Gas Nitriding Behaviour of 34CrAlNi7 Nitriding Steel

I. Altinsoya, K.G. Onderb, F.G. Celebi Efec and C. Bindala aSakarya University, Engineering Faculty, Department of Metallurgy and Materials Engineering, Esentepe Campus, Serdivan, Sakarya, Turkey bMikrosan Makina ve Kalıp San, A.S. Heat Treatment Department, Izmit, Kocaeli, Turkey cSakarya University, Karasu Vocational High School

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In this study, gas nitriding behavior of 34CrAlNi7-10 steel was investigated. Single stage processes were carried out at 500°C, 520°C and 540°C for 10, 20, 30 h, respectively. Nitrogen activity on surface was controlled by the nitriding potential KN which is known as thermodynamical control parameter for controlled gas nitriding process. The presence of nitrides formed on surface of test material was determined by X-ray diffraction analysis technique. The morphology of nitrided layer was studied by optical microscope. The microhardness of surface of nitrided sample in HV1 was observed between 975 and 1132. Choosing the right nitriding potentials for each temperature, which give the same nitrogen concentration and activity on surface by using the Lehrer diagram, showed that all the samples had almost the same surface roughness of Ra = 0.28-0.32 μm after gas nitriding cycles. The measurements showed that the white layer thickness varies between 4.38 μm and 28.80 μm and the growth of the layer was strongly affected by process time and temperature. Diffusion depths as Nht (HV) for each experiment were determined and compared.

DOI: 10.12693/APhysPolA.125.414 PACS numbers: 81.05.Bx, 81.65.Lp