DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click
HERE to register or log in.
Accession Number:
ADA090199
Title:
An Investigation Into the Susceptibility of Tantalum and Vanadium to Slow Strain-Rate Embrittlement Due to Oxygen, Nitrogen and Carbon.
Descriptive Note:
Final rept. 1 Apr 79-30 Jun 80,
Corporate Author:
FLORIDA UNIV GAINESVILLE
Report Date:
1980-08-31
Pagination or Media Count:
35.0
Abstract:
The phenomena of slow strain-rate embrittlement was studied in three metal-interstitial systems, tantalum-oxygen, vanadium-oxygen and tantalum-nitrogen. The embrittlement of tantalum by oxygen was investigated on specimens containing four levels of oxygen -- 0.33, 0.50, 0.85 and1.30 atomic percent. All of the compositions showed embrittlement between 500-1000K in specimens deformed at epsilon 8.8 x 10 to the 4th power sec to the minus one power. Associated with the embrittling phenomenon, and occurring in the same temperature range where the ductility is dropping, and three dynamic strain-aging effects a a yield stress plateau from 300-600K, b serrated yielding from 453-600K and an increasing work hardening rate from 300-600K Scanning electron microscope studies show that failures were by microvoid coalescence at low temperatures changing to a predominantly intergranular mode in the embrittlement range. Study of the vanadium-oxygen system also showed an embrittlement region between 600-875K. This embrittlement was accompanied by a yield stress plateau between 400-600K, an increasing work hardening rate between 300-650K and serrated yielding from 525K to 650K. A high level of titanium impurity limited testing to low oxygen concentrations. Tests on the tantalum-nitrogen system concluded that nitrogen did not produce slow strain-rate embrittlement in this metal although it served as a potent room temperature strengthener. The interval in which embrittlement is expected in this metal is at a sufficiently high temperature that dynamic recovery and sofening take place. Author
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
