Structure and properties of cast bimetallic composites for tools

Abstract

1. The transition zone of cast bimetallic tool steel-structural steel composites prepared by burnt-pattern casting is characterized by an increased concentration of carbide-forming elements and clearly defined structural heterogeneity. 2. The crack resistance of this bimetallic composite and its endurance in the presence of stress concentrators is higher than for one-piece specimens of tool steels due to occurrence of internal residual compressive stresses in the insert made of tool steel and the high damping capacity of the transition zone of the composite. 3. Formation of a transition zone for the hard alloy-structural steel composite with retention of a skin between the molten steel and sintered hard alloy occurs as a result of migration of the molten intermediate layer and dissolution in it of surface layers of the hard surfaces bounding this melt. 4. A composite with retention of a skin and an insert of hard alloy of the system Fe−Cr−C forms with a structure which has a multilayer structure with a sharp change in composition and properties from one zone to another. 5. The strength, reliability, and endurance characteristics of cast bimetallic hard alloy-structural steel composites are higher than for their soldered or fused analogs.