Tensile and Fatigue Properties of New Casting Alloys Using JIS-AC7A as Base Metal

Abstract

This study aimed to examine the impact of variations in Mg and Cu content within the Al-Mg-Zn-Cu cast alloy on its strength characteristics, utilizing JIS-AC7A as the base material. Two alloys were considered: an Al-Mg-Zn alloy with 3.0 mass% Zn and an Al-Mg-Zn-Cu alloy with added Cu. Tensile and fatigue tests were conducted to assess the alloy’s strength characteristics. The results of the tensile tests revealed a decrease in both yield strength and tensile strength with a decrease in the Mg content. Conversely, the addition of Cu resulted in improved yield and tensile strength. In the fatigue tests, a reduction in Mg content corresponded to an enhancement in fatigue strength, while an increase in Cu content led to a reduction in the fatigue strength ratio. To elucidate the observed strength improvements associated with decreased Mg and increased Cu content, a fracture toughness test was conducted. The Mg3.5-Cu1.0 alloy exhibited the highest stress intensity factor among the tested materials, providing further insights into the mechanism underlying the strength enhancement.