Incremental step load (ISL) technique was used to determine the material susceptibility of three different grades of tempered martensite steels 35CrMo4, 41Cr4 and 36NiCrMo4 to hydrogen embrittlement (HE). In addition to testing the steel grades in air, the environmental hydrogen embrittlement susceptibilities (EHE) of each material were determined by in-situ charging of hydrogen at three different cathodic potentials −0.85 V_SCE, −1V_SCE and −1.2V_SCE to obtain the entire threshold curves for these materials. Overall investigation implies that 35CrMo4 is more susceptible than 41Cr4 and 36NiCrMo4. The fracture surface morphology in case of 35CrMo4 is entirely intergranular at −1V_SCE and −1.2V_SCE showing the severity of embrittlement. The higher matrix-cementite interfaces along with high cementite and low manganese sulphide (MnS) inclusion content of 36NiCrMo4 influencing the hydrogen transport kinetics within the material are responsible for the lower material susceptibility. The thermal desorption analyses (TDA) further corroborate the observations.

使用增量阶梯载荷（ISL）技术确定三种不同等级的回火马氏体钢35CrMo4、41Cr4和36NiCrMo4对氢脆（HE）的材料敏感性。除了测试空气中的钢种之外，还通过在三种不同的阴极电位-0.85 V _SCE，-1V _SCE和-1.2V _SCE下对氢进行原位充电来确定每种材料的环境氢脆化率（EHE），从而获得这些材料的整个阈值曲线。总体研究表明，35CrMo4比41Cr4和36NiCrMo4易感。35CrMo4情况下的断裂表面形态在-1V _SCE和-1.2V _SCE时完全是晶间的表现出脆化的严重性。较高的基体-渗碳体界面以及36NiCrMo4的高渗碳体和低硫化锰（MnS）夹杂物含量会影响材料中的氢迁移动力学，这是导致材料敏感性降低的原因。热脱附分析（TDA）进一步证实了这些观察结果。