Investigation of abrasive + erosive wear behaviour of surface hardening methods applied to AISI 1050 steel N.Y. Sari a, * , M. Yilmaz b a Department of Mechanical Engineering, Kocaeli University, 41040 Kocaeli, Turkey b Department of Metallurgy and Materials Engineering, Kocaeli University, 41040 Kocaeli, Turkey Received 24 May 2004; accepted 16 November 2004 Available online 25 December 2005 Abstract In the present technology, machine parts which work at the industry area such as agriculture, mining and cement are subjected to wear. The wear resistance of these parts is improved by conventional heat treatments or surface heat treatments, which only improved the property surface and sub-surface of materials. In this study, samples of AISI 1050 steel are subjected to induction hardening and thermochemical treatments such as boronising, nitriding and thermal spraying which involves flame spraying, flame spraying plus melting, high velocity oxyfuel (HVOF) plus melt- ing apart from the conventional heat treatment, which is oil quenching. At the end of wear tests, it is observed that the amount of wear in base metal decreased with the oil quenching but on the contrary to that the wear resistance was not improved with induction hardening and the other thermochemical surface treatments. However, the amount of wear in base metal was significantly decreased with thermal spraying methods. Even the additionally applied remelting treatment after spraying reduced to more smaller amounts. So, the applied remelting treatment after spraying plays much more important role in reducing wear. At wear surfaces of thermal spraying samples, the regional surface damages with slight traces of abrasive wear are seen. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Abrasive wear; Erosive wear; Plasma nitriding; Thermal spraying; Flame spraying; High velocity oxyfuel (HVOF) 1. Introduction Friction and wear behaviour of materials largely de- pend upon surface material, mechanical properties, physical structure and chemical composition of surfaces and surface topographies. Thermo-chemical and ther- mo-mechanical processes are heavily used for increasing the abrasive wear resistance of materials [1–3]. When comparing these two groups of methods, particularly in thermo-mechanical processes, the coating material se- lected as well as the process parameters must be consid- ered as an important factor. Therefore, when comparing these two methods, the main criteria shall be the chem- ical composition of the surface layer and the surface adhesion of this layer. These two main criteria usually determine the wear conditions in which these methods can be preferred. For example, impact load and heavy load conditions restrict the use of thermo-mechanical processes. Although many methods may be selected in thermo-chemical surface treatments, we see that in this group plasma nitriding method is used extensively and gives very good results [4–6]. In these applications, the best process parameters must be determined in advance [6]. Coating material is naturally the most important parameter in thermo-mechanical processes, which are 0261-3069/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.matdes.2004.11.020 * Corresponding author. Tel.: +90 262 335 2812; fax: +90 262 335 0216. E-mail address: nsari@kou.edu.tr (N.Y. Sari). www.elsevier.com/locate/matdes Materials and Design 27 (2006) 470–478 Materials & Design