Comparison of Microstructure and Properties between Q450NQR1 Weather-ing Steel Laser Welding with laser filler welding and MAG Welding Joint
Through the experimental study of laser welding with wire feeding and MAG welding butt joint processes for Q450NQR1 high-strength weathering steel,the microstructure and mechanical properties of the welded joints under the two welding methods were investigated,and the tensile fracture surfaces were scanned and analyzed.The research indicates that the microstructure of the weld zone in both laser welding with wire feeding and MAG welding joints is based on granular bainite,accompanied by proeutectoid ferrite and a small amount of pearlite.The microhardness of the joints from the weld to the base metal shows an overall decreasing trend for both welding methods.The laser welding with wire feeding joint has a narrower heat-affected zone,and the fusion line is the position with the highest hardness,with its hardened area's aver-age hardness overall higher than that of the MAG welding joint in the same region.The bending performance of the speci-mens is good under both welding methods,and the tensile fracture positions are all in the base metal,with the laser welding with wire feeding joint having a higher strength bearing capacity.The scanning of the tensile fracture surfaces reveals that the fractures all exhibit typical characteristics of ductile fracture with microvoid coalescence.
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