Surface nano crystallization and nitriding on microstructure and properties of 304J1 stainless steel

Abstract

Abstract To improve the mechanical and antibacterial properties of 304J1 stainless steel, hybrid surface treatments, which include nitriding combined with shot peening operations, are used. Shot peening with different sizes of steel balls makes the material’s surface nanocrystalline, providing more diffusion channels for subsequent nitrogenating, and the nitriding efficiency is improved. Nitrogen cannot only improve the antibacterial property but also significantly enhance the strength of 304J1. The experimental results show that within a certain depth, the surface of 304J1 can be nanosized by shot peening for 20 min with a projectile diameter of 0.2 mm. The depth of the nitriding layer reaches 0.6 um, the surface hardness increases from 560 HV to 1100 HV, and the antibacterial property against Escherichia coli increases from 10% to 85%.