Influence of intermetallic phases on the corrosion properties of duplex stainless steel weld metals

Summary

The effect of intermetallic phases formed in the temperature range 675–1000 °C on corrosion resistance and toughness was studied in duplex weld metals with a composition comprising 22% Cr‐9% Ni‐3% Mo‐0.15% N. The R phase, rich in molybdenum, formed rapidly at 700 °C and was the most important phase which precipitated at 800 °C, while only σ phase formed at 900 °C. At 800 °C, a small quantity of phase x formed. A significant reduction in the ferrite content or an increase in hardness implies a reduction in corrosion resistance. Above 800 °C, corrosion resistance and toughness were both affected while, at temperatures below 800 °C, the deterioration in corrosion resistance occurs before embrittlement. Nevertheless, if the recommended welding procedures are followed, there is no loss of corrosion resistance.