Abstract
A study has been carried out on the cooling rate, dendrite arm spacing and mechanical strength for AC4B cylindrical aluminum alloy castings. The cooling rate of castings becomes smaller with increasing the sectional area and mass of castings because the diameter of cores becomes smaller. The dendrite arm spacing and mechanical strength also change with the cooling rate. The solidification time of the AC4B cylindrical aluminum alloy castings is expressed by a function of the casting's modulus. The calculated n value is 1.5, which is identical with the experimentally obtained n value. Therefore, an equation of tf=K(V/S)1.5 is obtained for the solidification time of castings. Linear relationships on the logarithmic graph are obtained between the casting's modulus (M) and the average cooling rate (VS) or the dendrite arm spacing (DS). Assuming that the mechanical strength is closely related to the reciprocal of the casting's modulus, the appropriate equation is obtained. Furthermore, equations describing the relationships between the colling rate of the AC4B cylindrical aluminum alloy casings and mechanical strength or the dendrite arm spacing are obtained as follows:
VS=(V/S)-1.75, DS=B(V/S)0.5
σB=K1(V/S)-n, HB=K2(V/S)-n
σB=B1VSn, HB=B2VSn, DS=CVSn.
