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《International Heat Treatment & Surface Engineering》2013,7(1):8-15
AbstractTwo experimental high silicon high carbon steels (with 5 and 24 ppm of boron separately) have been investigated for the development of superbainite structure. After austenitisation, the specimens were held respectively at three different isothermal transformation temperatures (150, 200, and 300°C) for a variety of time intervals. The microstructures were examined via optical metallography (with microhardness measurement) and transmission electron microscopy. It was found that after isothermal transformation at 200°C for 10 days, both steels produced a high volume fraction of sheaf structures with nanometre scaled bainitic ferrite subunits, which contributed to an ultrahigh microhardness, up to 675 HV. It was also found that adding 24 ppm of boron accelerated the bainitic transformation in the early stage of isothermal transformation at 200°C, but did not have a significant effect on reducing the finish transformation time. Both isothermal temperature of 150 and 300°C could not lead to the development of high amount of bainite. 相似文献
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A. A. Shul'ga 《Metal Science and Heat Treatment》1992,34(7):446-451
| 1. | The structure and properties of bearing steels subjected to EBT depend to a considerable extent on their initial structure and on the composition of the carbide phase. Electron-beam hardening is expedient for treating steels with initial finely disperse structure. Maximal hardness and dislocation density is found in the zone of solid hardening with incomplete dissolution of carbides. |
| 2. | In distinction to laser treatment, electron-beam treatment prevents decarburization of the surface layer and makes it possible to obtain a more uniform structure in the direction in which the beam moves, and a thicker hardened layer. |
| 3. | To obtain high contact fatigue strength of bearing steels, electron-beam treatment has to be carried out without fusion of the surface under such conditions that the carbides are not completely dissolved and a strengthened layer forms. |
| 4. | The contact fatigue strength of the rolling surfaces after electron-beam treatment depends on the thickness of the zone of secondary hardening. The life of surfaces after EBT treatment can be extended only if the strengthened layer is at least one-half thicker than the depth at which the zone of maximal tangential stresses arising in rolling lies. |
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T. D. Kubyshkina L. M. Pevzner L. S. Fedotova M. F. Alekseenko 《Metal Science and Heat Treatment》1963,5(4):211-215
Conclusions Low-temperature thermomechanical treatment considerably improves the mechanical properties of 1Kh12NVMFA and VNS-6 steels.Low-temperature thermomechanical treatment followed by tempering at secondary hardness temperatures produces a particularly favorable combination of properties.Low-temperature thermomechanical treatment increases not only the resistance to rupture but also the resilience.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 32–35, April, 1963 相似文献
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