Effect of thermal cycles on ferrite content of austenitic stainless steel

The properties of austenitic stainless steel weld metals are strongly influenced by the duplex structure of austenite and ferrite. The objective of the present study was to investigate the effect of thermal cycles on the ferrite content in austenitic stainless steel weld metal, and to explore the ferrite–austenite solid state transformation of austenitic stainless steel weld metal. The results indicate that the peak temperature, cooling rate, and number of thermal cycles have a significant effect on ferrite content in the austenitic stainless steel weld. As the cooling rate increases, or the number of thermal cycles decreases, the amount of retained ferrite is increased at room temperature. New δ ferrite phase can be formed if the reheating peak temperature is above the optimum γ solvus temperature of austenitic stainless steel, and this new δ ferrite can be retained under rapid cooling conditions.