Precipitation Behavior of Large Primary Carbides in Cast H13 Steel

The large primary carbides precipitated during solidification can significantly reduce the performance of H13 steel. To better inhibit the formation of primary carbides, it is necessary to obtain the precipitation mechanism of primary carbides in H13 steel. First, an electronic probe microanalyzer (EPMA) is used to analyze the microsegregation of alloying elements in the last-to-solidify region. The enrichment of elemental V, Mo, Cr, and C in the last-to-solidify region is the main reason for the formation of primary carbides. The number density, size, and morphology of the carbides in a two-dimensional (2D) observation are obtained through an automatic inclusion analysis system. A non-aqueous electrolysis method is used to show the three-dimensional (3D) morphology of the primary carbides. There is a large difference between the 2D and 3D primary carbide observation. Finally, the precipitation mechanism and process of carbides during solidification are calculated with the Thermo-Calc thermodynamic software, and the calculated results are in keeping with the experimental observation.