Ultrasonic quality control of thermal treatment of railway bearing rollers

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Ultrasonic quality control of thermal treatment of railway bearing rollers

Soldatov, A.I. / Fiks, I.I. / Tsekhanovskii, S.A.

Ultrasonic nondestructive testing methods are widely used in machine building. In this case, along with testing for the presence of local flaws of the discontinuity type, testing of physicochemical parameters is used, among which hardness testing is the most widespread. Note that this parameter is usually tested by destructive methods, thus making it impossible to achieve 100 % inspection of articles. In some papers, it is shown that ultrasonic vibration parameters depend on the mechanical properties of metals. In particular, the dependence of the velocity of ultrasound on elastic constants of various materials was analyzed. The theoretical possibility of measuring the hardness of articles made of different steel grades by establishing the correlative dependence of the propagating ultrasound group velocity on the hardness has been shown. A method for ultrasonic testing of the quality of heat treatment of cylindrical manufactured articles is considered. The delay of propagation of an ultrasonic beam is analyzed for different trajectories. Mathematical formulas for estimating the measurement error at different positions of a probe on a test object are obtained. The results of comparative hardness measurements by the ultrasonic method and the Rockwell hardness measurement method are presented.