| 摘要 |
PURPOSE:To obtain the desired material-quality accurately and in high yield throughout the wide range of rolling conditions containing also high rolling reduction and high speed rolling by specifying an equation of Ar3 to be used in a method for finishing rolling at the >=Ar3. CONSTITUTION:An Ar3 is calculated by using the equation I based on the information concerning the relations between the lapse of time after working and the rising rate of the Ar3 and between the speed of strain and the rising rate of the Ar3, for performing rolling while keeping the steel-material temperature of >=this estimated Ar3 in a hot rolling region. Symbols in the equation I are as follows, R: gas constant, Nc: nuclear density at time of starting transformation, QT: activation energy of nucleation, No: previously obtained constant, It depends on the equation II. Symbols in the equation II are as followd, alpha0: grain size of austenite before working, epsilon0: applied strain, (t): the lapse of time after rolling, tauN: time constant of strain recovery, nS, nrho, (m), C, K0, K1, Q0; preciously obtained constants, and epsilon1, K, Z are obtained respectively by the equations III-V, and further epsilon: strain speed, T: working temperature. |
