Influence of isothermal annealing on fracture behaviour of high chromium superferritic alloys doped with sulphur

Abstract

Controlled amounts of sulphur were added to superferritic alloys based on a composition of Fe–40 wt-%Cr. The sulphur distribution was studied in relation to a series of isothermal annealing and aging cycles. The formation of a dispersion of CrS spheroids increases the tensile ductility and the impact resistance. Deformation studies suggest that the sulphide particles can act as local centres for plastic slip. However, overheating causes severe embrittlement by both precipitation hardening and intergranular precipitation. The results suggest that higher contents of residual sulphur can be tolerated without affecting the mechanical properties adversely, providing the correct thermomechanical treatment is followed.

MST/1339