Process and Performance Study of FeMnSi Shape-Memory Alloy Coating Prepared by Laser Alloying on Stainless Steel Surface

This study investigates the use of FeMnSiCrNi shape-memory alloy coatings on 316 stainless steel surfaces to harness the stress-induced γ ↔ ε martensitic transformation, enhancing fatigue strength and wear resistance and reducing residual stresses and microcracks. Utilizing laser alloying for fabrication, we optimized the process parameters with ANSYS software to achieve precise melt pool dimensions. We employed SEM, XRD, stress analyzers, microhardness, and friction testers to assess the coatings’ microstructure and mechanical properties. The predominant γ austenite phase in the coatings, enriched with martensite because of laser-induced residual stress, shows a transition in residual stress from compressive in the central area to tensile along the edges. The coatings demonstrated significantly higher hardness, approximately 1.5 times that of the substrate, with a microhardness average of 290.14. They also exhibited reduced friction coefficients and enhanced wear resistance compared to the substrate under varying loads. Under dry friction with 10 N, 15 N, and 20 N loads, the Fe17Mn5Si10Cr5Ni coating has friction coefficients of 0.46, 0.57, and 0.97, while the 316 stainless steel substrate shows higher coefficients of 0.57, 0.98, and 1.33.