Effect of Surface Residual Stress and Inclusion Size on Very High Cycle Fatigue Properties of High Speed Tool Steel

In this work, the effect of a turning process on fatigue performance of a Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) titanium alloy is studied in the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) regimes. For this purpose, the surface characteristics including surface morphology, surface roughness and residual stress were investigated. Moreover, axial fatigue tests were conducted with an ultrasonic fatigue testing system working at a frequency of 20 kHz. The results show that the turning process deteriorated the fatigue properties in both HCF and VHCF regimes. The fatigue strength at 1 × 108 cycles of turned samples is approximately 6% lower than that of electropolished ones. Fracture surface observations indicate that turning marks play a crucial role in the fatigue damage process, especially in the crack initiation stage. It was observed that the crack of all the turned samples originated from turning marks. In addition, the compressive residual stress induced by the turning process played a more effective role in resisting crack propagation in the VHCF regime than in the HCF regime.

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804 Effect of Surface Treatment on Very High Cycle Fatigue Behavior in Developed High Speed Tool Steel

The Proceedings of Conference of Hokuriku-Shinetsu Branch ◽

10.1299/jsmehs.2010.47.275 ◽

2010 ◽

Vol 2010.47 (0) ◽

pp. 275-276

Author(s):

Takashi HIRANO ◽

Yuji SHIMATANI ◽

Kazuaki SHIOZAWA

Keyword(s):

Surface Treatment ◽

Tool Steel ◽

High Speed ◽

High Cycle Fatigue ◽

Fatigue Behavior ◽

Cycle Fatigue ◽

Very High Cycle Fatigue ◽

Very High ◽

Effect Of Surface

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

Materials ◽

10.3390/ma14092245 ◽

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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