EP0246986B1 - Process for manufacturing strips from partially recrystallized zircaloy 2 or zircaloy 4, and strips obtained in this way - Google Patents

Process for manufacturing strips from partially recrystallized zircaloy 2 or zircaloy 4, and strips obtained in this way Download PDF

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Publication number
EP0246986B1
EP0246986B1 EP87420129A EP87420129A EP0246986B1 EP 0246986 B1 EP0246986 B1 EP 0246986B1 EP 87420129 A EP87420129 A EP 87420129A EP 87420129 A EP87420129 A EP 87420129A EP 0246986 B1 EP0246986 B1 EP 0246986B1
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Prior art keywords
strip
last
intermediate annealing
heat treatment
zircaloy
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EP87420129A
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German (de)
French (fr)
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EP0246986A1 (en
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Gérard Bunel
Daniel Charquet
Max Dombre
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Compagnie Europeenne du Zirconium Cezus SA
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Compagnie Europeenne du Zirconium Cezus SA
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C22F1/186—High-melting or refractory metals or alloys based thereon of zirconium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C16/00—Alloys based on zirconium

Definitions

  • the present invention relates to a process for manufacturing a zirconium alloy strip for nuclear use "Zircaloy 2" (specification ASTM B52, grades R 60802 and R 60812) or "Zircaloy 4" (same specification, grades R 60804 and R 60814 ), resulting for this strip in a "restored” state corresponding to a compromise of mechanical strength and ductility.
  • “restored” state one indicates here a heat treated state without there being complete recrystallization as in an annealed state, in which the stresses due to hardening are partly at least relaxed.
  • the present invention also relates to the strip obtained.
  • Zircaloy 2 or 4 strip of thickness typically between 0.3 and 0.9 mm, having both: a good elastic limit at the operating temperature, and good ductility at room temperature (20 ° C) identified by the elongation distributed in the long direction and also in the transverse direction of the strip - so as to behave well vis-à-vis conformations of this manufacture of grids.
  • distributed elongation is the maximum elongation of a test piece during a tensile test, before the necking begins.
  • the characteristics thus sought for this strip are typically: E O , 2 at 315 ° C ⁇ 250 MPa A% distributed long direction sens 4 and if possible * 5 A% distributed direction across k 4 and if possible * 5.
  • the deformation rates (%) corresponding to each rolling or rolling sequence are calculated according to the formula: (1 - final thickness / initial thickness) x 100.
  • the intermediate deformation rates and the intermediate annealing conditions are chosen so that, after each of these intermediate anneals, a just recrystallized state is obtained, while avoiding a grain enlargement, which makes it possible to obtain an extremely equiaxed grain. end by annealing.
  • the rate of deformation and the conditions of final heat treatment are themselves chosen, and these are particularly important points, so that this treatment results in partial recrystallization of the strip.
  • Micrographically the strip then comprises very fine grains obtained by the last intermediate annealing and elongated by the last rolling, grains which often have a length of between 10 and 20 microns.
  • Electron microscope examinations show that in these elongated grains there are locally sub-grains a few microns in diameter which are fully recrystallized, while the surrounding matrix has remained hardened.
  • the fully recrystallized subgrains represent a volume of between 20 and 40% of the total.
  • the final heat treatment is preferably carried out at the runway between 600 and 625 ° C., the constant speed of the strip ensuring maintenance of 2 to 5 min at the processing temperature. And, more preferably, independently of, or in combination with the previous measurement, the strip is laminated between the last intermediate annealing and the final heat treatment with a deformation rate of 35 to 45%.
  • the deformations and the two preceding intermediate anneals also play a role in obtaining and improving the surprising compromise in the characteristics of the strip of the invention.
  • the adjustment of these re intermediate baking is then particularly desirable (obtaining states that are just recrystallized to 100%), and it is preferable to tighten the conditions of duration and temperature of these last two intermediate anneals: each then comprising for the strip a stay of 1 to 3 min between 680 and 720 ° C, whether this is the general case or the process already improved at the level of the final heat treatment or the final deformation rate.
  • An optimum consists in making the last two intermediate anneals as well as the final heat treatment at the constant speed parade, each of these two intermediate anneals is then preferably carried out between 680 and 720 ° C with a scrolling speed ensuring a maintenance of 1 3 min at processing temperature.
  • the final heat treatment is thus preferably carried out in the procession, under a protective atmosphere or possibly in air, and it is then followed either by a pickling, or by a slight brightening of the surface itself followed by a pickling.
  • the protective gas is preferably under slight overpressure in the heating chamber, and at the exit of this heating chamber, the strip enters an airlock or a cooling chamber where it is cooled below 300 ° C by blowing cold inert gas .
  • the subject of the invention is also the strip of the invention which, with its composition and its particular mechanical characteristics, is distinguished in particular from the strips previously known by a particularly fine grain, this grain being in cross section finer than the ASTM index. "11" with partial recrystallization affecting 20 to 40% of the volume.
  • Zircaloy 4 strip (nominal composition: Sn 1.5% - Fe 0.2% - Cr 0.1% - Zr the balance), originating from a flow X of oxygen content 1290 ppm and of carbon 90 ppm, laminated to thickness 0.44 mm.
  • the final deformation rate was 43% and the final heat treatment was done in static under vacuum as it was then usual at 460 ° C for 24 h, the intermediate anneals themselves being 3 to 4 h at 650/700 ° C.
  • the heat-treated samples have a recrystallized grain deformed in the long direction, corresponding on cross section to the ASTM index "10".
  • the parade heat treatments were carried out in an oven operating with a protective argon atmosphere.
  • the running speed of the strip was chosen so as to obtain the desired temperature residence time for each portion of the strip treated.
  • Each of the three intermediate anneals at the parade gives for the strip, according to examinations carried out with the electron microscope, a just state recrystallized with very fine grain.
  • the size of the fine grain recrystallized at the last intermediate annealing measured on cross section is from “11" to "11.5" ASTM.
  • the final recrystallization, assessed with the electron microscope, is very fine and affects 20 to 40% of the volume.
  • this strip is too stiff (E O , 2 strong cross) and difficult to conform (see also A% distributed across).
  • This strip is a little less stiff and a little easier to conform than that of the 2nd series of tests.
  • the method of the invention therefore allows precise quality adjustments, with particularly reproducible results in the case of parade treatments.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Metal Rolling (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Description

La présente invention concerne un procédé de fabrication d'un feuillard en alliage de zirconium pour usage nucléaire "Zircaloy 2" (spécification ASTM B52, grades R 60802 et R 60812) ou "Zircaloy 4" (même spécification, grades R 60804 et R 60814), aboutissant pour ce feuillard à un état "restauré" correspondant à un compromis de résistance mécanique et de ductilité. Par état "restauré", on désigne ici un état traité thermiquement sans qu'il y ait recristallisation complète comme dans un état recuit, dans lequel les contraintes dues à l'écrouissage sont en partie au moins relâchées. La présente invention concerne aussi le feuillard obtenu.The present invention relates to a process for manufacturing a zirconium alloy strip for nuclear use "Zircaloy 2" (specification ASTM B52, grades R 60802 and R 60812) or "Zircaloy 4" (same specification, grades R 60804 and R 60814 ), resulting for this strip in a "restored" state corresponding to a compromise of mechanical strength and ductility. By “restored” state, one indicates here a heat treated state without there being complete recrystallization as in an annealed state, in which the stresses due to hardening are partly at least relaxed. The present invention also relates to the strip obtained.

EXPOSE DU PROBLEMEEXPOSURE OF THE PROBLEM

Pour la fabrication de grilles d'espacement utilisées dans les éléments combustibles nucléaires, on souhaite disposer de feuillard en Zircaloy 2 ou 4, d'épaisseur typiquement comprise entre 0,3 et 0,9 mm, ayant à la fois : une bonne limite élastique à la température d'utilisation, et une bonne ductilité à la température ambiante (20°C) repérée par l'allongement réparti dans le sens long et aussi dans le sens travers du feuillard- de façon à bien se comporter vis-à-vis des conformations de cette fabrication de grilles. L"'allongement réparti" est l'allongement maximal d'une éprouvette lors d'un essai de traction, avant début de la striction.For the manufacture of spacing grids used in nuclear fuel elements, it is desired to have Zircaloy 2 or 4 strip, of thickness typically between 0.3 and 0.9 mm, having both: a good elastic limit at the operating temperature, and good ductility at room temperature (20 ° C) identified by the elongation distributed in the long direction and also in the transverse direction of the strip - so as to behave well vis-à-vis conformations of this manufacture of grids. "Distributed elongation" is the maximum elongation of a test piece during a tensile test, before the necking begins.

Les caractéristiques ainsi recherchées pour ce feuillard sont typiquement : EO,2 à 315°C ≧ 250 MPa A% réparti sens long ≧ 4 et si possible * 5 A% réparti sens travers k 4 et si possible * 5.The characteristics thus sought for this strip are typically: E O , 2 at 315 ° C ≧ 250 MPa A% distributed long direction sens 4 and if possible * 5 A% distributed direction across k 4 and if possible * 5.

De façon plus précise, on a cherché à obtenir un feuillard possédant ces caractéristiques en lui appliquant après laminage un traitement thermique final de courte durée, par exemple au défilé, et soit à l'air, soit sous atmosphère protectrice, suivi éventuellement d'un traitement de surface.More specifically, an attempt has been made to obtain a strip having these characteristics by applying to it after rolling a short heat treatment, for example on parade, and either in air or in a protective atmosphere, possibly followed by a surface treatment.

EXPOSE DE L'INVENTIONSTATEMENT OF THE INVENTION

L'invention concerne un feuillard en Zircaloy 2 ou Zircaloy 4, ayant typiquement : - une teneur en oxygène comprise entre 900 et 1600 ppm,

  • - et une teneur en carbone de préférence comprise entre 50 et 160 ppm.
The invention relates to a strip of Zircaloy 2 or Zircaloy 4, typically having: - an oxygen content of between 900 and 1600 ppm,
  • - And a carbon content preferably between 50 and 160 ppm.

Ce feuillard est dans un état "restauré" partiellement recuit et plus précisément partiellement recristallisé, répondant aux caractéristiques mécaniques indiquées dans 1"'exposé du problème". Le procédé de fabrication de ce feuillard comporte comme il est connu le corroyage à chaud d'un lingot en ébauche, puis le laminage à froid (température du métal laminé habituellement comprise entre 10 et 50°C) de cette ébauche en feuillard avec plusieurs recuits intermédiaires, puis un traitement thermique final du feuillard et éventuellement ensuite un traitement de surface. De façon particulière, le procédé de l'invention est caractérisé par l'ensemble des mesures suivantes :

  • a) pour chacun des deux derniers recuits intermédiaires, on effectue sur le feuillard un traitement de 0,5 min à 10 min entre 650 et 750°C;
  • b) on effectue sur le feuillard après le dernier laminage, un traitement thermique final de 1,5 à 7 min entre 590 et 630°C;
  • c) on lamine le feuillard avec les taux de déformation suivants entre recuits un traitement thermique consécutifs :
    • ci/avant l'avant-dernier recuit intermédiaire : 20 à 55 %
    • c2/entre les deux derniers recuits intermédiaires : 30 à 55%;
    • cS/entre le dernier recuit intermédiaire et le traitement thermique final : 30 à 55 %.
This strip is in a "restored" state partially annealed and more precisely partially recrystallized, responding to the mechanical characteristics indicated in 1 "'description of the problem". The manufacturing process for this strip comprises, as is known, the hot working of an ingot in the blank, then the cold rolling (temperature of the rolled metal usually between 10 and 50 ° C.) of this strip blank with several anneals intermediates, then a final heat treatment of the strip and possibly then a surface treatment. In particular, the method of the invention is characterized by all of the following measures:
  • a) for each of the last two intermediate anneals, a treatment is carried out on the strip of 0.5 min to 10 min between 650 and 750 ° C;
  • b) a final heat treatment is carried out on the strip after the last rolling for 1.5 to 7 minutes between 590 and 630 ° C;
  • c) the strip is laminated with the following deformation rates between annealed consecutive heat treatment:
    • here / before the penultimate intermediate annealing: 20 to 55%
    • c2 / between the last two intermediate anneals: 30 to 55%;
    • cS / between the last intermediate annealing and the final heat treatment: 30 to 55%.

Les taux de déformation (%) correspondant à chaque laminage ou séquence de laminage sont calculés selon la formule : (1 - épaisseur finale/épaisseur initiale) x 100.The deformation rates (%) corresponding to each rolling or rolling sequence are calculated according to the formula: (1 - final thickness / initial thickness) x 100.

Les taux de déformation intermédiaires et les conditions de recuits intermédiaires sont choisis de telle sorte que, après chacun de ces recuits intermédiaires, on obtienne un état juste recristallisé, tout en évitant un grossissement du grain, ce qui permet d'obtenir un grain équiaxe extrêmement fin par recuit. Le taux de déformation et les conditions de traitement thermique final sont eux-mêmes choisis, et ce sont là des points particulièrement importants, de façon que ce traitement entraîne une recristallisation partielle du feuillard. Micrographiquement le feuillard comporte alors des grains très fins obtenus par le dernier recuit intermédiaire et allongés par le dernier laminage, grains qui ont souvent une longueur comprise entre 10 et 20 microns. Les examens au microscope électronique montrent que dans ces grains allongés il y a localement des sous-grains de quelques microns de diamètre qui sont entièrement recristallisés, alors que la matrice environnante est restée écrouie. Les sous-grains entièrement recristallisés représentent un volume compris entre 20 et 40 % du total.The intermediate deformation rates and the intermediate annealing conditions are chosen so that, after each of these intermediate anneals, a just recrystallized state is obtained, while avoiding a grain enlargement, which makes it possible to obtain an extremely equiaxed grain. end by annealing. The rate of deformation and the conditions of final heat treatment are themselves chosen, and these are particularly important points, so that this treatment results in partial recrystallization of the strip. Micrographically the strip then comprises very fine grains obtained by the last intermediate annealing and elongated by the last rolling, grains which often have a length of between 10 and 20 microns. Electron microscope examinations show that in these elongated grains there are locally sub-grains a few microns in diameter which are fully recrystallized, while the surrounding matrix has remained hardened. The fully recrystallized subgrains represent a volume of between 20 and 40% of the total.

Les caractéristiques mécaniques recherchées sont obtenues en même temps que cette structure particulièrement fine, permettant d'avoir un très bel état de surface après conformation.The desired mechanical characteristics are obtained at the same time as this particularly fine structure, making it possible to have a very good surface condition after conformation.

De façon à obtenir avec une très bonne régularité la structure et les caractéristiques mécaniques recherchées, et à pouvoir les améliorer encore de façon fiable, on effectue de préférence le traitement thermique final au défilé entre 600 et 625°C, la vitesse constante du feuillard assurant un maintien de 2 à 5 min à la température de traitement. Et, de préférence encore, indépendamment de, ou en combinaison avec la mesure précédente, on lamine le feuillard entre le dernier recuit intermédiaire et le traitement thermique final avec un taux de déformation de 35 à 45%.In order to obtain the desired structure and mechanical characteristics with very good regularity, and to be able to further improve them reliably, the final heat treatment is preferably carried out at the runway between 600 and 625 ° C., the constant speed of the strip ensuring maintenance of 2 to 5 min at the processing temperature. And, more preferably, independently of, or in combination with the previous measurement, the strip is laminated between the last intermediate annealing and the final heat treatment with a deformation rate of 35 to 45%.

Comme on l'a vu plus haut, les déformations et les deux recuits intermédiaires précédents interviennent également dans l'obtention et dans l'amélioration du compromis surprenant de caractéristiques du feuillard de l'invention. L'ajustement de ces recuits intermédiaires est alors particulièrement souhaitable (obtention d'états juste recristallisés à 100 %), et on préfère resserrer les conditions de durée et de tempéra ture de ces deux derniers recuits intermédiaires : chacun comportant alors pour le feuillard un séjour de 1 à 3 min entre 680 et 720°C, qu'il s'agisse du cas général ou du procédé déjà amélioré au niveau du traitement thermique final ou du taux de déformation final. Un optimum consiste à faire les deux derniers recuits intermédiaires aussi bien que le traitement thermique final au défilé à vitesse constante, chacun de ces deux recuits intermédiaires étant alors de préférence effectué entre 680 et 720°C avec une vitesse de défilement assurant un maintien de 1 à 3 min à la température de traitement.As seen above, the deformations and the two preceding intermediate anneals also play a role in obtaining and improving the surprising compromise in the characteristics of the strip of the invention. The adjustment of these re intermediate baking is then particularly desirable (obtaining states that are just recrystallized to 100%), and it is preferable to tighten the conditions of duration and temperature of these last two intermediate anneals: each then comprising for the strip a stay of 1 to 3 min between 680 and 720 ° C, whether this is the general case or the process already improved at the level of the final heat treatment or the final deformation rate. An optimum consists in making the last two intermediate anneals as well as the final heat treatment at the constant speed parade, each of these two intermediate anneals is then preferably carried out between 680 and 720 ° C with a scrolling speed ensuring a maintenance of 1 3 min at processing temperature.

Le traitement thermique final est ainsi de préférence effectué au défilé, sous atmosphère protectrice ou éventuellement à l'air, et il est alors suivi soit d'un décapage, soit d'un léger avivage de surface lui-même suivi d'un décapage.The final heat treatment is thus preferably carried out in the procession, under a protective atmosphere or possibly in air, and it is then followed either by a pickling, or by a slight brightening of the surface itself followed by a pickling.

Lorsque le traitement thermique est fait au défilé, ou dans un four à passage, sous atmosphère protectrice à base d'argon ou d'hélium ou encore d'azote ou d'un mélange argon + hélium ou argon + azote, le gaz protecteur est de préférence en légère surpression dans la chambre de chauffe, et à la sortie de cette chambre de chauffe, le feuillard pénètre dans un sas ou dans une chambre de refroidissement où il est refroidi en-dessous de 300°C par soufflage de gaz inerte froid.When the heat treatment is carried out in a procession, or in a passing oven, under a protective atmosphere based on argon or helium or alternatively nitrogen or an argon + helium or argon + nitrogen mixture, the protective gas is preferably under slight overpressure in the heating chamber, and at the exit of this heating chamber, the strip enters an airlock or a cooling chamber where it is cooled below 300 ° C by blowing cold inert gas .

L'invention a aussi pour objet le feuillard de l'invention qui, avec sa composition et ses caractéristiques mécaniques particulières, se distingue notamment des feuillards précédemment connus par un grain particulièrement fin, ce grain étant en coupe travers plus fin que l'indice ASTM "11" avec un recristallisation partielle affectant 20 à 40 % du volume.The subject of the invention is also the strip of the invention which, with its composition and its particular mechanical characteristics, is distinguished in particular from the strips previously known by a particularly fine grain, this grain being in cross section finer than the ASTM index. "11" with partial recrystallization affecting 20 to 40% of the volume.

Les essais dont il est rendu compte ci-dessous permettront de mieux comprendre l'invention.The tests reported below will allow a better understanding of the invention.

ESSAIS EFFECTUESTESTS CARRIED OUT lère série d'essais (essais comparatifs)1st series of tests (comparative tests)

Elle concerne au feuillard en Zircaloy 4 (composition nominale : Sn 1,5% - Fe 0,2% - Cr 0,1% - Zr le solde), provenant d'une coulée X de teneur en oxygène 1290 ppm et de teneur en carbone 90 ppm, laminé à épaisseur 0,44 mm. Le taux de déformation final était de 43 % et le traitement thermique final a été fait en statique sous vide comme il était alors habituel à 460°C pendant 24 h, les recuits intermédiaires étant eux-mêmes de 3 à 4 h à 650/700°C.It relates to the Zircaloy 4 strip (nominal composition: Sn 1.5% - Fe 0.2% - Cr 0.1% - Zr the balance), originating from a flow X of oxygen content 1290 ppm and of carbon 90 ppm, laminated to thickness 0.44 mm. The final deformation rate was 43% and the final heat treatment was done in static under vacuum as it was then usual at 460 ° C for 24 h, the intermediate anneals themselves being 3 to 4 h at 650/700 ° C.

Les caractéristiques mécaniques mesurés étaient les suivantes:

  • . à la température ambiante, dans le sens travers : charge de rupture R = 550 à 570 MPa
  • EO,2 = 510 à 530 MPa
  • A% = 17 à 21
  • A % réparti = 4 à 5.
  • . à la température ambiante dans le sens long : A % réparti = 5 à 7
  • . à 315°C, dans le sens long :
  • Eo,2= 300 à 320 MPa.
The mechanical characteristics measured were as follows:
  • . at room temperature, crosswise: breaking load R = 550 to 570 MPa
  • E O , 2 = 510 to 530 MPa
  • A% = 17 to 21
  • A% distributed = 4 to 5.
  • . at room temperature in the long direction: A% distributed = 5 to 7
  • . at 315 ° C, in the long direction:
  • Eo, 2 = 300 to 320 MPa.

Les échantillons traités thermiquement présentent un grain recristallisé déformé dans le sens long, corespondant sur coupe travers à l'indice ASTM "10".The heat-treated samples have a recrystallized grain deformed in the long direction, corresponding on cross section to the ASTM index "10".

En microscopie électronique en transmission, ces échantillons montrent un degré de recristallisation très faible, compris entre 0,5 et 5 % du volume.In transmission electron microscopy, these samples show a very low degree of recrystallization, between 0.5 and 5% of the volume.

Ces conditions de fabrication ont l'inconvénient de comporter un traitement thermique final de longue durée et de donner pour. les caractéristiques souhaitées des résultats assez dispersés.These manufacturing conditions have the disadvantage of comprising a long-term final heat treatment and giving for. the desired characteristics of the results fairly dispersed.

2ème série d'essais fessais selon t'inventions2nd series of tests spank according to your inventions

Elle concerne un feuillard en Zircaloy 4 selon l'invention provenant d'une coulée Y de teneur en oxygène 1360 ppm et de teneur en carbone 120 ppm, laminé à épaisseur 0,43 mm, la gamme de transformation étant la suivante :

  • 1) Laminage à chaud jusqu'à épaisseur 6 mm.
  • 2) Recuit statique à plat : 3 à 4 h à 650/700°C.
  • 3) LAF (laminage à froid) à 3,5 mm.
  • 4) Recuit statique à plat : 3 à 4 h à 650/700°C.
  • 5) LAF à 2,5 mm, soudage en bobine, puis LAF à 1,85 mm (taux de déformation depuis 3,5 mm : 47 %).
  • 6) Recuit au défilé : 3 min à 700°C (1,5 m/mn)
  • 7) LAF à 1,45 mm (22 %).
  • 8) Recuit au défilé : 3 min à 700°C (1,5 m/mn).
  • 9) LAF à 0,75 mm (48 %).
  • 10) Recuit au défilé : 2 minutes et demie à 700°C (2 m/mn).
  • 11) LAF à 0,43 mm (43 %).
  • 12) Traitement thermique final au défilé sous argon, à 605°C, produisant un maintien de chaque portion du feuillard traité de 4 minutes à 605°C.
It relates to a Zircaloy 4 strip according to the invention originating from a casting Y of oxygen content 1360 ppm and carbon content 120 ppm, laminated to a thickness of 0.43 mm, the transformation range being as follows:
  • 1) Hot rolling up to 6 mm thickness.
  • 2) Static flat annealing: 3 to 4 hours at 650/700 ° C.
  • 3) LAF (cold rolling) at 3.5 mm.
  • 4) Static flat annealing: 3 to 4 hours at 650/700 ° C.
  • 5) 2.5 mm LAF, coil welding, then 1.85 mm LAF (deformation rate from 3.5 mm: 47%).
  • 6) Annealing on parade: 3 min at 700 ° C (1.5 m / min)
  • 7) LAF at 1.45 mm (22%).
  • 8) Annealing on parade: 3 min at 700 ° C (1.5 m / min).
  • 9) LAF at 0.75 mm (48%).
  • 10) Annealing on parade: 2 and a half minutes at 700 ° C (2 m / min).
  • 11) LAF at 0.43 mm (43%).
  • 12) Final heat treatment on parade under argon, at 605 ° C, producing a maintenance of each portion of the strip treated for 4 minutes at 605 ° C.

L'ajustement des taux de déformation successifs des étapes 7)- 9)- 11) résultait d'essais successifs, leurs niveaux ainsi que les conditions de traitement thermique suivant chacun des trois derniers laminages agissant en combinaison sur les caractéristiques mécaniques et la structure du feuillard obtenu.The adjustment of the successive deformation rates of steps 7) - 9) - 11) resulted from successive tests, their levels as well as the heat treatment conditions according to each of the last three rolling operations acting in combination on the mechanical characteristics and the structure of the strip obtained.

Les traitements thermiques au défilé étaient effectués dans un four fonctionnant avec une atmosphère protectrice d'argon. La vitesse de défilement du feuillard était choisie de façon à obtenir le temps de séjour à température souhaité pour chaque portion du feuillard traitée. Chacun des trois recuits intermédiaires au défilé donne pour le feuillard, d'après les examens effectués au microscope électronique, un état juste recristallisé à grain très fin.The parade heat treatments were carried out in an oven operating with a protective argon atmosphere. The running speed of the strip was chosen so as to obtain the desired temperature residence time for each portion of the strip treated. Each of the three intermediate anneals at the parade gives for the strip, according to examinations carried out with the electron microscope, a just state recrystallized with very fine grain.

Les caractéristiques mécaniques mesurées sur le feuillard étaient :

  • . à l'ambiante, dans le sens travers :
  • charge de rupture = 591 MPa
  • Eo,2= 552 MPa
  • A% réparti travers = 4,6 %
  • . à 315°C, dans le sens long :
  • EO,2= 298 MPa.
The mechanical characteristics measured on the strip were:
  • . ambient, crosswise:
  • breaking load = 591 MPa
  • Eo, 2 = 552 MPa
  • A% distributed across = 4.6%
  • . at 315 ° C, in the long direction:
  • E O , 2 = 298 MPa.

La grosseur du grain fin recristallisé au dernier recuit intermédiaire mesurée sur coupe travers, est de "11" à "11,5" ASTM. La recristallisation finale, appréciée au microscope électronique, est très fine et affecte 20 à 40 % du volume.The size of the fine grain recrystallized at the last intermediate annealing measured on cross section is from "11" to "11.5" ASTM. The final recrystallization, assessed with the electron microscope, is very fine and affects 20 to 40% of the volume.

On a en outre fait des examens de texture sur un échantillon de feuillard et obtenu des figures de pô- les 002, sur lesquels on a mesuré les facteurs de Kearn :

  • fN= 0,70
  • fT= 0,21
  • fL= 0,09.
We also carried out texture examinations on a strip sample and obtained pole figures 002, on which the Kearn factors were measured:
  • f N = 0.70
  • f T = 0.21
  • fL = 0.09.

La différence entre fr et fL montre que l'anisotropie reste relativement faible, ce qui est favorable pour le comportement en réacteur, les déformations des grilles y étant alors moins gênantes (moins de distorsions en service). Le feuillard obtenu réalise ainsi un bon compromis entre aptitude à l'emboutissage et isotropie de texture.The difference between fr and f L shows that the anisotropy remains relatively low, which is favorable for the behavior in the reactor, the deformations of the grids then being less troublesome (less distortions in service). The strip obtained thus achieves a good compromise between drawing ability and isotropy of texture.

3ème série d'essais (essais comparatifs)3rd series of tests (comparative tests)

Elle concerne un feuillard de la même coulée Y transformé de la même façon à l'exception du traitement thermique final (opération 12)) qui a été effectué dans les conditions de la 1 ère série d'essais : sous vide à 460°C pendant 24 h.It relates to a strip of the same casting Y transformed in the same way with the exception of the final heat treatment (operation 12)) which was carried out under the conditions of the 1st series of tests: under vacuum at 460 ° C. for 24h.

Les caractéristiques mécaniques mesurées étaient les suivantes :

  • . à la température ambiante, dans le sens travers :
    • charge de rupture R = 608 MPa
    • E0,2=572 MPa
    • A % réparti travers = 3,8 %
  • . à 315°C, dans le sens long :
  • E0,2 330 MPa.
The mechanical characteristics measured were as follows:
  • . at room temperature, crosswise:
    • breaking load R = 608 MPa
    • E 0.2 = 572 MPa
    • A% distributed across = 3.8%
  • . at 315 ° C, in the long direction:
  • E 0.2 330 MPa.

D'après des essais de conformation et correspondant à certaines de ses caractéristiques, ce feuillard est trop raide (EO,2 travers fort) et difficile à conformer (voir également A% réparti travers).According to conformation tests and corresponding to some of its characteristics, this strip is too stiff (E O , 2 strong cross) and difficult to conform (see also A% distributed across).

4ème série d'essai (essais selon l'inventionl4th series of tests (tests according to the inventionl

Elle concerne un feuillard de la même coulée Y, transformé selon le procédé de l'invention, selon les mêmes étapes 1 ) à 11) que le feuillard de la 2ème série d'essais et en faisant le traitement thermique final (opération 12)) dans les conditions suivantes :

  • Traitement au défilé sous argon à 620°C avec maintien d'environ 2,5 min à 620°C.
It relates to a strip of the same casting Y, transformed according to the method of the invention, according to the same steps 1) to 11) as the strip of the 2nd series of tests and by making the final heat treatment (operation 12)) under the following conditions:
  • Parade treatment under argon at 620 ° C with maintenance of approximately 2.5 min at 620 ° C.

Les caractéristiques mécaniques mesurées étaient :

  • . à l'ambiante dans le sens travers :
    • charge de rupture = 573 MPa
    • Eo,2= 534 MPa
    • A % réparti travers = 5,6 %
  • . à 315°C dans le sens long :
    • Eo,2 = 285 MPa.
The mechanical characteristics measured were:
  • . at ambient in the cross direction:
    • breaking load = 573 MPa
    • Eo, 2 = 534 MPa
    • A% distributed across = 5.6%
  • . at 315 ° C in the long direction:
    • Eo, 2 = 285 MPa.

La grosseur du grain fin recristallisé au dernier recuit intermédiaire est la même que dans la 2ème série d'essais (seul le traitement thermique final diffère). La recristallisation finale affecte 20 à 40 %The size of the fine grain recrystallized during the last intermediate annealing is the same as in the 2nd series of tests (only the final heat treatment differs). Final recrystallization affects 20 to 40%

Ce feuillard est un peu moins raide et un peu plus facile à conformer que celui de la 2ème série d'essais.This strip is a little less stiff and a little easier to conform than that of the 2nd series of tests.

Le procédé de l'invention permet donc des réglages précis de qualité, avec des résultats particulièrement reproductibles dans le cas des traitements au défilé.The method of the invention therefore allows precise quality adjustments, with particularly reproducible results in the case of parade treatments.

Claims (6)

1. A process for the production of a strip of Zircaloy 2 or 4 with an oxygen content of between 900 and 1600 ppm and with mechanical characteristics corresponding to the following three conditions:
EO.2 at 315°C ≥ 250 MPa
"long" uniform A% at 20°C 4 and
"transverse" uniform A% at 20°C ≥4,
wherein an ingot is transformed into a billet by hot rolling and then said billet is cold rolled to form a strip, with intermediate annealing operations, characterized in that:
a) for each of the last two intermediate annealing operations, the strip is subjected to a treatment for fram 0.5 min to 10 min at between 650 and 750°C;
b) after the last rolling operation the strip is subjected to a final heat treatment for from 1.5 to 7 min at between 590 and 630°C;
c) the strip is rolled with the following degrees of deformation between consecutive annealing or heat treatment operations:
c1) before the penultimate intermediate annealing operation: 20 to 55%
c2) between the last two intermediate annealing
operations: 30 to 55% and
c3) between the last intermediate annealing operation and the final heat treatment: 30 to 55%.
2. A process according to claim 1 characterized in that the final heat treatment is carried out in a moving mode at between 600 and 625°C, the constant speed of the strip ensuring a holding time at the treatment temperature of from 2 to 5 minutes.
3. A process according to claim 2 characterized in that the strip is rolled between the last intermediate annealing operation and the final heat treatment, with a degree of deformation of 35 to 45%.
4. A process according to claim 1 characterized in that, for each of the last two intermediate annealing operations, the strip is subjected to a treatment for from 1 to 3 minutes at between 680 and 720°C.
5. A process according to claim 2 characterized in that each of the last two intermediate annealing operations is carried out in a moving mode at between 680 and 720°C, the constant speed of the strip ensuring a holding time at the treatment temperature of from 1 to 3 minutes.
6. A strip of Zircaloy 2 or 4, obtainable by the process of any of the claims 1 to 5, with an oxygen content of between 900 and 1600 ppm and with mechanical characteristics corresponding to the following three conditions:
EO.2 at 315°C ≥ 250 MPa
"long" uniform A% at 20°C 4
"transverse" uniform A% at 20°C > 4
characterized in that in cross-section it has a finer grain than the index ASTM "11" and partial recrystallisation affecting 20 to 40% of the volume.
EP87420129A 1986-05-21 1987-05-18 Process for manufacturing strips from partially recrystallized zircaloy 2 or zircaloy 4, and strips obtained in this way Expired EP0246986B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8607760A FR2599049B1 (en) 1986-05-21 1986-05-21 PROCESS FOR THE MANUFACTURE OF A ZIRCALOY 2 OR ZIRCALOY 4 SHEET PARTIALLY RECRYSTALLIZED AND SHEET OBTAINED
FR8607760 1986-05-21

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EP0246986A1 EP0246986A1 (en) 1987-11-25
EP0246986B1 true EP0246986B1 (en) 1989-11-23

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US (2) US4775428A (en)
EP (1) EP0246986B1 (en)
JP (1) JPS6324048A (en)
KR (1) KR920000526B1 (en)
DE (1) DE3761023D1 (en)
ES (1) ES2011818B3 (en)
FR (1) FR2599049B1 (en)

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US5156689A (en) * 1991-05-20 1992-10-20 Westinghouse Electric Corporation Near net shape processing of zirconium or hafnium metals and alloys
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US5266131A (en) * 1992-03-06 1993-11-30 Westinghouse Electric Corp. Zirlo alloy for reactor component used in high temperature aqueous environment
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JPS6410590B2 (en) 1989-02-22
JPS6324048A (en) 1988-02-01
DE3761023D1 (en) 1989-12-28
US4881992A (en) 1989-11-21
US4775428A (en) 1988-10-04
FR2599049B1 (en) 1988-07-01
FR2599049A1 (en) 1987-11-27
KR920000526B1 (en) 1992-01-14
KR870011259A (en) 1987-12-22
ES2011818B3 (en) 1990-02-16
EP0246986A1 (en) 1987-11-25

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