Tensile Properties of Helium Injected and Neutron Irradiated Vanadium and Various Vanadium Alloys PDF Download

Author: J.A. Dijkstra
Publisher:
ISBN:
Category :
Languages : en
Pages : 16

View

Book Description

Author: J. A. Dijkstra
Publisher:
ISBN:
Category :
Languages : en
Pages : 16

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
Mechanical properties and microstructure of vanadium-20% titanium were examined following helium-injection and reactor irradiation. Helium was injected at ambient temperature to concentrations of 90 and 200 at. ppM; neutron irradiation was at 400, 575, 625, and 700°C to fluence of 3 x 1026 n/m2, E> 0.1 MeV. Cavities representing negligible volume swelling were observed in all helium-injected specimens. Degradation of mechanical properties, especially loss of ductility due to helium, occurred at temperatures of 625 and 700°C. The levels of helium produced in the fusion spectrum can be expected to alter the response of vanadium alloys from that observed in fast reactor irradiations.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
Specimens of V-15Cr-5Ti, VANSTAR-7, and V-3Ti-1Si were encapsulated in TZM tubes containing 7Li to prevent interstitial pickup and irradiated in FFTF (MOTA experiment) to a damage level of 40 dpa. The irradiation temperatures were 420, 520, and 600°C. For a better simulation of fusion reactor conditions, helium was preimplanted in some specimens using a modified version of the ''tritium trick.'' The V-15Cr-5Ti alloy was most susceptible to irradiation hardening and helium embrittlement, followed by VANSTAR-7 and V-3Ti-1Si. VANSTAR-7 exhibited a relatively high maximum void swelling of approx. 6% at 520°C while V-15Cr-5Ti and V-3Ti-1Si had values of less than 0.3% at all three temperatures. The V-3Ti-1Si clearly outperformed the other two vanadium alloys in resisting the effects of neutron irradiation.

Author: DN. Braski
Publisher:
ISBN:
Category : Helium embrittlement
Languages : en
Pages : 20

View

Book Description
Specimens of V-15Cr-5Ti, VANSTAR-7, and V-3Ti-1Si were encapsulated in molybdenum alloy tubes containing 7Li to prevent interstitial pickup and irradiated in the Fast Flux Test Facility (FFTF), using Materials Open Test Assembly (MOTA) experiments, to a damage level of 40 displacements per atom (dpa). The irradiation temperatures were 420, 520, and 600°C. For a better simulation of fusion reactor conditions, helium was preimplanted in some specimens using a modified version of the "tritium trick." The V-15Cr-5Ti alloy was most susceptible to irradiation hardening and helium embrittlement, followed by VANSTAR-7, and V-3Ti-1Si. VANSTAR-7 exhibited a relatively high maximum void swelling of ~6% at 520°C while V-15Cr-5Ti and V-3Ti-1Si had values of

Author: DN. Braski
Publisher:
ISBN:
Category : Fusion reactors
Languages : en
Pages : 18

View

Book Description
Tensile specimens of V-15Cr-5Ti, Vanstar-7, V-3Ti-lSi, and V-20TJ were irradiated at 420°C in FFTF-MOTA to a damage level of 82 dpa. Helium was preimplanted to levels up to 480 appm in selected specimens using a modified tritium trick. Irradiation hardeningwas the dominant effect influencing the post irradiation tensile properties, and it markedly increased the yield strength and reduced the total elongation. The V-15Cr-5Ti alloy was very sensitive to helium embrittlement, but Vanstar-7 and V-3Ti-lSi were only slightly affected. Without helium, negligible swelling was found in V-15Cr-5Ti and Vanstar-7, and only small values of swelling (

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13

View

Book Description
One property of vanadium-base alloys that is not well understood in terms of their potential use as fusion reactor structural materials is the effect of simultaneous generation of helium and neutron damage. In the present Dynamic Helium Charging Experiment (DHCE), helium was produced uniformly in the specimen at linear rates of (almost equal to) 0.4 to 4.2 appm helium/dpa by the decay of tritium during irradiation to 18--31 dpa at 425--600 C in Li-filled capsules in a sodium-cooled fast reactor. This paper presents results of postirradiation examination and tests of microstructure and mechanical properties of V-5Ti, V-3Ti-1Si, V-8Cr-6Ti, and V-4Cr-4Ti (the latter alloy has been identified as the most promising candidate vanadium alloy). Effects of helium on tensile strength and ductility were insignificant after irradiation and testing at> 420 C. However, postirradiation ductilities at 250 C were higher than those of the non-DHCE specimens (

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 21

View

Book Description
The current knowledge is reviewed on (1) the effects of neutron irradiation on tensile strength and ductility, ductile-brittle transition temperature, creep, fatigue, and swelling of vanadium-base alloys, (2) the compatibility of vanadium-base alloys with liquid lithium, water, and helium environments, and (3) the effects of hydrogen and helium on the physical and mechanical properties of vanadium alloys that are potential candidates for structural materials applications in fusion systems. Also, physical and mechanical properties issues are identified that have not been adequately investigated in order to qualify a vanadium-base alloy for the structural material in experimental fusion devices and/or in fusion reactors.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
From fifth symposium on engineering problems of fusion research; Princeton, New Jersey, USA (6 Nov 1973). Sheet tensile samples of V-15 wt% Cr-5 wt% Ti were implanted with ~25 atomic ppM of helium at the ANL Cyclotron and tested at temperatures from 650 to 900 deg C. When compared with the control samples, the helium-injected samples show an increasing loss of ductility with increasing temperatures above 700 deg C. The loss of ductility in the helium- injected samples is accompanied by transition from a ductile, transgranular fracture to a completely intergranular fracture. The control samples fracture transgranularly throughout the range of test temperature. The effect of helium on void swelling was studied in two grades of vanadium using heavy-ion bombardment. High-purity vanadium (145 ppM C + N + O) and commercial-purity vanadium (1220 ppm C + N + O) were bombarded with 3.25-MeV Ni ions at 650 and 750 deg C to a damage level of 60 displacements per atom after preinjection with helium. Quantitative microscopy of the irradiated samples showed that the overall swelling was unaffected at 650 deg C, but was significantly reduced at 750 deg C, if the helium content was increased from 10 to 100 atomic ppM. The reduction in swelling appears to be associated with the presence of a high concentration of small helium bubbles that act as the predominant sinks for the radiation-induced point defects. (auth).

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 34

View

Book Description
A series of experimental vanadium alloys have been designed with small MC-type carbides in their microstructures to trap helium produced during neutron irradiation, thereby reducing helium embrittlement. The tensile properties and fabricability of the alloys were strongly influenced by the amounts of MC-forming-elements, especially carbon. Alloys with 0.05 and 0.10 wt % carbon exhibited slightly lower yield strengths at 420 to 600°C than vanadium alloys such as V-5Cr-5Ti, Vanstar-7, V-3Ti-1Si, and V-15Cr-5Ti. However, this characteristic may actually be an asset from the standpoint of resistance to irradiation hardening. After implantation with 300 appm 3He, both the V-Ti-C and V-Ti-Zr-C alloys exhibited less ductility losses at 600°C than the other vanadium alloys tested under comparable conditions. Examination of the experimental alloy microstructures by AEM showed that the small MC-type carbides did, in fact, trap helium and that they were responsible for the increased resistance to helium embrittlement of these alloys. 16 refs., 12 figs., 2 tabs.