RAKHADILOV Bauyrzhan D.Serikbayev East Kazakhstan State Technical University

Spoluautoři SKAKOV Mazhyn, BATYRBEKOV Erlan, SCHEFFLER Michael, KARYPBAYEVA Gaukhar

Wear-resistance of cutting tools depends on surface layer state. To increase the hardness, strength and durability of cutting tools made from high-speed steels are widely used different thermal and chemistry-thermal methods. Recently, the plasma nitriding methods use widely that can eliminate the shortcomings of traditional methods of nitriding. The purpose of this work is studying the changes of structural-phase state and the wear-resistance of R6M5 HSS surface layer at electrolytic-plasma nitriding. Metallographic investigations were carried out on “ALTAMI-MET-1M” optical microscope. Microstructure of steel investigated on JSM-6390LV scanning electron microscope. The surface morphology was studied by C3M Solver HV atomic-force microscope. Study of phase composition and crystal structure of samples were carried out by X-ray structure analysis on D8 ADVANCE diffractometer. Tribological tests on sliding friction conducted on high-temperature THT-S-BE-0000 tribometer according to “Ball – Disk” scheme. The tests of samples for wear-resistance have been executed using an experimental apparatus for abrasive wear tests according to “Rotatory roll – Flat surface” schema and to State Standard 23.208-79 (ASTM S 6568). It is experimentally established, that modified layer with increased hardness and wear-resistance is formed on R6M5 steel surface after electrolytic-plasma nitriding. Determined that modified layer consists of nitrogen martensite and nitride Fe4N. It was found that after processing R6M5 steel wear intensity decrease and increases its resistance to wear and abrasion. The main factor affecting the increase of R6M5 HSS wear resistance is the formation of nitrogen martensite with Fe4N (’-phase)monophasic nitride, and formation of fine inclusions with hardening phases in surface layers. Perspectivity of electrolytic-plasma nitriding method application to improve the performance of cutting tools was shown.