新型1500MPa级高强钢的氢脆敏感性研究

根据钢材组织设计的思想，通过优化成分和工艺设计、研制出一种新的1500MPa级高强纲。采用阴极电解充氢的方法对其氢脆敏感性进行了研究，并与同一强度级别的42CrMo高强钢进行了对比。结果表明，所设计的1500MPa级高强钢的氢脆敏感性低于传统的42CrMo高强钢。SEM断口观察显示，两者的断口形貌也不同，1500MPa级高强纲为准解理断裂，而42CrMo高强钢为沿晶断裂。断口金相表明，前者的裂纹主要沿着贝氏体/马氏体（B/M）边界扩展，断裂模式为板条界分离，后者的裂纹沿着晶界扩展。对1500MPa级高强钢进行了TEM观察，发现其组织为贝氏体/马氏体复相组织，残留奥氏体以薄膜状存在贝氏体内部及贝氏体条片、马氏体板条间。

Study on Susceptibility to Hydrogen Embrittlement for Novel 1500MPa Level High Strength Steel

The susceptibility to hydrogen embrittlement for novel 1500MPa high strength steel designed by optimized composition and technology based on the idea of microstructure design was investigated by means of cathodic electrolytic hydrogen charging in this paper,which was compared with 42CrMo high strength steel in similar strength grade.The results show that the susceptibility to hydrogen embrittlement of the novel 1500MPa high strength steel is inferior to that of conventional 42CrMo high strength steel.The fractographic analysis suggests that the fracture appearance in the novel 1500MPa high strength steel is quasicleavage,wheras the fracture appearance in the 42CrMo high strength steel is intergranular.Profile fractographic specimens show that the crack in the former propagates preferentially along bainite/martensite lath boundary,and suggests that fracture mode is predominantly lath boundary separation;the crack in the latter propagates along grain boundary.The transmission electron microscope(TEM)observation shows that the novel 1500MPa high strength steel possesses bainite/martensite dual phase microstructure which exhibits a better resistance to hydrogen embrittlement.The retained austensite films are precipitated in bainite or between bainite plate and martensite lath.