Grebeneva A. Phase transformations and structure formation for heat treatment of high-chromium cast iron for rolling tools with increased durability and wear resistance

Processes of structure formation and properties of high-chromium cast iron 280Х32Н3Ф and nickel-chromium alloy "nikorin" for the manufacture of mandrels for tube rolling. Development of modes of iron 280Х32Н3Ф heat treatment based on a study of phase transformations and regularities of structure formation to improve the strength and durability of the rolling tool. Calorimetric and microquenching research methods; mechanical tests; light microscopy, carbide, phase X-ray and local X-ray analyzes; measurement of hardness and microhardness; transmission and scanning microscopy; tribological tests. The particularities of structure formation, phase composition, mechanical properties, the distribution of alloying elements between phases and structural components of cast heat-resistant nickel-chromium alloy "nikorin" and high-chromium cast iron pots and in the heat-treated condition, after isothermal quenching from different temperatures are investigated. The possibility of bainite nanostructure formation in the isothermal tempering of 280Х32Н3Ф cast-iron is established. The connection between micro-mechanical properties of phases and the structural components and indexes of shock viscosity of cast-iron 280Х32Н3Ф is established. A pilot batch of mandrels has been made under Nikopol repair plant and the results obtained are used in the educational process at NmetAU. Quantitative parameters of structural components of isothermal quenched cast iron are determined, and the possibility of formation of bainite nanostructures consisting of alfa-phase with the width of the plates 20-30 nm and nanoscale layers of carbide or austenite is presented. Introduced. Metallurgy.