Deformation processes in refractory metals. Progress report, December 1, 1977--November 30, 1978
The initial stages of strain aging due to oxygen in vanadium, where aging is due to Snoek ordering of the interstitial around the dislocation, was studied. The results include the observation that the magnitude of the yield point return, ..delta.. sigma, maximizes at an aging stress equal to 0.92 sigma/sub f/ where sigma/sub f/ is the prestrain flow stress at a strain-rate of 6.7 x 10/sup -/5 s/sup -1/. Above this aging stress, the value of ..delta.. sigma falls sharply. Below 0.92 sigma/sub f/ the yield point return drops more slowly falling to about one third of its value at 0.10 sigma/sub f/ which may be taken as a measure of its value for aging at zero stress. Another observation is that for aging at a stress giving the maximum yield point return, aging occurs while the specimen is undergoing strain at a finite rate. This strain-rate is only about two and a half orders of magnitude smaller than that at which the specimen was prestrained. This implies that the maximum yield point return occurs under a condition where the mobile dislocations existing during prestrain are still mobile. In other words, aging under stress occurs essentially under dynamic conditions and has to be closely related to dynamic strain-aging. (GHT)
- Research Organization:
- Florida Univ., Gainesville (USA). Engineering and Industrial Experiment Station
- OSTI ID:
- 6428020
- Report Number(s):
- ORO-3262-58
- Country of Publication:
- United States
- Language:
- English
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