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Sui, Fangfei
Publications (2 of 2) Show all publications
Sui, F. & Sandström, R. (2019). Creep strength contribution due to precipitation hardening in copper-cobalt alloys. Journal of Materials Science, 54(2), 1819-1830
Open this publication in new window or tab >>Creep strength contribution due to precipitation hardening in copper-cobalt alloys
2019 (English)In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 2, p. 1819-1830Article in journal (Refereed) Published
Abstract [en]

In spite of its huge technical significance, there does not seem to be consensus about how to model the precipitation contribution to the creep strength. Most contributions in the literature are based on a constant internal stress (also called back stress or threshold stress) from the precipitation. It is well-known and it will also be demonstrated in the paper that this assumption is at variance with observations except for some ODS alloys. There is, however, one model developed by Eliasson et al. (Key Eng Mater 171-174:277-284, 2000) that seems to be able to represent experimental data without the use of any adjustable parameters. It has successfully been applied to describe the creep strength of austenitic stainless steels. Due to the fact that various mechanisms contribute to the creep strength in these steels, the model has not been fully verified. The purpose of this paper is to apply the model to published creep data for Cu-Co alloys, where the precipitation totally dominates the strength contribution to validate the model. In the paper, it is demonstrated that the model can indeed describe the influence of applied stress, alloy composition and heat treatment for the three analysed Cu-Co alloys.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Metallurgy and Metallic Materials
urn:nbn:se:kth:diva-239460 (URN)10.1007/s10853-018-2922-z (DOI)000448833200064 ()2-s2.0-85053782001 (Scopus ID)

QC 20181128

Available from: 2018-11-28 Created: 2018-11-28 Last updated: 2020-03-09Bibliographically approved
Sui, F., Sandström, R. & Wu, R. (2018). Creep tests on notched specimens of copper. Journal of Nuclear Materials, 509, 62-72
Open this publication in new window or tab >>Creep tests on notched specimens of copper
2018 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 509, p. 62-72Article in journal (Refereed) Published
Abstract [en]

In Sweden, spent nuclear fuel is planned to be disposed off by placing it in canisters which are made of oxygen free copper alloyed with 50 ppm phosphorus. The canisters are expected to stay intact for thousands of years. During the long term disposal, the canisters will be exposed to mechanical pressure from the surroundings at temperatures up to 100 degrees C and this will result in creep. To investigate the role of the complex stress conditions on the canisters, creep tests under multiaxial stress state are needed. In the present work, creep tests under multiaxial stress state with three different notch profiles (acuity 0.5, 2, and 5, respectively) at 75 degrees C with net section stresses ranging from 170 MPa to 245 MPa have been performed. To interpret the experimental results, finite element computations have been conducted. With the help of the reference stress, the rupture lifetime in the multiaxial tests was estimated. The prediction was more precise for the higher acuities than for the lower one. In order to predict the creep deformation of the canisters for the long service period, fundamental creep models are considered. Previously developed basic models are used to compute the creep deformation in the multiaxial tests. Although the scatter is large, the agreement with the experiments is considered as acceptable, indicating that the basic models which have been successfully developed for uniaxial creep tests can also be used to describe multiaxial creep tests. Notch strengthening was observed for copper.

Place, publisher, year, edition, pages
Elsevier, 2018
Multiaxial stress state, Creep, Notched specimen, Finite element modelling, Copper
National Category
Applied Mechanics
urn:nbn:se:kth:diva-234562 (URN)10.1016/j.jnucmat.2018.06.018 (DOI)000442483300007 ()2-s2.0-85048759534 (Scopus ID)
Swedish Nuclear Fuel and Waste Management Company, SKB

QC 20180919

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-19Bibliographically approved

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