Plasma Nitriding Process of Cast Camshaft to Improve Wear Resistance

A. Dayança, B. Karacaa, L.C. Kumruoğlub aESTAŞ Eksantrik San. ve Tic. A.Ş., 58060 Sivas, Turkey bCumhuriyet University, Department of Metallurgy and Materials Eng., 58100 Sivas, Turkey

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The aim of this study was to investigate the effect of plasma nitriding heat treatment on the microstructure, hardness and abrasion resistance of the GG25 grade gray cast iron camshaft. For this purpose, in the first stage, casting simulation was carried out by using NOVACAST computer software program of GG25 grade gray cast iron camshaft to optimize casting quality and production of camshaft with sand casting method. Casting process was performed between at 1410-1420° and casting time was between 14-16 s. Plasma nitriding was carried out for 120 minutes and 240 minutes for cast gray iron camshafts for each gas mixture at gas mixture ratios of 80% H2 + 20% N2, 90% H2 + 10% N2, 94% H2 + 6% N2 at 500°. Plasma nitrided camshafts were subjected to optical microscopy, SEM, XRD analyzes and mechanical tests (hardness and wear). For the cas iron camshaft made from GG25 grade, the optimum hardness (583 HV0.1) and the wear resistance (1.90 mg/500 cycles), were obtained from the diffusion layer depth (603 μm) and the white layer thickness (10 μm) reached 240 min. plasma nitriding of the 94% H2 + 6% N2 gas mixture.

DOI:10.12693/APhysPolA.135.793 topics: casting, plasma nitriding, tribological properties, SEM