Insights into the Impact Behavior and Deformation Substructure Evolution of the N-Bearing QN1803 and 304 Stainless Steels

The impact behaviors of N-bearing QN1803 and 304 stainless steels are studied using instrumented Charpy impact test in the range of -192-100 degrees C. The fracture and deformation substructures are systematically investigated by scanning electron microscopy and transmission electron microscopy. The results show that QN1803 presents ductile-brittle transition temperature (DBTT) and 304 shows ductile fracture. With increasing temperature, the stacking fault energy (SFE) of QN1803 and 304 increases, but the former is always lower than the latter. QN1803 presents low impact toughness with low-density dislocation at -192 degrees C. At high temperature, QN1803 and 304 show good impact toughness and the deformation substructures are dominated by high-density dislocations and deformation twinning.