Recrystallisation after hot deformation of two phase stainless steels

Abstract

A series of model stainless steels containing 0, 30, 50, 70 and 100% volume fraction of δ was prepared. In these two phase alloys a duplex structure of equiaxed grains of δ and γ with a uniform distribution was established through hot deformation and heat treatments. The static recrystallisation kinetics were followed in all five alloys after hot torsion at a constant strain rate of 0.7 s¹ in the temperature range 1000 - 1150 ° C applying a constant strain of 0.28. Comparison of the static recrystallisation behaviour of the single and two phase alloys has been carried out at 1050 ° C. The results show that both phases recrystallise after hot deformation. However, a significant retardation of recrystallisation in both δ and γ phases has taken place in the two phase alloys in comparison with the single phase alloys, with the delay being larger for the δ phase. The possible causes of the retardation of recrystallisation of δ and γ phases in the two phase alloys are discussed.