Modeling of molding and treatment technologies for the СHT-process, which consists in the heat treatment of castings removed in the hot state from sand molds

Abstract

In order to identify and realize the reserves of resource efficiency in the production of metal billets, the concepts of methods for combining casting and heat treatment (CHT) are considered, in particular, on the basis of high-speed knocking out of a hot casting from a sand casting mold and its immediate heat treatment, which will reduce energy consumption and the cycle of manufacturing heat-treated castings. By analogy with the traditional solution to the problem of hardening a sand mixture of a single casting mold, approaches are shown to modeling molding processes from the standpoint of the “inverse” problem of softening a sand mold mixture for quickly removing hot casting from it and further hardening of the casting according to various heat treatment schemes with increasing its mechanical properties, shown mainly by the example of isothermally hardened ductile iron, which after heat treatment is identified as Austempered Ductile Iron (ADI). An overview of the properties and advantages of bainitic cast irons among common metallic materials is given to remind and justify the technical and economic motives for creating the CHT-process and interest in the manufacture of castings with improved heat treatment properties. The CHT-process is presented as a result of research and a combination of reserves of sand molding (1), recently discovered reserves and methods of metal structure formation introduced into production (2), studies and technological processes based on which have been intensively published in the technical literature in recent years, as well as of individual treatment operations (3) for the controlled cooling of the casting with the rational use of the heat of the metal obtained from the process of its smelting. The proposed combination of knockout, treatment and heat treatment operations is analyzed as the problem of optimizing their complementarity to increase resource saving of the manufacturing process for manufacturing metal products.

Keywords

• cooling of castings
• heat treatment
• iron-carbon alloys
• isothermal hardening
• ductile iron
• adi
• cht-process
• ferrite
• austenite
• bainite