Cr_2O_3活性剂对双丝焊接头组织和熔深的影响

应用扫描电镜、X射线衍射和光学显微镜等测试方法对双丝熔化极惰性气体保护焊(MIG)焊活性焊接接头组织、熔深与活化机理进行了分析与研究。结果表明:添加Cr2O3活性剂试件的焊缝和热影响区与未添加的相比晶粒明显粗化,并且随着活性剂涂敷量的增加,晶粒尺寸增大,但增大趋势逐渐变小;焊接热输入量的增加与Mg2Si相数量的减少是活性焊接接头焊缝和热影响区晶粒粗化的主要原因;添加Cr2O3活性剂试件的焊缝与未添加试件的焊缝相比相组成未发生改变,仍为α-Al和Mg2Si;焊缝熔深随着活性剂涂敷量的增加而增大,活性剂涂敷量达到一定值时活化效果趋于饱和;电弧收缩与弧柱温度升高是导致活性双丝MIG焊熔深增大的重要因素。

Effect of Cr_2O_3 fluxes on the microstructures and penetration of twin wire MIG welded joint

The microstructures,penetration and mechanism of the welding joint by twin wire Metal Inert Gas(MIG) welding with Cr2O3 activating flux were studied by using SEM,XRD and optical microscopy.Results show that,in Hot Affect Zone(HAZ),the grain size with the flux is bigger than that without the flux.The grain size increases with the flux but the growth rate gradually slows down.The penetration depth into the welding joint increases sharply with the flux first then slows down to a stable state.More welding heat input and less Mg2Si content are the main reasons leading to the growth of grain size.The phase compositions of the joint with flux do not change compared to the joint without flux,which are still α-Al and Mg2Si.The arc constriction and higher arc temperature are the main factors for the deeper penetration into the welding joint.