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Showing papers by "Mines ParisTech published in 1975"


Journal ArticleDOI
TL;DR: In this article, the authors proposed that stage I (stress-intensity dependent) growth kinetics were predominantly controlled by the elastic stress field while stage II (nearly stress-intensity independent) kinetics are controlled by plastic stress field.
Abstract: Analysis of hydrogen-stress field interactions have led to kinetic criteria for slow crack growth. Using both elastic and plastic stress fields under opening-mode loading, criteria for stage I, II, III growth are developed in terms of the pressure tensor gradient at the crack tip. It is proposed that stage I (stress-intensity dependent) growth kinetics are predominantly controlled by the elastic stress field while stage II (nearly stress-intensity independent) kinetics are controlled by the plastic stress field. Measurements of slow crack growth in cathodically-charged AISI 4340 steel verify the overall aspects of the correlation. Detailed measurement and analysis of the increase in crack-tip radius with increasing applied stress intensity have led to a proposed decrease in crack growth rate during stage II growth. Some experimental evidence corroborates this later hypothesis and is consistent with long range diffusional flow of hydrogen as the controlling mechanism for crack growth kinetics.

118 citations



Journal ArticleDOI
TL;DR: In this article, an etching technique is described which can be used for Inco 718 and it is suitable to measure the plastic zone sizes in INCO 718, which is currently being used in a study of the fatigue behavior of this alloy.
Abstract: An etching technique is described which can be used for Inco 718. This etching technique is suitable to measure the plastic zone sizes in INCO 718. It is currently being used in a study of the fatigue behavior of this alloy. Since this method is specific to the $gamma$'' $Yields$ $beta$ phase transformation it can also be used for INCO 706 which is also strengthened by $gamma$''. The same principle of post-deformation heat-treatment to delineate plastic zones could be used, for instance, in Fe--Ni--Cr--Ti alloys which exhibit a strain-accelerated $gamma$' $Yields$ eta (DO$sub 24$) transformation. (auth)

47 citations


Journal ArticleDOI
TL;DR: In this paper, the authors obtained experimental methods for determining critical loads of columns and square plates made of composite materials (boron or glass fibres in an epoxy or aluminium matrix).

33 citations





Book ChapterDOI
01 Jan 1975
TL;DR: In this article, the Shape Memory Effect (S.M.E), superelasticity (or pseudo-elasticity), transformation plasticity and internal friction of the martensitic transformation were investigated.
Abstract: We have studied the behavior of the iron-platinum alloys of the Fe3Pt type subjected to various mechanical conditions before, during and after the martensitic transformation. Previous papers (1) (2) and (3) have shown that the characteristics of this martensitic transformation depend strongly on the long range order state of the parent austenitic phase; the Ms temperature is lowered as the degree of order is raised. When the order parameter S is ≥ 0,60, the transformation is thermoelastic (2) (3), and when this parameter is < 0,60, the transformation exhibits an appreciable thermal hysterisis. We have shown that the value S = 0,60 defines a limiting order parameter from which the disordering of the stoechiometric Fe3Pt alloy becomes a two-phase process. We shall report in this paper the results obtained in our study of the Shape Memory Effect (S.M.E.), superelasticity (or pseudo-elasticity), transformation plasticity and the internal friction. Theses effects are all related to the martensitic transformation and they will be discussed in connection with the initial order state of the austenite.

10 citations


Journal ArticleDOI
TL;DR: In this paper, three allotropic versions of iron monogermanide have been studied using the Mossbauer effect and the nature of these magnetic transformations was further studied using X-ray diffraction spectra and dilatometer measurements.

6 citations


Journal ArticleDOI
TL;DR: In this article, the authors analyse ensuite the finalite des operations morphologiques, en distinguant leur aspect descriptif, traduit par le concept de “critere, de la recherche de lois, qui s’expriment par les “modeles”.
Abstract: La petrologie, comme toute science, devient quantitative par la formalisation, en termes logiques, des conditions de coherence intrinseques a toute operation du sujet. On reduit ici ces contraintes a quatre principes: l’invariance locale par translation, la compatibilite avec les homotheties, la connaissance locale, et la semi-continuite superieure. On analyse ensuite la finalite des operations morphologiques, en distinguant leur aspect descriptif, traduit par le concept de “critere”, de la recherche de lois, qui s’expriment par les “modeles”.

4 citations


Journal ArticleDOI
S.K. Marya1, G. Wyon1
TL;DR: In this article, the fragilisation intergranulaire de l'aluminium par le gallium liquide, comme la faible ductilite de l's aluminium ecroui par laminage sont bien connues.
Abstract: La fragilisation intergranulaire de l'aluminium par le gallium liquide, comme la faible ductilite de l'aluminium ecroui par laminage sont bien connues. Le laminage controle a la temperature ambiante permet d'obtenir avec un alliage Al-Ti a 0,26 % Ti, des cristallites equiaxes de 1 a 3 microns. Dans cet etat une impregnation par du gallium liquide provoque une fragilisation transitoire puisque la ductilite reparait par maintien a 50 °C. Pour des quantites de gallium de 6 a 18 % en poids, et apres 125 a 225 h a 50 °C, le materiau devient superplastique a l'ambiante, la valeur du coefficient de sensibilite m de la relation σ = K[MATH]m etant comprise entre 0,3 et 0,5 pour [MATH] = 0,02 par minute. La deformation est alors essentiellement intergranulaire et la superplasticite est attribuee a l'existence d'un film de solution solide intergranulaire riche en gallium, donc a bas point de fusion. La taille et la morphologie des cristallites, la quantite de gallium introduite et le temps de maintien avant deformation, sont des parametres qui conditionnent la ductilite finale.

Journal ArticleDOI
TL;DR: In this paper, the process of dezincification is studied and it is shown that the stresses imposed by the migration and elimination of zinc atoms lead to the introduction of many dislocations.


Journal ArticleDOI
TL;DR: In this article, the influence of the interface shape on the chemical diffusion process in the liquid is evaluated and the periodicity of the boundary conditions allows a Fourier analysis of the problem of the mass transfer in liquid.

Journal ArticleDOI
TL;DR: In this article, a troisieme fournit un modele du processus de degradation granulometrique des roches dans un broyeur, and le second elabore le critere le plus adapte a l’analyse in situ de sections polies de roches volcaniques, and aboutit au concept d'ouverture circulaire.
Abstract: Ces trois exemples illustrent la recherche de criteres et de modeles en petrologie quantitative. Le premier traite de l’interpretation theorique des cliches d’argile au microscope a balayage, et substitue a la notion de surface specifique celle de dimension fractionnaire, mieux adaptee. Le second elabore le critere le plus adapte a l’analyse in situ de sections polies de roches volcaniques, et aboutit au concept d’ouverture circulaire. Le troisieme fournit un modele du processus de degradation granulometrique des roches dans un broyeur.

Journal ArticleDOI
TL;DR: In this article, the results of the survey are connected with the cycle of work in the face, and statistical analysis of the measurements has been automated thus making it possible to supply an answer to the aims of the study only a few weeks after completion of a survey.

Journal ArticleDOI
TL;DR: In this article, a method to calculate the residual thermal stresses was proposed, based on exact measure of temperature profiles in the sample, which is more particularly able to calculate residual stresses.