Title: Examination on surface films of plasma nitrided and post-stream oxidised H13 steel

Authors: Yongan Min, Xiaochun Wu, Luoping Xu

Addresses: School of Materials Science and Engineering, Shanghai University, P.R. China. ' School of Materials Science and Engineering, Shanghai University, P.R. China. ' School of Materials Science and Engineering, Shanghai University, P.R. China

Abstract: Different surface structures have been obtained on H13 steel by plasma nitriding under a mix current of ammonia and argon at 520°C, and a simple current of ammonia at 550°C. Post-stream oxidation gives the H13 samples a compact oxide film. The surface films and structures of these samples have been investigated with optical microscopy, X-ray diffraction, scanning electron microscopy and high distinguishability energy diffraction spectrometry. Only a single nitrogen diffusion layer is obtained on the 520°C-nitrided H13 samples, while a white Fe_2-3N nitride film and a deeper diffusion layer with needle-like nitride is obtained on the 550°C-nitrided samples. These two type samples are covered by the films of Me₃O₄ mainly as well as Fe₂O₃ after post-oxidation. It is also discussed on the application chances of the duplex treatment, which is cleaner and more environment friendly than conventional salt bath or gaseous techniques.

Keywords: plasma nitriding; stream oxidation; hot work tool steel; surface films; surface engineering; duplex treatment.

DOI: 10.1504/IJMMP.2008.018732

International Journal of Microstructure and Materials Properties, 2008 Vol.3 No.2/3, pp.254 - 261

Published online: 16 Jun 2008 *

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