Structure forming and managing of properties of phosphorous cast irons for parts of internal combustion engine

Abstract

Purpose. Improving the mechanical and operational properties of details of internal combustion engines by managing the structure formation of phosphorous cast irons.
 Research methods. Graphitized and bleached phosphorous cast irons with lamellar and globular graphite of laboratory and industrial melts, melted in electric induction furnaces with alloying modification and fractional casting into dry sand molds were investigated. Chemical composition, microstructure, physical and mechanical properties were determined using standard methods. Non-destructive quality control of engine parts, statistical analysis of experimental data and deterministic factor analysis of the influence of structural components on the properties of the cast irons were carried out according to the methods developed with the participation of the authors. Bench and road motor tests of optimal composition cast irons details were carried out in engines according to standard and factory methods in accordance with state standards.
 Obtained results. The general laws and principles of the formation of the microstructure of cast irons with lamellar and nodular graphite are determined depending on the degree of their alloying with phosphorus and the influence of the scale factor. It has been established that phosphide eutectic in an amount of up to 5.8 % is a strengthening structural component and increases strength, hardness, wear resistance, heat resistance, and machin-ability of phosphorous cast irons with blade tools. The negative effect of phosphide eutectic on plastic properties and cyclic fracture toughness is less significant than the effect of increasing amounts of ferrite, its grain size and graphite. Optimal chemical compositions and microstructures of phosphorous cast irons for internal combustion engines details are recommended.
 Scientific novelty. For the first time, a comprehensive system for managing the properties of phosphorous cast irons has been developed, including the analytical determination of the required characteristics of structural components and the technology for their production.
 Practical value. Methods and technologies for melting, alloying, modifying, heat treatment and surface hardening of phosphorous cast irons have been developed. They make it possible to provide the required level of mechanical and operational properties of internal combustion engines details.