Microstructural characteristics and mechanism of toughness improvement of laser and electron-beam welds of V-4Cr-4Ti following postwelding heat-treatment
- Argonne National Laboratory, IL (United States)
The authors are conducting a program to develop an optimal laser welding procedure for large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Microstructural characteristics were investigated by optical microscopy, X-ray diffraction, transmission electron microscopy, and chemical analysis to provide an understanding of the mechanism of the drastic improvement of impact toughness of laser and electron-beam (EB) welds of V-4Cr-4Ti following postwelding annealing at 1000{degrees}C. Transmission electron microscopy (TEM) revealed that annealed weld zones were characterized by extensive networks of fine V(C,O,N) precipitates, which appear to clean away O, C, and N from grain matrices. This process is accompanied by simultaneous annealing-out of the dense dislocations present in the weld fusion zone. It seems possible to produce high-quality welds under practical conditions by controlling and adjusting the cooling rate of the weld zone by some innovative method to maximize the precipitation of V(C,O,N).
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- OSTI ID:
- 415826
- Report Number(s):
- DOE/ER-0313/20; ON: DE97000700; TRN: 97:001880
- Resource Relation:
- Other Information: PBD: Oct 1996; Related Information: Is Part Of Fusion materials semiannual progress report for the period ending June 30, 1996; PB: 358 p.
- Country of Publication:
- United States
- Language:
- English
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