EFFECTS OF POLARIZATION ON FAILURE IN ACIDS OF COLD-WORKED 18CR-10NI STEELS

The fracture of tensile specimens of heavily cold-worked 18Cr{single bond}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 H2SO4 and HCl + NaCl (a) under open circuit conditions and (b) polarized galvanostatically, cathodic and anodic at c.ds. up to 100mA/cm2. 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 H2SO4 and appeared to be promoted by plastic deformation). Experiments on pre-pitted specimens indicated that the effect of pitting was chemical rather than metallurgical. © 1969.