Tested typical duplex stainless steel grades S32707 ( 022Cr27Ni7Mo5N)、S32750 ( 022Cr25Ni7Mo4N)、 S32205(022Cr23Ni5Mo3N) and S31803(022Cr22Ni5Mo3N) are sampled from produced billet

and by various heat treatment

hot working and hot piercing process as well as chemical composition adjustment

the effect of microstructure and pro¬duced process on hot working performance has been studied. The results show that the phase ratio and phase precipitation are closely related to the temperature of hot piercing and solution treatment and cold forming annealing

and the precipitation speed and amount of second phase in S32707 far exceed S32750

S32205 and S31803 duplex stainless steel grades. For S32707 duplex stainless grades

lowering Cr(≤27% )and N(≤0.4%) content

increasing Mo (4% ~5%Mo) content

properly controlling the heating rate(2 ~2.5℃/min) and finishing rolling(forging) temperature(≥1060℃.) and paying attention to the effect of reheating and tube billet drilling could improve hot working ductility and prevent cracking.