In order to clarify the fatigue process of steel balls, an X-ray diffraction apparatus capable of carrying out various functions automatically has been constructed. The automatic functions include the X-ray measuring process, the process for changing and setting a steel ball on the specimen mount as well as renewing the measuring point, and the recording and computing process of the measured values. With this apparatus, the fundamental experiments for predicting the life of balls were carried out. The results obtained are summarized as follows;
(1) With the present automatic X-ray diffraction apparatus, manual operations are only to set the first steel ball onto the specimen mount and to feed the punched tape of measured values to a computer.
(2) This apparatus increases the measuring capacity and the efficiency of the calculation enormously. Furthermore, the personal errors, induced often during the X-ray diffraction profile analysis, can be eliminated completely.
(3) By exchanging the machine parts of the ball supply system, this apparatus becomes applicable to steel balls of different diameters ranging between 6.35mm and 25.4mm.
(4) There was a strong correlation between the variation of half-value breadth and the B10 life. The smaller the variation was, the longer the fatigue life became. From this fact, it was possible to estimate the fatigue strength of steel balls.