Effect of casting modulus on mechanical strength and dendrite arm spacing of AC4B flat aluminum alloy castings

Abstract

The average cooling rate, dendrite arm spacing (DAS), tensile strength and hardness of AC4B aluminum alloy castings were investigated. The average cooling rate decreases with increasing thickness of the casting and increasing casting mass. The DAS increases and tensile strength and hardness decrease with increasing thickness of the casting. The solidification time, t_f of the casting was represented by t_f=K(M)ⁿ, using casting modulus, M=V/S (V: volume of a casting, S: surface area of a casting) as proposed by Chvorinov. In the present work, n=1.8 and K=138 were experimentally determined. The relationship between the n-th power of the casting modulus (M), and the average cooling rate (V_S), DAS (D_S), tensile strength (σ_B) and hardness (HV) were linear on a logarithmic scale. The following equations were obtained in the present experiment for the casting modulus, the average cooling rate, dendrite arm spacing, tensile strength and hardness; V_S=360(M)^-0.1, D_S=1.4(M)^-0.6, &simga;_B=200(M)^-0.24, HV=40(M)^-0.24, &simga;_B=4800 V_S^-2.0, HV=3000 V_S^-2.0, D_S=20 V_S^-0.6