Electrochemical Studies on Corrosion Behavior of Austenitic Stainless Steel Weld and Clad Metals

Two electrochemical techniques, anodic polarization and controlled potentiostatic etching, were used to evaluate the general and intergranular corrosion of austenitic weld and clad metals deposited by different fusion welding processes. It is shown that weld heat input and delta ferrite significantly affect anodic polarization behavior under active potential conditions. Potentiostatic etching studies revealed that ferrite as such is harmful only in a limited potential range, namely, below Epp, because it is passivated at more active potentials than austenite is. The heat treatment at 650 C was found to affect the anodic polarization behavior significantly. The results of ferric sulfate-50% sulfuric acid test (ASTM A262 - B), which was conducted to yield a comparison with electrochemical tests, supported the above conclusions. The study indicated the possibility of using the short duration electrochemical technique to assess the general and intergranular corrosion behavior of weld and clad metals.