[Relaxation des contraintes lors de traitements thermiques – une comparaison des techniques in-situ et ex-situ de diffraction des neutrons]
Nous présentons lʼétude par diffraction des neutrons de lʼeffet de traitements thermiques de vieillissement sur la relaxation des contraintes résiduelles dans des polycristaux de superalliages à base nickel trempés à lʼeau. Deux expériences distinctes ont été menées ; la première consiste en une étude ex-situ au cours de laquelle les échantillons ont subi différents niveaux de vieillissement avant les mesures. La deuxième est un traitement thermique in-situ, qui a nécessité de chauffer puys de maintenir lʼéchantillon en température pendant la mesure par diffraction des neutrons. La technique in-situ a été conduite deux fois en utilisant le même dispositif expérimental afin de déterminer sa répétabilité, qui sʼest avérée bonne, à lʼincertitude des mesures près. Un agrément satisfaisant entre les techniques ex- et in-situ est obtenu, particulièrement en ce qui concerne la manière avec laquelle les contraintes sont relaxées au cours du temps. Dans les deux études nous obtenons que la relaxation des contraintes est initialement rapide, environ 200 MPa en 15 à 30 min, puis on observe une relaxation linéaire plus lente pendant le reste du traitement. Ce comportement suggère que la relaxation des contraintes au cours du traitement de vieillissement a lieu par un mécanisme de fluage.
The effect of ageing heat treatment on the relaxation of residual stress in a water quenched polycrystalline nickel-base superalloy has been measured using neutron diffraction. Two separate experiments have been conducted; the first experiment was an ex situ study in which samples were individually processed with varying degrees of age time before measurement. The second experiment was an in situ heat treatment, which required heating and then holding the sample at ageing temperature while measuring strain using neutron diffraction. The in situ experiment was carried out twice using the same setup to assess the repeatability of the technique and found to be repeatable within experimental error. The agreement between in situ and ex situ experiments was found to be reasonable, particularly the manner in which the stresses relaxed with time. In both studies it was found that initial stress relaxation was rapid, approximately 200 MPa in 15–30 min, after this a slower linear relaxation remained for the rest of the ageing heat treatment. This behaviour suggests creep may be the means by which stress relaxation takes place in this material during ageing.
Mot clés : Traitement thermique de vieillissement, Diffraction des neutrons, Superalliage à base nickel
@article{CRPHYS_2012__13_3_307_0,
author = {James Rolph and Alex Evans and Ania Paradowska and Michael Hofmann and Mark Hardy and Michael Preuss},
title = {Stress relaxation through ageing heat treatment {\textendash} a comparison between in situ and ex situ neutron diffraction techniques},
journal = {Comptes Rendus. Physique},
pages = {307--315},
publisher = {Elsevier},
volume = {13},
number = {3},
year = {2012},
doi = {10.1016/j.crhy.2011.10.020},
language = {en},
}
TY - JOUR AU - James Rolph AU - Alex Evans AU - Ania Paradowska AU - Michael Hofmann AU - Mark Hardy AU - Michael Preuss TI - Stress relaxation through ageing heat treatment – a comparison between in situ and ex situ neutron diffraction techniques JO - Comptes Rendus. Physique PY - 2012 SP - 307 EP - 315 VL - 13 IS - 3 PB - Elsevier DO - 10.1016/j.crhy.2011.10.020 LA - en ID - CRPHYS_2012__13_3_307_0 ER -
%0 Journal Article %A James Rolph %A Alex Evans %A Ania Paradowska %A Michael Hofmann %A Mark Hardy %A Michael Preuss %T Stress relaxation through ageing heat treatment – a comparison between in situ and ex situ neutron diffraction techniques %J Comptes Rendus. Physique %D 2012 %P 307-315 %V 13 %N 3 %I Elsevier %R 10.1016/j.crhy.2011.10.020 %G en %F CRPHYS_2012__13_3_307_0
James Rolph; Alex Evans; Ania Paradowska; Michael Hofmann; Mark Hardy; Michael Preuss. Stress relaxation through ageing heat treatment – a comparison between in situ and ex situ neutron diffraction techniques. Comptes Rendus. Physique, Volume 13 (2012) no. 3, pp. 307-315. doi : 10.1016/j.crhy.2011.10.020. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2011.10.020/
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