Investigation On The Electron Beam Welding Process Of SAE9310 Steel And Microstructure And Properties Of The Welded Joints

SAE9310 steel is a low-cost and good overall performance carburizing bearing steel which is widely used abroad. Until now, there are no published reports on the welding and properties of joints of such steel. The electron beam welding, with high energy density, weld depth to width ratio, better protection of the environment and many other advantages, is the best choice of a precision welding for such steel. Therefore, research on electron beam welding and joints properties of SAE9310 steel has important significance meaning to production guiding.Electron beam welding of SAE9310 steel was investigated in this paper.The effect on welding seam formation for SAE9310 steel EB welding parameters is analysed.The microstrcture and properties of welding jiont were investigate with room-temperaturetensile test, room-temperature impact test, microhardness test , metallographic phase and scanning electron microscopy. The test pieces of SAE9310 steel material was designed and manufactured, and was welded by the electron beam welding.The results show that: weldability of SAE9310 steel is good, the good welded joints can be got at appropriate processing parameters. The welded joints have the same tesile strength as the parent material at room temperature.the welded seam have high impact toughness.SEM observation of fracture toughness of welded joints to the main fracture, crack propagation during brittle fracture. The hardness of the welded joint and the HAZ are both higher than that of the base metal. The microstructure of weld joint consists of plate martensite , and includes a small amount of residual austenite, columnar crystal close to the fusion line and equiaxed austenite in the centre. SAE9310 steel welding residual stress distributions in distribution.Finally, the test pieces of tail rotor gear shaft with SAE9310 steel was designed and manufactured, and was welded by the electron beam welding. Results show a good weld, no welding defects, weld parallel narrow aspect ratio, welding deformation, microstructure and properties to meet the project needs.