Study on CMT welding technology of a steel in automotive manufacturing: weld bead geometry mechanical property and welding metallurgy

Abstract

In this research, the objective was to investigate and measure the weld bead geometry, mechanical property, and welding metallurgy when JIS G3113 steel are welded using CMT. The study examines a number of welding variables, including weld current ( 10, 12, 14, 16, and 18 V) , and weld travel speed ( 25, 50, 75, 100, and 125 mm/min). The experiment was run using a CMT welding machine under an argon atmosphere. The quality of welded specimens was determined by their weld bead height, bead width, penetration, strength and microstructure. The optimal welding conditions were found to be 12 V of weld current and 25 mm/min of weld travel speed. The optimal welding conditions provided weld bead geometry and strength of quality which were able to pass the specifications of the making and inspecting welds on automotive steel. However, the welding travel speed no influence on the bead geometry, while the weld bead height, bead width and penetration exhibited a non-uniform pattern. After welding, only an Fe 0.9 intermetallic compound was observed in the microstructures. In addition, the larger degree of preferred orientation was detected at the {100} plane with a increase residual strain in the microstructure.