Role of lattice strain and texture in hydrogen embrittlement of 18Ni (300) maraging steel

Abstract

Hydrogen embrittlement causes engineering components to fail unexpectedly. Maraging 300 steel was hydrogen charged and subjected to slow strain rate tensile test until fracture.Electron backscatter diffraction analysis of fractured specimen revealed that cracks initially propagated intergranulary along prior-austenite grain boundaries. When cracks faced martensitic f111ga planes parallel to normal direction (ND) they were deflected and continued to propagate transgranulary through f001ga==ND planes. Finally, cracks were arrested by f111ga==ND planes. Crystallographic planes on which cracks propagate/are arrested, correlate well with planes that exhibit highest/lowest magnitude of lattice strain determined during tensile loading using in situ synchrotron X-ray diffraction.