The Influence of Tool Tilt Angle on 1050 Aluminum Lap Joint in Friction Stir Welding Process

In this paper, the effect of tool tilt angle on tensile-shear failure load and weld zone properties for 1050 aluminum plates, welded by friction stir lap welding, were investigated. For this purpose, tool tilt angle was varied from 0° to 5° under the constant other parameters, such as tool geometry, tool rotation speed of 1200 rpm and tool travel speed of 30 mm/min. The tensile-shear test was employed to test the mechanical properties of the joint. Optical microscope examinations, microhardness and temperature measurements were also performed in weld zone of lap joints. According to overall results, the tool tilt angle has a reasonable influence on the joint soundness and weld defect formation. If the tool axis was perpendicular to plate surface or a larger tool tilt angle was used, such configurations had harmful effect for the weld zone. In such case the tensile-shear failure load dropped from 4853 N to 2799 N. Recorded peak temperatures varied from 381°C to 438°C in the weld center. The measured mean hardness values of the stir and heat-affected zones were 31.5 HV and 28.3 HV, respectively, which are lower than that of aluminum 1050 base metal (40.7 HV).