Analysis of enhanced hydrogen embrittlement fracture for pre-strain hardening 2205 duplex stainless steel

The enhanced behavior of hydrogen embrittlement (HE) fracture for pre-strain hardening 2205 duplex stainless steel was investigated. Specimens with various degrees of engineering strain were pre-charged by cathodic charging, and then immediately loaded up to facture under uniaxial tensile test. Results demonstrated that the susceptibility to HE increased with increasing level of pre-deformation, manifested by loss of ductility and transition from dimple fracture to quasi-cleavage morphology. Post-mortem microstructural analyses revealed hydrogen-induced cracks preferentially initiated at ferritic sites in less pre-strained specimens (0% and 5%), whereas cracks tended to form at austenitic sites in pre-strained specimens with large pre-deformations (10%, 15% and 20%). This is mainly owing to the difference of increased plastic strain and dislocation density in ferrite and austenite caused by plastic deformation after pre-strain hardening.