Effect of Welding Speed on Microstructure and Mechanical Properties of 30CrMnSiNi2A Steel Electron Beam Welded Joint

30CrMnSiNi2A steel has become an important material for manufacturing aircraft landing gear and flaps due to its excellent mass-strength ratio. The welding speed of electron beam welding in engineering applications can greatly affect the microstructure and mechanical properties of 30CrMnSiNi2A steel. In this study, the microstructure of the joint changes from a small equiaxed tempered sorbite and martensite mixed structure in the heat-affected zone to a dendritic lath martensite structure in the weld area. The microhardness gradually increases from the base material to the center of the weld. The microhardness (HV0.2) of the weld area can reach up to 6940 MPa, which is about twice that of the base material. The tensile strength is up to 842 MPa, reaching 96.9% of the base material strength. In addition, as the welding speed increases, the grain size decreases and the microhardness increases. However, the decrease in the number of HAGB and cementite is detrimental to the strength of the joint, and the tensile strength of the joint decreases with the increase in welding speed. The fracture methods of the joints at different welding speeds are all brittle fractures. © 2022, Science Press. All right reserved.