Achieving high strength-ductility balance in ferritic stainless steel via thermomechanical processing of a bimodal microstructure

This study investigates the influence of annealing temperature on the microstructure, texture, and mechanical properties of asymmetrically rolled AISI 430 ferritic stainless steel with a bimodal grain structure. Annealing from 600°C to 800°C induced a transition from partial to complete recrystallization, accompanied by martensite decomposition in the mid-thickness and fragmentation of coarse grains near the surface. Despite martensite elimination at 800°C, a bimodal grain distribution was retained. Texture analysis revealed that higher temperatures enhanced α-fiber (<110>//RD) and γ-fiber ({111}//ND) components. With increasing temperature, hardness and tensile strength decreased while ductility and mechanical uniformity improved. Work-hardening and fractographic analyses confirmed more homogeneous deformation and a transition to fully ductile fracture at 800°C. The 600°C condition offered the best balance between strength and ductility.