Efremenko B. Structure formation in Cr-Ni-Fe-C coatings, intended for use in high-temperature wear

The object of investigation - the processes of formation of the structural-phase state in high-alloy wear-resistant alloys, obtained by electro-arc surfacing. The subject of research – the structure and tribological properties of alloys 300Cr25Ni3Si3 and 500Cr40Ni40Si2BZr at high-temperature wear. The purpose of the study is to increase the durability of protective Fe-Cr-Ni-C coatings obtained by arc-weld surfacing with the use of powdered tapes of PL-AN-101 and PL-AN-111 in high-temperature wear conditions. Methods of research: optical and scanning electron microscopy, 3D-profilometry, energy-dispersion spectroscopy, X-ray diffraction analysis, microhardness measurement; high-temperature oxidation tests, abrasive and high-temperature abrasion-erosion wear; methods of mathematical statistics and planning of a full factor experiment. Obtained results – Defined the interfacial distribution of elements in height of the coatings of Sormait and 500Cr40Ni40Si2BZr. It is shown that with the distance from the fusion zone, carbides are enriched on Cr with a corresponding depletion of the matrix, and the carbides themselves have an elevated Ni content. For the first time, was established the fact of crystallization of graphite in an alloy of 500Cr40Ni40Si2BZr at an overlay in two layers with 50% overlap of rollers. Was revealed the graphitization of carbides at temperatures above 1000 ° C due to the inhomogeneous distribution of Cr and Ni in the carbide volume. The graphitization of carbides at temperatures above 1000 ° C was revealed due to the heterogeneous distribution of Cr and Ni in the carbide volume. It is shown that the overlay of a longitudinal magnetic field during surfacing of the alloy 300Cr25Ni3Si3 provides the shredding of structural components and the alignment of the content of carbon, silicon and chromium in the metal matrix, which prevents the formation of perlite in the coating and increases its abrasive wear resistance. For the first time, the solid-phase reaction of the allocation of secondary nanosized carbides from austenite in welded alloys Sormait and 500Cr40Ni40Si2BZr was observed, which occurs at 850 ... 950 oC and provides a rise in the hardness of alloys. The results of the work were introduced into the educational process at the Faculty of Mechanical Engineering and Welding of the SHEI «Priazovskyi State Technical University». Areas of use are enterprises of the mining and metallurgical and machine-building industries.