Effect of pH on pitting corrosion of stainless steel welds in alkaline salt water

Pitting corrosion was studied in the weldment of 304L austenitic stainless steels joint with 308L austenitic stainless steels. The corrosion behavior of three different weldment zones (weld metal (WM), base metal (BM) and heat affected zone (HAZ)) in alkaline solutions with NaCl was characterized by a series of electrochemical tests. The results indicated that pH values played an important role in the corrosion behavior of the weldment. With the pH increasing, the film resistance, polarization resistance and Ecorr increases, the charge carrier density N and the site of the pitting on the weldment decreases. In addition, WM showed a better corrosion resistance, followed by HAZ and BM. The pittings in BM were much bigger than that in WM and HAZ.