Conclusions
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1.
We determined the critical cooling rates to obtain a defect-free structure of the outer (peripheral) zone of the case with high microhardness (>H 550). The critical rate is highest for carburized steel 25KhGT and lowest for carburized steel 20Kh2N4A.
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2.
It was found that the cooling rate at the base of the teeth and in the valleys is lower than the cooling rate at the tip of the teeth (in the zone of meshing) even with a high cooling rate.
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3.
Diagrams were plotted to determine the optimal quenching conditions for gearwheels wigh m=6–14 mm.
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4.
Quenching with the optimal cooling rate ensures a defect-free structure of the outer zone of the case on steel 25KhGT and fairly high microhardness of this zone. This treatment more than doubles the resistance to scoring in comparison with quenching in still oil.
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Literature Cited
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Additional information
Moscow Auto-Mechanical Institute. All-Union Scientific-Research and Design-Technological Institute of Coal Mining Machine Construction. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 7–10, June, 1980.
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Kozlovskii, I.S., Manevskii, S.E. & Kazachkov, V.A. Effect of quenching conditions on the structure of the case and the antiscoring properties of carburized steel. Met Sci Heat Treat 22, 386–390 (1980). https://doi.org/10.1007/BF00693637
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DOI: https://doi.org/10.1007/BF00693637