镁铝异种合金搅拌摩擦焊综述

铝镁合金搅拌摩擦焊中峰值温度超过Al12Mg17和Al3Mg2形成的共晶温度,两种金属间化合物的形成不可避免。通过将镁合金置于前进侧、搅拌针偏向镁合金,采用液氮或水下搅拌摩擦焊,加入中间层过渡金属等方法可降低搅拌摩擦焊过程中的热输入,有效减少焊核区金属间化合物的数量。采用锥形螺纹搅拌针对接、配合直径约为3.5倍板厚的内凹型轴肩可提供适当的热输入,促进材料塑性流动,增加两种材料相互交融的程度,提高接头抗拉强度;超声辅助搅拌摩擦焊技术可破坏脆性界面层进而提高接头强度。

Review on friction stir welding of magnesium and aluminum dissimilar alloys

Because the peak welding temperature of the Al-Mg dissimilar friction stir welding (FSW) exceeds the eutectic temperature of Al12Mg17 and Al3Mg2,formation of these two intermetallic compounds (IMC) is invitable.However,the heat input of FSW process and the amount of IMC can be reduced by placing the magnesium alloy on the advancing side,transfering the pin into magnesium alloy,crarrying out the FSW process in the water or liquid nitrogen and employing a third transition material.The tapered threaded pin and a concave shoulder with the diameter of 3.5 times of the thickness of plate can provide the proper heat input and promote the material flow,as a consequence,the intermixing of these two materials and the tensile strength of the joint will increase.Ultrasound supported friction stir welding can also break the brittle interface layer and improve the joint strength.