Research on the structure and properties of laser welding of ultra-high strength wear-resistant plate 40CrNi2Si2MoVA
40CrNi2Si2MoVA (300M) wear-resistant plate is an ultra-pure high-strength structural wear-resistant plate with excellent performance. It has comprehensive ductility, rigidity and toughness, high fatigue resistance and creep performance. It is ideal for manufacturing aviation forgings such as aircraft landing gear. important structural materials. Laser welding is a new welding method that uses high-energy laser beams to locally heat materials. The energy of laser radiation diffuses into the interior of the material through heat conduction, melting the material to form a specific molten pool to achieve the purpose of welding. Laser welding depth High aspect ratio, small weld width, small heat affected zone, small deformation, fast welding speed, smooth and beautiful weld, no need for post-welding treatment or only simple treatment, high weld quality, no pores, precise control, focus The light spot is small, the positioning accuracy is high, and it is easy to realize automation. At present, the welding of 40CrNi2Si2MoVA wear-resistant plates is mostly done by vacuum electron beam welding, TIG or MIG. There are few reports on laser welding of this wear-resistant plate. The 40CrNi2Si2MoVA wear-resistant plate was welded with CO2 laser, focusing on analyzing the structure and mechanical properties of the laser welded joint of the wear-resistant plate.
Welding samples were prepared using wire-cut 40CrNi2Si2MoVA wear-resistant plates. The sample size was 55mm×20mm×1mm. The welding process parameters are: focal length 315mm, spot diameter 1mm, output power 1.6kW, scanning speed 150 (mm.min-1), and the protective gas is argon.
The structure of the ultra-high strength wear-resistant plate 40CrNi2Si2MoVA laser welded seam is equiaxed crystals in the center area, small columnar crystals near the center, columnar dendrites and coarse columnar crystals in the edge area, and columnar crystals and cellular crystals in the fusion zone. The main structures of HAZ are lath martensite, island martensite, bainite and a small amount of retained austenite. The average hardness of the weld zone is 595HV, with the maximum hardness value in HAZ, which is 637HV; the hardness value drops significantly from HAZ to the base material; the impact toughness of the welded joint is 54.5J/cm2. The tensile fracture part of the sample occurred in the area close to the base material of the weld. The tensile fracture is a dimple fracture. Its tensile strength value is equivalent to the tensile strength value of the base material, with an average value of 1607.8MPa; from the center area of the weld to the base In the material area, the welding residual stress first increases and then decreases, with significant changes.
