Irradiation hardening of Fe ions in additive manufacturing 316 stainless steels

The 316 stainless steels were fabricated by selective laser melting (SLM) additive manufacturing and compared to the traditionally manufactured counterparts. The microstructure and performance of the traditionally manufacturing and additive manufacturing 316 stainless steels were characterized by metallographic microscopy, scanning electron microscopy, X-ray diffraction, and Vickers hardness testing. To investigate the irradiation-induced hardening effects, these two 316 stainless steels were irradiated by 3.5 MeV Fe ions at room temperature. The results indicate that the additive manufacturing 316 stainless steels show the columnar crystal structure with the single austenite γ phase, accompanied by the high-density subgrain-like cell wall structure, and the hardness exhibits the anisotropy between the scanning and deposition planes. Irradiation hardening effects are observed on two types of 316 stainless steels after Fe ions irradiation, and the hardening rate of the 316 stainless steels produced by additive manufacturing is found to be lower than that of the traditionally manufactured steels, but it also shows the anisotropy of irradiation hardening in the additive manufacturing steels.