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Fatigue testing and microstructural characterization of tungsten heavy alloy Densimet 185

Pasalic, M.; Rustempasic, F.; Iyengar, Srinivasan LU ; Melin, Solveig LU and Noah, Etam LU (2014) In International Journal of Refractory Metals and Hard Materials 42. p.163-168
Abstract
A rotating target consisting of helium-cooled tungsten has been chosen for the European Spallation Source (ESS) facility to be built in Lund. Thermo-mechanical cycling due to the incidence of the proton beam every 2 s on any given tungsten slab in the rotating wheel could lead to crack formation and failure over the lifetime of the target. This work reports tensile and fatigue data obtained at room temperature for the Densimet 185 alloy in the non-irradiated condition. Methods for extracting relevant parameters from fatigue curves with small sets of data are discussed. Fatigue results show a large spread of data for which the application of such methods is challenging. Stress controlled fatigue testing was carried out in this study with... (More)
A rotating target consisting of helium-cooled tungsten has been chosen for the European Spallation Source (ESS) facility to be built in Lund. Thermo-mechanical cycling due to the incidence of the proton beam every 2 s on any given tungsten slab in the rotating wheel could lead to crack formation and failure over the lifetime of the target. This work reports tensile and fatigue data obtained at room temperature for the Densimet 185 alloy in the non-irradiated condition. Methods for extracting relevant parameters from fatigue curves with small sets of data are discussed. Fatigue results show a large spread of data for which the application of such methods is challenging. Stress controlled fatigue testing was carried out in this study with mean stress approaching zero and amplitudes in the range 250 to 450 MPa, with 50 MPa increments. A frequency of 25Hz was employed and the fatigue tests lasted until failure was registered or until the upper limit of 2 x 10(6) cycles was reached. No failure due to fatigue occurred in specimens subjected to stress amplitudes below 300 MPa. Microstructural and fractographic studies on the fatigue samples using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) showed that the samples had low porosity, large and nearly spherical tungsten grains, and with a fairly uniform distribution of the ductile phase rich in nickel andiron. However, bonding between tungsten grains in some areas was found to be inadequate. Intergranular fracture was predominant in the specimens at room temperature. Data for the D185 alloy are compared to those for IT180 and D176 alloys obtained in a previous study and strategies for improving the fatigue strength are discussed. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Tungsten heavy alloy, Spallation target, Fatigue life, Microstructure
in
International Journal of Refractory Metals and Hard Materials
volume
42
pages
163 - 168
publisher
Elsevier
external identifiers
  • wos:000329553500024
  • scopus:84888868943
ISSN
0263-4368
DOI
10.1016/j.ijrmhm.2013.09.001
language
English
LU publication?
yes
id
8311d7bc-a7b9-4f3f-937c-c7876c5c761a (old id 4319637)
date added to LUP
2014-02-26 13:58:22
date last changed
2017-01-22 03:58:13
@article{8311d7bc-a7b9-4f3f-937c-c7876c5c761a,
  abstract     = {A rotating target consisting of helium-cooled tungsten has been chosen for the European Spallation Source (ESS) facility to be built in Lund. Thermo-mechanical cycling due to the incidence of the proton beam every 2 s on any given tungsten slab in the rotating wheel could lead to crack formation and failure over the lifetime of the target. This work reports tensile and fatigue data obtained at room temperature for the Densimet 185 alloy in the non-irradiated condition. Methods for extracting relevant parameters from fatigue curves with small sets of data are discussed. Fatigue results show a large spread of data for which the application of such methods is challenging. Stress controlled fatigue testing was carried out in this study with mean stress approaching zero and amplitudes in the range 250 to 450 MPa, with 50 MPa increments. A frequency of 25Hz was employed and the fatigue tests lasted until failure was registered or until the upper limit of 2 x 10(6) cycles was reached. No failure due to fatigue occurred in specimens subjected to stress amplitudes below 300 MPa. Microstructural and fractographic studies on the fatigue samples using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) showed that the samples had low porosity, large and nearly spherical tungsten grains, and with a fairly uniform distribution of the ductile phase rich in nickel andiron. However, bonding between tungsten grains in some areas was found to be inadequate. Intergranular fracture was predominant in the specimens at room temperature. Data for the D185 alloy are compared to those for IT180 and D176 alloys obtained in a previous study and strategies for improving the fatigue strength are discussed. (C) 2013 Elsevier Ltd. All rights reserved.},
  author       = {Pasalic, M. and Rustempasic, F. and Iyengar, Srinivasan and Melin, Solveig and Noah, Etam},
  issn         = {0263-4368},
  keyword      = {Tungsten heavy alloy,Spallation target,Fatigue life,Microstructure},
  language     = {eng},
  pages        = {163--168},
  publisher    = {Elsevier},
  series       = {International Journal of Refractory Metals and Hard Materials},
  title        = {Fatigue testing and microstructural characterization of tungsten heavy alloy Densimet 185},
  url          = {http://dx.doi.org/10.1016/j.ijrmhm.2013.09.001},
  volume       = {42},
  year         = {2014},
}