The influence of butt gap on weld stability of 12-mm-thick AH36 steel with different heat source configurations

In recent years, with the rapid development of the shipbuilding Industry, the stability of single-pass welding of AH36 steel has received more attention. In this paper, by studying the effect of different butt gaps and heat source configurations on 12-mm-thick AH36 steel, it is found that the increase of butt gap is favourable to improve the weld morphology and weld stability. In the A-L configuration, relatively greater welding stability was achieved, whereas in the L-L configuration, defects such as undercut and root humping were more likely to occur. In addition, a well-formed laser-arc hybrid welded joint was obtained under the A-L configuration. Through comparative analysis of droplet transfer and molten pool flow characteristics under the optimal process parameters corresponding to different heat source configurations, the reasons for suppressing the formation of root hump defects and undercut defects in the A-L configuration were better explained. It was further demonstrated that the A-L configuration exhibited superior gap tolerance and ensured a more stable welding process.