Title: Effect of pulse plasma nitriding on tribological properties of AISI 52100 and 440C steels

Authors: Sukru Taktak; Ibrahim Gunes; Sukru Ulker

Addresses: Department of Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, 03200 Afyonkarahisar, Turkey ' Department of Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, 03200 Afyonkarahisar, Turkey ' Department of Mechanical Engineering, Faculty of Technology, Afyon Kocatepe University, 03200 Afyonkarahisar, Turkey

Abstract: AISI 52100 and 440C bearing steels were nitrided in conventional plasma (CPN) and pulsed plasma (PPN) consisting of 0.33 and 1 N2/H2 gas ratios at temperature of 500°C for 4 h under a constant pressure of 5 mbar. The surface of nitrided steels was investigated using optical microscopy, X-ray diffraction (XRD) and microhardness. The tribological behaviour of plasma nitrided steels was studied by means of unlubricated ball-on-disc method under constant loads of 5 and 20 N, sliding speed of 0.3 m/s at room temperature. The SEM and EDS techniques were used to analyse the worn surfaces of the steels. The results showed that γ'-Fe4N and α-Fe(N) were dominant phases for pulsed plasma nitrided 52100 and 440C steels, respectively and pulsed plasma nitriding slightly improved the wear behaviour of both steels.

Keywords: pulsed plasma nitriding; tribological properties; wear rate; friction coefficient; unlubricated wear; microhardness; bearing steels; tribology.

DOI: 10.1504/IJSURFSE.2014.059310

International Journal of Surface Science and Engineering, 2014 Vol.8 No.1, pp.39 - 56

Received: 12 Dec 2012
Accepted: 18 Aug 2013

Published online: 17 Feb 2014 *

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