Temperature change induce crack mode transition of 316L stainless steel in H2S environment revealed by dislocation configurations

The crack propagation mechanism of 316L austenitic stainless steel in the H2S environment is revealed by dislocation configurations. Slow strain rate tensile test results show that the fracture elongation first decreases and then increases as temperature rises, and the fracture morphology transforms "transgranular-intergranular-transgranular" concomitantly. Dislocation configurations beneath the fracture surface are shear bands, dislocation pile-up, and dislocation tangles, respectively; it indicates the stress concentration positions are located at grain interior, boundaries, and interior in turn. The relationship between crack propagation resulted from hydrogen embrittlement and stress concentration is analyzed, and the mechanism of fracture morphology change with temperature is proposed. [Display omitted] •The fracture elongation of 316L decreased first and then increased as the temperature rose.•The cracking mode underwent "transgranular-intergranular-transgranular" transition as temperature rose.•Dislocation configurations change was the reason for the cracking mode transition.•Hydrogen embrittlement caused failures below 200℃ but anode dissolution dominated failures at higher temperatures.