Forming of bimetallic castings with aluminum alloy surface on a steel frame

Investment casting, designed to produce billets with complex geometry and high precision, is characterized by a significant number and duration of process steps. This, coupled with the high cost of materials, necessitates the search for energy- and material-efficient options for producing and expanding the range of defect-free castings from ferrous and non-ferrous alloys. Thermophysical processes accompanying the heating and cooling of pattern materials negatively impact the surface quality of castings. A series of experiments established that compaction of powders of pattern compositions makes it possible to produce investment patterns of relatively simple configurations, free of shrinkage and other surface defects. This method for manufacturing products with simple configurations eliminates the need to develop and use thermally stable pattern compositions. To eliminate the negative impact of elastic aftereffects that occur when forming geometrically complex patterns by compaction of wax powders, it is necessary to adhere to compaction conditions, which consist of experimentally determined values ​​of deformation rate and holding time of the compact under load. Taking these factors into account, it becomes possible to create combined investment casting patterns for experimental bimetallic castings (the functional portion of which is a surface made of aluminum alloys, and the structural portion is a steel frame) of practical interest. This paper presents a fundamental approach to producing bimetallic castings of this design and examines preferred conditions for forming compacts by single-sided compaction of wax powders with minimal elastic response values ​​of the compacted material, achieved by regulating the stress-strain parameters of the compacts. The technological aspects of forming bimetallic castings with a surface made of Zamak 5 and D16 alloys are presented, achieving uniform mating of the frame materials and the bimetallic casting surface.