Determination of the paste composition for the formation of reinforced layers on martensitic steel by combined processing
Abstract
The problem of increasing wear resistance requires new materials science approaches to solving problems of surface hardening. Martensitic stainless steels have high anticorrosive properties and strength characteristics, but weakly resist abrasive and erosive wear. The existing methods of chemical-thermal hardening no longer correspond to the operational and economic indicators. The use of a combined hardening technique that combines borating and high-speed heating by high-frequency currents makes it possible to intensify diffusion processes. This approach makes it possible to obtain relatively thick hardened layers and to obtain a hardened layer structure with a fundamentally new morphology.
As a result of the processing of martensitic steel, layers with a thickness of 25 - 240 microns with an intermediate hardened layer between the diffusion zone and the base metal were obtained. This architecture of the hardened layer effectively resists punching, abrasive, erosional and cavitation wear.
The main structures in the boron layer are borides of the Fe2B type, carboborides located in a solid solution of boron in iron and alloying elements.
The microhardness of the borated layer exceeds 10000 MPa. The microhardness of the hardened layer reaches 8000 MPa, which corresponds to the microhardness of structureless martensite.
The transition from the diffusion layer to the main structure occurs through the hardening structure, which was formed under the action of high-speed microwave heating, and a sufficiently high-speed heat removal deep into the metal. It is shown that fine grains of the matrix material formed at the interface are formed as a result of active penetration of boron atoms along the boundaries of the substructure and the formation of new boundaries of the structure.
Keywords: boron layer, microhardness, hardened layer, boron carbide, high frequency currents.
