Effect of multi-layer specific energy input variation on the properties of laser cladding

Abstract

This study investigates the effect of varying energy input across different cladding layers on the microstructure, porosity, hardness, residual stress, and distortion of martensitic stainless steel coatings deposited onto ductile cast iron. This research introduces a novel approach by implementing different energy inputs within the same deposition process. Experimental analyses, including optical microscope for microstructure and digital image processing for porosity, X-ray diffraction (XRD) for residual stress measurement, and real-time thermal monitoring, provide a comprehensive understanding of the impact of layer-specific energy variations. The findings indicate that energy input distribution significantly influences porosity formation, with lower energy inputs in the first layer reducing defect formation. Additionally, microhardness analysis reveals that higher cooling rates resulting from optimized energy input lead to improved hardness, whereas excessive heat input contributes to softening effects. Residual stress evaluations show that compressive stresses dominate across all specimens, with higher energy inputs in the final layer resulting in increased thermal expansion and distortion. The study also integrates Simufact simulations to validate the experimentally observed distortions, reinforcing the correlation between energy input and mechanical stability. By optimizing process parameters for multi-layer laser cladding, this research provides valuable results for industrial applications, particularly in mold repair processes where durability and precision are essential.