Arc and molten pool behavior on quality of hybrid cold metal transfer and tandem pulsed narrow gap gas metal arc welds: a study.

This research proposes a novel hybrid cold metal transfer (CMT) and tandem Pulsed gas metal arc welding (P-GMAW) process for narrow gap welding (NGW) of high strength low alloy (HSLA) steel plates. Investigating three sets of lead and trail wire feed speed (WFS) ratios [WFS_L/T - 1.4, 1, 0.7], the study delves into the complex arc and metal transfer behavior within the narrow gap. Utilizing synchronized arc images and current-voltage waveforms, the research assesses their influence on fusion and mechanical properties. The root pass employs the single wire CMT process, while filling and closing passes leverage tandem P-GMAW, effectively minimizing incomplete fusion and reducing heat input. Results indicate that a lower WFS_L/T (0.7) reduces the molten pool hump and overflow within the narrow gap while enabling direct weld arc engagement with the previously deposited layer, enhancing weld penetration. WFS_L/T of 1.4 and 0.7 revealed higher and lower Charpy impact toughness. [ABSTRACT FROM AUTHOR]