Wear resistance of a high nitrogen austenitic stainless steel coated with amorphous carbon films: influence of grain size and film composition L. Valentini a, * , A. Di Schino a , J.M. Kenny a , Y. Gerbig b , H. Haefke b a Materials Engineering Center, University of Perugia, 05100 Terni, Italy b CSEM, Rue Jaquet Droz 1, CH-2007 Neuchatel, Switzerland Received 18 February 2002; received in revised form 15 May 2002; accepted 19 June 2002 Abstract In this paper, the wear resistance of nitrogen alloyed austenitic stainless steels is, for the first time, investigated and compared to that measured for the same samples coated with amorphous carbon (a-C:H) films deposited by means of plasma enhanced chemical vapour deposition. Ball on Disk (BoD) tests are performed in order to investigate the wear stability of coated and uncoated substrates with different grain sizes. For the uncoated samples, the BoD results show a strong dependence of the wear track volume versus grain size. Furthermore, a strong improvement of the wear resistance is found in a-C:H coated specimens with respect to the uncoated ones with the same substrate microstructure. The effects of nitrogen incorporation into the films are also investigated showing an improvement of the tribological properties of the coated stainless steel. In particular, a synergic effect is detected between the grain refining and the film in the case of nitride amorphous carbon overcoats with a consequent increase of the wear resistance. D 2002 Published by Elsevier Science B.V. Keywords: High nitrogen austenitic stainless steel; Grain size; Thin films; Wear Nitrogen alloyed austenitic stainless steels exhibit attractive properties as high strength and ductility, good corrosion resistance and reduced tendency to grain boundary sensitation [1]. The high austenitic potential of nitrogen allows the reduction of nickel content in steel, offering additional advantages such as cost savings. The production of these low nickel steels is made possible by the addition of manganese that allows the increase of N solubility in the melt and decreases the tendency to Cr 2 N formation [2]. Due to the above-mentioned properties, in the last years many efforts [3] have been devoted to the production of 0167-577X/02/$ - see front matter D 2002 Published by Elsevier Science B.V. PII:S0167-577X(02)00972-2 * Corresponding author. Tel.: +39-744-492924; fax: +39-744- 492925. E-mail address: mic@unipg.it (L. Valentini). www.elsevier.com/locate/matlet Table 1 Chemical composition (mass%) of the studied high nitrogen austenitic stainless steel C Si S P Mn Cr Ni Mo Cu N 0.026 0.04 0.003 0.026 10.5 18.6 0.42 0.07 0.07 0.37 Materials Letters 57 (2003) 1281 – 1287