Additively manufactured SiC-reinforced stainless steel with excellent strength and wear resistance

Additive manufacturing enables in-situ alloying of multi-component materials for the development of novel and high-performance materials. Here laser powder bed fusion (LPBF) of SiC-reinforced 316L stainless steels metallic matrix composites (MMCs) for improved strength and wear resistance were investigated. The densification behaviour, microstructural evolution, crystallographic orientation and properties of the LPBF-processed MMCs with different SiC contents were systematically investigated. The formation mechanisms of pores and cracks are discussed. Microstructural observations reveal that the microstructure changes from equiaxed to dendritic with increasing SiC are related to the different temperature gradient and solidification rates. The SiC addition affects crystallographic orientation and causes grain refinement to 316L. In addition, micron SiC particles are refined to nano-scale after laser processing, which induces massive dislocations in the 316L matrix. The strength and tribological properties of 316L are significantly improved by SiC addition, in which the 9 vol% SiC reinforced MMC reaches a high tensile strength of about 1.3 GPa, together with a low wear rate of 0.77 × 10−5 mm3/Nm. The achieved strength and wear resistance are at the highest level among literature, and the underlying strengthening mechanisms are elucidated.