Strain‐Induced Martensite and Reverse Transformation in 2304 Lean Duplex Stainless Steel and its Influence on Mechanical Behavior

Abstract

Duplex stainless steels (DSS) combine the mechanical properties of ferrite ( α ) with the corrosion resistance of austenite ( γ ), and is widely used in industrial applications. The γ can transform into martensite (SIM) during a deformation. When annealed, these types of steel undergo a reverse transformation, namely, SIM reversed to austenite (SIMRT). The aim of this study is to evaluate SIM and SIMRT in 2304 lean DSS (LDSS) as well as its influence on the mechanical properties after a 60% reduction in thickness. The annealing is conducted within a range of 600–900 °C with a soaking time of 1800s. The samples undergo X‐ray diffraction, EBSD, and a tensile test. The results show that, after cold rolling, the amount of α ′‐martensite formed is made up 24%. The α ′‐martensite collaborates with the enhanced yield strength and reduces the total elongation. The orientation among γ and α ′‐martensite, and (111)γ//(110) α [110] γ //[111] Kurdjumov‐Sachs and (111) γ //(110) α [110] γ //[001] α Nishiyama–Wassermann, is observed after deformation and during the reversion process. The EBSD shows a high misorientation inside the γ after the cold rolling. The SIMRT shows diffusional and shear reversion characteristics, at 900 °C, yield strength is 468 MPa, and the elongation is 32%.