The Composition and Microstructure Character of Bond Area of Supereutectic ZA Alloy in TIG Welding

The influence of the evaporation and oxygenation of zinc during welding process was studied.The character of microstructure and micro-rigidity of bond area of the ZA alloy in the TIG welding was investigated using TME、SME and other methods.The results show that when filler material is similar to parent mental,Zn content in bond area is lower than that in the weld and the parent metal.The Cu and Al contents in bond area are higher than that in the parent metal.The microstructure morphology of the bond area is mainly columnar dendrite.The microstructure in room temperature is mainly Zn phase、αphase and compounds of Al₄Cu₉、CuTi₂、Al₇Cu₃Mg₆.The microstructure in bond area has bigger change and is tiny near the weld.Some fine and thin lamella Zn and α-Zn similar to pearlyte can be observed ther.The microstructure near the parent metal is coarser,but it is still thinner than that in the the parent metal.The coarse grained zone did not appear as the case in alloy steels.The thin compounds of the bond area have higher micro-hardness.They can strengthen the basic structure.When welding super eutectic ZA alloy by TIG welding method,there is no coarse overheated microstructure happened.But thin microstructure and compound can strengthen base.This is advantageous to improve the mechanical properties of the welded joint.