Effect of preliminary nanostructuring frictional treatment on the efficiency of nitriding of metastable austenitic steel in electron beam plasma

Abstract

The paper studies the effect of the temperature of nitriding in electron beam plasma, ranging between 250 and 500 °, on the nitrogen concentration, phase composition and microhardness of the surface of the AISI 321 chromium-nickel austenitic steel in two initial states - quenched undeformed and after nanostructuring frictional treatment. The lowest nitriding temperature (350 °C) for the efficient hardening of the steel has been established. The application of frictional pretreatment with a sliding synthetic diamond indenter in an argon environment is shown to be highly efficient for increasing the depth of the layer nitrided at this temperature. The contribution of the formed S-phase (nitrogen-oversaturated austenite γN) to the intensive hardening of the steel nitrided at low temperatures (300 to 400 °) is noted. © 2017 Author(s).