Coarsening resistance of MC carbides in secondary hardening steels: Part I. Theoretical model for multicomponent coarsening kinetics.

The development of very high-strength levels in many alloy steels is achieved by a secondary hardening reaction. In high Co-Ni steels containing the strong carbide-forming elements Mo, Cr, and W, secondary hardening is accomplished by the precipitation of fine-scale MC alloy carbides. Coarsening resistance of the MC precipitates depends on the alloy content of these elements, and there should be an addition to the alloy of these carbide-forming elements which optimizes the MC coarsening resistance. Current Lifshitz-Slyozov-Wagner (LSW) theory cannot properly be used to describe, the coarsening behavior of multicomponent carbides, which involves concentrations and diffusivities of two or more solutes and nonspherical carbide morphologies. A model is introduced for the coarsening resistance of multicomponent carbides. This model treats the coarsening of shape-preserving particle and is applicable to rodlike particles. [ABSTRACT FROM AUTHOR]