Effect of Heat Treatment on Microstructure and Hardness of T122 Steel Welding Joint

The hardness and microstructure of T122 weld joint at different tempering temperaturs has been studied.The hardness of weld joint reduced with the increase of tempering temperature and could satisfy the requirement when tempered at 740-760 ℃,no apparent softening phenomenon appeared in the HAZ after tempering.Microstructure analysis showed that the weld joint was composed of martensite and small quantity of δ ferrite.Temper martensite with apparent lath character could be got by tempering at 740-760 ℃.The tempering temperature had little effect on the hardness and microstructure of base metal.