PILOT PRODUCTION AND EVALUATION OF TANTALUM ALLOY SHEET
Abstract
Two 80-pound, 4-inch diameter double arc cast T-222 ingots were produced and converted to three wide sheets. Excellent primary (forging) and secondary (rolling) fabricability was displayed by the material, and an approximately 1/3 ingot-to-sheet conversion yield was obtained. The sheets displayed physical and mechanical properties comparable to those previously reported for T-222, as well as good product consistancy. Light microscopy, electron microscopy, and x-ray diffraction techniques were employed to study the morphology and structure of precipitated phases in T-222. Second phases present after aging T-222 were found to be dependent upon mechanical-thermal history. For example, aging as-rolled material at temperatures from 1600 to 2000F produced the FCC monocarbide phase, (Hf,Ta,W)C, while in contrast aging solution treated material in this temperature range produced the HCP dimetal carbide phase only, (Ta,W,Hf)2C. Preferential grain boundary nucleation or phase stabilization due to dissolved oxygen or nitrogen are thought to be probable explanations for the anomolous behavior. Analysis of metallographic and mechanical property data on T-222 indicate that the interstitial strengthening effect may result from immobilization of dislocations by strain induced precipitation and/or precipitation during cooling from the solution annealing temperature. Results of this study also indicate that the optimum metallurgical condition for T-222 alloy is that obtained by recrystallization and solution annealing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 30, 1965
- Accession Number
- AD0626622
Entities
People
- A. M. Filippi
- D. L. Harrod
- R. L. Ammon