Effect of flux-cored wire position on welding stability in multiple solid-flux cored wires arc hybrid welding process
In order to achieve high-quality and efficient welding of high-strength steel,a new high-efficiency welding process for Q960E high-strength steel,namely multiple solid-flux cored wires arc hybrid welding process,is proposed.This process uses an integrated three-wire torch to achieve the combination of two solid welding wires and one flux-cored welding wire,which can realize optimizing the mechanical properties of the welded joint by using flux-cored welding wires and realize efficient welding by using three welding wires.The flux-cored welding wire can be located directly in front of,directly behind,and on the side of two solid welding wires.By comparing and analyzing the welding process and weld formation,the optimal position of the flux-cored welding wire was determined,and the microstructure and microhardness of the welded joint with the optimal position of the flux-cored welding wire were analyzed.The results show that when the flux-cored wire is located directly behind or on the side of the two solid wires,one of the solid wires is prone to short-circuit transition in contact with the molten pool,the former will cause uneven width of the weld,while the latter will cause the weld to significantly lean towards the flux-cored wire being fed to one side.When the flux-cored wire is located directly in front of two solid wires,the flux-cored wire is one-pulse multi-droplet transition,the two solid wires are one-pulse one-droplet transition,at this time,the welding process is stable,and the weld is well formed after welding.The cross-sectional morphology of the weld shows a"double peak"shape,which is the best flux-cored wire position.In addition,when the flux-cored wire is located directly in front,the microstructure of the weld zone is mainly fine acicular ferrite,the coarse grain zone is mainly coarse lath martensite and a very small amount of granular bainite,the fine grain zone is mainly fine martensite,and the incomplete quenching zone is mainly tempered martensite.In addition,both softening and hardening phenomena occur in the heat-affected zone.The hardness of the base metal near the incomplete quenching zone is the lowest,only 296 HV,while the hardness in the complete quenching zone is the highest,reaching 396 HV,and the hardness of the base metal and weld zone is between 320 and 340 HV.
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