Examining the contribution of tamping effect on inter-splat bonding during cold spray

Abstract

In Cold Spray Additive Manufacturing (CSAM), the 'tamping effect'—resulting from continuous impact of incoming particles enhances the mechanical properties of deposited layers. While the impact of tamping on porosity is well-studied, its influence on inter-splat bonding remains unexplored. In this study a multiparticle simulation based on Finite Element Analysis (FEA) is employed, featuring 120 particles distributed across 12 layers to model the deposition process in cold spray. A methodology is developed to discern the effect of tamping, enabling the estimation of particle boundary temperatures under conditions with and without tamping. Energy analysis and inter-splat boundary temperature variations obtained from simulations are examined to understand the contribution of tamping to bonding. Our findings reveal a significant increase in inter-splat boundary temperatures, attributed to energy transfer from overlying layers, positively impacting bonding. The proposed hypothesis is substantiated through mechanical testing and the assessment of inter-splat bonding-related properties, including hardness, tensile strength, scratch resistance, and corrosion resistance, as a function of deposit thickness. CSAM IN718 and Cu deposits with a thickness of 4 mm are used as subjects for this study.