Work

Influence of hatch spacing on molten pool evolution, defects generation and mechanical properties of SLM fabricated diamond/CuSn20 composites

Year: 2025

Type: article

Abstract: Selective laser melting (SLM) is considered as an effective technology in fabricating high performance metal-bonded diamond tools with integrated internal cooling and chip evacuation channels. However, defects such as pores and micro-cracks generated in SLM fabricating process, which hinder its further application. The generation of defects is closely correlated with laser processing parameters. Among these, laser hatch spacing constitutes a critical factor governing successful laser spot overlapping between adjacent molten tracks, thereby ultimately determining the mechanical properties of diamond-metal composites. Through integrated CFD-based numerical simulation and experimental approaches, the effects of varying hatch spacings on molten pool evolution, defect generation mechanisms, and mechanical properties of diamond-metal composites were investigated. The principal findings are as follows: I. The residual temperature from the first molten track alters the initial temperature of the second molten track. Simultaneously, the temperature gradient generated by the second laser pass induces remelting of the overlapping. II. At smaller hatch spacing, thermal damage tends to occur in diamond, whereas at larger scanning spacing, defects such as pores, unmelted regions, and gaps are prone to form in the overlapping regions. III. The specimen fabricated at a hatch spacing of 80 μm exhibits the highest compressive strength. Although its coefficient of friction (COF) initially surpasses that of the 100 μm hatch spacing specimen, it decreases below the latter after 14 minutes of testing. This work systematically analyzes the mechanisms of diamond migration and molten pool defects generation during the melting-solidification process.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.08.056