Hot cracking of ZRE1 alloy in constant joint stiffness condition

ZRE1 alloy with addition of Zn, Zr and rare earth elements is gravity casted to sand casting moulds, and is used mainly in aerospace and automotive industries. Magnesium alloy castings often have defects, such as misruns and micro-shrinkage. This defects are repaired with welding and overlay welding techniques. Main practical difficulty during welding of magnesium alloys is their susceptibility to hot cracking in the crystallization process. The paper intends to evaluate susceptibility of magnesium alloys to hot cracking and examine influence of heat treatment on cracking of the ZRE1 magnesium alloy with addition of zinc and rare earth elements during welding in conditions of constant stiffness. The results of tests of susceptibility to hot cracking of repair welding joints of ZRE1 alloy castings have been described. The range of research has included the Fisco test and metallographic tests. It has been observed that heat treatment decreases susceptibility of the ZRE1 alloy to hot cracking.