A novel method of surface modification for steel by plasma electrolysis carbonitriding

A novel method of surface carbonitriding modification for Q235 steel in an ethanolamine electrolyte was proposed and demonstrated in this paper. Microstructure, chemical and phase composition and properties of the carbonitriding layer were investigated. The results show that the thick carbonitriding layer can be obtained. When the substrate was processed at 150 V for 75 s, the highest thickness is about 70 μm, and the corresponding microhardness is HV750, which is 4.5 times higher than that of the substrate. The carbonitriding layers are composed of martensite, remained austenite, carbonides and nitrides with iron, such as Fe3C, Fe5C2 and ɛ-Fe2–3N. Wear test shows that the wear resistance of the sample is improved significantly compared to the substrate.