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Microstructure and Mechanical Properties of a 10CrNi3MoV Thick Plate Welded Joint Using Narrow Gap Laser Welding with Filler Wire
Y. Zhao, F. Su, J. Huang, J-S. Zou and Y-X. Wu

10CrNi3MoV thick steel plate was welded using CO2 laser welding with filler wire and the groove was narrow. Droplet transfer behaviour was studied using high speed camera. The microstructures in different zones were observed using optical microscope, and the mechanical properties including hardness and tensile properties were also tested by microhardness testing machine and hydraulic universal testing machine. It was found no defects were noted on the joint under optimized parameters when stable liquid-bridge transition formed. The middle zone of the weld consisted of martensite and granular bainite, and the hardness of this zone is improved because of martensite with high hardening tendency. The surface layer of the weld consisted of proeutectoid ferrite and granular bainite, which increased the plasticity. All the fractures occurred on the base metal. On observing the microhardness distribution, peak value was generated in the coarse grain heat affected zone (HAZ) of the surface layer of the weld.

Keywords: CO2 laser, 10CrNi3MoV steel, filler wire, laser welding, microstructure, mechanical properties, high strength steel, droplet transfer behaviour

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