Investigation of Basic Creep Mechanisms.
Final rept. 1 Sep 74-1 Sep 75,
ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CALIF SCIENCE CENTER
Pagination or Media Count:
The effect of processing variables on the creep resistance of Ti-5Al-5Zr-0.5Si was studied at 1000F 811K. Variables studied included solution temperature, cooling rate from the solution temperature, time at solution temperature, and metal working processes of cold swaging and hot rolling. The effects of these variables on both creep resistance and alloy stability post-creep ductility were evaluated. Optimum parameters for creep resistance with attendant residual ductility proved to be a solution temperature of 2192F 1473K0.5 hr followed by an air cool. In addition, it was shown that the creep rate controlling mechanism goes through a transition at approximately 0.00005hr creep rate. This transition is marked by an increase in apparent activation energy at creep rates above 0.00005hr. The creep rate controlling mechanism at low creep rates or 0.00005hr is not however permanently altered by brief overload periods during which the creep rate is increased to levels up to 0.001hr. Conversely, overload conditions resulting in creep rates approximately or 0.003hr were shown to have a lasting effect on subsequent steady state creep rates.
- Metallurgy and Metallography