Effect of Cr3C2 content on 316L stainless steel fabricated by laser melting deposition

Abstract

316L stainless steels with different Cr3C2 contents were fabricated by laser melting deposition (LMD) to investigate the effect of Cr3C2 content on microstructure, microhardness and wear resistance. The microstructure, chemical composition, phase constituents and microhardness were determined by using SEM, EDS, XRD and microhardness tester, respectively. The wear mechanisms were investigated using a ball-on-disc machine under dry condition. As the Cr3C2 content of deposited sample increased from 5 to 25 wt%, the morphology of carbides transited from a network to a blocky shape. The laser melting deposited samples mainly consisted of γ-Fe, Cr23C6 and (Cr,Fe)7C3, while in the sample added with 25 wt% Cr3C2, the Cr3C2 phase was presented as the minor phase. The microhardness of samples increased obviously from 390 ± 23 HV to 488 ± 23 HV with the addition of Cr3C2, which was 2 times that of LMD 316L stainless steel sample (243 ± 20 HV). The wear resistance of three sample was significantly improved with the addition of Cr3C2 and the sample with 15 wt% Cr3C2 exhibited the highest wear resistance, which could be attributed to the fact that the in situ synthesized eutectic carbides network led to the fine γ-Fe which has a good combination of strength and toughness.