Experimental study on the effects of FSP and nanoparticle dispersion on the mechanical properties and microstructure of 316L stainless steel produced by SLM

Abstract

The study investigates the effects of friction stir processing (FSP) and silicon carbide (SiC) nanoparticle dispersion on the mechanical properties and microstructure of 316L stainless steel produced by selective laser melting (SLM). To achieve defect-free samples, FSP was conducted at 710 rpm and 31.5 mm/min, providing sufficient heat input to prevent void formation. Significant grain refinement was observed, with SiC nanoparticle–reinforced samples achieving an average grain size of 205 nm, compared to 715 nm for FSP-only samples and 12 µm for the base metal. X-ray diffraction confirmed the material remained single-phase austenitic. Mechanical testing showed that hardness increased by 95% with SiC nanoparticles and 55% without, while tensile strength and yield stress improved by 30–40% for SiC-reinforced sample and 15–20% for only FSPed sample, without significant reduction in elongation and ductility. The study concludes that FSP, especially with SiC nanoparticles, effectively enhances the mechanical properties and refines the microstructure of 316L stainless steel, making it a promising post-processing technique for SLM-produced parts.