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Title: Correlation of Yield Stress And Microhardness in 08cr16ni11mo3 Irradiated To High Dose In The Bn-350 Fast Reactor

Abstract

The relationship between values of the microhardness Н and the engineering yield stress, 02, in steel 08Cr16Ni11Mo3 (Russian analog of AISI 316) heavily irradiated in the BN-350 reactor has been experimentally derived. It agrees very well with the previously published correlation developed by Toloczko for unirradiated 316 in a variety of cold-work conditions. Even more importantly, when the correlation is derived in the KΔ format where the correlation involves changes in the two properties, we find excellent agreement with a universal KΔ correlation developed by Busby and coworkers. With this KΔ correlation, one can predict the value of yield stress in irradiated material based on measured values of microhardness. The technique is particularly suitable when the material of interest is in an inconvenient location or configuration, or when significant gradients in mechanical properties are anticipated over small dimensions. This approach makes it possible to reduce the labor input and risk when conducting such work. It appears that the derived correlation is equally applicable to both Russian and Western austenitic steel, and also in both irradiated and unirradiated conditions. Additionally, this report points out that microhardness measurements must take into account that high temperature sodium exposure alters the metal surface tomore » produce ferrite, and therefore the altered layers should be removed prior to testing.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
966321
Report Number(s):
PNNL-SA-46855
AT6020100; TRN: US0903940
DOE Contract Number:
AC05-76RL01830
Resource Type:
Book
Resource Relation:
Related Information: Fusion Materails Semi-Annual Report for the period ending June 30, 2005, DOE/ER-313/38, 77-82
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; AUSTENITIC STEELS; BN-350 REACTOR; CONFIGURATION; DATA; DIMENSIONS; FAST REACTORS; FERRITE; MECHANICAL PROPERTIES; MICROHARDNESS; SODIUM; STEELS; TESTING

Citation Formats

Maksimkin, O P, Gusev, M N, Tivanova, O S, Silnaygina, N S, and Garner, Francis A. Correlation of Yield Stress And Microhardness in 08cr16ni11mo3 Irradiated To High Dose In The Bn-350 Fast Reactor. United States: N. p., 2006. Web.
Maksimkin, O P, Gusev, M N, Tivanova, O S, Silnaygina, N S, & Garner, Francis A. Correlation of Yield Stress And Microhardness in 08cr16ni11mo3 Irradiated To High Dose In The Bn-350 Fast Reactor. United States.
Maksimkin, O P, Gusev, M N, Tivanova, O S, Silnaygina, N S, and Garner, Francis A. Fri . "Correlation of Yield Stress And Microhardness in 08cr16ni11mo3 Irradiated To High Dose In The Bn-350 Fast Reactor". United States. doi:.
@article{osti_966321,
title = {Correlation of Yield Stress And Microhardness in 08cr16ni11mo3 Irradiated To High Dose In The Bn-350 Fast Reactor},
author = {Maksimkin, O P and Gusev, M N and Tivanova, O S and Silnaygina, N S and Garner, Francis A},
abstractNote = {The relationship between values of the microhardness Н and the engineering yield stress, 02, in steel 08Cr16Ni11Mo3 (Russian analog of AISI 316) heavily irradiated in the BN-350 reactor has been experimentally derived. It agrees very well with the previously published correlation developed by Toloczko for unirradiated 316 in a variety of cold-work conditions. Even more importantly, when the correlation is derived in the KΔ format where the correlation involves changes in the two properties, we find excellent agreement with a universal KΔ correlation developed by Busby and coworkers. With this KΔ correlation, one can predict the value of yield stress in irradiated material based on measured values of microhardness. The technique is particularly suitable when the material of interest is in an inconvenient location or configuration, or when significant gradients in mechanical properties are anticipated over small dimensions. This approach makes it possible to reduce the labor input and risk when conducting such work. It appears that the derived correlation is equally applicable to both Russian and Western austenitic steel, and also in both irradiated and unirradiated conditions. Additionally, this report points out that microhardness measurements must take into account that high temperature sodium exposure alters the metal surface to produce ferrite, and therefore the altered layers should be removed prior to testing.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}

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  • The relationship between the microhardness and the engineering yield stress in 08Cr16Ni11Mo3 steel after irradiation in the BN-350 reactor has been experimentally derived and agrees with a previously published correlation developed by Toloczko for unirradiated 316 in a variety of cold-work conditions. Even more importantly, when the correlation is derived in the K? format where the correlation involves changes in the two properties, excellent agreement is found with a universal K? correlation developed by Busby and coworkers. Additionally, this report points out that microhardness measurements must take into account that sodium exposure at high temperature alters the metal surface tomore » produce ferrite, and therefore the altered layers should be removed prior to testing.« less
  • Russian ferritic martensitic (F(slash)M) steels EP(dash)450, EP(dash)852 and EP(dash)823 were irradiated in the BN(dash)350 fast reactor in the form of gas-pressurized creep tubes. The first steel is used in Russia for hexagonal wrappers in fast reactors. The other steels were developed for compatibility with Pb(dash)Bi coolants and serve to enhance our understanding of the general behavior of this class of steels. In an earlier paper we published data on irradiation creep of EP(dash)450 and EP(dash) 823 at temperatures between 390 and 520 degrees C, with dpa levels ranging from 20 to 60 dpa. In the current paper new data onmore » the irradiation creep and swelling of EP(dash)450 and EP(dash)852 at temperatures between 305 and 335 degrees C and doses ranging from 61 to 89 dpa are presented. Where comparisons are possible, it appears that these steels exhibit behavior that is very consistent with that of Western steels. Swelling is relatively low at high neutron exposure and confined to temperatures less then 420 degrees C, but may be camouflaged somewhat by precipitation related densification. These irradiation creep studies confirm that the creep compliance of F(slash)M steels is about one half that of austenitic steels.« less
  • Russian ferritic/martensitic steels EP-450 and EP-823 were irradiated to 20-60 dpa in the BN-350 fast reactor in the form of pressurized creep tubes and small rings used for mechanical property tests. Data derived from these steels serves to enhance our understanding of the general behavior of this class of steels. It appears that these steels exhibit behavior that is very consistent with that of Western steels. Swelling is relatively low at high neutron exposure and confined to temperatures less then 420 degrees C, but may be camouflaged somewhat by precipitation-related densification. The irradiation creep studies confirm that the creep compliancemore » of F/M steels is about one-half that of austenitic steels, and that the loss of strength at test temperatures above 500 degrees C is a problem generic to all F/M steels. This conclusion is supported by post-irradiation measurement of short-term mechanical properties. At temperatures below 500 degrees C both steels retain their high strength (yield stress 0.2=550-600 MPa), but at higher test temperatures a sharp decrease of strength properties occurs. However, the irradiated steels still retain high post-irradiation ductility at test temperatures in the range of 20-700 degrees C.« less
  • Pure iron and nickel were irradiated to very high exposures in two fast reactors, BOR-60 and BN-350. It appears that both nickel and iron exhibit a transient-dominated swelling behavior in the range of 2 to 15x10-7 dpa/sec, with the shortest transient at approximately 500 C in nickel, but at less than 350 C for iron. It also appears that the duration of the transient regime may be dependent on the dpa rate. When the two metals are irradiated at 345-355 C, it is possible to obtain essentially the same swelling level, but the evolution of mechanical properties is quite different.more » The differences reflect the fact that iron is subject to a low-temperature embrittlement arising from a shift in ductile-brittle transition temperature, while nickel is not. Nickel, however, exhibits high temperature embrittlement, thought to arise from the collection of helium gas at the grain boundaries. Iron generates much less helium during equivalent irradiation.« less
  • Ferritic/martensitic (F/M) steels are being considered for application in fusion reactors, intense neutron sources, and accelerator-driven systems. While EP-450 is traditionally used with sodium coolants in Russia, EP-823 and EI-852 steels with higher silicon levels have been developed for reactor facilities using lead-bismuth coolant. To determine the influence of silicon additions on short-term mechanical properties and microstructure, ring specimens cut from cladding tubes of these three steels were irradiated in sodium at 490°С in the BN-350 reactor to 50 dpa. Post-irradiation tensile testing and microstructural examination show that EI-852 steel (1.9 wt% Si) undergoes severe irradiation embrittlement. Microstructural investigation showedmore » that the formation of near-continuous phase precipitates on grain boundaries is the main cause of the embrittlement.« less