Oscillating energy deposition of 17-4 PH alloy reinforced with tungsten carbide particles

Abstract

17-4 PH is a martensitic precipitation-hardening stainless steel, renowned for its exceptional strength and high-temperature resistance, making it extensively employed in the fabrication of aircraft engines and flight control systems. The strengthening method of this alloy involves precipitation strengthening through thermal treatment. However, it is also susceptible to grain growth, which can diminish the alloy's mechanical properties and corrosion resistance. This research proposes to use circular oscillating laser deposition of 17-4 PH alloy reinforced with tungsten carbide (WC) and compares it with Gaussian laser deposition. The research findings indicate that the circular oscillating laser induces a stirring effect on the molten pool, facilitating the transformation of columnar dendrites into equiaxed grains and thereby refining the grain size. The convection, intensified by the high temperature and stirring effect, promotes the melting and diffusion of WC particles. The reaction between W, C elements, and 17-4 PH alloy facilitates the precipitation of hard phase carbides. Compared to Gaussian laser deposition, the microhardness of the 7 wt% WC/17-4 PH material prepared by circular oscillating laser deposition increased by 21.25 %, and the wear rate decreased by 70.06 %. The electrochemical test results have revealed that the 7 wt%WC/17-4 PH composite material fabricated using Gaussian laser exhibits optimal corrosion resistance. The circular oscillating laser induces carbide deposition at grain boundaries, resulting in the formation of microcells and exacerbating the corrosion.