Investigation of strategies to enable the bonding of Alsi10mg on 316L stainless steel using the extreme High-speed Laser Material Deposition (EHLA) process

Abstract

The metallurgical joining of aluminum alloys to stainless steels remains a significant challenge in additive manufacturing due to the formation of brittle intermetallic com- pounds (IMCs) and high residual thermal stresses. This work investigates the feasibility of depositing AlSi10Mg onto 316L stainless steel using the Extreme High Speed Laser Material Deposition (EHLA) process, aiming to enable multilayer deposition while mini- mizing interfacial defects. A systematic experimental approach was employed, including direct deposition trials, the use of metallic buffer layers (In625 and CuNiSiCr), and ther- mal management strategies such as substrate preheating and controlled cooling. Direct deposition and In625 based configurations were unable to support stable multilayer growth, consistently exhibiting delamination and cracking. In contrast, the combination of a CuNiSiCr buffer layer with preheating at 350°C and controlled post deposition cooling enabled the successful deposition of up to 12 layers of AlSi10Mg without delam- ination and with only minor interfacial cracks. The results were analysed using optical microscopy and hardness measurements. Hardness testing confirmed the extreme brittleness of IMC rich regions, often leading to crack initiation during indentation. The results show that mitigating at least one of the two dominant failure mechanisms, IMC formation and residual stress, is essential to enable a reliable bond. The dual mitigation attempt strategy adopted here offers a promising path for the manufacture of hybrid components using EHLA in dissimilar metal systems.