Influence of Structure on the Plastic Flow of Steel above the A3-Point

Abstract

IN connexion with the work done on the plastic flow of steel above theA3-point, a detailed account of which will be published elsewhere, it was desirable to determine whether the relationship between the temperature and flow-rate at a given stress, hitherto determined by means of a series of experiments, each involving the flow of a separate specimen at a different temperature, could not be deduced without appreciable error from a single experiment in which flow took place under conditions of rising temperature. This possibility was investigated in two similar experiments. In each the specimen was first annealed in vacuo at 950° for approximately twenty minutes in situ. Then it was allowed to flow at that temperature under a constant tensile stress until the steady flow had definitely established itself, when the temperature was raised at an approximately constant rate from 950° to 1,250° C. in twelve minutes. The extension, time and temperature were recorded simultaneously. The natural strain-rates at temperatures in this range, which were deduced from these readings, were found to be considerably higher (upper curve) over most of the range than the corresponding values obtained under conditions of constant temperature.