Flow of Mild Steel in the Austenite Range, 950-1,400° C.

Abstract

IN the case of pure metals of cubic symmetry subject to external stresses at temperatures Where work-hardening is practically absent, the theory of molecular rate processes yields for the natural tensile strain-rate ε̇_v of the quasi-viscous flow, as observed after the termination of the period characterized by internal adjustments due to transient creep, the expression¹: where σ is the applied tensile stress, q a constant which can be considered as the product of a dimensionless stress-concentration factor and a constant having the dimensions of a volume. Although the parameter A, which also embodies the entropy of activation of the process by which dislocations are assumed to be generated, is dependent upon the dimensions of the mosaic blocks and upon the specific mode of slip which is operative, it is regarded as constant in the present work, particularly as variations in its magnitude at temperatures above the A₃-point would be largely concealed even by small errors in the exponential term of equation (1).