强度-塑性/抗延迟开裂（耐氢脆）的这种“倒置关系”已经成为制约高强钢发展和应用的瓶颈。中锰钢通过调制成分和热处理工艺，虽然其抗拉强度可达1100MPa以上（处于对氢致延迟开裂较为敏感的范围），但其超高延伸率（可以超过40%）和超细晶粒的特点是否具有高的抗氢脆性能呢？这是值得研究的。我们前期对不同强度和Mn含量的中锰钢进行试验发现，其强塑积可由无氢时的56 GPa•%急剧降低至含氢时的10 GPa•%。本申请首先要建立氢含量与氢致开裂门槛值KIH和裂纹扩展速率da/dt的定量关系；阐明氢在超细晶粒中的分布和作用规律，以及超细晶晶界对氢的陷阱作用；研究TRIP效应中奥氏体和新生马氏体对延迟开裂的影响机理；获得冷加工对氢的吸附和扩散的影响规律。寻找成分、微观组织结构、TRIP效应和氢含量等因素的协同作用机制对中锰钢延迟开裂性能的影响规律。通过优化组织结构和时效工艺，获得抗氢脆延迟开裂的中锰钢。

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. For medium manganese steels, their fracture strength can be over 1100MPa. Their total elongation can be more than 40%. Normally materials with such good ductility should show low sensitivity to hydrogen embrittlement. However, their product of strength-ductility can reduce from 56 GPa•% free of hydrogen to 10 GPa•% with hydrogen. Their high strength and high ductility are from the TRIP effect and ultra-fine grains. Therefore, we want to find the effect of different hydrogen concentrations to KIH and da/dt. This study will focus on how hydrogen distributes in ultra-fine grains and its effect on the grain boundaries. We also want to investigate the effect of hydrogen to residual austenite and martensite from TRIP. In addition, how cold working can affect the hydrogen embrittlement will be studied. The synergistic effect of various factors (chemical composition, microstructure, TRIP and the concentration of hydrogen) will be emphasized. Eventually, we want to adjust the chemical composition and the heat treatment in order to improve the anti-delayed cracking properties of medium manganese steels.