High-velocity laser accelerated deposition: Microstructure and mechanical properties of the aluminum-steel bonding interface

Abstract

High-velocity laser accelerated deposition (HVLAD) is a cladding method that can achieve uniform adhesion between coating-substrate systems with unprecedented potential. Unlike thermally driven processes, HVLAD relies on laser peening technology to propel small areas of a thin film onto a substrate. An essential aspect of this technique is that it prevents significant temperature variations between the substrate and thin film, reducing the likelihood of thermally induced defects. An intense plasma pressure wave generated by the laser pulse, along with micro-level melting that occurs at the interface, leads to complex microstructure at the interface. This research studies the bonding process of 1100 aluminum (Al) of approximately 60 μm thickness to a 52,100 steel (St) substrate using this technique. The microstructure at the interface as well as nano hardness, and bonding strength using advanced microscopy and indentation techniques were investigated. It was concluded that the substantial grain refinement observed near the weld interface might be linked to the intense pressure as well as the melting and subsequent recrystallization induced by the high-speed heating and cooling rates inherent in the HVLAD process. Measurements of the scratch resistance and adhesion of the cladded aluminum coatings showed a critical load of delamination initiation in the range of 1–2 N. While this study focused on the bonding of Al and St, additional research is needed for other materials. With further development, HVLAD has the potential for cost-effective coating deposition on complex geometries without strength limitations. This method can apply corrosion-resistant, wear-resistant, thermal-resistant, and impact-resistant coatings with strong bonding on the substrate.