Optimizing laser spot size for improved structural integrity in additively manufactured copper alloy components

Abstract

Laser powder bed fusion (LPBF) offers significant advantages for printing Cu–Cr–Zr alloy, such as thermal stability, design flexibility, and impressive strength. However, surface defects and pore formation, often caused by using unoptimized parameters, can impact the efficiency of complex geometries and parts. The primary goal of this research is to minimize these defects by optimizing key processing parameters. In this research, laser spot size (100, 200, and 300 µm), scan speed (450, 650, and 850 mm/s) and layer thickness (30, 60, and 90 µm) were examined to achieve a defect-free copper alloy part. Nanohardness, porosity and surface roughness were considered as the response variables. Analysis of variance (ANOVA) coupled with complex proportional assessment (COPRAS) approach was performed to identify the optimal parameter settings. While adopting the optimal parameter settings, there was a 69.9% reduction in the surface roughness, 98.5% reduction in the porosity and 91.9% reduction in the nanohardness of the printed Cu alloy parts. Additionally, the effects of different combinations of input parameters on surface roughness and the mechanism that lies behind the porosity formation were demonstrated. The implementation of 100 µm spot diameter, 30 µm layer thickness and 650 mm/s scan speed resulted in defect-free Cu alloy parts with reduced porosity of 0.13%, minimum surface roughness of 10.37 µm, and maximum nanohardness of 6.2 GPa, according to confirmation experiments conducted for the ideal and initial settings. Moreover, the obtained result from the confirmation experiments has a greater concurrence with the COPRAS approach.