Tamin, Mohd Nasir and Hamzah, Esah and Ong, Wei Rex Effects of chromium content on fatigue crack growth behavior of Ti-48Al-xCR alloys. In: 2nd Regional Conference on Vehicle Engineering & Technology, 15 - 16 July 2008, Hotel Istana, Kuala Lumpur.
stiffness and strength. However, limited room-temperature ductility of these alloys calls for investigation on fatigue crack growth resistance. In this respect, a series of fatigue crack growth tests are conducted on precracked M(T) specimens at constant load ratio of minimum to maximum stress, R = 0.1. All tests are performed at room temperature for baseline fatigue crack growth behavior. Effects of different chromium content on fatigue crack growth rates, da/dN and threshold stress intensity factor ranges, Î”Kth for Ti-48Al-xCr alloys (x = 0, 2, 4 and 8 at.%) are examined. Results show that fatigue crack growth behavior of these alloys displays a threshold growth stage followed by a power-law growth behavior until final fracture of the sample. The threshold Î”Kth ranges from 11 MPaâˆšm for Ti-48Al to the lowest magnitude of 4.5 MPaâˆšm for Ti-48Al-8Cr alloy. In the Parislaw crack growth region, da/dN ranges between 10-4 to 10-2 mm/cycle while the crack-tip driving force, Î”K varies from 11 to 35 MPaâˆšm, respectively. The magnitude of Î”K at final fracture for Ti-48Al-xCr (x = 0, 2, 4 at.%) is about 34 MPaâˆšm which approximate the fracture toughness of the alloys. Fracture toughness of Ti-48Al-8Cr alloy is much lower at 18 MPaâˆšm. Threshold Î”Kth is linearly correlated with microstructure features of lamellar grain size and lath spacing. Dominant fatigue fracture mechanisms observed are crack deflection, stepped crack growth and formation of shear ligaments. These mechanisms are responsible for the observed torturous crack path and collectively improved crack growth resistance of Ti-48Al-xCr alloys.
|Item Type:||Conference or Workshop Item (Paper)|
|Uncontrolled Keywords:||titanium aluminides, fatigue crack growth rates, threshold stress intensity factor range, fatigue fracture mechanisms|
|Subjects:||T Technology > TJ Mechanical engineering and machinery|
|Deposited By:||Shamsuri Ehsan|
|Deposited On:||07 Jan 2009 01:44|
|Last Modified:||01 Jun 2010 15:51|
Repository Staff Only: item control page