Effects of ion irradiation on microstructure of 316L stainless steel strengthened by disperse nano TiC through selective laser melting

The manufacturing of the new generation of radiation-resistant structural materials is an extremely interesting and challenging topic in the field of additive manufacturing research. Understanding the special microstructure characteristics and the influence on the radiation resistance of these additive manufactured materials is still superficial. In this study, high-quality bulk 316L stainless steels (SSs) strengthened by dispersed nano TiC were successfully prepared by selective laser melting (SLM). The results of transmission electron micrograph and small angle neutron scattering showed that TiC existed in the matrix of 316L SSs in the form of nanoparticles with average size less than 50 nm. TiC particles were distributed inside the subgrains and on the subgrain boundaries. Smaller helium bubbles were observed after the same flux of He2+ ion irradiation in the case of 316L SSs with 4% TiC compared with pure SLM 316L SSs. In comparison with the case on the grain boundaries and intragranular, the helium bubbles at TiC/316L interfaces have the smallest size and the largest density. The results Nanoindentation results showed that 4% TiC doping had a remarkable inhibiting effect on irradiation-induced hardening at a low dose. This condition is because numerous interfaces of TiC/316L acted as sink/trap sites for the irradiation-induced defects.