Ultrasonic fatigue testing of thin MP35N alloy wire
| Autor: | Markus Reiterer, M. Fitzka, D. Irrasch, Dhiraj Catoor, Herwig Mayer |
|---|---|
| Jazyk: | angličtina |
| Předmět: |
Ultrasonic fatigue testing
Yield (engineering) Materials science business.industry 020502 materials Resonance 02 engineering and technology Structural engineering Microstructure Fatigue limit Corrosion Characterization (materials science) MP35N 020303 mechanical engineering & transports 0205 materials engineering 0203 mechanical engineering Ultimate tensile strength Very-high cycle fatigue Composite material thin wire testing business Electrical conductor Earth-Surface Processes |
| Zdroj: | Procedia Structural Integrity. :1039-1046 |
| ISSN: | 2452-3216 |
| DOI: | 10.1016/j.prostr.2016.06.133 |
| Popis: | MP35N (35% Co, 35% Ni, 20% Cr, 10% Mo; % weight) in the form of thin wires (≈ 100 µm diameter) is commonly used in medical applications [1]. Materials used as conductors in cardiac leads require excellent corrosion resistance and high fatigue strength. This becomes apparent when one assumes a typical adult human heart rate of 72 beats per minute, which over 10 years of implant deployment will roughly yield 3.8 × 10 8 cycles. Tensile properties of MP35N are considerably enhanced through extensive cold-working. Static strength of the material is in the range of 2 GPa [1]. Fatigue testing of very thin wires is time consuming with conventional fatigue testing methods. In previous investigations [1] the wire was stressed at a cyclic frequency of 60 Hz in monotonic loading tests, requiring approximately 96 days for one single specimen to reach 5 × 10 8 cycles. A complete characterization of the material’s fatigue properties however requires many specimens to be tested well into the very-high cycle fatigue (VHCF) regime, calling for an accelerated testing method. A new method to test thin wires with the ultrasonic fatigue testing method is presented. Rather than vibrating in resonance as in conventional ultrasonic fatigue tests, the wire is stressed with cyclic tension loads. Results of fatigue tests of MP35N thin wire performed at a cycling frequency of ≈ 20 kHz at load ratio R = 0.3 are shown. The influence of secondary phase particles on crack initiation will be discussed. Mechanisms of fatigue crack initiation and measured lifetimes measured at 60 Hz and 20 kHz will be compared and discussed with respect to possible frequency influences. [1] M.J.N.V. Prasad, M.W. Reiterer, K.S. Kumar, Microstructure and mechanical behavior of an as-drawn MP35N alloy wire, Materials Science and Engineering: A, 610 (2014) 326-337. |
| Databáze: | OpenAIRE |
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