THE EFFECT OF SCALE ON STAINLESS-STEEL INTERGRANULAR CORROSION TESTING BY THE ACCELERATED ELECTROCHEMICAL METHOD

Scale affects the results of accelerated electrochemical testing 12Kh1 8N10T steel for intergranular corrosion (IGC) susceptibility. In 10% H 2SO4 + 0.0025 g/l KCNS scale enhances the anodic dissolution and activ ates the grain boundaries, which promotes IGC of steels that are not s usceptible to IGC according to Russian Standard GOST 6032-89. Layer-by -layer etching of the scale and then the superficial metal layer under conditions of predominant activation of grain boundaries does not rem ove the scale completely because the scale is left between the grains and makes the steel susceptible to IGC. Mechanical polishing prior to testing, which removes the scale completely, precludes IGC.