Effect of solidification times on crack opening displacement of aluminium alloy castings

The effects of mold temperature, solidification time, and metallurgical structure on the crack opening displacement (COD) at maximum load and ultimate tensile strength (UTS) of Al-10.6Si, 0.9Mg, 0.9Cu alloy have been investigated, using rectangular bars obtained from a copper mold that was preheated at different temperatures before the alloy was poured and allowed to solidify. It was found that the COD values increase and the UTS decreases as the mold temperature and solidification time increases. These parameters, which can be related to the metallographic microstructure differences, were found to have a probable effect on the fracture toughness of Al-alloys. The longer the solidification times, the coarser the silicon crystals in a alpha-aluminum matrix.