ФОРМИРОВАНИЕ НАНОКРИСТАЛЛИЧЕСКОГО МАРТЕНСИТА НА РАБОЧЕЙ ПОВЕРХНОСТИ ИНСТРУМЕНТАЛЬНОЙ СТАЛИ ПРИ АБРАЗИВНОМ ИЗНАШИВАНИИ

Abstract

The most common type of mechanical wear the machines and aggregates of mining, construction and road industries and transport are exposed to is the abrasive wear. The development of new wear-resistant materials and modes of thermal treatment against this type of wear is one of the most important issues of material science. Wear-resistant materials within various conditions of mechanical wear should have a structure with the metastable austenite developing into disperse austenite while in operation. The paper studies the influence of structural changes on a working surface on the wear resistance of H12ML steel during the process of production, thermal treatment and abrasive wear of parts. It is determined that when quenching from temperatures of 850–1000 °C, the martensite is formed in the structure of high-chromium H12ML steel that ensures high hardness, however, maximum wear resistance is not achieved within the abrasive wear conditions. The rise of heating temperature for the following quenching up to 1170 °C causes the decrease in the initial hardness that is associated with the carbides solution and the increase in the retained austenite quantity; however, it is accompanied by the significant increase of wear resistance during the abrasive wear. The retained austenite produced in the result of high-temperature quenching (from 1170 °C) is metastable and develops into deformation marten-site during wear process; it results in the maximum wear resistance of steel due to the high capacity for frictional hardening of a working surface. Martensite formed on a working surface of H12ML steel during the abrasive wear process has the nanocrystalline structure and periodic distribution.