A comparison of load relaxation, tensile, and creep data of AlMg alloys in the range of alloy-class creep behavior

Stone, Donald S.; Wilson, H.; Kuo, R.C.; Li, Che‐Yu

doi:10.1016/0036-9748(87)90300-0

Cited by 9 publications

(4 citation statements)

References 6 publications

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“…The only material carefully studied that produces a load‐relaxation response similar to that seen in our experiments on olivine—and only in part—is Al‐5.1 at. % Mg, a face‐centered cubic solid‐solution alloy [ Kuo , ; Stone et al , ]. In creep and load‐relaxation experiments performed at 300 and 360°C (0.66 and 0.73 of the solidus temperature), the log

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versus log σ load‐relaxation response overlaid that for steady state creep but only for the window of shear stresses of 1–2 × 10 –3 G , the highest shear stress applied to a specimen prior to relaxation, to 5 × 10 −4 G ; the relaxation curves at stresses below 5 × 10 −4 G diverged, one from another, in a consistent manner, i.e., one matching the physics shown schematically in Figure .…”

Section: Discussionmentioning

confidence: 99%

Load relaxation of olivine single crystals

2016

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Single crystals of ferromagnesian olivine (San Carlos, AZ, peridot; ~Fo88‐90) have been deformed in both uniaxial creep and load relaxation under conditions of ambient pressure, T = 1500°C and pnormalO2 = 10−10 atm; creep stresses were in the range 40 ≤ σ1 (MPa) ≤ 220. The crystals were oriented such that the applied stress was parallel to [011]c, which promotes single slip on the slowest slip system in olivine, (010)[001]. The creep rates at steady state match well the results of earlier investigators, as does the stress sensitivity (a power law exponent of n = 3.6). Dislocation microstructures, including spatial distribution of low‐angle (subgrain) boundaries, additionally confirm previous investigations. Inverted primary creep (an accelerating strain rate with an increase in stress) was observed. Load relaxation, however, produced a singular response—a single hardness curve—regardless of the magnitude of creep stress or total accumulated strain preceding relaxation. The log stress versus log strain rate data from load‐relaxation and creep experiments overlap to within experimental error. The load‐relaxation behavior is distinctly different than that described for other crystalline solids, where the flow stress is affected strongly by work hardening such that a family of distinct hardness curves is generated, which are related by a scaling function. The response of olivine for the conditions studied, we argue, indicates flow that is rate limited by dislocation glide, reflecting specifically a high intrinsic lattice resistance (Peierls stress).

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Section: Discussionmentioning

confidence: 99%

Load relaxation of olivine single crystals

2016

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“…It was found that shear strain rate, obtained from C-L creep and C-S creep (SRT) tests conducted on copper [6], showed linearity with the normalized stress. The stress-strain rate relationship obtained from SRT test on Al-Mg alloys was consistent with that of C-L creep, found by Li et al [7]. Based on SRT data, the pseudotensile and creep strain-time curves were constructed by Woodford et al [8].…”

Section: Introductionmentioning

confidence: 90%

“…Thus, according to the two kinds of tests, results from one can be used to calculate behavior in the other. However, the researches [6][7][8][9] above are mostly performed aimed at high-temperature property or life-evaluation at service temperature, while few were on hot sizing of titanium alloy.…”

Section: Introductionmentioning

confidence: 99%

Relationship between constant-load creep, decreasing-load creep and stress relaxation of titanium alloy

Liu

Zong

Shan

et al. 2015

Materials Science and Engineering: A

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“…Dans une seconde partie, nous proposons d'étudier le comportement en relaxation par indentation car il aété montré qu'il pouvaitêtre utilisé pour classer les matériaux selon leur sensibilité au fluage [16][17][18].À partir des travaux de Hart [19,20], nous déterminons le coefficient d'homothétie déduit de la droite de translation permettant de construire une courbe maîtresse unique. L'intérêt de ce coefficient est qu'il est lié au coefficient de sensibilitéà la contrainte obtenu par fluage, le premierétant l'inverse de l'autre.…”

Section: Introductionunclassified

Fluage et relaxation par indentation d’aciers au chrome

Kamta

Chicot

Roudet

et al. 2017

Matériaux & Techniques

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Reçu le 7 décembre 2016, accepté le 24 mars 2017Résumé -L'étude du comportement en fluage et en relaxation de matériaux soumisà des conditions sévères en termes de température, de contrainte et de déformation est nécessaire mais parfois coûteuse avec les essais classiques. En effet, ces essais, particulièrement celui du fluage, sont très consommateurs de temps, ils peuvent durer plus d'une année. Pour ramener cette durée d'essaisà quelques minutes, nous proposons d'utiliser l'indentation instrumentée qui, avec l'évolution des conditions d'application de la charge et du déplacement de l'indenteur, permet de solliciter le matériau dans des conditions de chargement proches de celles imposées dans les essais classiques. Dans cetteétude, nous proposons d'étudier le comportement de deux aciers au chrome utilisés pour la fabrication d'appareils sous pression. Il s'agit des aciersà 9 % de chrome (T91) età 2,5 % de chrome (T22), l'objectifétant de classer les matériaux selon leur sensibilité au fluage età la relaxation. Dans ce travail, nous nous limitonsà l'indentationà température ambiante pouŕ etudier l'applicabilité de la technique d'indentation. En fluage, nous déterminons le coefficient de sensibilité a la contrainte et en relaxation le coefficient d'homothétie défini dans la théorie de Hart. L'intérêt de ces deux coefficients est qu'ils sont liés, l'un est l'inverse de l'autre, ce qui permet de comparer les deux modes de sollicitation. Mots clés : Fluage / relaxation / indentation / modélisation / aciers T91 et T22Abstract -Creep and relaxation by indentation of chromium-based steels. Study of creep and relaxation behaviours of materials submitted to severe conditions in terms of temperature, stress and strain is necessary but sometimes very expensive with classical tests. Indeed, these tests, mainly the creep one, are very time-consuming since it can last more than one year. In order to drastically reduce this duration, we suggest the use of the instrumented indentation test which allows testing the material with loading conditions comparable to that of the classical tests. This is now possible thanks to the development of the instrumented indentation. In this work, we propose to study the mechanical behaviour of two based chromium steels, 9 wt.% Cr (T91) and 2.5 wt.% Cr (T22), the objective being to classify the materials according to their creep and relaxation sensibilities. We limit our work to indentation experiments at room temperature in order to study the applicability of the indentation technique. With creep indentation, we determined the stress exponent and with relaxation by indentation the homothetic coefficient defined in the Hart's theory. The main advantage to study these two coefficients is that there are linked by a simple relation, one being the reciprocal of the other, thus allowing to easily compare these two solicitation modes.

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A comparison of load relaxation, tensile, and creep data of AlMg alloys in the range of alloy-class creep behavior

Cited by 9 publications

References 6 publications

Load relaxation of olivine single crystals

Load relaxation of olivine single crystals

Relationship between constant-load creep, decreasing-load creep and stress relaxation of titanium alloy

Fluage et relaxation par indentation d’aciers au chrome

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