クリープき裂の発生および伝ぱに関する力学的考察

抄録

A study of the mechanics of creep fracture of metals and alloys was carried out on the basis of the following assumptions. (1) The nucleation rate of a microcrack and the rate of creep crack propagation are proportional to the rate of a locally concentrated microstrain. (2) The rate of a local microstrain can be expressed by an equation as a function of macroscopic stress, strain and temperature. (3) The locality and the inhomogeneity of such microstrains come from easy concentration of creep deformation along grain boundaries and/or sub-boundaries, in the vicinity of precipitated particles and so on. As the result, the propagation rate of a grain boundary crack was given analytically by a power function of a net section stress. This was substantiated by the experiment on the creep crack propagation in notched specimens of 1Cr-1Mo-1/4V steel at the test temperature of 600°C.