Mechanical and corrosion properties of additively manufactured SiC-reinforced stainless steel

Laser additive manufacturing (LAM) provides an opportunity for the in-situ preparation of high-performance ceramic particle-reinforced metal matrix composites (MMCs) with complex shapes. 316L stainless steel has excellent corrosion resistance but suffers from low strength and poor wear resistance, limiting its wide application. Here, laser powder bed fusion (LPBF) of SiC-reinforced 316L metallic matrix composites (MMCs) for obtaining better mechanical and corrosion properties were investigated, and the role of SiC contents on the microstructures and properties were discussed in detail. Besides, the post heat treatment was conducted to further improve the mechanical properties of MMCs. The micron-sized SiC is refined to the nano-level, together with the formation of many dislocations in the matrix during the LPBF process. The addition of SiC significantly improves the strength of 316L, with the highest tensile strength up to 1.3 GPa. The 6 vol% SiC-reinforced MMC reaches a tensile strength of 1069 MPa and an elongation of 9% while keeping a similar corrosion resistance with 316L. The heat treatment achieves a better strength-ductility in the 6 vol% SiC-reinforced MMCs, in which the tensile strength is slightly reduced to 900 MPa, but the elongation increased significantly to 18.4% due to the release of residual stress and reduction of dislocation density. In addition, the underlying strengthening mechanism and corrosion behaviour are investigated.