Effect of Pulse Current on the Tensile Deformation of SUS304 Stainless Steel

The effect of pulse current on the mechanical properties of SUS304 metastable austenitic stainless steel was studied by tension test with and without air-cooling under different current densities. The microstructural variations at different conditions were also studied by SEM, TEM, and Feritscope. A negative effect on the plasticity was observed when current pulse was applied without air-cooling. But when Joule heating resulting from current pulse was excluded by air-cooling, the elongation of SUS304 stainless steel was increased to 72.4% at a current density of 2.95 A/mm(2), which is 23.3% higher than that tested without pulse current at room temperature. Pulse current can decrease the dislocation density and dislocation pile-ups. Furthermore, EP effect from pulse current can accelerate martensitic transformation and enhance TRIP effect. The mechanism of current-induced martensitic transformation was discussed from Gibbs free energy change.