High temperature tensile properties and deformation mechanism of 2205 duplex stainless steel fabricated by laser powder bed fusion

Abstract

Compared with cast specimens, 2205 duplex stainless steel produced by laser powder bed fusion (LPBF) demonstrates a superior combination of strength and ductility at room temperature. However, although 2205 is widely applied in high-temperature environments such as chemical processing and nuclear power, its high-temperature tensile behavior after LPBF processing remains insufficiently understood. In this study, highly dense 2205 duplex stainless steel was fabricated via LPBF, and its microstructural evolution and deformation mechanisms during tensile testing from 20 °C to 800 °C were systematically investigated following a solution treatment at 1050 °C. The results revealed that the specimen exhibited high strength (648 MPa) and elongation (40 %) at room temperature, primarily attributed to its fine grain size and high density of dislocations. At room temperature, the deformation mechanisms include dislocation planar and cross-slip in ferrite, while austenite undergoes planar slip, deformation twinning, and transformation-induced plasticity (TRIP). As the deformation temperature rises to 200 °C and 400 °C, a notable reduction in elongation is observed, primarily because the increased stacking fault energy (SFE) in austenite suppresses both twinning and the TRIP, resulting in a deformation mechanism dominated by dislocation slip. The LPBF-produced 2205 duplex stainless steel demonstrates outstanding mechanical performance from room temperature to 400 °C, with UTS, 0.2YS, and elongation all exceeding the ASTM 240 standard, highlighting its promise for structural applications in extreme environments.