Characterization of Mg/Al butt joints welded by gas tungsten arc filling with Zn–29.5Al–0.5Ti filler metal

• Mg alloy AZ31B and Al alloy 6061 are butt welded by fusion welding.
• The effect of Ti in filler metal is investigated.
• The formation of Mg–Al intermetallic compounds is avoided.

The multivariate alloying design of a welding joint is used in the Mg to Al welding process. A Zn–29.5Al–0.5Ti alloy is added as filler metal in gas tungsten arc welding of Mg and Al alloy joint based on the analysis of Al and Mg alloy characteristics. The tensile strength, microstructure, and phase constitution of the weld seam are analyzed. The formation of brittle and hard Mg–Al intermetallic compounds is avoided because of the effects of Zn, Al, and Ti. The average tensile strength of the joint is 148 MPa. Al3Ti is first precipitated and functions as the nucleus of heterogeneous nucleation during solidification. Moreover, the precipitated Al–MgZn2 hypoeutectic phase exhibited a feather-like structure, which enhances the property of the Mg–Al dissimilar joint.

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