Microstructure And Properties Of Inertia Friction Welded Joints Of Magnesium-titanium Dissimilar Materials

As Magnesium and titanium alloys,as typical lightweight metal materials,have broad application prospects in aerospace and road transportation.In practical engineering applications,in order to make full use of their material advantages,it is often necessary to weld the two objects together to obtain the best service performance,so the welding of magnesium and titanium has important engineering significance.However,the mutual solubility of magnesium and titanium elements is low and no compound is formed,and the difference in melting point is large,which makes the two kinds of connections difficult.Therefor,the inertial friction welding method is adopted in this study to conduct welding research on magnesium alloy?ZK60 magnesium alloy and AZ magnesium alloy?and pure titanium.The main conclusions are as follows:?1?In inertia friction welding,the elements Mg,Zr and Zn on the ZK60magnesium alloy side migrated to the titanium side through the welding interface,forming a thin reaction layer at the weld.The fracture occurs at the weld interface and is dominated by brittle fracture characteristics.In the friction pressure is 15 MPa-60 MPa,when the friction pressure is 60 MPa,the tensile strength of the joint reaches a maximum value of 177 MPa,which is 58%of the ZK60 magnesium alloy base material.At the joint interface,the highest microhardness on the ZK60 side is 105 HV and the Ti side is 239 HV.At low frictional pressures,most of plastic layer remains at the weld interface,resulting in a higher Vickers hardness at the weld.As the pressure increases,the weld near the layer of the magnesium alloy exhibits a higher hardness value due to grain refinement.?2?During the welding process,the elements Mg,Al and Zn on the AZ-based magnesium alloy side diffuse toward the titanium side,and a thin reaction layer is formed at the weld.The fracture occurs at the weld interface and is dominated by brittle fracture characteristics.The strength of the joint is:AZ31<AZ61<AZ80,and the AZ80has the maximum tensile strength of the welded joint 188 MPa,which is 59.5%of the AZ80 magnesium alloy base material.The hardness of the cross section of the joint is larger than that of the base material,and the maximum value of the microhardness of the joint is at the following order:AZ31<AZ61<AZ80,wherein the highest microhardness on the AZ80 side is 97 HV,and the Ti side is 239 HV.?3?In the joint corrosion of ZK60 magnesium alloy and pure titanium,joint quality loss?acidity and neutrality?decreases with frictional pressure increasing.In the joint corrosion of the AZ-based magnesium alloy and pure titanium,the joint quality loss?acidicity and neutrality?decreases as the Al content increases.?4?TiZn₁₆,Mg_0.91Zn_0.03,MgZn₂ and other compounds were produced at the joint of ZK60 magnesium alloy.Ti₃Al,Al₃Ti,TiZn₁₆,Mg_0.91Zn_0.03,Mg₁₇Al₁₂ and other compounds were produced at the joint of AZ magnesium alloy.These compounds have an beneficial effect on the strength and corrosion of dissimilar joint between magnesium alloy and pure titanium.