원통 인장시험과 고변형률의 유동특성을 이용한 체적소성가공용 실용적 혼합 유동모델

Abstract

The fundamental flow models of metallic materials at room temperature, including the Ludwik, Hollomon, Swift and Voce models, were evaluated in terms of tensile test with an emphasis on the necking phenomena and post-necking behavior, to emphasize their limitation in satisfying tensile strength and Considère condition as well as the pre-necking and post-necking strain hardening. To resolve this limitation and enhance the applicability of the new proposed flow model to typical strain hardening materials, the Ludwik-Swift blended flow model is proposed after investigation into three blended flow models among the Ludwik, Voce and Swift models. Results revealed there is no interpolation-based blended flow model of the fundamental flow models, for the example flow curve exhibiting typical strain hardening but that the extrapolation-based combination of them can provide an engineering solution when the Ludwik and Swift models are blended. It was revealed that the reason for their good matching lies in the distinct difference in the strain hardening exponent, between the Ludwik and Swift models in the case of metallic materials with typical strain hardening.