Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

İ. Altinsoya, G.F. Çelebı Efea, T. Yenera, K.G. Önderb and C. Bındala aSakarya University, Department of Metallurgical and Material Engineering, Sakarya, Turkey bMikrosan Makina ve Kalıp San. A.S. Heat Treatment Department, Izmit, Kocaelı

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In this study, effect of double stage gas nitriding of 34CrAlNi7-10 steel was analyzed. Nitriding processes were carried out in two stages. in the first stage, samples were nitridied at 500°C for 10 h and then in second stage nitriding process was continued at 530 and 550°C for 20 h. During both stages, the nitrogen activity on surface was controlled by the nitriding potential, which is a thermodynamical control parameter for controlled gas nitriding process. The nitriding potential was kept constant, at value of 10, during the first stage and was varied in the range of 3.2-0.2, for both nitriding temperatures, in the second stage. The presence of nitrides, formed on the surface of test materials was determined by XRD analysis technique. The morphology of nitrided layer was studied by optical microscopy. The microhardness of the surfaces of nitrided samples in HV1 was between 955 and 1029. The measurements have shown that the thickness of the compound layer (white layer) has varied between 6.85-23.90 μm and that the growth of the white layer and microhardness gradient were strongly affected by the nitriding potential and the temperature. Diffusion depths as Nht(HV) for Vickers Hardness were determined and compared.

DOI: 10.12693/APhysPolA.132.663 PACS numbers: 81.05.BX, 81.65.LP, 81.70.BT