The TIG Welding Of Magnesium Alloy Under Double Inversion Impulse Magnetic Field

For the requiement of environment profection and power saving, magnesium alloys have drawn extensive attention as a representative of new materials. In this paper, the TIG welding of magnesium under the double inversion pulse magnetic field was investigated. First, the TIG welding of magnesium without magnetic field was studied, AZ31 and AM50 were selected as the testing materials. After experiments with different processing parameters and comparative analysis on the performances and microstructure of the welding joint, the effecting laws of different processing parameters on the performances of welding joint were found, and then a suit of favorable technology parameters was made out. The range of final optium processing parameters are such as: the welding current 80-100A, gas feed rate 6-9 L/min, speed of welding6-8 mm/s. During the experiments with different processing parameters, some welding deficiencies were found, the chief ones of them are hot cracking and gas cavity. The forming mechanics and prevention means is discussed in the paper. The forming mechanics of hot cracking is the appearance of β— Al₁₂Mg₁₇, which has low melting point. By controlling the heat input can suppress the appearance of hot cracking. The appearance of gas cavity is because of the magnesium can react with lots of gas which are included in air. After the action, lots of gas can not effuse and stay in welding joint. Through treating before welding and properly protecting during welding can reduce the gas cavities.On the bases of f(?) processing p(?), the wekling of AZ3(?) (?) (?)loy under double inversion pulse magnetic field was proceeded. During the experiments, the magnetic frequency was fixed and the magnetic current was variable, comparative analysis on the performances and microstructure of the welding joint was proceeded, which were welded in the different processing parameters. Through comparing analyses, found that the properties of weld joint under the magnetic field was obvious improved, and reach 85% of matrix. At thesame time, the input of magnetic field can suppress the appearance of hot cracking and pure the organize, reduce foreign substance. At the last, the influence mechanics of magnetic field on the magnesium alloys TIG welding was discussed.