I. A. Zumbilev, A. Zumbilev, TU-Sofia Branch Plovdiv, Plovdiv, Bulgaria; K. Nikolov, DOC Dortmunder Oberflächencentrum GmbH, Dortmund, Germany
The aim of this paper is to investigate the influence of the processes of nitriding and carbonitriding in smouldering discharge on the parameters of the obtained layers and on certain mechanical and technological properties of 25CrMnSiNiMo steel. The influence of the two processes has been examined under three considerably different modes of treatment. Ammonia and propane-butane in certain percentage proportion at different time and constant temperature are used as saturating gases.
The results show that at the same temperature (550 0C) and time of treatment (4h), but at different saturating gas media (NH3, C3H8 – C4H10), the layers formed after ion carbonitriding are with lower thickness and micro hardness than the ones formed after ion nitriding. It has been established that after conducting the processes of carbonitriding and nitriding in low temperature plasma, the impact strength of 25CrMnSiNiMo steel reduces by 15 %. Bigger reduction of the relative extension of 25CrMnSiNiMo steel is observed after carbonitriding. After ion carbonitriding the heat resistance of 25CrMnSiNiMo steel is higher than after nitriding.
