Ultrasonic Fatigue Test of Mild Stee1

抄録

In an ultrasonic fatigue test of mild steel, the authors investigated the effects of strain amplitude, mean stress, and pre-strain on the changes of resonant frequency, and found a close relationship between the reduction of resonant frequency due to ultrasonic fatigue and the change of the microscopic structure. "The yield point for the stress of vibration" was defined by a strain amplitude which causes a rapid decrease of resonant frequency. Moreover, from an ultrasonic fatigue test with mean stress, a fatigue limit diagram was made for practical use.