HOT-WORKING CHARACTERISTICS OF STEELS IN AUSTENITIC STATE

The behavior of C, HSLA, tool and stainless steels in the austenitic c ondition during industrial hot forming is reviewed. In the constitutiv e relations, it is primarily the activation energy which rises with al loy additions. Strain hardening is reduced mainly by dynamic recovery as indicated by its stress dependence and confirmed microscopically in the austenitic stainless steels. Dynamic recrystallization provides a dditional softening, possible grain refinement and enhanced ductility. After deformation, the metal undergoes static recovery and static rec rystallization at longer times to provide grain refinement and stress reduction in any following stage. With rapid cooling, it is possible t o retain either hot-work substructures in elongated grains or fine new grains which strengthen the product directly or through refined ferri te.