X-ray tomographic observation of environmental assisted cracking in heat-treated lean duplex stainless steel

[Display omitted] •Internal corrosion and EAC was observed in heat-treated lean duplex stainless steel.•Internal corrosion was triggered by applied plastic strain.•Predominantly intergranular cracks at ferrite-ferrite boundaries were observed.•EAC propagation was observed, in operando, with reduced resistance attributed to hydrogen embrittlement effects. The occurrence of environmental assisted cracking (EAC) has been observed in heat-treated lean duplex stainless steel via X-ray computed tomography (X-ray CT) and cross-sectional microstructure analysis. Selective corrosion of the ferrite phase occurred at the sample surface, with internal corrosion triggered by applied plastic strain. The observed cracks mainly propagated along ferrite-ferrite boundaries, with crack arrest associated with ferrite-austenite grain boundaries. Crack propagation during EAC fracture was observed, in-operando. The sudden appearance of EAC occurred due to the suppression of crack opening by ductile austenite phase. The reduced EAC resistance was attributed to hydrogen embrittlement effects.