Improvement of Static Strength and Fatigue Crack Propagation Resistance in Ductile Cast Iron by Austempering from (.ALPHA.+.GAMMA.)Phase Region.

1991 ◽  
Vol 40 (453) ◽  
pp. 675-681
Author(s):  
Yoshihiro SUGIYAMA ◽  
Katsutoshi ASAMI ◽  
Shinobu MATSUOKA
Keyword(s):  
Fatigue Crack ◽  
Cast Iron ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Static Strength ◽  
Phase Region ◽  
Ductile Cast Iron ◽  
Gamma Phase ◽  
Propagation Resistance ◽  
Crack Propagation Resistance

Degenerated graphite nodules influence on fatigue crack paths in a ferritic ductile cast iron

2015 ◽  
Author(s):  
Francesco Iacoviello ◽  
Vittorio Di Cocco
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Path ◽  
Annealing Treatment ◽  
Ductile Cast Iron ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Crack Paths ◽  
Scanning Electron

Focusing on ferritic-pearlitic DCIs, these alloys are characterized by a microstructure that ranges from a fully ferritic to a completely pearlitic matrix, and they are widely used for many applications (e.g. wheels, gears, crankshafts in cars, exhaust manifolds, valves, flywheels, boxes bearings, hubs, shafts, valves, flanges, pipelines ...). Considering the graphite elements, their morphology can be considered as degenerated when its nodularity is too low and this can be due to different causes (e.g., a partially failed nodularization process or a wrong inoculant). In this work, a ferritic DCI with degenerated nodules was obtained by means of an annealing treatment and the fatigue crack propagation resistance was investigated by means of fatigue crack propagation tests performed according to ASTM E647, focusing on the influence of degenerated graphite nodules on the fatigue crack paths. This analysis was performed both analysing the crack path profile by means of a scanning electron microscope (SEM) and by means of a SEM fracture surfaces analysis.

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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