Posted 28 Dec 2010 19:43
According to the Japanese company ChikaraOoki of NTN by grain refinement of austenite grain size of the bearing of the steel rolling contact fatigue life is improved. SAE 2004 World Congress titled "bearing steel by grain refinement to improve the rolling contact fatigue life" (SAE2004-01-0634) the paper reported progress. Grain refinement is a newly developed heat treatment process called the results of FA. In the JIS-SUJ2 (SAE52100) bearing steel austenite grain size in the original diameter of about 5 m, half the size of conventional grains. Rolling contact fatigue test results are: two different lubrication conditions, the grain refinement SUJ2 the fatigue life is carbonitriding steel samples twice. Whether in the clean, or in the case of contaminated grain refinement of steel in tensile strength and dimensional stability are time advantage. The results show that the original hardened steel quenching austenite grain size depends on the heating temperature. Commonly known, in the lower quenching temperature, the observed grain size decreases. However, when quenched at lower temperature is the main obstacle to reduce the carbon content in the matrix, resulting in lower hardness. To determine performance, specializing in two different heat treatment process. First, using traditional methods of steel quenching. Second, the heating temperature is lower than the traditional heat treatment to reduce the temperature. Direct result of the martensite grain size are smaller, refined microstructure and hardness than HV700. Were cylindrical, tapered roller bearings and ball bearings rolling fatigue test 3. Test components by standard heat treatment, carbonitriding and the new FA heat treated. The results show that the FA treated by the fatigue life of components is twice the sample carbonitriding, and dimensional stability when compared to also be fully improved. In addition, the FA deal with the strength of steel by nearly the same as the standard treatment of the material, and with or without the presence of carbonitriding layer has nothing to do.