種々の亜鉛含有率をもつ黄銅の広範囲ひずみ速度における変形抵抗と延性(<特集>塑性工学)

概要

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Tension tests were performed on five α-brasses with 1 to 30-w.t% Zn, 60-40 brass and OFHC copper at a wide range of strain rates of 2.2×10^<-4> to 2.1×10^2S^<-1>. The strain-rate sensitivity to flow stress in α-brasses reduces with increasing Zn-content, and almost no strain-rate effect is found in 70-30 brass. The fracture elongation, which strongly depends on the uniform elongation, increases with increasing Zn-content, whereas the reduction of area slightly decreases with Zn-content. The n-value in the Hollomon-type constitutive equation, which governs the uniform elongation, becomes smaller at the strain region just before the onset of local necking. To describe the above-mentioned mechanical properties, the Ludwik-type costitutive equation with the power law of strain-rate sensitivity: σ=(σ_0+Cε^n)ε^^.^m, is proposed, in which two sets of material constants σ_0, C and n should be determined for two different strain regions.
1995-05-15