Microstructure And Mechanical Properties Of Gas Tungsten Arc Welded Al5052/Ti6Al4V Alloy Lap Joint

Titanium alloys owing to remarkable combination of its properties such as outstanding mechanical strength,excellent corrosion resistance and high specific strength have wide applications in aerospace and aircraft industrial sectors.Aluminum alloys having lightweight with two-thirds of titanium alloys density and other favorable properties have extensive potential in automobile and transportation industries for weight reduction purposes.Presently,environmental preservation and energy-saving are major issues that need to be essentially resolved.Since reduction in weight of components that consumes energy like aircrafts and vehicles is an effectual course,the lightweight alloys joining of aluminum to titanium alloys would be a promising perspective to accomplish this goal.In this study,sound lap joining of 5052 aluminum alloy and Ti6Al4V titanium alloy sheets was carried out by gas tungsten arc welding?GTAW?with AlSi12 and AlSi5 filler wire.The formation of Al5052/Ti6Al4V weld mechanism were studied and the effect of welding heat input on the microstructure,tensile and fracture properties,accordingly,were investigated.The Al5052/Ti6Al4V dissimilar lap joints were obtained by GTAW with AlSi12 filler wire.The welded lap joints showed dual features of welding and brazing on the aluminum and titanium parts of the joint,respectively.The continuous reaction layer established in the brazed area and its chemical composition by EDS analysis revealed that the intermetallic compound?IMC?layer of Ti?Al,Si?₃ phase formed and aluminum was partially substituted by silicon.The thickness of reaction layer differed from 1?m to 3.5?m with increase in welding heat input accordingly.Al,Ti and Si elements in the weld region and IMC layer were recognized by analysis of EPMA.The maximum tensile shear strength attained at the optimized welding heat input was 376 Nmm^-1 and the joint fractured from Al5052 base metal.Furthermore,the microhardness was measured and the hardness was higher at the Al5052/Ti6Al4V interface than in the weld seam and Ti6Al4V alloy base metal because of the development of IMCs.Al5052/Ti6Al4V lap joining was conducted by GTAW with AlSi5 filler wire.Microstructure examination revealed that non-uniform persistent reaction layer developed in Al5052/Ti6Al4V interfacial area,and the IMCs layer of Ti?Al,Si?₃ phase formed with the partial substitution of aluminum by silicon.The thickness of IMCs layer varied from<1?m to>5?m in accordance with rise in welding current.Aluminum,silicon and titanium elements in the IMCs layer and weld zone were identified by EPMA.The results demonstrated that sound Al5052/Ti6Al4V joints can be achieved in the range of 50 A-60 A welding current.The maximum tensile shear strength of 293Nmm^-11 was attained at the optimized welding parameter and the joint fractured in the weld zone.Additionally,the micro-Vickers hardness at Al5052/Ti6Al4V interface was relatively higher in comparison with the weld seam and Ti6Al4V base metal as a consequence of IMCs formation.