Investigation of CMT welding for end-surfacing applications in bimetallic mechanical composite pipes

Pipe end surfacing represents a standard welding technique employed in the fabrication of bimetallic mechanical composite pipes. This study investigates the application of cold metal transfer (CMT) welding technology for pipe end surfacing of bimetallic composite pipes. The effect of CMT welding parameters, including welding current, welding speed, weave width, weave frequency, and dwell time, on the weld width, weld height, heat-affected zone (HAZ) width, and fusion ratio was analysed. The results show that the main factors affecting welding forming are welding current, welding speed and weave width, which basically determine both the width and height of the weld. The orthogonal test shows that the more suitable welding parameters are 120 A welding current, 3.28 mm/s welding speed, 5 mm weave width, 3 Hz weave frequency, and 0.05 s dwell time on both sides. To improve welding efficiency and ensure arc stability, the adjusted surfacing welding parameters are 120 A welding current, 5.12 mm/s welding speed, 5 mm weave width, 2 Hz weave frequency, and 0.05 s dwell time on both sides. The lap surfacing weld was well formed.