Study Of End Cracking During One-sided Submerged ARC Welding With Flux-copper Backing

Longitudinal hot tearing, popularly called as end cracking, frequently takes place in the end portions of the butt welds of large steel panels, using one-sided, submerged-arc welding with flux copper backing welding process(FCB welding) for the shipbuilding construction. In this paper, in order to look for the possibility to improve and/or prevent end cracking issue, residual stress measurement was devised and studied for five different concrete cases of FCB welding for better understanding the mechanism of hot tearing, influence factors and possible prevention measures. Unpredictable result was observed for all five cases that transverse compressive stress was found on the shallow surface of weld seams, which could give supplementary research results to the previous conventional assumption that tensile stresses across the welded joints caused the initiation of these cracks.Finally concluded that the end cracking of FCB welding is resulted from comprehensive function of different stresses, and that using of proper tack welding practice, elastic run-off plate and relatively low heat input energy will decrease the susceptibility of end cracking for the tested materials; meanwhile, it’s highly possible to reduce the end cracking susceptibility by means of optimizing of groove dimension and welding parameters on the basis of literature review and welding procedure qualification tests relevant.