Effects of Fe and Si on hot-cracking of Al-Zn-Mg alloys

Studies on weld cracking of AI-Zn-Mg alloys (2nd report)

Abstract

This paper describes the effects of additional Fe and Si on hot-cracking of Al-Zn-Mg alloys containing Zr or Ti + B, or not.
The susceptibility to hot-cracking was evaluated by Fisco type weld cracking test and ring cast cracking test.
The results obrained were as follows:
(1) Addition of Fe had a little effect on the reduction of susceptibility to hot-cracking of Al-Zn-Mg alloys.
(2) However, when Fe was added to Al-Zn-Mg alloys containing Zr, the effect of cracking resistance of Zr was markedly decreased, which made the susceptibility to cracking larger. The rate of decrease was higher with the increase of additional Fe. Whereas, the addition of Fe to the alloys containing Ti + B had little effect on cracking resistance.
(3) The addition of Si had remarkable effect on the reduction of susceptibility to hot-cracking of Al-Zn-Mg alloys containing Zr or Ti + B, or not.