Preventing heat cracks in a1 containing mg casting - alloys by addition of bi or sn

摘要

For castings of Mg alloys contng. 3-30% by wt. Al and 0.3-2% by wt. Zn, which because of their shape or casting method show increased tendency to form heat cracks. Preferably 0.2-0.3% by wt. Bi or Sn are included in the alloy which may also contain up to 0.5% by wt. Mn, 0.5% by wt Si, 0.5% by wt Cu and optionally a fire-resistive material such as Be in the usual amounts. The method was tested with AZ 91 alloys. Bi proved to be most effective in reducing the formation of heat cracks.