Material flow and mechanical properties of friction stir welded AA 5052-H32 and AA6061-T6 alloys with Sc interlayer

Friction stir welding (FSW) is superior to fusion welding for joining incompatible alloys. In FSW Al/Mg alloys, developing IMCs like Al3Mg2 and Al12Mg17 is almost predictable and undesirable. Continuous IMCs produce a simple fracture propagation path, increasing brittleness and reducing weld strength. AA5052-H32 and AA6061-T6 were joined with a scandium (Sc) strip in the current study to improve material flow and reduce brittleness. Interlayer added on these alloys are the military-grade aluminium alloys used in the production of ship hull constructions and armoured helicopters. During FSW, a threaded cylinder tool with a rotating speed (TRS) of 1600-2000 rpm, welding speed (WS) of 60-80 mm/min and tool pin depth (TPD) of 0.1-0.4 mm were used to create the weld joints. To improve the strength of the above material combination during FSW, a 2 mm thickness Sc interlayer was added. The mechanical and metallurgical characteristics of the weld joints were studied. The maximum ultimate tensile strength value obtained from the cylinder-threaded tool pin profile with 0.1 mm TPD presented 237.63 MPa. Experimental interpretations were employed using response surface methodology-box Behnken design (RSM- BBD). FSW variables' influence was investigated using the analysis of variance (ANOVA) technique.