Study on hydrogen embrittlement of AISI430 ferritic stainless steel during cold rolling-annealing-aging

Microstructure transformation, hydrogen distribution and hydrogen-induced brittle fracture of Ferritic stainless steels (FSSs) under cold rolling, annealing and aging processes was investigated in the present work. Enrichment of C, Mn and trace intergranular carbides during aging significantly changed the hydrogen-induced fracture mode, from quasi-cleavage (QC) to intergranular (IG) fracture. Grain boundaries, despite experiencing significant localized deformation, demonstrated an effective barrier effect against crack propagation. Comparative analysis revealed that the Ag-120 specimen exhibited more pronounced lattice distortion in the vicinity of grain boundaries and crack paths than Ag-60 specimen, primarily attributed to the hydrogen-enhanced localized plasticity (HELP) mechanism. Due to the dominant effect of the hydrogen-enhanced decohesion (HEDE) mechanism, cracks gradually nucleated and propagated along grain boundaries as hydrogen concentration at the boundaries increased.