The Study Of Electron Beam Welding Process For AZ61 Magnesium Alloy And Its Numerical Simulation Of Temperature Field

As the lightest structure material, Magnesium alloys have many advantages, such as low density, high specific strength, damping capacity, better mechanical properties, recyclable and so on, which are attracting more attention from the domestic and foreign. It is well known that the advanced manufacturing techniques such as an appropriate joining technique play an important role in exploiting the new fields of magnesium alloy's applications.The electron beam welding technique, with the characteristics of high depth to width ratio, high energy density, no obvious heat affect zone and high speed is the proper method for thick plate material, which is being paid more attention by the domestic and foreign researchers. It is helpful to understand the physical mechanism of the welding process by numerical simulation and to approach the goal of controlling the welding quality further.Taking wrought magnesium alloys AZ61 as the research object, this dissertation investigated the technical characteristics of vacuum electron beam welding process, systemically analyzed the influence of welding parameters such as focus beam, weld beam and weld speed to the butt weld depth of fusion, the melt width, surface width, the microstructure characteristic and the mechanical properties of joint. The research results show that due to the energy characteristic of the EBW, the joint of cross section appeared a typical"nail"type in which the HAZ is not evident. With the increase of focus current the weld depth of fusion is increasing while the melt width, surface width is decreasing. The weld beam adds with the addition of width of surface and melt contrary to the weld speed. The fusion zone (FZ) is consisted of fine-equiaxed grain, theβdispersedly distributed, The mechanical properties of weld was better than that of the base metal.Based on the study of EBW welding process the ANSYS software was applied to simulate the parameters of weld current and speed with optimized double ellipsoid heat source model selected. The results show that the temperature in molten pool was about 1136℃～1669℃. The computed results of geomorphic parameters above can match that of measurement within the error range from 9.5% to 11.3%. The heat cycle curve between simulation and measuring was in good agreement. All of which illustrate that the temperature field simulation within the parameters selected was an advisable method.