The effects of an integrated process of fine particle peening and plasma nitrocarburizing on the performance of low-carbon steel

• Highlight 1: The composite processes of fine particle peening and plasma nitrocarburizing was proposed to enhance the wear resistance of gear. • Highlight 2: The composite processes could increase the surface hardness and the depth of the diffusion layer, but the strengthening mechanism was different. • Highlight3: The PNC-FPP specimen had a smoother surface and significant residual compressive stress state compared to the FPP-PNC specimen. In this paper, the integrated process of fine particle peening (FPP) and plasma nitrocarburizing (PNC) is proposed to enhance the wear resistance of a low-carbon alloy steel. The overall performance of specimen after the integrated process, including surface roughness, residual stress, microstructure, and tribological properties, is systematically evaluated by some characterization tests. Results reveal that the integrated processes can increase the surface hardness and the depth of the diffusion layer, but the strengthening mechanism are different. Furthermore, the PNC-FPP specimen has a smoother surface and more significant residual compressive stress state compared to the FPP-PNC specimen. However, we find that the integrated process of FPP-PNC-FPP to be the most effective, and it approximately doubles the wear resistance of the low-carbon alloy steel.