(α+β) 黄銅の微細結晶粒超塑性

概要

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The superplastic behavior was investigated for 60/40 brass and free cutting brass containing 3% lead. The former alloy was cut off from a large ingot and was grain refined by the low temperature extrussion process after β quenching. The latter alloy was extruded at a low temperature from a 50 mm diameter tests were carried out between 500〜750℃ at the initial strain rates from 2.78 ×10^<-4> to 2.78×10^<-2>S^<-1>. The following results were obtained: (1) A maximum neck-free total elongatin of 640% for 60/40 brass was obtained at 675℃ and the strain rate of 2.78×10^<-4> s^<-1>. (2) The volume of cavities increased as the true strain increased, while at the same true strain, the volume of cavities at a small strain rare was smaller than that at a large strain rate for 60/40 brass. (3) The strain enchanced grain grotwth of α and β phases showed a small increase with increment of true strain at 675℃ and 2.22×10^<-3>S^<-1>, but that of soft β phase was considerably larger than that of α phase at 675℃ and 5.56×10^<-4>S^<-1> for 60/40 brass. (4) By refining grain size, superplasticity was recognized even in free cutting brass which has low Pb content and thus essentially shows low ductility at high temperatures.
社団法人日本材料学会の論文
1989-07-15