Effect of annealing temperature on transformation induced plasticity effect of a lean duplex stainless steel

Effects of annealing temperature on the mechanical property and martensite transformation of a new lean duplex stainless steel have been investigated. It was found that the elongation increased with the annealing temperatures and reached the maximum of 61.2% after annealing at 1150 °C. A sequential γ → ε → α ʹ martensite transformation was generated during tensile and brought the transformation induced plasticity effect. More than 30% α′ martensite was induced after tensile in the specimens annealed at 800 ~ 1000 °C, whereas only 8.8% α′ was induced at 1150 °C. The Md(30/50) temperatures of austenite phase reduced from 97 °C to 46 °C with the annealing temperatures varying from 800 °C to 1150 °C. Therefore the austenite phase became more stable and transformed to ε and α′ martensite phase gradually in a wide region and thus caused better plasticity. This also indicated that γ → ε transformation was important for transformation induced plasticity effect.