Study of the fatigue behaviour of synthetic nodular cast irons at low and high frequency cyclic loading

Abstract

The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100. High frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both of them were carried out at sinusoidal cyclic push-pull loading (stress ratio R =-1) at ambient temperature (T ≈ 20 °C). The relationship σa = f (N) and fatigue strengths were determined experimentally; mechanical properties, microstructures and fracture surfaces were investigated.