著者

西野 知良 本間 浩夫

出版者

社団法人日本鉄鋼協会

雑誌

鐵と鋼 : 日本鐡鋼協會々誌 (ISSN:00211575)

巻号頁・発行日

vol.56, no.7, pp.859-868, 1970-06-01

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The dependence of the yield stress of mild steel at low temperatures on grain size, strain rate and temperature was studied mainly by compressive deformation test. (1) The following equation relating strain rate (ε), temprature (T) and frictional stress (σ_t) of Petch equation was obtained ; ε=Cσ^n_t exp(-E/RT) This is applicable when σ_t is in the range of 8.7 to 28.2kg/mm^2. Strain rate exponent n and activation energy E are constant, both being independent on temperature, strain rate or stress. Above this stress level, n becomes larger but E is substantially invariable. (2) According to the study on BCC metals, it can be said that they behave in a similar manner to mild steel. That is, n is in the range of 7 to 9, being constant and specific to BCC metals, and in addition, E is approximately proportional to an energy of μb^3, where μ is the shear modulus and b the Burgers vector. (3) The relations between strain rate, grain size and ductile-brittle transition temperature were studied by using the above equation, and the calculated temperatures are generally in accordance with the measured values.