Radiation-induced swelling and hardening of 316L stainless steel fabricated by selected laser melting

Abstract

Additive manufacturing (AM) has remarkable application potential in the field of nuclear engineering materials. Although considerable effort has been exerted to improve the mechanical properties of additive-manufactured materials, research on radiation-induced degradation of AM materials must also be conducted to meet the needs of nuclear engineering. This paper describes the radiation-phase stability of 316L stainless steel (SS) fabricated via selective laser melting (SLM) technology and the influence of microstructure change on the swelling and hardening of materials. Results showed that the austenite phase in SLM 316 SS was more stable than that of cold-rolled (CR) 316L SS. However, the swelling of SLM 316L SS occurred earlier than that of CR 316L SS in the room temperature (RT) case, while no distinct difference was observed between the two materials in the 350 °C case. Two 316L SSs behave differently in swelling, due to their difference in misorientation and density of grain boundaries and dislocations. In addition, the hardening of CR 316L SS was stronger than that of SLM 316L SS. Analysis indicates that the inhibiting effect on radiation-induced martensite formation in SLM 316L SS leads to the improved resistance to the radiation hardening.