Abstract
Heat-treatment features are considered for steels prepared from mechanical powder mixtures. The rise in the temperature of the critical point Ac1 and the fall in the point Ac3 as the homogeneity of steel increases is described by a linear dependence on the coefficient of concentration variation. A chemically inhomogeneous low-alloy powder steel has the kinetics of the pearlite-austenite transformation limited by the diffusion growth of nuclei. In more homogeneous steels, the limiting stage is nucleation. Decrease in stability of the supercooled austenite and narrowing of a temperature diffrence between the pearlite and intermediate regions occur with reduction in homogeneity of a high-alloy powder steel. The porosity and chemical inhomogeneity activate the decomposition of martensite on low-temperature annealing and reduce the temperatures of the four transformations on tempering.
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