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timken bearing steel special purpose ultra-clean development

     In recent years, with high-speed and miniaturization have become increasingly demanding, therefore, timken bearings high performance requirements. Especially in the automotive industry to reduce fuel consumption and reduce vehicle of this size has a high demand. On the other hand, the electronics industry also requires very little relationship to promote energy conservation and more time when there is no electronic equipment vibration.
    A, with ultra-clean production timken bearing steels
    1, ultra-clean steel production
    To reduce the nitride inclusions, it is necessary to make minimum titanium content of the steel. Mainly from titanium, chromium steel, in particular for adjusting the chemical composition. Typically, in the ladle refining process of chromium added to the molten steel. Since low levels of oxygen in the molten steel, so the titania (titanium dioxide) in the form of titanium is very difficult to eliminate. Kobe Steel, chromium is added when the converter blowing and melting, at which point the oxygen content is very high, with oxygen to form titanium dioxide, and the converter slag absorbing reaction.
    2, the performance of ultra-clean steel
    52100 in the ultra clean steel, the oxygen content can be controlled to a 4.1ppm, 6.0ppm average titanium content average. Ultra clean steel and steel fatigue life 52,100 compared to comparative tests, L10 higher. In addition, the use of ultra-clean steel and ordinary steel cleanliness detection methods were compared. In contrast, ultra clean steel and timken bearing steel cleanliness generally little difference, but ultra clean steel fatigue life than steel long.
    B, identifying new inclusions in the steel
    Due to very low oxygen content super clean steel, so the traditional ASTM test methods and oxygen content were measured included and fatigue life can not give a good correspondence. To this end, the test to determine the clean steel inclusions electron beam melting. Kobe Steel, researchers trying to find a number from the inclusion size and clean up the evaluation of new measurement methods. Accordingly, the acid dissolution method to detect small inclusions and the detected number of inclusions.
    First, 30-100 g of sample was dissolved in nitric acid and heated to 90 ℃. After cooling, the solution filtered, the filter residue isolated inclusions. 10 mesh screen size greater than 10 mesh inclusions remain in the filter. SEM observation of inclusions, electron probe microanalysis analysis of inclusions.
    By using these methods can detect a large number of inclusions, to avoid carbon. By using the acid dissolution method, researchers can detect the oxygen content of less than 9ppm, fatigue life test sample is low. Test results show that ultra-clean inclusions and inclusions quantity is less than the maximum size of the steel lower than ordinary steel. When the oxygen content of less than 9ppm, acid dissolution method can also measure ultra clean steel ordinary steel cleanliness differences.


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