Joining of AISI 1040 Steel to 6082-T6 Aluminium Alloy by Friction Welding

Aluminium alloys AA 6000 series are being used for automotive applications due to their ability to strengthen by artificial aging after forming. The joining of aluminium especially to other alloys becomes increasingly important. Joining of aluminium to steel presented distinctive metallurgical and mechanical properties and selection of suitable joining methods are challenging. This paper describes friction welding of 6082-T6 aluminum alloy to 1040 steel via several process parameters. The influence of friction time and forging pressure on mechanical and metallurgical properties were evaluated. The maximum joint strength of 220 MPa was achieved at optimized conditions and it has been observed that strength of the joints varied with increasing friction time at constant forging pressure. However, the strength of the welds varied gradually and increased with increasing forging pressure at constant friction time. Thus, the forging pressure has a major role over the friction pressure and friction time on strength of the joints. Microstructural characterization was done using optical microscopy and SEM analysis. The elemental composition of welds was analyzed by EDS technique. The presence of AlFe chemical species was characterized via a thin layer of transition zone on bond lines and the significance of percentage of compositions seems to be related to the Fe2Al5 and FeAl intermetallic compounds. The tensile fracture of the welded joint occurred in 6082-T6 aluminium side near the interface. The characterization of fractured surfaces reveals the pattern of dimple structure