AN INVESTIGATION OF METHODS FOR DETERMINING THE CRACK-PROPAGATION RESISTANCE OF HIGH-STRENGTH ALLOYS

1961 ◽  
Author(s):  
J. D. MORRISON ◽  
J. R. KATTUS
Keyword(s):  
Crack Propagation ◽  
High Strength ◽  
Propagation Resistance ◽  
Crack Propagation Resistance

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.

scholarly journals Degradation in Fatigue Crack Propagation Resistance of a Gas Turbine Vane after Long Term Service

2011 ◽  
Vol 278 ◽  
pp. 375-380
Author(s):  
Masakazu Okazaki ◽  
Motoki Sakaguchi ◽  
Yosuke Sasaki ◽  
Koichi Namba
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Gas Turbine ◽  
Fatigue Crack Propagation ◽  
Trailing Edge ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Turbine Vane ◽  
Edge Part

Degree of long term degradation damage of a retired gas turbine vane made of a Ni-based superalloy which had been operating for about 20000 hrs in a land-based gas turbine, was experimentally evaluated, through an assessment on the change in fatigue crack propagation resistance. For the purpose, a new testing apparatus has been developed to measure the local area fatigue crack propagation resistance, by extracting the miniature size compact tension specimens from the vane, where the specimens were extracted from the leading and the trailing edge, respectively. It was shown, the propagation rate of the crack that grew at the trailing edge part was significantly higher that that at the leading edge part. It was also shown that the crack propagation rates in the miniature specimen were generally higher than those in the standard size specimen. In order to explore an possibility to recover the degradation damage, the effect of a simple reheat treatment on the fatigue crack propagation resistance was also investigated

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