Improved mechanical properties of steel/aluminium laser welding joint by Ti powder addition: experimental and first-principles investigations

The generation of brittle intermetallic compounds (IMCs) need be solved for steel/aluminium welding quality. In this study, Ti powder was selected as interlayer and the experiments of laser penetration welding for steel/aluminium through addition of interlayer were carried out. The effect of adding Ti powder on mechanical properties of the weld was investigated. Experimental results showed that the increased penetration depth was obtained, and the average tensile-shear strength of Ti-added joint was 10% higher than that of no-added joint. First-principle calculations revealed that the effect of reduced brittleness of IMCs with the addition of alloying elements was in accordance with the improved mechanical properties. When Ti powder was added, the grain was small, the layer thickness and brittleness of IMCs decreased, ductile phase Fe2Ti were formed. Hence, mechanical properties of the weld were significantly improved.