Investigating the microstructure, mechanical properties and corrosion behavior of dissimilar welding of biodegradable magnesium alloy AZ31 to Ti-6Al-4V alloy by friction welding

In this research, dissimilar joining of biodegradable AZ31 alloy to Ti-6Al-4V titanium alloy by rotary friction welding method was investigated with aim of preparation of pin or screw for orthopedic applications. optical and scanning electron microscope (sem) were used to investigate the microstructure, x-ray diffraction was conducted for phase analysis, torsion and micro-hardness tests were carried out to investigate mechanical properties, and polarization and electrochemical impedance spectroscopy were employed to evaluate corrosion resistance. in the welding procedure, rotational speed of 1100, 1200 and 1300 rpm and friction time of 2 and 4 seconds were considered as variable parameters, and two parameters of friction pressure and forge pressure were considered as constant parameters at 50 and 40 MPa, respectively. The microstructure of the joint zone showed that there is no deformation in the titanium alloy side. However, in the magnesium side, the greatest amount of deformation occurred with the distance from the joint line, where weld center zone (CZ), dynamic recrystallization zone (DRX), thermomechanical affected zone (TMAZ) and partial deformation zone (PDZ) are detected. The formation of intermetallic phases such as Mg2AlZn, Ti3Al and also the refining the grains size is the main reason for increasing the hardness of the magnesium side near the joint line up to 150 HV. The results of the torsion test showed that the welded sample has the highest shear strength of 81.51 MPa and also the highest corrosion resistance among other samples at a rotation speed of 1200 rpm and a friction time of 4 seconds.