The relationships between properties of chloride fluxes, welding voltage, and flux-assisted GTA fusion zone dimensions have been investigated using argon and helium shielding gases. Simple-metal chlorides (LiCl, CaCl_2, CdCl_2, PbCl_2) and cerium trichloride (CeCl_3) were dissolved in water and brushed onto 10-mm-thick AZ21 magnesium alloy plates. Experiments showed that chloride fluxes could double fusion zone penetration when voltage and heat input were increased, as fulfilled with chlorides incorporating metallic elements that were difficult to ionize. Although voltage and heat input generally correlated with fusion zone dimensions, the combination of helium and certain stable chlorides (LiCl, CeCl_3) did not create large fusion zones despite high voltages. Observations, supplemented by thermodynamic calculations, showed that oxide disruption with these two chlorides was reduced. With aggressive chlorides, as with the less stable chlorides, the first ionization potential (IP) of the chloride metallic elements (M in M_xCl_y) correlated well with the effects on fusion zone dimensions. Cadmium (IP=8.99eV) produced deeper fusion zones than the other metallic elements selected in this study (for which IP<8.99eV).
展开▼
