Nanostructured surfaces

Nitriding of steels with a low tempering temperature
Andreev A.A., Stolbovoy V.A., Serdiuk I.V.

Institute of Solid State Physics, Materials Science and Technologies, National Scientific Center "Kharkov Institute of Physics and Technology" of the NAS of Ukraine.
Akademicheskaya Street, 1, Kharkov-61108, Ukraine.
E-mail: aandreev@kipt.kharkov.ua

One of the external factors affecting the adhesion of nanostructured multilayer coatings is the difference in properties, in particular in hardness and modulus of elasticity between the substrate and the coating itself, which is important to minimize. One way to achieve this goal is to increase these parameters by nitriding the steel base.
The most effective way of nitriding is in the gas plasma of a vacuum arc discharge [1]. However, this process is impossible for steels with low tempering temperatures, since it is carried out at temperatures of about 500 C. After such nitriding the hardness of the surface layer is 8 ... 11 GPa with a thickness of 50 microns. In this paper it is proposed to change the usual sequence of operations, namely, first to carry out nitriding, then heat treatment and cleaning before coating.
After heat treatment (heating, quenching and tempering), the microhardness of the nitrided layer is 8 ... 11 GPa and reaches a depth of 2.5 mm with the formation of a decarburized layer up to 70 ... 150 μm thick and hardness up to 6 ... 8 GPa.

1.	Andreev A.A., Sablev L.P., Grigoriev S.N. Vacuum-arc coatings. (In Russian). // Kharkov.-NSC KIPT.-2010.-P. 317.