Embrittlement of 316L stainless steel in electropulsing treatment

Electropulsing treatment is known to induce the so-called electroplastic effect, which is accompanied by an increase in ductility of metals. However, in this study we find that the application of electric current pulse reduces the flow stress and strain-to-failure in a 316L stainless steel, and it also induces premature fracture with a fracture mode transition from full ductile to partial transgranular cleavage. The results indicate a reverse electroplastic effect, i.e. electropulsing-induced embrittlement. By using transmission electron microscopy (TEM), it is found that the dislocation cell structure became refined, and the density of deformation-induced twins increased as increasing the voltage. The variation of dislocation structure cannot be solely attributed to the heating of sample due to electricity. The embrittlement is believed to be a synthetic effect of Joule heat and electropulsing-enhanced dislocation motion.