Influence of temperature on mechanical properties, fracture morphology and strain hardening behavior of a 304 stainless steel

The strain hardening behavior of an AISI 304 stainless steel at different temperatures was investigated in this work. Specimens were tensile tested up to rupture at temperatures of 25, 50, 75, 100, 125 and 150 ºC by using a universal testing machine with an attached environmental test chamber. The induction of martensite by strain was assessed by X-ray diffraction and Rietveld refinement. The resultant fracture morphologies were analyzed by scanning electron microscopy. The changes in the mechanical properties as a function of temperature were evaluated through the variations in the stress-strain curve and the strain hardening behavior was described in terms of strain hardening rate, instantaneous strain hardening exponent and Crussard-Jaoul analysis. Six strain hardening stages were detected at lower temperatures, transitioning into three strain hardening stages at higher temperatures. Fracture surface was ductile at all studied temperatures, although differences in terms of dimple and void morphology were observed.