Effect of prolonged temperature exposure on pitting corrosion of duplex stainless steel weld joints

Abstract

This study aimed at evaluating the pitting corrosion of duplex stainless steel (2205) welded by filler metal (2209) after exposure to increased service temperatures. In this work selected welded samples were aged at different temperatures (650 °C, 850 °C, 950 °C and 1050 °C), in order to simulate heat exposure during processing or service stages. The results showed that the pitting corrosion rate increased in chloride environments with increasing aging temperature till 850 °C; afterward pitting corrosion rate started to decrease and the joints restored their original pitting resistance at 1050 °C; and after that increasing the aging to above 1050 °C, pitting resistance was believed to decrease again, as a result from decreasing γ/δ. A correlation between different welding processes and aging times was also conducted. Keywords: Duplex stainless steel, Sigma phase, Chi phase, Pitting corrosion, Welding method