耐候钢激光-电弧复合焊接微观组织及性能研究OA

In this paper,multi-layer multi-pass welding and high-power single-pass welding were carried out on 16mm thick Q500 weathering steel by laser-arc hybrid welding technology.The results show that the width of the heat affected zone of the high-power single-pass welding joint(1.28mm)is reduced by 40％compared with that of the multi-layer multi-pass welding joint(2.1mm),and the weld area is reduced by 53％.The microstructure analysis shows that fine grain boundary ferrite is formed in the upper part of the weld of high-power single-pass welding joint,and the dendrite spacing of ferrite decreases,but the average size of M-A component increases to 1.8 μm.The lower part of the weld is dominated by granular bainite+lath bainite,which reflects the microstructure stratification dominated by the cooling rate in the thickness direction.In terms of mechanical properties,the tensile strength of high-power single-pass welding joint(728.6MPa)is higher than that of multi-layer multi-pass welding joint(711.2MPa),and the strength fluctuation range in the thickness direction is smaller.Low heat input single pass welding significantly improves the comprehensive mechanical properties of welded joints by refining grains and optimizing microstructure uniformity.