Fatigue property comparison of TIG welded joints of magnesium alloy and aluminum alloy

The fatigue properties of the TIG welded joints of both AZ31B magnesium alloy and 5A06 aluminum alloy were investigated.The four types of welded joints were used in fatigue tests,such as butt joints,transverse cross joints,fillet joints and lateral connecting joints.The fatigue strengths at 2×10~6 cycles of the four welded joints of AZ31B magnesium alloy are 39.0 MPa,24.4 MPa,32.1 MPa and 24.2 MPa,which are 55.0%,42.2%,78.0% and 50.2% of that of 5A06 aluminum alloy,respectively.The fatigue strength levels at slope m=3 of the aluminum alloy's welded joints are mostly higher than the FAT recommended by the International Institute of Welding (IIW),while those of the magnesium alloy's welded joints are all lower than the FAT.It is indicated that the FAT of magnesium alloy's welded joints should be established as early as possible in order to be applied in the design of magnesium alloy's welded structures.