25-27 April 2022
Conventum Conference Center
Europe/Vienna timezone

Novel development of an NbC-containing powder metallurgical martensitic steel with outstanding tribocorrosion resistance

25 Apr 2022, 14:10
20m
Room 1

Room 1

Speaker

Isabel Hahn (Ruhr-Universität Bochum, Lehrstuhl Werkstofftechnik)

Description

The development of martensitic steels suitable for exposure to corrosion with simultaneous wear attack is a challenging task, as corrosion and wear resistance are opposite properties in terms of alloying. With the development of NbC-containing corrosion-resistant steels, it has been possible to combine these properties. Due to its higher hardness, NbC increases the wear resistance of the steel more effectively than chromium carbide. In addition, the solubility of chromium in NbC is very low, so that no chromium depletion occurs due to the carbide formation and the chromium in the alloy is almost completely available for the formation of the passive layer.

Until now, steels containing NbC have not been produced according to the industrial powder metallurgy route, because even in low contents Nb tends to form primary carbides catching the carbon in the melt, which leads to clogging of the nozzle during the atomization process.

Diffusion alloying can circumvent this problem by first atomizing a C-free melt and adding the carbon to the steel powder in the form of graphite. However, this complex process is difficult to implement in the industrial production of powder metallurgical steels.

In the work presented, a corrosion-resistant martensitic steel with a volume content of 2 % NbC was developed with the aid of computer-controlled alloy development, which can be produced by the usual powder metallurgical route. The NbC are present as an evenly distributed dispersion with a carbide size < 1 μm. The steel achieves a hardness of >750 HV30 and exhibits very good pitting corrosion resistance in 0.9% NaCl solution. This combination of properties also leads to excellent tribocorrosion resistance.

Production on the industrial PM route has already been successfully carried out.

Speaker Country German

Primary author

Isabel Hahn (Ruhr-Universität Bochum, Lehrstuhl Werkstofftechnik)

Co-authors

Dr Sabine Siebert (Ruhr-Universität Bochum, Lehrstuhl Werkstofftechnik) Prof. Sebastian Weber (Ruhr-Universität Bochum, Lehrstuhl Werkstofftechnik) Prof. Werner Theisen (Ruhr-Universität Bochum, Lehrstuhl Werkstofftechnik)

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