Microstructures and properties of laser welding joint of super-eutectic ZA alloy

In this paper, we describe the experimental laser welding of ZA alloy. The formation of the weld demonstrated that pulsed laser welding for ZA alloy was more effective than continuous laser welding. The characteristics of microstructures and properties of the ZA alloy’s bond area welded by pulsed laser were investigated using an optical microscope, X-Ray Diffractometer (referred to as XRD) and other methodologies. The applicable technological parameters include welding speed of 0.9 m/min, pulsed laser power of 1.8 kW, impulse period of 3 ms and duty cycle of 3:4. The average micro-hardness of the laser welding seam zone is higher than that of the ZA alloy substrate, which is as high as 183HV. The microstructures in the weld consist of primary η phase (the white dendritic structure), β phase (the black block distribution around η phase), and eutectic phases (β + η) (platy layer). The average strength of the joints is 119 MPa, 70% of that of the base metal.