青熱脆性を考慮した広い温度域に適用可能な炭素鋼の構成式

概要

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This paper presents a temperature dependent static constitutive equation for carbon steels, which can be applied for wide temperature range involving the range where blue brittleness occurs. Generally, a stress induced in steel at a certain strain decrees with the temperature. However, the occurrence of blue brittleness of steels increases the values of work hardening. As a result, the stresses increase with the temperature due to the blue brittleness. Thus, the stress-strain relationships of steels seemingly have negative dependence to the temperature within the range involving the blue brittleness. Since this phenomenon arises remarkably at static strain-rate, the present paper has proposed a temperature dependent static constitutive equation. Concretely, the paper decomposes the stress-strain relation of steels into an unaffected part and affected part by the blue brittleness, and derives equations revealing those parts respectively. The proposed constitutive equation is expressed by the sum of them. The paper actually obtains unknown material constants involved in the proposed equations by a nonlinear least squares from measured results and confirms the appropriateness of the proposed constitutive equation over the wide temperature range.
社団法人日本機械学会の論文
2005-03-25