Friction strengthening of parts made of hightension cast iron

Problem. High-strength cast iron with nodular graphite is widely used in transport engineering instead of cast and forged steel in the manufacture of complex-shaped parts. The durability of parts largely depends on the quality of their surface layer. The quality of the surface layer is formed in the final operations of the manufacturing process. The problem of choosing a technological process that ensures the necessary quality of the surface layer of cast iron products, is sufficiently economical and simple to implement, does not require complex equipment and significant expenditure of energy resources is an urgent problem. Frictional hardening can be attributed to such a process. Goal. The purpose of the work is to study the features of frictional processing of high-strength cast iron with different microstructures to obtain a high-quality hardened layer. Method. Methods of measuring microhardness, thickness of the hardened layer, and roughness were used in the work. Results. The paper investigated the effect of friction as a heat source of concentrated energy flow during friction hardening on the quality of the surface layer, which depends on the microstructure of cast iron and technological processing parameters. Among the technological parameters of processing, the longitudinal feed of the strengthening tool-disc has a significant influence. The optimal value of the longitudinal feed was determined, which ensures minimum roughness, maximum hardness and depth of the white layer for cast irons with different microstructures. Scientific novelty. The hardness of the white layer obtained as a result of friction hardening treatment depends on the initial microstructure and processing parameters. The white layer obtained on cast iron with a troostite microstructure has the maximum hardness. The greatest degree of hardening relative to the hardness of the original state of cast iron is characteristic of the pearlite-ferrite microstructure. Practical significance. Friction hardening can be used in the treatment of crankshafts and camshafts to obtain a wear-resistant white layer with low roughness. Friction treatment is the final technological operation, which combines strengthening treatment with finishing.