Microstructure And Properties Of WE43/1060 Dissimilar Alloy FSW Joint Assisted By Zn Foil

WE43 magnesium alloy is a kind of rare earth magnesium alloy.Its main elements are Y,Nd,Gd and Zr.WE43 rare earth magnesium alloy has excellent strength and low density.Therefore,WE43 rare earth magnesium alloy has therefore become one of the commercially promising rare earth magnesium alloys.Connecting different materials has always been a major difficulty in the manufacture of multi-layer structures used in vehicle manufacturing and electronics.Due to the significant differences in melting temperature,thermal conductivity and thermal expansion coefficient,as well as a large amount of heat input in the fusion zone,pores and brittle intermetallic compounds(IMC)are inevitably produced during the welding process,which severely weaken the strength of joint and limit its application in the industry of equipment manufacturing.Friction stir welding(FSW)technology with one or more auxiliary processes has great research value for regulating the type,quantity and shape of IMC.This study takes WE43 rare earth magnesium alloy and 1060 pure aluminum as the research objects.Referring to the evolution law of process parameters in temperature field numerical simulation,the welding speed is determined as 50mm/min,the rotation speed is 1050 rpm,and 0.05 mm Zn foil is selected for FSW experiment.The results shows that:(1)Based on the simulation software,a heterogeneous FSW model of WE43/1060 alloy is drawn,and the heat source model is determined by friction work during welding,and the temperature field nephogram is analyzed.The evolution of welding speed,stirring head speed,and addition of Zn on the temperature field distribution of WE43/1060 dissimilar metal FSW joints are found,and key theoretical support is provided for studying the WE43/1060 dissimilar metal FSW process.(2)After adding Zn,the weld surface is free of deformation,obvious cracks and other defects.And,the microstructure observation shows that small and discontinuous Mg-Zn IMC particles form in the weld area to replace the continuous Al-Mg IMC in the joint without Zn,thus significantly improving the type and quantity of IMC in the joint and improving the welding quality of the joint.(3)After adding Zn,the tensile strength of the joint is 117 MPa,which is higher than 62.3 Mpa of the FSW joint without adding Zn,and the yield strength is 83 MPa,which matches the 79.2 Mpa equivalent strength of the FSW joint without adding Zn,and the elongation is 9.4%,which is slightly higher than 6.3% of the FSW joint without adding Zn.The fracture morphology of weld fracture appears tear feature after adding Zn,and shear dimples appear on different cleavage planes in the fracture,showing that the fracture mode is mixed fracture of toughness and brittleness.In addition,the microhardness value of Zn foil-assisted FSW joint fluctuates gently,and the internal mechanical strength of the joint is more stable.Therefore,the WE43/1060 alloy dissimilar FSW joint assisted by Zn foil has better mechanical properties.This study not only provides an important understanding of the influence of friction stir welding technology on the microstructure and mechanical properties of WE43/1060 dissimilar welded joints,but also provides valuable technical guidance for the development of WE43 magnesium alloy products,Mg/Al dissimilar connection and other practical applications.Figure [27] table [9] reference [97]...