The effects of polarization on the failure in acids of cold-worked 18Cr [sbnd]10Ni steels

Abstract

The fracture of tensile specimens of heavily cold-worked 18Cr 10Ni austenitic stainless steels subjected to a low strain-rate at room temperature has been examined by optical microscopy. Experiments were performed in air and in both H 2SO 4 and HCl + NaCl (a) under open circuit conditions and (b) polarized galvanostatically, cathodic and anodic at c.ds. up to 100mA/cm 2. Two types of fracture were induced by the environment: (i) s.c.c. occurred in HCl + NaCl under conditions of anodic polarization (this was associated with the prior occurrence of pitting and crevice attack and fracture did not always occur across the narrowest section of a specimen), (ii) embrittlement under conditions of cathodic polarization in both solutions (this was associated with blister formation which occurred more readily in H 2SO 4 and appeared to be promoted by plastic deformation). Experiments on pre-pitted specimens indicated that the effect of pitting was chemical rather than metallurgical.