Microstructure Evolution and Temperature/Stress Field Simulation of Laser Cladded EA4T Axle Steel with Inconel 625 Alloy

Abstract

To reduce the scrapping rate of railway axles and extend their service life, laser cladding technology is employed to deposit Inconel 625 alloy on the surface of EA4T axle steel for axle repair. This study validates the effectiveness of the numerical models of the temperature field and stress field in laser cladded EA4T axle steel by comparing the results of experiments with simulations. Subsequently, the formation process and distribution pattern of the microstructure in different regions were analyzed, and the critical positions of the laser-clad repair specimens were examined. The surface morphology, microstructure, internal defects, microhardness, and microscopic mechanical properties of the cladded specimens were characterized. The results indicate that the surface roughness of the specimens significantly increased after cladding. The formation and distribution of the microstructure in the clad layer and heat-affected zone (HAZ) were primarily influenced by the heat input and cooling rate during laser cladding, with the critical position of the clad specimen located at the interface between the clad layer and the substrate. A small number of near-spherical pores are present within the cladding layer. The microhardness of the HAZ significantly increases, with reduced elastic deformation and crack resistance in this region, which adversely affects axle repair. This study provides a methodology and theoretical support for the optimization and evaluation of parameters in the laser cladding repair of EA4T axle steel.