Coating of 1.4404 stainless steel by a combination of brazing and nitriding

  • Ali Hussein Al-Azzawi Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, Miskolc
  • Peter Baumli Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, Miskolc
Keywords: Stainless steel 1.4404, Nickel alloy, Silicon, Brazing, Nitriding, Phase composition.

Abstract

In the current research, surface hardening of 1.4404 stainless steel was investigated. A hard Ni-containing coating was prepared by brazing at 1150 °C using a Ni foil with Si powder. The hardness behavior was increased by nitriding as well. The nitriding experiments were performed at low and high temperatures (460 and 640 °C) for a different period (3 and 6 h). The microstructure and material properties were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Micro Vickers hardness testing. Results show that the hard phase and the binding Ni foil were well distributed into the hard layer. The hard coating material was composed of a Si-phases and Ni-containing compound dispersion.

After the nitriding, the hardness of the samples was increased with increasing the nitriding time and temperature and increasing the brazing time. The 10 min brazing and 6h nitriding at 640°C resulted in 32% higher hardness than the non-nitride sample.

Strong metallurgical bonding is formed between the stainless steel substrate and the coating layer, as well as between the binding Ni foil and the hard phase; because of the mutual diffusion of alloying elements, the hardness of this hard coating was 2 to 3 times higher than the initial hardness of steel substrate.

Author Biography

Ali Hussein Al-Azzawi, Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, Miskolc
Institute of Physical Metallurgy, Metal Forming and Nanotechnology

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Published
2018-10-19
Section
Full length research papers