Conclusions
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1.
The tendency of steel 18KhGN2MFB towards internal oxidation and austenite grain growth during CHT is markedly lower than for steel 20KhNZA normally used for gear wheels. Steel 18KhGN2MFB has sufficiently high hardenability for the carburized and carbonitrided layers.
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2.
The fatigue limit in bending for carbonitrided specimens of steel 18KhGN2MFB is 15% higher than for carburized steel 20KhNZA, 20% higher than for carbonitrided steel 18KhGT, which may be explained by formation of a finely dispersed structure in the hardened of the suggested steel.
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3.
Use of steel 18KhGN2MFB instead of 20KhNZA makes it possible to reduce the duration of CHT for gear wheels as a result of using direct quenching after impregnation, and a reduction in the required overall thickness of the diffusion layer. In this way there is a marked reduction in the level of residual strains for gear wheels and their endurance increases by a factor 2–2.5.
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Literature cited
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Additional information
All-Union Scientific-Research Institute of Machine Building Technology (VNIITMASh), Volgograd Tractor Factory. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 21–26, May, 1987.
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Tel'dekov, V.A., Merilova, E.A. & Shevchuk, V.P. Complex alloy steel for heavily loaded carburized gear wheels. Met Sci Heat Treat 29, 344–350 (1987). https://doi.org/10.1007/BF00715839
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DOI: https://doi.org/10.1007/BF00715839