Laser penetration welding of an overlap titanium-on-aluminum configuration

An overlap titanium-on-aluminum configuration based on laser penetration welding was designed to suppress the formation of intermetallic compounds. Weld surface appearance, weldgeometry, microstructure, and mechanical property of the joint were investigated. The collaps of upper liquid titanium closes keyhole filled with boiling aluminum vapor, which induces welding spatter. Optimizing processing parameters could control the welding spatter to some extent. Weld geometry is characterized by depth of the weld loss, depth of the penetration of titanium into aluminum and width of joining, which depends on processing parameters strongly. The overlap titanium-on-aluminum configuration can suppress the formation of intermetallic compounds inside Ti weld. Interfacial reaction appears between Ti weld and Al, and the reaction layers are composed of TiAl and TiAl3. The banded structures with Ti3Al were found inside Ti weld. Tensile capacity of the joint increases firstly and then decreases with increasing laser power or decreasing welding speed, depending on weld geometry and interfacial reaction. Moreover, there are two broken modes of the joints, which are fractured in interface and in Ti weld, respectively. When joints fracture in the Ti weld, the joint has the higher tensile property, up to 184 N/mm.