Hydrogen Assisted Cracking Studies of a 12 Chromium Martensitic Stainless Steel - Influence of Hardness, Stress and Environment

摘要

Martensitic stainless steels, in general, become more susceptible to Environmentally Assisted Cracking (EAC), specifically Hydrogen Assisted Cracking (HAC), with increasing tensile strength (as reflected by increasing hardness). The aim of this test programme was to determine the susceptibility to HAC of a 12% chromium stainless steel as a function of material hardness, stress and environment. Incremental Step Loading (ISL) tests demonstrate a reduction in failure stress with increasing hardness due to the presence of hydrogen. Relationships between failure stress and hardness/tempering temperature are described. Testing also clearly supports the concept that there is a critical value of nominal stress, at each tempering temperature/hardness, below which HAC does not occur. Constant displacement testing results show that susceptibility to HAC is dependent upon a complex interplay between microstructure (tempering temperature/hardness), stress and environment (availability of hydrogen).