Increasing the gap tolerance in friction stir welded joints of AA6082-T6

This research project was conducted to increase weld gap tolerance in Friction Stir Welding (FSW) of 8 mm thick aluminum alloy 6082 – T6. Investigation was done on I-STIR PDS platform and a Johnford milling machine. The research project involved tool-pin design with varying re-entrant features and varying parameters as a method of weld gap closing to produce successful welds. Direction of spindle rotation and dwell time were established as part of a preliminary study. Clockwise spindle rotation with 20 seconds dwell time allows sufficient plasticity and improved material flow which assisted in achieving welds with prior 30 percent weld gap of the plate thickness. Final welds were made using three rotational speeds and feed rates with sufficient plunging to prevent root defects. Analysis of the results were detailed which include vickers microhardness test, tensile test and metallographic observation to access the suitability of the weld structure. From the set of tool-pins designed, the flare tool-pin gave a well-defined weld nugget with improved stirring at the weld root. Also, with a concave shoulder, right hand threaded tool-pin and counterclockwise flutes undergoing a clockwise spindle rotation, plasticized material flow was upward which was beneficial in reducing the amount of plate thinning. The right hand thread counter clockwise flute with a flute machined in the foot exhibited superior tensile strength for welds containing 30 percent weld gap

Increasing the gap tolerance in friction stir welded joints of AA6082-T6

This research project was conducted to increase weld gap tolerance in Friction Stir Welding (FSW) of 8 mm thick aluminum alloy 6082 – T6. Investigation was done on I-STIR PDS platform and a Johnford milling machine. The research project involved tool-pin design with varying re-entrant features and varying parameters as a method of weld gap closing to produce successful welds. Direction of spindle rotation and dwell time were established as part of a preliminary study. Clockwise spindle rotation with 20 seconds dwell time allows sufficient plasticity and improved material flow which assisted in achieving welds with prior 30 percent weld gap of the plate thickness. Final welds were made using three rotational speeds and feed rates with sufficient plunging to prevent root defects. Analysis of the results were detailed which include vickers microhardness test, tensile test and metallographic observation to access the suitability of the weld structure. From the set of tool-pins designed, the flare tool-pin gave a well-defined weld nugget with improved stirring at the weld root. Also, with a concave shoulder, right hand threaded tool-pin and counterclockwise flutes undergoing a clockwise spindle rotation, plasticized material flow was upward which was beneficial in reducing the amount of plate thinning. The right hand thread counter clockwise flute with a flute machined in the foot exhibited superior tensile strength for welds containing 30 percent weld gap

A Comparative Study of Tool-Pin Profile on Process Response of Friction Stir Welding of AA6082-T6 Aluminium Alloy

This paper presents research work conducted to experimentally establish the process response of two diverse shaped tool-pin profiles for friction stir welding (FSW) AA6082-T6 aluminium. The dwell time was optimised by plunging each tool-pin into a plate sample until the spindle torque stabilised thus ensuring sufficient plasticised material in contact with tool shoulder and the tool-pins. The welds were conducted by employing the optimised dwell time, which in turn revealed a minimised process response time and distance to reach weld stability with respect to (1) the force exerted on the tool-pin in the welding direction, Fx , and (2) the spindle torque, T, during the welding process. Both Fx and T stabilised well within the set (pre-determined) ramp-up distance of 20 mm, indicating that the effective (useful) weld length is maximised. The macrographs also revealed good dynamic material flow within the nugget zone regions and more evident in the nugget zone of the flared tool

Increasing the gap tolerance in friction stir welded joints of AA6082-T6

This research project was conducted to increase weld gap tolerance in Friction Stir Welding (FSW) of 8 mm thick aluminum alloy 6082 – T6. Investigation was done on I-STIR PDS platform and a Johnford milling machine. The research project involved tool-pin design with varying re-entrant features and varying parameters as a method of weld gap closing to produce successful welds. Direction of spindle rotation and dwell time were established as part of a preliminary study. Clockwise spindle rotation with 20 seconds dwell time allows sufficient plasticity and improved material flow which assisted in achieving welds with prior 30 percent weld gap of the plate thickness. Final welds were made using three rotational speeds and feed rates with sufficient plunging to prevent root defects. Analysis of the results were detailed which include vickers microhardness test, tensile test and metallographic observation to access the suitability of the weld structure. From the set of tool-pins designed, the flare tool-pin gave a well-defined weld nugget with improved stirring at the weld root. Also, with a concave shoulder, right hand threaded tool-pin and counterclockwise flutes undergoing a clockwise spindle rotation, plasticized material flow was upward which was beneficial in reducing the amount of plate thinning. The right hand thread counter clockwise flute with a flute machined in the foot exhibited superior tensile strength for welds containing 30 percent weld gap