Chehrehrazi, S. (2019). Influence of stress ratio on the torsional fatigue behaviour of 17-4PH stainless steel used for biomedical applications [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2019.47746
E308 - Institut für Werkstoffwissenschaft und Werkstofftechnologie
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Date (published):
2019
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Number of Pages:
72
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Keywords:
fatigue; martensitic stainless steel; defect tolerance; load ratio
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Abstract:
Precipitation-hardened chromium-nickel-copper stainless steel 17-4PH has a high strength, toughness and good corrosion resistance. According to these features, the 17-4PH stainless steel has a great application in biomedical advices such as hand tools and surgical staplers. In this study, the fatigue behavior of 17-4PH stainless steel under torsional loading condition in the very high cyclic fatigue regime was studied. To test the specimens in reasonable time, the ultrasonic fatigue testing equipment was used, which applies a sinusoidal load at a frequency of about 20 kHz. The results were compared with torsional tests that were conducted using conventional servohydraulic testing. Furthermore, the frequency effect and also the effect of delta ferrite grains on initiation of cracks at different loading frequencies are discussed. In addition, the area as a geometric parameter is used to determine the effect of small artificial defects on the torsional fatigue limit. Furthermore, the effect of different R-ratios on smooth and defect containing specimens is investigated.
