低炭素鋼の低温における捩り変形と破壊

概要

論文の詳細を見る
The present investigation was carried out for the effects of testing temperatures and the ferrite grain diameters on the low temperature torsional deformation and fracture behaviour of 0.08 percent carbon steel, using a newly developed dynamic torsion machine. Dynamic torque-twist curves were obtained photographically at various temperatures. Variation of lower yield stress τ_y with grain size 2d in torsional deformation satisfied the Petch formula τ_y=τ_i+k_yd^<-1/2>, which was obtained from tension test. Value of τ_i increased rapidly with a decreasing of the testing temperature and also k_y increased with a lowering of the testing temperature. It is shown experimentally that the flow stress τ_f at constant strain is related to the grain diameter by τ_f=τ_<if>+k_fd^<-1/2> where τ_<if> and k_f are constants. Value of k_f at various testing temperatures is lower than those of k_y and k_f has a small sensitivity to temperature. At the slow rate of straining, a transition from ductile to completely brittle behaviour occurs at -183℃, when the grain diameter is d^<-1/2>≤5.23. Substituting values of τ_<y2> d^<-1/2> and k_y obtained in this experiment into Cottrell's formula of ductile to brittle fracture, the effective surface energy γ is found to be γ≥7.45×10^3 erg/cm^2. This value of the surface energy for fracture is expected to be greater than the true surface energy, but it is the same value as that of γ obtained by tensile test. Large plastic deformation to fracture took place in the torsion test, even in the specimen broken by cleavage fracture.
社団法人日本鉄鋼協会の論文
1965-01-01

低炭素鋼の低温における捩り変形と破壊

スポンサーリンク

概要

著者

関連論文

スポンサーリンク