Features of nitroquenching of medium-carbon steel during anodic electrolyte–plasma processing

Abstract

The research described in this paper is devoted to short term anodic nitriding of grade 45 steel with postquenching (nitroquenching) in the aqueous solution of ammonia and ammonia chloride. The mod ified layer structure, as revealed, is composed of alternate layers: a surface oxide layer composed of FeO and Fe 3 O 4 ; a layer of dispersed nitrides Fe 4 N and Fe 2-3 N with retained austenite; next, a martensitic zone com posed of nitrogen and carbon; and the initial nitrogen enriched ferrite-pearlitic structure. It is found that concentrations of electrolyte components and processing conditions affect the formation character and prop erties of diffusion layers. The possibility is shown for obtaining a nitroquenched layer 130 μm in thickness with a surface microhardness of to 1200 HV with a decrease in roughness R a from 0.57 to 0.55 μm, R z from 1.75 to 1.62 μm, and R max from 5.74 to 4.00 μm.

Study of the Properties of Iron and Vanadium Nitride Coatings by CCPD on 1080 Steel

“…In addition to SEM images, the diffusion layer can also be evidenced by the slight shift of the α-Fe phase peaks to the left. The initial microstructure of the steel, including features such as grain boundaries and defects, plays a crucial role in nitrogen diffusion and the subsequent formation of nitrides 45 . When the microstructure has a favorable grain distribution and an adequate density of defects, it can facilitate the absorption and diffusion of nitrogen atoms into the material [46][47][48] .…”

Surface Modification of Steel by Anodic Plasma Electrolytic Boronitriding and Polishing

“…The nitrogen diffusion decreases the austenitization temperature and results in formation of martensite after the sample cooling in the electrolyte [8]. An electrolyte composition (5-7.5 % of ammonia and 10-15 % of ammonium chloride) and a nitriding mode (750 °С, 10 min) are proposed, which makes it possible to obtain a nitroquenched layer 130 μm in thickness with a surface microhardness to 1200 HV with decreasing roughness Ra from 0.57 to 0.55 μm [9].…”