Influence of Grain Size and Lamellar Spacing on the Fatigue Crack Propagation in γ-TiAl Alloy

2014 ◽  
Vol 941-944 ◽  
pp. 1513-1516
Author(s):  
Yan Rui Zuo ◽  
Zhi Yuan Rui ◽  
Rui Cheng Feng ◽  
Chang Feng Yan ◽  
Hai Yan Li
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Tial Alloy ◽  
Lamellar Spacing ◽  
Crack Growth Resistance ◽  
Experimental Results ◽  
Fatigue Crack Growth Resistance ◽  
Crack Propagation Resistance

Study of grain size and lamellar spacing on fatigue crack propagation resistance in TiAl alloy has been done. The effects have been analyzed specifically. Meanwhile, the influence has been verified with some fatigue crack propagation experimental results and Paris formula. The experimental results confirmed that the grain size and lamellar spacing have significant effect on fatigue crack growth resistance. According to the Paris formula, the specific values of the constants in the formula were calculated.

50-Fold Difference in Region-II Fatigue Crack Propagation Resistance of Titanium Alloys: A Grain-Size Effect

1979 ◽  
Vol 101 (1) ◽  
pp. 86-90 ◽  
Author(s):  
G. R. Yoder ◽  
L. A. Cooley ◽  
T. W. Crooker
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Load Ratio ◽  
Plastic Zone Size ◽  
Crack Propagation Resistance ◽  
Order Of Magnitude ◽  
Region Ii

Fatigue crack growth rates (da/dN) in ambient laboratory air have been determined for a wide variety of materials from four basic α + β titanium alloy systems. Each material was cyclically loaded with a haversine waveform and a load ratio, R = 0.10. The results indicate that, at a constant value of stress-intensity range (ΔK), the width of the da/dN data band exceeds an order of magnitude. For example, at ΔK = 21 MPa·m1/2, a 50-fold difference in fatigue crack propagation rates is observed. Analysis of the crack growth rate data at this point indicates a systematic dependence on grain size (l), viz. that da/dN decreases with increasing l. An interpretation of this effect is offered in terms of reversed (cyclic) plastic zone size considerations.

Influence of Microstructure and Stress Ratio on Fatigue Crack Propagation in TiAl Alloy

2014 ◽  
Vol 881-883 ◽  
pp. 1330-1333 ◽  
Author(s):  
Yan Rui Zuo ◽  
Zhi Yuan Rui ◽  
Rui Cheng Feng ◽  
De Chun Luo ◽  
Chang Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Ratio ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Stress Ratios ◽  
Fully Lamellar

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

Enlarged Zn, Mg Contents with a same Zn/Mg Ratio Improve Fatigue Crack Propagation Resistance of Al-Zn-Mg-Cu Alloys with T7651 State

2020 ◽  
Vol 1003 ◽  
pp. 3-10
Author(s):  
Kai Wen ◽  
Bai Qing Xiong ◽  
Hua Zhou ◽  
Xi Wu Li ◽  
Zheng An Wang ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Aging Treatment ◽  
Fracture Morphology ◽  
Precipitate Size ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Cu Alloys ◽  
The Difference

The fatigue crack propagation of Al-Zn-Mg-Cu alloys could be influenced by the content of main alloying element. In the present work, two Al-Zn-Mg-Cu alloys with a same Zn/Mg ratio were treated by two stage over-aging aging treatment and typical T7651 states were extracted via mechanical properties. Fatigue crack propagation of the two alloys were tested and the related precipitation characteristics and fracture morphology were observed. The results showed that the alloy with higher Zn, Mg contents possessed a better fatigue crack propagation resistance compared with the alloy with lower Zn, Mg contents. The corresponding fracture morphology also showed the difference of fatigue striation, which provided an additional support. The precipitation observation demonstrated that the both alloys possessed GPII zone, η' phase and η phase while the alloy with higher Zn, Mg contents had a larger average precipitate size and a larger proportion of large size precipitates compared with the alloy with lower Zn, Mg contents. Cut and bypass mechanisms of dislocation-precipitate interactions were used to explain the difference of fatigue crack propagation between the two alloys.

Comparison of the Fatigue Crack Propagation Resistance of α+β and β Titanium Alloys

2008 ◽  
Vol 378-379 ◽  
pp. 117-130
Author(s):  
Matteo Benedetti
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Titanium Alloys ◽  
Fatigue Crack Propagation ◽  
Propagation Resistance ◽  
Microstructural Parameters ◽  
Crack Propagation Resistance ◽  
Microcrack Propagation ◽  
Small Cracks ◽  
The Relationship

The present paper tries to summarize the relationship between microstructure, extrinsic mechanisms and fatigue crack propagation resistance of α+β and β titanium alloys. Emphasis is placed on microstructural parameters, which can be varied by processing, and their effects on the material inherent fracture properties, governing the resistance against microcrack propagation. Moreover, the resistance against macrocracks as well as small cracks in the presence of notch plasticity has been discussed on the basis of secondary extrinsic mechanics such as crack front geometry, crack bridging and crack closure.

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