Tensile response of 304 HCu SS at different temperatures using different plastic–flow relationships

Tensile and fracture behaviour of 304HCu austenitic stainless steel was studied from 300 to 1023 K at a constant strain rate of 3 × 10− 4 s− 1. A significant drop in yield strength (YS) and ultimate tensile strength (UTS) occurred between 300 and 473 K due to dynamic recovery and reduced dislocation interactions. Between 473 and 873 K, strength degradation was gradual, while near 1023 K, softening was pronounced, attributed to dislocation annihilation and grain boundary weakening. In the 523–673 K range, serrated flow associated with dynamic strain ageing (DSA) was observed, marked by increased flow stress and reduced ductility. Compared to 316LN SS, 304HCu SS showed higher strength but slightly lower ductility. Fracture surfaces were mainly ductile, with mixed-mode features at 1023 K. Dimple size decreased at intermediate and increased at higher temperatures. The Voce model accurately predicted true YS and UTS, and work-hardening behaviour aligned with Hollomon, Swift, Ludwik, and Voce relationships.