Effect of laser texturing on the interface and properties of aluminum/steel arc fusion brazed joints

Using the high-performance aluminum/steel welding parts is the goal of automotive lightweight. Aim at the problem that the brittle intermetallic compound layer at the joint interface of aluminum/steel leads to a poor joint performance and limits its application, a TIG brazing test of aluminum upper steel is designed. The steel is texturing with low-power laser. The morphology and distribution of intermetallic compounds are analyzed via scanning electron microscopy. The effects of texturing line spacing on wetting and spreading behavior, the distributing of intermetallic compound at interface and the joint mechanical are researched. Results as following: the wetting and spreading of liquid aluminum on steel is deteriorated after texturing. However, the morphology of steel from flag to jag groove increases the reaction contact area and mechanical occlusion. Meanwhile, the groove blocks the cracks growth so that the mechanical properties improved. The intermetallic compounds distribution changes from uniform continue along the interface to non-uniform inside the groove. Under the condition of the line spacing is 130 μm, the average tensile strength of the joint reaches 85.5 MPa.