Solidification of high speed steels: thermodynamic and kinetic aspects. Erstarrung von Schnellarbeitsstaehlen: Thermodynamische und kinetische Aspekte

On the basis of thermodynamic equilibrium calculations with the Thermo-Calc method and of kinetic considerations, the solidification of two representative high speed steels (AISI T1 and M7) is analyzed. Comparison of the calculated and the observed solidification path indicates that the formation of the primary carbide phases is delayed. Using the empirical composition of the residual liquid at the moment of carbide nucleation as input for a new set of Thermo-Calc calculations, a correct description is obtained of the carbide phases which crystallize from the melt, of the sequence in which they appear, of their compositions and, qualitatively, of the influence of the solidification rate on their relative amounts. (orig.)