This study addresses critical issues of hydrogen embrittlement (HE) and liquid metal embrittlement (LME) in Al-Si-coated and Zn-coated hot-press-forming (HPF) steel sheets, respectively, by proposing an innovative approach of incorporating (24–30) wt% Zn into the conventional Al-Si (AS) coating to mitigate HE issues while leveraging the absence of LME associated with Zn coating. To the best of the authors' knowledge, no other paper has considered this subject. The optimal Al-Si-Zn (ASZ) sheet formed a surface oxide layer and Zn-enriched zone, acting as local trap sites to reduce H intrusion, while the AS sheet lacked this zone, leading to continuous H intrusion. The ASZ sheet reached complete H emission in 4 weeks, whereas significant H remained in the AS sheet even after 4 weeks due to higher H intrusion. This result emphasizes the crucial role of Zn addition in impeding H diffusion and ensuring excellent resistance to HE. Bending angles at peak load, crucial for assessing bending and sheet forming properties, were adversely affected by diffusible H contents within the sheets. When austenitized at 900 °C for 3 min and then cooled to 800 °C for tensile testing, the ASZ sheet experienced abrupt premature fracture due to selective Zn diffusion from the liquid alloy to grain boundaries, inducing LME. However, prolonged austenitization to 6 min mitigated LME, with no expected issues on LME. These findings underscore the significance of the tailored Al-Si-Zn coating in enhancing resistance to HE, making it suitable for broad applications in high-strength HPF steel sheets.

中文翻译：

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通过优化 Al-Si-Zn 涂层提高高强度热压成型钢板的抗氢脆性


本研究通过提出一种创新方法，将 （24-30） wt% Zn 加入传统的 Al-Si （AS） 涂层中以缓解 HE 问题，同时利用与 Zn 涂层相关的 LME 的缺失，分别解决了 Al-Si 涂层和 Zn 涂层热压成型 （HPF） 钢板中氢脆 （HE） 和液态金属脆化 （LME） 的关键问题。据作者所知，没有其他论文考虑过这个主题。最佳的 Al-Si-Zn （ASZ） 片材形成了表面氧化层和富锌区，作为局部陷阱位点以减少 H 侵入，而 AS 片材缺乏该区，导致连续的 H 侵入。ASZ 片在 4 周内达到完全 H 发射，而由于较高的 H 侵入，即使在 4 周后，AS 片中仍有显著的 H 残留。这一结果强调了 Zn 添加在阻碍 H 扩散和确保对 HE 的出色抵抗性方面的关键作用。峰值载荷下的弯曲角度对于评估弯曲和片材成型性能至关重要，但受到片材内可扩散 H 含量的不利影响。当在 900 °C 下奥氏体化 3 min，然后冷却至 800 °C 进行拉伸试验时，由于 Zn 选择性地从液态合金扩散到晶界，ASZ 薄板经历了突然的过早断裂，从而诱导了 LME。然而，将奥氏体化时间延长至 6 分钟减轻了 LME，预计 LME 没有问题。这些发现强调了定制的 Al-Si-Zn 涂层在增强抗 HE 性方面的重要性，使其适用于高强度 HPF 钢板的广泛应用。