Hot tear susceptibility of aluminium-silicon binary alloys

Hot tear susceptibility (HTS) of Al-Si alloys in the 0-5-3.0 wt-%Si has been determined using a constrained rod casting test and a quantitative index. Hot tear susceptibility was seen to decrease with increasing silicon content. Hot tear severity varied directly with solidification shrinkage beta, the non-equilibrium freezing range Delta T', dendrite arm spacing and the effective grain size d(eff). The highest HTS was seen in the Al-0.5%Si alloy with the largest Delta T', the highest beta, the largest dendrite arm spacing, the lowest amount of eutectic phase f(eu), and, hence, the longest local freezing time t(f). Correlation was observed between HTS and the theoretical hot tear criteria Clyne-Davies CSC, Feurer and Campbell CSCb indices, with Campbell's criterion showing a very strong correlation as HTSc approximate to 0.03CSC(b)+6 with R-2=0.93, where HTSc is HTS of rod C.