Mechanical Properties of Friction Welded Joints of Az31 Magnesium Alloy at High Temperatures

Creep tests were carried out for friction welded joints of AZ31 magnesium alloy rods under an ambient atmosphere at temperatures between 423 and 573K. Tensile tests were also performed at temperature from room to 573K. The obtained results were compared with those of the base metal. AZ31 extruded rods of 19 mm in diameter were joined by brake type friction welding machine. Creep and tensile specimens were machined out of the welded rods. The tensile strength of the joints was almost the same as that of the base metal at room temperature. However, joint efficiencies of welded joints were about 92% at above 373K. The elongation of welded joints was lower than those of base metal. The welded joints showed appreciably higher minimum creep rate and shorter rupture time than the base metal at all the tested temperatures and initial creep stresses. Creep and tensile rupture of the joints always occurred at near the weld interface. Thus, friction welded joints of AZ31 alloy showed lower creep and tensile strength than the base metal at elevated temperature.