TP321 stainless steel is widely used in hydrogenation refining pipes owing to its excellent performance of creep stress resistance and high-temperature resistance. In this study, thermal simulation tests were carried out on the welding heat-affected zone (HAZ) of TP321 stainless steel at temperatures of 1300 °C, 1100 °C, and 850°C using a Gleeble 3800 testing machine. Slow strain tensile tests were conducted under the condition of electrolytic hydrogen charging (EHC) and the metallographic microstructure of cracks as well as the morphology of fractures were analyzed in detail. The result shows that hydrogen can change the fracture mode of tensile specimen and the cracks initiated from and near the specimen surface after EHC. Hydrogen significantly decreases the plastic deformation capability of HAZ in TP321 stainless steel. The reduction of area after the fracture decreases by 58%, 41%, and 45% for HAZ at 1300 °C, 1100 °C, and 850 °C, respectively. The existence of δ ferrite was considered to be the main reason for the aggravation of hydrogen-induced plasticity loss.
Damage evolution in a tensile specimen of a ductile stainless steel
