In-situ generation of high-strength AISI 1045 steel with SiO2 nano-precipitation by selective laser melting (SLM)

High-strength AISI 1045 steel with SiO2 nano-precipitated particles is prepared via selective laser melting (SLM). The microstructure and mechanical properties of the as-built samples were studied and characterized by Scan-ning electron microscope (SEM), X-Ray Diffraction (XRD), Electron backscatter diffraction (EBSD) and Trans-mission electron microscope (TEM). XRD analysis shows that the powder mainly contains alpha-Fe phase, while gamma-Fe phase appears in the SLMed specimen. The peak intensity increases slightly with the increasing of the processing energy density. In addition, ultra-fine martensite and SiO2 nano-precipitated particles were found in the as-built samples. Moreover, excellent mechanical performances were achieved by SLM-AISI 1045 (Vickers hardness: 502 +/- 25 HV0.1, yield strength: and 1250 MPa), which are 1.63 times and 3.29 times higher than those of traditional commercial AISI 1045 respectively. Finally, the strengthening mechanism of the SLM-AISI 1045 was analyzed and discussed.