In the X-ray measurement of residual stress at most accuracy is required and the appearance of the measured value is important. It is well known that if X-ray diffraction pattern is sharp, that will be good reappearance of the measured value. In hardened and ground bearing steel, however, merely extremely broadened diffraction pattern can be gained. In this case, it is questionable whether the measured value is reliable or not.
From bearing steel, we made seven kinds of test pieces which were heat treated. They were found in different levels of hardness, and we practiced measurement, of their stress at their respective levels. Consequently, it was found that the scattered range of their measured value was 6∼13kg/mm2 and between broadened diffraction pattern and sharpened one, the difference at scattered range of the measured value was not particularly noticed.
