Effects of mix activated fluxes coating on microstructures and mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joints

Abstract

The effects of mix activated fluxes on the penetrations, microstructures and mechanical properties of tungsten inert gas (TIG) welded AZ31 magnesium alloy joints were studied. The results showed that an increase in the amount of TiO₂ coating improved the weld penetration and depth/width ratio of the TIG welded AZ31 magnesium alloy seams. The α-Mg grains of the fusion zone (FZ) became fine gradually with the addition of CaF₂ coating but coarsened sharply when the amount of TiO₂ coating was over 70%. In addition, the porosities and total length of solidification cracks in the FZ were reduced by the CaF₂ and TiO₂ coatings. The ultimate tensile strength value of the welded joints increased with the addition of TiO₂ coating but decreased sharply when more TiO₂ coating was adopted.

Keywords:

• AZ31 magnesium alloy
• TIG welding
• Microstructure
• Micropores
• Crackings
• Mechanical property

This research was financially supported by Fundamental Research Funds for the Central Universities of China (project no. CDJZR11135501), Fundamental Research Funds for the Central Universities (project no.CDJXS10131155) and Supported by Sharing Fund of Chongqing University’s Large-Scale Equipment (project no. 2011063023).