scholarly journals A Method for Predicting the Effects of Specimen Geometry and Loading Condition on Fatigue Strength

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 811 ◽  
Author(s):  
Chengqi Sun ◽  
Qingyuan Song
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
Weibull Distribution ◽  
Loading Condition ◽  
Control Volume ◽  
Great Influence ◽  
Local Stress ◽  
High Strength ◽  
Specimen Geometry ◽  
Rotating Bending Fatigue

Specimen geometry and loading condition usually have a great influence on the fatigue strength of metallic materials, which is an important issue in evaluating the reliability of component parts. In this paper, a rotating bending fatigue test is performed at first on an hourglass specimen and a notch specimen of a high strength titanium alloy. Experimental results indicate that, in terms of local stress, the notch specimen endures higher fatigue strength in comparison with the hourglass specimen due to its relatively smaller control volume. Then, a probabilistic control volume method is proposed for correlating the effects of specimen geometry and loading condition on the fatigue strength based on Weibull distribution and the concept of control volume. A simple formula is obtained for the fatigue strength in relation to control volumes, in which the parameter is the shape parameter of Weibull distribution of fatigue strength. The predicted results are in good agreement with the present experimental data for high strength titanium alloy and the data for the high strength steel and the full scale EA4T axle in the literature.

scholarly journals Effect of Ultrasonic Surface Impact on the Fatigue Properties of Ti3Zr2Sn3Mo25Nb

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2107
Author(s):  
Zhangjianing Cheng ◽  
Xiaojian Cao ◽  
Xiaoli Xu ◽  
Qiangru Shen ◽  
Tianchong Yu ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
Fatigue Cracks ◽  
Dislocation Motion ◽  
Fatigue Properties ◽  
Surface Residual Stress ◽  
Initiation Zone ◽  
Rotating Bending Fatigue ◽  
Average Size ◽  
Grain Surface

The effect of nano grain surface layer generated by ultrasonic impact on the fatigue behaviors of a titanium alloy Ti3Zr2Sn3Mo25Nb (TLM) was investigated. Three vibration strike-numbers of 24,000 times, 36,000 times and 48,000 times per unit are chosen to treat the surface of TLM specimens. Nanocrystals with an average size of 30 nm are generated. The dislocation motion plays an important role in the transformation of nanograins. Ultrasonic surface impact improves the mechanical properties of TLM, such as hardness, surface residual stress, tensile strength and fatigue strength. More vibration strike numbers will cause a higher enhancement. With a vibration strike number of 48,000 times per square millimeter the rotating-bending fatigue strength of TLM at 107 cycles is improved by 23.7%. All the fatigue cracks initiate from the surface of untreated specimens, while inner cracks appear after the fatigue life of 106 cycles with the ultrasonic surface impact. The crystal slip in the crack initiation zone is the main way of growth for microcracks. Crack cores are usually formed at the junction of crystals. The stress intensity factor of TLM titanium alloy is approximately 7.0 MPa·m1/2.

scholarly journals Effects of Loading Frequency and Specimen Geometry on High Cycle and Very High Cycle Fatigue Life of a High Strength Titanium Alloy

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1628 ◽  
Author(s):  
Yanqing Li ◽  
Qingyuan Song ◽  
Shichao Feng ◽  
Chengqi Sun
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Fatigue Test ◽  
High Cycle Fatigue ◽  
High Strength ◽  
Specimen Geometry ◽  
Ultrasonic Frequency ◽  
Loading Frequency ◽  
Very High Cycle Fatigue ◽  
Very High

Titanium alloys have been widely used in the structural parts of deep-sea equipment and aviation industries. In this paper, the effects of loading frequency and specimen geometry on the high cycle and very high cycle fatigue life of the high strength titanium alloy Ti-6Al-2Sn-2Zr-3Mo-X is investigated by conventional fatigue test and ultrasonic frequency fatigue test. The results indicate that ultrasonic frequency could enhance the fatigue life of the highstrength titanium alloy compared with that under conventional frequency, and the frequency effect is related to the stress amplitude. This phenomenon is explained by the heat generation in specimens and heat dissipation, in combination with the high strain rate leading to the higher yield strength in the ultrasonic fatigue test. Moreover, it is indicated that the effect of specimen geometry on the fatigue life of the highstrength titanium alloy could be evaluated from the view of control volume.

Study on Rotating Bending Fatigue Property of Ti65 Titanium Alloy

2016 ◽  
Vol 849 ◽  
pp. 347-352
Author(s):  
Xu Wang ◽  
Si Qing Li ◽  
Jing Nan Liu
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
Room Temperature ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Notched Specimens ◽  
Different Temperatures ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

The rotating bending fatigue properties of Ti65 titanium alloy blisk forging was studied in the present investigation. The smooth and notched specimens were prepared to test the fatigue properties at room temperature and 650°C. Meanwhile, the influences on rotating bending fatigue of temperature and type were analyzed. Furthermore, the fractural morphology was observed through scanning electron microscopy. The results showed that the medium fatigue strength of Ti65 titanium alloy decreased at 650°C compared with that at room temperature, and the fatigue strength of notched specimens indicated the same significant declination at different temperatures compared with smooth specimens. At room temperature the medium fatigue strength of smooth and notched are 473MPa and 173MPa, respectively, and the fatigue notch sensitive coefficient was 0.87. At 650°C the medium fatigue strength of smooth and notched specimens are 427MPa and 168MPa, where the fatigue notch sensitive coefficient was 0.78.

scholarly journals Fatigue Strength of Nitrided High-Strength Titanium Alloy.

2001 ◽  
Vol 67 (656) ◽  
pp. 719-725 ◽  
Author(s):  
Tatsuro MORITA ◽  
Syunsuke FUCHIKAWA ◽  
Jun KOMOTORI ◽  
Masao SHIMIZU ◽  
Kuninori MINAKAWA ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
High Strength

Fatigue Strength of Nitrided High-Strength Titanium Alloy

2000 ◽  
Vol 2000.3 (0) ◽  
pp. 41-42
Author(s):  
Tatsuro MORITA ◽  
Syunsuke FUCHIKAWA ◽  
Jun KOMOTORI ◽  
Masao SHIMIZU ◽  
Kuninori MINAKAWA ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Strength ◽  
High Strength

Influence of Thrice-Induction-Heating and Once-Quenching on Fatigue Strength of SAE52100 Steel

2014 ◽  
Vol 893 ◽  
pp. 415-418 ◽  
Author(s):  
Koshiro Mizobe ◽  
Hitonobu Koike ◽  
Katsuyuki Kida
Keyword(s):  
Fatigue Strength ◽  
Induction Heating ◽  
Heat Affected Zone ◽  
Cooling Water ◽  
High Strength ◽  
Bearing Steel ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Rotating Bending Fatigue ◽  
Quenching Method

Martensitic high-carbon high-strength SAE 52100 bearing steel is one of the main alloys used as the principal alloys for rolling contact applications. We developed a novel repeated quenching method by induction heating in order to enhance the materials strength. The steel bar passed through the heated coil several times and finally quenched by cooling water. The rotating bending fatigue tests was done in order to investigate the fatigue strength of the steel bars. The heat affected zone (HAZ) was not expanded by the heat treatment however it was found that the thrice-induction-heating and once-quenching improved the fatigue strength. These two features indicated that the size of heat affected zone does not dominate the strength of heated-samples.

Effect of Laser Assistance Machining on Residual Stress and Fatigue Strength for a Bearing Steel (100Cr6) and a Titanium Alloy (Ti 6Al 4V)

2006 ◽  
Vol 524-525 ◽  
pp. 569-574 ◽  
Author(s):  
Guenael Germain ◽  
Franck Morel ◽  
Jean Lu Lebrun ◽  
Anne Morel ◽  
Bertrand Huneau
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Surface Layer ◽  
Fatigue Strength ◽  
High Strength ◽  
Cutting Parameters ◽  
Bearing Steel ◽  
Slight Reduction ◽  
Residual Stress State ◽  
Titanium Alloy Ti6al4v

The use of Laser Assisted Machining (LAM) can improve different aspects of the machinability of high strength materials. A study was undertaken to determine the optimum cutting parameters and to quantify their influence on fatigue strength according to the type of microstructure created. Two different materials were studied: a bearing steel (100Cr6 / AISI 52100) and an aeronautical titanium alloy (Ti6Al4V). In the bearing steel a significant increase of the fatigue resistance was observed due to the transformation of the surface layer into martensite. For the titanium alloy, a slight reduction in the fatigue strength was found as in this case the microstructure and residual stress state of the surface layer was less beneficial. The surface roughness has also been measured and no significant variation has been observed for different laser powers in each material.

Phase separation in sol gel-derived ceramic films of silica-zirconia, alumina-zirconia, and titania-zirconia system

1994 ◽  
Vol 52 ◽  
pp. 646-647
Author(s):  
J. Tong ◽  
L. Eyring
Keyword(s):  
Fracture Toughness ◽  
Phase Separation ◽  
Sol Gel ◽  
Great Influence ◽  
High Strength ◽  
Chemical Durability ◽  
Separation Method ◽  
Toughening Mechanism ◽  
Ceramic Films ◽  
Zirconia Toughened Alumina

There is increasing interest in composites containing zirconia because of their high strength, fracture toughness, and its great influence on the chemical durability in glass. For the zirconia-silica system, monolithic glasses, fibers and coatings have been obtained. There is currently a great interest in designing zirconia-toughened alumina including exploration of the processing methods and the toughening mechanism.The possibility of forming nanocrystal composites by a phase separation method has been investigated in three systems: zirconia-alumina, zirconia-silica and zirconia-titania using HREM. The morphological observations initially suggest that the formation of nanocrystal composites by a phase separation method is possible in the zirconia-alumina and zirconia-silica systems, but impossible in the zirconia-titania system. The separation-produced grain size in silica-zirconia system is around 5 nm and is more uniform than that in the alumina-zirconia system in which the sizes of the small polyhedron grains are around 10 nm. In the titania-zirconia system, there is no obvious separation as was observed in die alumina-zirconia and silica-zirconia system.

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