Fatigue behavior of DIN 1.4307 and DIN 1.4306 stainless steels under high frequency loading

Two stainless steels DIN 1.4307 and DIN 1.4306 were tested by an ultrasonic fatigue loading device under push-pull mode (stress ratio R = -1). Life-time curves were determined in the high and very high cycle fatigue regions. The time dependence of frequency was monitored and evaluated. At the beginning of the tests (up to 1 × 107 cycles), an increase of the frequency was observed, followed by a slow frequency decrease. It relates to changes of microstructure. No failure occurred in the region between 1 × 109 and 1 × 1010 cycles. The steel 1.4306 exhibits a higher fatigue life-time than the steel 1.4307. This is caused by the difference in the chemical composition of the two steels, namely by the higher nickel content in the 1.4306 steel.