Effects of grain refiner additions (Zr, Ti-B) and of mould variables on hot tearing susceptibility of recently developed Al-2 wt-%Cu alloy

摘要

The hot tearing susceptibility of the new Al-2 wt-%Cu based alloys prepared using Zr and Ti-B additions was tested using the constrained rod casting mould under different mould variables. The 206 alloy type was used to evaluate the results obtained from this new alloy. It was found that the hot tearing susceptibility of the alloys under investigation decreases proportionally as the mould temperature is increased; thus, the hot tearing susceptibility of the Al-2 wt-%Cu and 206 alloys decreases from 21 for both the alloys to 3 and 9 respectively as the mould temperature is increased from 250 to 450℃. This beneficial effect of elevated mould temperatures may be attributed to a reduction in the contraction strain rate and in the porosity level. Grain refinement additions of Ti-B or Zr-Ti-B enhance the hot tearing resistance of the Al-2 wt-%Cu to a significant level.