Al-Mg 合金板の引張変形におけるひずみ速度と温度の関係

概要

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Uniaxial tension tests were performed on a fine-grain Al-Mg alloy (5083-O) sheet at a wide range of strain in rates of 5.6×10^<-5> to 5.3×10s^<-1> at various temperatures of 173 to 623 K. In a certain range of strain and temperature, the serration in the stress-strain curves were found due to the dynamic strain ageing (the Portevin-Le Chatelier effect). In that strain-rate and temperature condition, the stretcher strain mark, which is not preferable in sheet metal forming, appeared on the sheets. The range of strain-rate and temperature in which the stretcher strain mark appears was experimentally determind. The tensile ductility is strongly affected by strain rates and temperatures. At a strain rate of below 10^<-2>s^<-1>, the ductility becomes extremely higher (e. g., over elongation of 1.0 at 623K) with temperature rise, but it is low (below elongation of 0.25) at a strain rate of over 10^<-1>s^<-1> at all the tested temperatures. It is because this Al-Mg alloy exhibited the superplasticity under the condition of low strain rates and high temperatures. At a high strain rate of over 10^<-1>s^<-1>, even at a high temperature, the strain-rate sensitivity exponent (m-value) becomes smaller, and the localized necking likely occurs at the strain rate.
弓削商船高等専門学校の論文
1996-02-28