The Mechanical Properties Of Welded AZ31 Magnesium Alloy Joints Under Dynamic Load

Magnesium alloy's density is the smallest in the metal materials. With the rapid development of industrial technology and the energy need of the world, rational use of energy is received more and more attention, and lightweight materials is becoming the research hotspot in the world. Magnesium alloy meet the social needs of environmental protection and energy-saving because of the better performances of light weight,high strength-to-weight ratio,good vibration damping,high resistance to electromagnetic interference,recovery.It is used widely in the transport aerospace and information industry. Welding is an important way to form one structures.AS a new high-performance structural materials, magnesium alloy adopt welding.Magnesium alloys has so poor welding that the developments were limited. Magnetic welding is a new welding technology,it given to attention because of it has a lot of advantages such as low cost,attachment simple,effective action of the mechanical properties of welding joints and so on.The process of TIG welding AZ31 magnesium alloy plates with 5mm thickness in a external transverse AC magnetic field was studied.Rearch on the effect of adscititious transverse magnetic current on the mechanical properties of welded magnesium alloy joints. The tensile strength and Brinell hardness were tested and SEM were used to investigate the micro structures of weld. The effect of magnetic parameters on the microstructure and properties of AZ31 magnesium alloy joints and the effective mechanism of magnetic field were studied.1. Under state without magnetic field, the mechanical properties of welding joints are best at I=80A and the argon gas flow is 7-10.5 L/min.In this state,σb =239.51MPa,δ=8.6%,ψ=12.8% and hardness of welding joints is 62.1HB。2. The comprehensive properties of welding joints are best at I=80A,Ic=1.5A and f=15Hz.In this state,σb=273.8MPaδ=12.3%,ψ=16.4% and hardness of welding joints is 74.6HB.3. Electromagnetic stirring effect which originates from the interaction with adscititious transverse magnetic,arc and weld pool impacts processes of welding metal's,nucleation and growth.It improves the solubility of alloy elements and refines grain.Tensile strength and hardness of welded joints are improved,and the mechanical properties of welded joints are optimum for appropriate magnetic parameters.