Microstructure and Mechanical Property of Mg-Al-Zn Alloy Joint by Laser Beam Welding with Filler Wire
Mg-Al-Zn magnesium alloy with the thickness of 4 mm was welded by using laser beam welding with filler wire.The microstructure of the welded joints was analyzed by using optical microscope,scanning electron microscope,transmission electron microscope and X-ray diffractometer,and the tensile property and microhardness of the welded joints were tested.The results show that the weld zone is mainly composed of matrix phase α-Mg and strengthening phase β-Mg17Al12.Compared with that of the base metal,the hardness of the heat-affected zone decreases in a certain extent,which is related to the coarse grains in this region.Under the welding parameters of laser power of 3.0 kW,welding speed of 1.5 m/min and wire feeding rate of 2.1 m/min,the welded joint with good appearance is obtained.The tensile strength of the welded joint is 315 MPa,which is close to that of the base metal.Some dimples and river pattern are distributed on the tensile fracture of the joint,and it is overall characterized by the mixed mode of ductile-brittle fracture.
Mg-Al-Zn alloylaser beam welding with filler wiremicrostructuremechanical property
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