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■■■■■■■■■■■■■■■■■■■ 川崎製鉄技報 KAWASAKI STEEL GIHO Vol.5 (1973) No.2 ■■■■■■■■■■■■■■■■■■■ |
| 内部摩擦による冷延鋼板の歪時効の研究 Study of Strain Ageing of Mild Steel Sheet Using Internal Friction Technique 志賀 千晃(Chiaki Shiga) 佐々木 徹(Tooru Sasaki) 松村 洽(Ko Matsumura) |
| 要旨 : 商用のAlキルド，リムド冷延鋼板を用い，Snoek dampingを測定した結果，AlNが析出していると，固溶炭素量が減少することがわかった。加工後，固溶している，Ｃ，Ｎ原子が転位へ固着していく過程，また，その固着が試料に弾性限内の再付加応力を加えると，はずれる現象をdislocation dampingの測定により検討した。固着過程の速度は，Granato-Luckeの理論とKoehlerの分布を用いると説明できる。また，この固着過程の時間則としてt1/3を見出し，その活性化エネルギーは，Ｃ，Ｎの拡散の活性化エネルギーの約６〜７割に相当することがわかった。 |
| Synopsis : It was found by the measurements of the Snoek damping that the precipitation AlN decreases the amount of carbon atoms in solution, in the specimens quenched from 700℃. The increase in yield strength Δσ was compared with the decrease of the amplitude independent dislocation damping, during the strain-ageing for the commercial Al-killed and rimmed steel. It was found that the increase in yield strength was observed only for the rimmed steel, in spite of decrease in the dislocation damping of both steels. The phenomenon that no increase in yield strength is observed for Al-killed steel aged for a long time, is due to the breakaway of dislocations from the pinning points by the application of a static stress below the flow stress. This breakaway could well be followed by the immediate increase in the damping due to the applied stress. The damping after the immediate increase due to the applied stress usually decreased faster than that pre-strain. This difference in the kinetics can be explained by the Koehler-Granato-Lucke theory, on the basis of the new distribution of the pinning lengths with longer average loop length produced by the applied stress. The kinetics of the recovery obeys a t 1/3 ageing law rather than the more familiar t 2/3 ageing law. The recovery process obeying a t 1/3 ageing law had activation energies of approximately 11.8 kcal/mole and 14.0 kcal/mole in the rimmed and Al-killed steel, respectively, the values of which are from 60 to 70% of those normally associated with bulk interstitial diffusion in a strain free lattice. |
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