Investigation of anodic plasma electrolytic carbonitriding on medium carbon steel

In this paper, anodic plasma electrolytic carbonitriding (APEC/N) treatment was employed to fabricate a hardened layer on medium carbon steel. The optical emission spectroscopy (OES) and the acoustical signal characterizations of plasma discharge during APEC/N process were analyzed for the first time. The results showed that the discharge plasma was in a local thermal equilibrium (LTE) state and the electron temperature in discharge zone was 4000 K-8000 K. The high electron temperature and strong acoustical signal corresponded with the intense discharge process, while the high-frequency noise up to 20 KHz related to the discharge taking place. Beneath the oxide layer, there was a 60 mu m thick carbonitrided layer, which contained Fe3C and Fe4N phases. After APEC/N treatment, the wear resistance of medium carbon steel was improved. The wear rate of treated steel was about 2.61 x 10(-4) mm(3)/N.m, which was only half of the bare steel substrate. (C) 2017 Elsevier B.V. All rights reserved.