomenon (YPP) is generally eliminated or reduced in aged sheet metals to avoid defects during metal forming applications; however, it may be beneficial in specific applications and could be induced to enhance certain properties. For example, bake hardening (BH), peculiarized by a sharply elevated yield stress after baking of pre-strained low carbon steel, can be used to improve the dent resistance in automotive sheet metal forming applications. However, many previous investigations about the bake hardenability concentrate primarily on the hardening response under uniaxial tension and related influence factors. Additionally, various numerical studies on dent resistance rarely consider the BH effect in their model. In this study, the BH behavior of a dual phase (DP) steel is comprehensively investigated under uniaxial loading cases, and the static dent experiments are conducted in pre-strained and bake-hardened conditions to study their effects on dent resistance. We develop a constitutive model considering both BH and YPP implemented using a robust implicit stress-integration algorithm for finite element analysis. Numerical simulations corresponding to the experiments are conducted to further investigate the dent resistance of the DP steel. The proposed numerical procedure is shown to be able to capture the BH behavior of the DP steel reasonably well and appropriately assess its enhanced dent resistance.

中文翻译：

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由屈服点现象引起的双相钢抗凹痕性的实验和数值研究

摘要 时效金属板通常会消除或减少屈服点现象（YPP），以避免金属成形应用过程中出现缺陷；然而，它在特定应用中可能是有益的，并且可以被诱导以增强某些特性。例如，烘烤硬化 (BH) 的特点是预应变低碳钢烘烤后屈服应力急剧升高，可用于提高汽车钣金成型应用中的抗凹痕性。然而，许多先前关于烘烤硬化性的研究主要集中在单轴拉伸下的硬化响应和相关影响因素上。此外，关于抗凹痕性的各种数值研究很少在他们的模型中考虑 BH 效应。在这项研究中，全面研究了双相 (DP) 钢在单轴加载情况下的 BH 行为，并在预应变和烘烤硬化条件下进行了静态凹痕实验，以研究它们对抗凹痕性的影响。我们开发了一个考虑 BH 和 YPP 的本构模型，使用稳健的隐式应力积分算法进行有限元分析。进行与实验相对应的数值模拟以进一步研究 DP 钢的抗凹痕性。所提出的数值程序被证明能够相当好地捕捉 DP 钢的 BH 行为，并适当地评估其增强的抗凹痕性。我们开发了一个考虑 BH 和 YPP 的本构模型，使用稳健的隐式应力积分算法进行有限元分析。进行与实验相对应的数值模拟以进一步研究 DP 钢的抗凹痕性。所提出的数值程序被证明能够相当好地捕捉 DP 钢的 BH 行为，并适当地评估其增强的抗凹痕性。我们开发了一个考虑 BH 和 YPP 的本构模型，使用稳健的隐式应力积分算法进行有限元分析。进行与实验相对应的数值模拟以进一步研究 DP 钢的抗凹痕性。所提出的数值程序被证明能够相当好地捕捉 DP 钢的 BH 行为，并适当地评估其增强的抗凹痕性。