Influence of material condition and surface properties of high strength steels with regard to their susceptibility to hydrogen-induced stress corrosion cracking

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The need for lightweight construction in many fields of application comes along with the demand for an increased use of high strength steels. Due to this development there is a considerable risk for high-strength steel components to fail by hydrogen-induced stress corrosion cracking (H-SCC), when certain conditions are present.The following requirements must be met for the occurrence of H-SCC:Stress, e.g. residual stress, operational stressHydrogen supply, e.g. from manufacturing (pickling process) or operation (corrosion)Condition of the material, for example high strength, surface microstructure, delta ferrite.Therefore, there is a fundamental need for research to gather knowledge of the fundamental mechanisms between the condition of the material and its susceptibility to H-SCC and thereby the microstructural based mechanisms, which are responsible for H-SCC.Based on recent phenomenological findings, systematical investigations are carried out, taking into account the influence of the material, the mechanical properties, the microstructure, the hardening procedure (quenched and tempered or bainitic) and the surface state. From the findings, a mecha-nism based conceptual model is formulated, that describes the material condition-specific factors and their relative influence in terms of their contribution to the susceptibility of high strength steels to H-SCC.