Performance Of Laser-arc Hybrid Welding Of Thick Weathering Steel

S355J2W+N weathering steel is a low-alloy structural that has high strength and goodresistance to atmospheric corrosion, so it is chosen manufactured the partial structures of thehigh speed rail bogie. Laser-arc hybrid welding technology make full use of coupling the heatsource of laser and arc. It has the advantages of litte welding spatter, low heat input, highproduction efficiency, and good gap adaptability. Through laser-arc hybrid multilayer weldingtechnology, S355J2W+N weathering steel of20mm beam pipe butt joint and12mm side beamT-joint were respectively adopted three layers and two layers of hybrid welding process. Theweld joints were obtained through the rational choice of welding process parameters that havegood weld formability, little heat affected zone and good metallurgical bond.The microstructure of the weathering steel multi-weld joints has been observed by opticalmicroscope, the results show that the the weld metal is mainly composed of ferrite and pearlite,and the organization of the bottom weld is more fine than the filler weld. Microhardness testresults show that the hardness value of the weathering steel weld joints is higher than the basemetal, the highest hardness value is313HV in the overheated zone. The tensile and180°sidebend of the weld specimens have been tested by electronic universal mechanical testingmachine. All tensile test specimens are broken in the base metal, the strength of the weld jointsis adequate. A small amount of microcracks is appeared in the central portion and inter-layerfusion line of the weld, its maximum crack length is1.5mm that meet the relevant requirement.Impact energy of the base metal, the upper weld that is mainly effected by arc source and thelower weld that is mainly effected by laser source has been tested at the temperature of-20℃.The impact energy value of the upper weld(130.2J) is less than the base metal(217.7J), andthat of the lower weld(204.8J) is almost with the base metal, the impact energy value of theweld joints meet the technical requirement of high-speed rail bogie(≥47J). The fracturemorphology of the upper weld is mainly equiaxed dimple, and that of the metal and the lowerweld is tear dimple and equiaxed dimple.