Mechanical performance and microstructural characteristics of SiC dispersed 316L stainless steel manufactured by wire + arc additive manufacturing (WAAM)

Abstract

Wire + Arc Additive Manufacturing (WAAM) has emerged as a highly efficient metal additive manufacturing technique for producing near-net-shape components with reduced tooling requirements, cost, and lead time. This study investigates the fabrication of SiC-dispersed 316L stainless steel using the WAAM process and assesses its influence on microstructural development and mechanical properties. The addition of silicon carbide (SiC) led to a significant improvement in mechanical performance, with hardness increasing by approximately 14% and tensile strength rising by nearly 20% compared to monolithic WAAM-fabricated 316L stainless steel. Microstructural analysis using SEM and X-ray diffraction (XRD) neither resolved SiC/second phase particles nor indicated noticeable refinement in grain size. TEM analysis revealed that the SiC-dispersed alloy exhibits a high density of dislocations, deformation twins, and twin bundles, whereas these twinning features are absent or significantly less pronounced in the monolithic WAAM-fabricated 316L stainless steel. This behavior is attributed to solute redistribution within the matrix, which promotes the formation of secondary phases and contributes to a localized reduction in stacking fault energy (SFE). The combined effects of compositional modification, particle-induced lattice strain, and dislocation accumulation near particle–matrix interfaces are considered responsible for facilitating deformation twinning in the SiC-dispersed material. Furthermore, the absence of clearly resolved SiC particles suggests that the elevated thermal conditions during processing may have caused partial SiC decomposition, followed by the diffusion of silicon and carbon into the steel matrix.