Mechanism and Kinetics of Formation of Intermetallic Layers on the Surface of Steel Press Molds in Casting of Silumins

Resumo

Regular features of the mechanism and kinetics of formation of transition layers under interaction between castable silumins and die steel 4KhVMFS (DI-22) used for making press molds are determined. The process of dissolution of the material of the press molds in AL-2 (AK12) silumin is accompanied by formation of aluminum-enriched intermetallic compounds of FeAl₃ and Al₄Si₂Fe types and then by formation of Fe₂Al₅ and Fe₃ Al intermetallic compounds with elevated iron content on the contact surface. Cross diffusion of aluminum is activated in regions under the continuous intermetallic layer on the surface of the mold and causes formation of a layer of a solid solution of aluminum in the steel, which is responsible for sticking of the material of the casting to the mold.