The effects of constraint, loading rate and irradiation on the toughness-temperature behavior of a V-4Cr-4Ti alloy
- Univ. of California, Santa Barbara, CA (United States). Dept. of Mechanical and Environmental Engineering
The influence of loading rate and constraint on the effective fracture toughness as a function of temperature [K{sub e}(T)] of the fusion program heat of V-4Cr-4Ti was measured using subsized, three point bend specimens. The constitutive behavior was characterized as a function of temperature and strain rate using small tensile specimens. Data in the literature on this alloy was also analyzed to determine the effect of irradiation on K{sub e}(T) and the energy temperature (E-T) curves measured in subsized Charpy V-notch tests. It was found that V-4Cr-4Ti undergoes normal stress-controlled cleavage fracture below a temperature marking a sharp ductile-to-brittle transition. The transition temperature is increased by higher loading rates, irradiation hardening and triaxial constraint. Shifts in a reference transition temperature due to higher loading rates and irradiation can be reasonably predicted by a simple equivalent yield stress model. These results also suggest that size and geometry effects, which mediate constraint, can be modeled by combining local critical stressed area {sigma}{sup *}/A{sup *} fracture criteria with finite element method simulations of crack tip stress fields. The fundamental understanding reflected in these models will be needed to develop K{sub e}(T) curves for a range of loading rates, irradiation conditions, structural size scales and geometries relying (in large part) on small specimen tests. Indeed, it may be possible to develop a master K{sub e}(T) curve-shift method to account for these variables. Such reliable and flexible failure assessment methods are critical to the design and safe operation of defect tolerant vanadium structures.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-87ER52143
- OSTI ID:
- 679538
- Report Number(s):
- CONF-960643-; TRN: 99:009470
- Resource Relation:
- Conference: 18. symposium on effects of radiation on materials, Hyannis, MA (United States), 25-27 Jun 1996; Other Information: PBD: 1999; Related Information: Is Part Of Effects of radiation on materials: 18. international symposium; Nanstad, R.K. [ed.] [Oak Ridge National Lab., TN (United States)]; Hamilton, M.L.; Garner, F.A. [eds.] [Pacific Northwest National Lab., Richland, WA (United States)]; Kumar, A.S. [ed.] [Univ. of Missouri, Rolla, MO (United States)]; PB: 1261 p.; ASTM special technical publication 1325
- Country of Publication:
- United States
- Language:
- English
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