Characterization and Evaluation of a Railway Wheel Steel in the HCF and VHCF Regimes

Abstract

As technology advances, the need for higher life components increases. This results in a growing need for better comprehension of the materials’ life for higher numbers of cycles. Therefore, the study of the fatigue life in all the operation regimes is gaining preponderance in engineering design and maintenance. The material studied here was retrieved from a wheel provided from a railway transportation company. The material was defined to follow the European standard EN 13262+A1 and this specific wheel had been in operation and was already fully worn out. Specimens were retrieved and machined for fatigue testing. Both conventional and ultrasonic fatigue testing machines were used in order to characterize the fatigue behavior of the material in study. The ultrasonic fatigue testing characterizes the material life for more than 10E6 cycles. This machine uses a piezoelectric transducer to induce free-vibration conditions on a specimen in its first axial resonance mode, applying tension-compression stresses at 20 kHz. The conventional servo-hydraulic machine is used to evaluate the material life up to 10E6 cycles. Both types of tests were carried out in IDMEC laboratories at IST. Fracture surfaces of each specimen were analyzed and the metallography of the material was also carried out. The respective S-N curve of the material was obtained and some remarks regarding the mechanical characterization of the material are drawn.