Pitting corrosion resistance and treatment of heat tint in stainless steel welding

Objective The aim was to clarify effect of heat tint in stainless steel welding on its pitting corrosion resistance, especially the pitting behavior, and to provide a basis for post-weld treatment in engineering. Methods Welding heat tint with different colors was prepared and correlated with welding peak temperatures. Pitting potential was measured and compared with that of base metals. Various post-weld treatment methods such as rough grinding, fine grinding and pickling were applied to evaluate pitting corrosion resistance. Results The formation temperature of welding heat tint was higher than that of heat treatment heat tint (lightest color above 430 ℃). Pitting potential decreased significantly with the darker colors, and light yellow could not meet the requirements for fluid containers. Corrosion resistance after treatment was positively correlated with surface roughness. The greater the roughness, the worse the performance. Conclusion Welding heat tint markedly reduces corrosion resistance. Rough grinding and fine grinding or electrolysis can replace pickling in engineering. High-Cr stainless steel requires higher temperature for heat tint formation and is more difficult to pickle.