Phase formation in high-chromium steel under electron-ion-plasma treatment

Abstract

The surface alloying was carried out by single-cycle and multi-cycle (5 cycles «sputtering-irradiation», in each cycle the thickness of the titanium film 0,5 µm), i.e. high-speed melting of the system «film (Ti)/(steel AISI 310S) substrate» by pulsed electron beam. Nitriding (793 K; for 1, 3 and 5 hours) was carried out under conditions of realization of the elion (electron and ion) treatment mode. The isothermal cross sections of the ternary systems of the state diagram of the Cr – Fe – Ni – Ti – N alloy formed at different stages of the complex treatment of steel are considered. It is shown that (1) irradiation of steel by a pulsed electron beam is accompanied by the formation of a structure of high-speed cellular crystallization of solid solution based on γ–Fe; (2) nitriding of steel in the initial state is accompanied by formation of nitrides of iron Fe4N and chrome CrN with a total content of 79,8 wt.%; (3) pulsed electron-beam pre-irradiation of steel leads to a decrease in the rate of nitride formation during subsequent nitriding; the total nitride content of 53 wt.%; (4) regardless of the number of alloying cycles (titanium concentration in the surface layer) after five hours of nitriding in the samples formed a surface layer of nitrides of chromium and iron (1 cycle of doping) or nitrides of chromium and titanium (5 cycles of doping).

Keywords

• complex electron-ion-plasma treatment
• electron plasma component heating of samples
• high-chromium steel
• surface alloying
• phase composition