The phase diagram of S32760 (022Cr25Ni7Mo3WCuN) super duplex stainless steel during solidification process is determined by Thermo-Calc thermodynamic calculation software

and the solidification mode of S32760 duplex steel is FA (Ferrite-Austenite). By changing the content of austenite and ferrite fanning elements and the different chemical compositions to determine the hot working properties、 Cr

2

N and ct phase precipitation temperatures

the hot working temperature range of S32760 is enlarged with increasing the content of austenite forming elements C、N、Ni and Mn

and reduced with increasing the content of ferrite forming elements Si、Cr and Mo

however W has no effect on hot working performance. According to the therm

odynamic calculation

the optimal chemical composition (/%：0.022C

0.30Si

0.80Mn

25.60Cr

6.20Ni

0.54Cu

3.50Mo

0.54W

0.27N) is determined. The optimal thermoplastic temperature of duplex steel S32760 is 1195;℃

the precipitation temperature of Cr

2

N phase is1050

℃

andthe precipitation temperature of

σ

phase is 1020 ℃;

and the hot working range is 145°C

which has been verified by subsequent production practice.