超高强度钢的使用是汽车轻量化的重要途径，其在汽车中的使用比例逐年提高。材料强度越高，越易发生延迟开裂。超高强度钢的延迟开裂主要是由氢脆引起的。淬火配分钢（QP）和中锰钢的相变诱发塑性（TRIP）效应使强塑积可达56GPa•%，含1ppm的氢则急剧降低至10GPa•%。在弹性范围内，高强钢的延迟开裂基本都是沿晶的，而且是沿原奥氏体晶界。各种微观组元和晶界杂质元素偏析对氢在原奥氏体晶界的富集的影响对理解在有塑性变形的条件下，塑性变形过程是如何输运氢而影响氢富集这一问题具有重要意义。汽车用超高强度DP、QP钢经过加工成形喷漆烘烤工艺后，强度升高，塑形有时完全丧失，这一现象的研究还是空白。本申请通过对氢和C、位错、超细晶、界面等微观组元间相互作用的研究，建立TRIP-H耦合作用模型，获得晶界、碳化物类型和尺寸与氢脆的关系，以及残余奥氏体形貌、尺寸和比例与氢致塑性损失的规律；明确氢脆与应变烘烤脆化之间的交互作用机理；弄清汽车超高强钢在服役过程中垢下腐蚀和缝隙腐蚀的析H规律及对延迟开裂的影响机理；获得汽车颠簸震动服役工况下的疲劳-氢脆交互作用机理，对超高强度钢在汽车行业中的安全使用提供理论依据和应用指导。

The application of ultra high strength steels is one of the most useful ways to reduce the overall weight of automotives. As a result, the persentage of the use of ultra high strenght steels is increasing. The delayed cracking phenomena for high strength steels are normally due to hydrogen embrittlement. The sensitivity to hydrogen embrittlement increases with the increase of the strength. DP and QP steels and medium Mn steels can maintain their ductility with high strength. However, their product of strength-ductility can reduce from 56 GPa•% free of hydrogen to 10 GPa•% with hydrogen. The mechanism of this behavior is still unknown. After the pre-straining and baking process, the tensile strength of QP steels increases and ductility decrease. Sometimes, they can loss their ductility completely, which is still not understood. This application will focus on the interaction between H and C, dislocations, ultra fine crystal grains. A model of synergy effect of TRIP and H can be established. The trapping abilities of grain boundaries and carbides in terms of their sizes and types will be assessed. The effect of the shape, size and ratio of retained austenite to hydrogen embrittlement (HE) will be studied. The research of interactions of HE and baking embrittlement will be carried out. How hydrogen in the deep traps cooperates with fatigue will be studied. First principle methods together with machine learning methods will be used to understand the mechanisms of HE. Anti-HE solutions will be suggested.