Hydrogen embrittlement in martensitic press-hardened steel (PHS) presents a great challenge to the automotive industry that employs largely PHS in the critical parts of body-in-white. It is often a complex problem due to the coupling of martensitic transformation and hydrogen diffusion. Experimental studies often encounter difficulties in resolving the hydrogen diffusion in martensitic microstructure and its relation to hydrogen embrittlement in PHS. The present work develops a combined model coupling the phase field model for martensitic transformation together with a modified hydrogen diffusion model. We demonstrated, through both experiments and simulations, that hydrogen in PHS preferably resides in microstructure defects such as lath boundaries (LB) and prior-austenite grain boundaries (PAGB) where the hydrostatic stress and dislocation density remain high. Therefore, these boundaries are at risk from hydrogen embrittlement when the average hydrogen concentration of the material reaches a critical value. Furthermore, the ability of the model in resolving microscopic distribution allows us to predict fracture modes at any location by simply comparing the local concentration with the critical hydrogen concentration.

马氏体压制硬化钢 (PHS) 中的氢脆对在白车身关键部件中大量使用 PHS 的汽车行业提出了巨大挑战。由于马氏体转变和氢扩散的耦合，这通常是一个复杂的问题。实验研究在解决马氏体微观结构中的氢扩散及其与 PHS 中氢脆的关系时经常遇到困难。目前的工作开发了一个组合模型，将马氏体转变的相场模型与改进的氢扩散模型相结合。我们通过实验和模拟证明，PHS 中的氢优选存在于微观结构缺陷中，例如板条边界 (LB) 和原奥氏体晶界 (PAGB)，其中静水应力和位错密度仍然很高。因此，当材料的平均氢浓度达到临界值时，这些边界存在氢脆的风险。此外，模型解析微观分布的能力使我们能够通过简单地将局部浓度与临界氢浓度进行比较来预测任何位置的断裂模式。