Abstract
In order to determine the effect of δ-ferrite on the hot workability of 309S stainless steel, γ and δ single phase alloys which are constituent phase of 309S steel have been prepared and examined.
It is demonstrated that 309S steel, compared with γ and δ single phase alloys, exhibits quite poor workability in the temperature range of 900-1200°C. This is mainly caused by the fact that cracks originate more easily at the γ/δ interface than γ/γ and δ/δ grain boundaries and no recrystallization nucleates at the crack tip during deformation. Ductility dip in the vicinity of 1150°C is noticiable. This is probably due to the segregation of S at the γ/δ interface and formation of void followed by the solution of δ into γ phase. In the temperature range of 1200-1300°C, recrystallization arrests crack propagation and ductility of 309S steel increases remarkably.
