Study on narrow gap laser welding of 42CrMo steel bevel gear shaft

The manufacture of heavy type bevel gear shafts is generally machined separately, and then jointed by welding. Aimed to the joining of quenched and tempered 42CrMo bevel gear shafts for heavy-duty machine, a 3500W Slab CO2 laser was applied and narrow gap laser welding process was adopted with filler wire of TGS-2CM, at the same time, the performance and metallographic structure of the joint were studied. The experimental results demonstrate that there are no cracks in the joint even without preheating and post-weld heat treatment when the appropriate processing parameters are used. The microstructure of the weld bead and heat-affected zone is fine bainite. The micro-hardness of fusion area is about HV0.1 530, and no apparent softened zone exists in the welding joint. The average tensile strength value of the joint is 1020MPa, equivalent to that of the base material, which is satisfied with the service demand. Currently, the actual welding products were already used in industry.