| The steady-state creep mechanism and behaviour of Zircaloy-4 have been investigated in air environment over the temperature and stress ranges from 535℃ to 620℃ (0.38-0.42Tm) and from 6㎏/㎟ to 9㎏/㎟, respectively. Constant stress creep tests were carried out in this experiment. The work lead to the following results; 1) The stress exponents, n were 5.4, 5.2, 5.1, 5.0, and 4.9 at temperatures of 550, 565, 580, 590 and 600℃, respectively. In other words, the stress exponents decreased as the temperature increased. 2) The apparent activation energies, Q were 67.9, 65.7, 63.8, and 62.2 ㎉/mole at stresses of 6, 7, 8, and 9㎏/㎟, respectively. In other words, the apparent activation energy for the creep deformation decreased as the stress increased. 3) The activation energies for the creep deformation were nearly equal to that of the volume self diffusion of Zr in the Zr-Sn-Fe-Cr system. 4) From the above facts, the creep deformation For Zircaloy-4 seemed to be controlled by dislocation climb over the range of experimental conditions. |
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