Influence of annealing temperature on deformation behavior of 329LA lean duplex stainless steel

Tensile behavior of a 329LA lean duplex stainless steel at room temperature is investigated after annealing at different temperatures. The austenite composition and thereby, its stability depend on the annealing temperature. For recrystallized alloys, austenite stability increases with the annealing temperature. Therefore, martensitic transformation is effectively suppressed during cooling and deformation, which results in low tensile strength and strain hardening rate, when the steel is annealed at higher temperature. Accordingly, transformation-induced plasticity is more pronounced in alloys annealed at lower temperature. During deformation, alpha'-martensite forms with a blocky morphology with the absence of the deformation bands indexed as an hcp phase. Thus, it is suggested that austenite directly transforms to a'-martensite during deformation rather than via the deformation bands due to a relatively high driving force for a'-martensite transformation in the present alloy.