Strain Hardening of Annealed 304 Stainless Steel by Creep

Abstract

Combined axial-torsional experiments have been conducted at room temperature on thin-walled tubes to investigate the strain hardening behavior of annealed 304 stainless steel due to creep. The constant strain-rate dynamic loading (or SCISR) surfaces representing the state of material before and after creep have benn determined. It has been found that transient creep essentially causes the loading surface to undergo kinematic hardening with insignificant amount of isotropic hardening for this material. A conclusion is drawn that the loading surface hardened by transient creep is the same as that hardened by plastic deformation. This is true both for specimens with pure tension and pure torsion loading paths. The results confirm assumptions of the overstress theory of viscoplasticity.