Vlas M. Thermal and time casting regimes to produce bimetal castings with cast iron wear-resisting outer layer by static methods into moulds

The physical model for bimetal casting forming while pouring metal on the steel core base is developed. The specific feature of this model is in applying of thin-wall pipes to compensate the shrinkage of the poured metal. Metal of the thin-wall pipes is heated up to the temperature to possess plasticity and due to the band deformation of pipes while crushing, band shrinkage compensation occurs. Methods to calculate the crushing conditions of thin-wall pipes, which are arranged around steel core base, are developed. The number and size of thin-wall pipes are determined. The zone where thin-wall pipes act to compensate the band shrinkage is recommended to determine according to Saint-Venant method. The technology and methodology to calculate the post-operational band breaking stresses are developed. Band breaking occurring after operations allows us to eliminate of the expensive mechanical cutting of the wearresisting outer layer as well as decrease the metal losses and the envi-ronmental pollution while metal chips recycling with the metallurgical units. The specific behavour of solidification and cooling of bimetallic castings in the moulds is investigated. The mould applied for this production method is a cast iron mould with steel core round which thin-wall piped are arranged to compensate the shrinkage of high chromium cast iron band. The macrostructure and microstructure formation of high chromium cast iron band are determined. The structural investigations are in agreement with the corresponding mechanical tests of band metal sam-ples.