Strain rate and temperature dependent mechanical response of laser powder bed fused 321 stainless steel
摘要
Laser powder bed fusion (LPBF) of 321 stainless steel (SS) exhibits great potential for high-temperature and impact-prone applications due to its unique microstructure and Ti stabilization. This study systematically investigated the mechanical performance and deformation mechanisms of LPBF 321 SS under quasi-static tensile and representative high-strain-rate compressive conditions over a wide temperature range (25–800 °C). Optimized short-term heat treatment (600°C for 2 h) significantly improved strength while maintaining excellent ductility, with a yield strength of 645 MPa, tensile strength of 833 MPa, and elongation of 58.7%. Quasi-static tensile tests revealed a transition in deformation mechanisms from slip-twinning at 25 ° C to slip-dominated deformation at elevated temperatures, with dynamic strain aging observed at 600 ° C and predominantly intergranular fracture at 800 ° C. In contrast, dynamic compression tests using a split Hopkinson pressure bar showed that twinning remained active even at 600 ° C, and the microstructure retained its austenitic stability. These findings clarify the coupled influence of temperature, loading mode, and strain rate on the deformation behavior of LPBF 321 SS and provide useful guidance for its application in thermo-mechanically demanding environments.