SKOŁEK Emilia Warsaw University of Technology Faculty of Materials Science and Engineering

Spoluautoři POBIEDZIŃSKA Karolina, KAMIŃSKI Janusz, ŚWIĄTNICKI Wiesław. A.

The bearing steel 67SiMnCr6-6-4 was subjected to nanostructuring treatment consisted of austempering with an isothermal quenching at 240 °C. The treatment produced homogenous nanobainitic structure consisting of 49±3.7 nm thick laths of carbide-free bainite separated by layers of retained austenite of thickness of 39±2.6 nm. The investigations of microstructure using transmission electron microscopy revealed that the content of retained austenite was about. 38 % vol. The microhardness measured for the produced nanostructure was 658 HV2. The study of corrosion resistance was carried out in Na2SO4 acidic and neutral environment using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. The corrosion resistance of bearing steel 67SiMnCr6-6-4 with nanostructure was determined and compared with the same steel after a quenching and tempering at 350 °C for 1 h treatment. Time and temperature of tempering was chosen so that the hardness of both samples (nanostructured and quenching and tempered) was similar. The obtained results indicate, that the nanobainitic structure produced in bearing steel 67SiMnCr6-6-4 does not affect the corrosion resistance of the steel in comparison with traditional quenching and tempering treatment in both acidic and neutral environment.

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