Q355B低合金高强钢MAG焊和激光叠焊工艺对比研究OA

This paper systematically compares the process characteristics and joint performance of traditional MAG welding and laser overlay welding for joining dissimilar-thickness Q355B low-alloy high-strength steel sheets in truck frames(1.5 mm)and bottom plates(2.8 mm).Laser overlay welding experiments were conducted by optimizing parameters such as la-ser power,oscillation width,and welding speed.The welds were evaluated using X-ray inspection,macrostructural analysis,and mechanical testing.The results show that the optimal process parameters for laser overlay welding are:laser power 2.1-2.7 kW,oscillation width 3-4 mm,and welding speed 12-14 mm/s.Under these parameters,the weld exhibits continuous and uniform formation with a width of 3.3-4.4 mm and a penetration depth into the bottom plate of 1.4-2.8 mm,significantly su-perior to the MAG weld(weld width 9.3 mm,penetration depth into the bottom plate only 0.4 mm).Although keyhole-type porosity exists in the laser overlay welded joints,their shear strength(32.4-35.5 kN)and tear strength under most parameters are higher than those of the MAG weld(shear strength 30.1 kN,tear strength 10.9 kN).Moreover,the fracture location shifts from the heat-affected zone in MAG welding to the base metal in laser overlay welding.The study demonstrates that laser overlay welding outperforms traditional MAG welding in both welding efficiency and mechanical joint performance,meet-ing the requirements for engineering applications.