High Cycle Fatigue Properties of Haynes 230 (registered trademark) Before and After Exposure to Elevated Temperatures (Preprint)

2011 ◽  
Author(s):  
R. J. Morrissey ◽  
R. John
Keyword(s):  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Haynes 230 ◽  
Registered Trademark ◽  
Before And After

Mechanical Behaviours of Coronary Stents

2006 ◽  
Vol 49 ◽  
pp. 91-96 ◽  
Author(s):  
György Ring ◽  
Eszter Bognár ◽  
János Dobránszky ◽  
János Ginsztler ◽  
László Major
Keyword(s):  
High Cycle Fatigue ◽  
Mechanical Strain ◽  
Fatigue Tests ◽  
Coronary Stents ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Energy Dispersive Analysis ◽  
Before And After ◽  
Mechanical Behaviours

The role of the stents is to prevent restenosis. The rapid growth of stents’ application in the treatment of cardiovascular diseases resulted in the unique development of these implants. This is mainly due to the effective clinical trials, the success of which determined the use of these endoprostheses. In this study the surface properties of the coronary stents were described by using different methods (stereomicroscopy, scanning electron microscopy and energy dispersive analysis) before and after balloon expansion. Furthermore, the most frequent failures caused by the expansion were introduced. For investigating fatigue properties two high cycle fatigue test equipments were used: the first one simulates the bending stress, and the second one simulates the effect of the pulsating mechanical strain. Surface features of the stents were examined after the fatigue tests as well: macroscopic damages were not originated on the stents, and the implants were not broken down. Only small traces of fatigue occurred on the surface, which became rough; and slip lines and grain boundaries were outlined.

High Cycle Fatigue Properties of Modified 9Cr-1Mo Steel at Elevated Temperatures

2012 ◽  
Author(s):  
Yoshiaki Matsumori ◽  
Jumpei Nemoto ◽  
Yuji Ichikawa ◽  
Isamu Nonaka ◽  
Hideo Miura
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Room Temperature ◽  
Structural Reliability ◽  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Cyclic Softening ◽  
Fatigue Properties ◽  
Cycle Fatigue

Since high-cycle fatigue loads is applied to the pipes in various energy and chemical plants due to the vibration and frequent temperature change of fluid in the pipes, the high-cycle fatigue behavior of the alloys used for pipes should be understood quantitatively in the structural reliability design of the pipes. The purpose of this study, therefore, is to clarify the high-cycle fatigue strength and fracture mechanism of the modified 9Cr-1Mo steel at temperatures higher than 400°C. This material is one of the effective candidates for the pipes in fast breeder demonstration reactor systems. A rotating bending fatigue test was applied to samples at 50 Hz in air. The stress waveform was sinusoidal and the stress ratio was fixed at −1. The fatigue limit was observed at room temperature and it was about 420 MPa. This value was lower than the 0.2% proof stress of this alloy by about 60 MPa. This decrease can be attributed to the cyclic softening of this material. The limited cycles at knee point was about 8×105 cycles. All fracture was initiated from a single surface crack and no inclusion-induced fracture was observed in the fracture surface by SEM. Thus, the high-cycle fatigue design based on the fatigue limit may be applicable to the modified 9Cr-1Mo steel at room temperature. The fatigue limit of about 350 MPa was also observed at 400°C, and it appeared at about 107 cycles, while it appeared at around 106 cycles at room temperature. Thus, it was confirmed that the fatigue strength of this alloy decrease with temperature. However, the fatigue limit didn’t appear at 550°C up to 108 cycles. The fatigue limit may disappear in this alloy at 550°C. It is very important, therefore, to evaluate the ultra-high cycle fatigue strength of this alloy at temperatures higher than 400°C.

scholarly journals Influence of structure sensitising of the AlSi 316Ti austenitic stainless steel on the ultra-high cycle fatigue properties

2018 ◽  
Vol 157 ◽  
pp. 05011 ◽  
Author(s):  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
Libor Trško ◽  
Monika Oravcová
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Structural Changes ◽  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Testing ◽  
Engineering Application ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Ultra High Cycle Fatigue

Austenitic stainless steels are the wide-spread materials, used mainly in the power industry. In that kind of engineering application, structural parts of rotating elements reach during their lifetime very high numbers of loading cycles, exceeding 107 numbers of cycles. With regard to this fact, the data of ultra-high cycle fatigue properties are needed to be used in the qualified design. Increasing demands on the efficiency cause the increase of the operating temperature, and exposition of these materials to the elevated temperatures can cause some important structural changes, which result in the sensitising of the structure. In this study authors present their own experimental results about fatigue properties of AISI 316Ti austenitic stainless steel after sensitising, in the ultra-high cycle region (Nf = 106 ~ Nf = 3×109 cycles). Fatigue tests were carried out using ultrasonic fatigue testing device with frequency f = 20 kHz at the coefficient of cycle asymmetry R = -1, and temperature T = 20±5°C. In the ultra-high cycle region was observed the continuous decrease of the fatigue properties of the AISI 316Ti, and there was recorded the negative effect of the sensitising on the ultra-high cycle fatigue properties of the AISI 316Ti.

scholarly journals High Cycle Fatigue Properties of Mod.9Cr-1Mo Steel at Elevated Temperatures

2013 ◽  
Vol 62 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Isamu NONAKA ◽  
Junpei NEMOTO ◽  
Yuji ICHIKAWA ◽  
Hideo MIURA
Keyword(s):  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Properties ◽  
Cycle Fatigue

scholarly journals 226 High Cycle Fatigue Properties of Modified 9Cr-1Mo steel at Elevated Temperatures

2012 ◽  
Vol 2012.47 (0) ◽  
pp. 258-259
Author(s):  
Jumpei Nemoto ◽  
Yuji Ichikawa ◽  
Isamu Nonaka ◽  
Hideo Miura
Keyword(s):  
High Cycle Fatigue ◽  
Elevated Temperatures ◽  
Fatigue Properties ◽  
Cycle Fatigue

scholarly journals Usability of Ultrasonic Frequency Testing for Rapid Generation of High and Very High Cycle Fatigue Data

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2245
Author(s):  
Michael Fitzka ◽  
Bernd M. Schönbauer ◽  
Robert K. Rhein ◽  
Niloofar Sanaei ◽  
Shahab Zekriardehani ◽  
...  
Keyword(s):  
Strain Rate ◽  
High Cycle Fatigue ◽  
Fatigue Properties ◽  
Ultrasonic Frequency ◽  
Cycle Fatigue ◽  
Reinforced Polymer ◽  
Very High Cycle Fatigue ◽  
Ultrasonic Fatigue ◽  
Fibre Reinforced Polymer ◽  
Very High

Ultrasonic fatigue testing is an increasingly used method to study the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) properties of materials. Specimens are cycled at an ultrasonic frequency, which leads to a drastic reduction of testing times. This work focused on summarising the current understanding, based on literature data and original work, whether and how fatigue properties measured with ultrasonic and conventional equipment are comparable. Aluminium alloys are not strain-rate sensitive. A weaker influence of air humidity at ultrasonic frequencies may lead to prolonged lifetimes in some alloys, and tests in high humidity or distilled water can better approximate environmental conditions at low frequencies. High-strength steels are insensitive to the cycling frequency. Strain rate sensitivity of ferrite causes prolonged lifetimes in those steels that show crack initiation in the ferritic phase. Austenitic stainless steels are less prone to frequency effects. Fatigue properties of titanium alloys and nickel alloys are insensitive to testing frequency. Limited data for magnesium alloys and graphite suggest no frequency influence. Ultrasonic fatigue tests of a glass fibre-reinforced polymer delivered comparable lifetimes to servo-hydraulic tests, suggesting that high-frequency testing is, in principle, applicable to fibre-reinforced polymer composites. The use of equipment with closed-loop control of vibration amplitude and resonance frequency is strongly advised since this guarantees high accuracy and reproducibility of ultrasonic tests. Pulsed loading and appropriate cooling serve to avoid specimen heating.

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