Effect of Duplex Aging on the Initiation and Propagation of Fatigue Cracks in the Solute-rich Metastable β Titanium Alloy Ti 38-644

2011 ◽  
Vol 42 (9) ◽  
pp. 2652-2667 ◽  
Author(s):  
P. Schmidt ◽  
A. El-Chaikh ◽  
H.-J. Christ
Keyword(s):  
Titanium Alloy ◽  
Fatigue Cracks ◽  
Initiation And Propagation ◽  
Duplex Aging

Influence of Heat Treatment on Fatigue Crack Growth in Ti-6Al-4V Alloy

2011 ◽  
Vol 465 ◽  
pp. 463-466 ◽  
Author(s):  
Dariusz Rozumek
Keyword(s):  
Heat Treatment ◽  
Titanium Alloy ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Experimental Work ◽  
Fatigue Cracks ◽  
Stress Concentrators ◽  
Initiation And Propagation

The paper contains the results of experimental work carried out in order to analyse the initiation and propagation of fatigue cracks in Ti-6Al-4V titanium alloy. The tests were performed on plane specimens with the stress concentrators in form of one-sided sharp notches. The tested specimens were made of the oxygenated Ti-6Al-4V subjected to various variants of heat treatment.

scholarly journals Initiation and Propagation Processes of Internal Fatigue Cracks in β Titanium Alloy Based on Fractographic Analysis

2020 ◽  
Vol 11 (1) ◽  
pp. 131
Author(s):  
Gaoge Xue ◽  
Takashi Nakamura ◽  
Nao Fujimura ◽  
Kosuke Takahashi ◽  
Hiroyuki Oguma
Keyword(s):  
Titanium Alloy ◽  
Crack Initiation ◽  
Fatigue Cracks ◽  
Initiation Site ◽  
Fatigue Tests ◽  
Fractographic Analysis ◽  
Crack Initiation Site ◽  
Material Constants ◽  
Paris Law ◽  
Initiation And Propagation

Uniaxial fatigue tests were conducted for a β titanium alloy Ti-22V-4Al up to a very high cycle fatigue (VHCF) regime. The initiation and propagation processes of the internal fatigue cracks were investigated using 3D fractographic analysis. Multiple facets were observed at the crack initiation site. Three facet initiation models were proposed based on the surface appearances and the 3D facet bonding patterns of the multiple facets, and the major facet was determined to be the true crack initiation site. Using the size of the major facet, a Tanaka–Akiniwa model, which can determine the material constants for the Paris law using only conventional fatigue tests, was applied to reveal the propagation process of the internal cracks. A reverse fatigue life prediction was also conducted to evaluate the accuracy of the material constants obtained using the Tanaka–Akiniwa model. When the facet initiation models were applied, the predictions showed less deviation and better agreement than when the facet initiation process was not considered. The findings of this study indicate that the formation of multiple facets in β titanium alloys is sequential rather than simultaneous.

Fatigue Testing of Large-Scale Models of Submarine Structural Details

1965 ◽  
Vol 2 (03) ◽  
pp. 299-307
Author(s):  
Frank W. Dunham
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Pressure Variation ◽  
Test Tank ◽  
Initiation And Propagation ◽  
Scale Models ◽  
Structural Details

The conversion of a 30-ft-dia test tank to a facility for subjecting large-scale models of submarine structural details to cyclic loading is described. By means of automatically controlled valves, models were subjected to a pressure variation simulating a submarine diving to its test depth and returning to the surface. The cyclic rate was slightly less than one per minute. The system was so designed that the test tank itself was not subjected to the pressure variations. Details of a series of models designed to simulate particular structural details of interest in recent submarine construction are described. Results of the tests to date are summarized, and several observations relative to the initiation and propagation of fatigue cracks in submarine structural details are presented.

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.

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