Preparation of Bimetal Objects by Lost Foam Casting

The possibility of obtaining bimetallic steel castings by the lost foam casting method is demonstrated, in which an insert of special steel is placed in an expanded polystyrene mold. Bottom casting is used. With the optimum choice of the casting temperature, fusion of the steels is guaranteed and there is no warping of flat inserts. Stages of bimetallic casting formation are considered and the parameters affecting filling of the mold and ensuring the production of a finished casting are determined. It is shown that the heat treatment of objects with air cooling provides hardness of 20–46 HRC for steel of 20X13 with different tempering conditions. The technology is recommended for parts of the locking assembly of pipeline fittings and other products where a combination of local special properties and workability is required.