EP0095953A1 - Method of heating coated strips for the transformation of a coating structure, especially at the production of galvanized sheets - Google Patents
Method of heating coated strips for the transformation of a coating structure, especially at the production of galvanized sheets Download PDFInfo
- Publication number
- EP0095953A1 EP0095953A1 EP83400920A EP83400920A EP0095953A1 EP 0095953 A1 EP0095953 A1 EP 0095953A1 EP 83400920 A EP83400920 A EP 83400920A EP 83400920 A EP83400920 A EP 83400920A EP 0095953 A1 EP0095953 A1 EP 0095953A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- gas
- heating
- carried out
- strip
- blowing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title claims abstract description 14
- 239000011248 coating agent Substances 0.000 title claims description 7
- 238000000576 coating method Methods 0.000 title claims description 7
- 230000009466 transformation Effects 0.000 title description 3
- 238000004519 manufacturing process Methods 0.000 title description 2
- 238000007664 blowing Methods 0.000 claims abstract description 7
- 238000009434 installation Methods 0.000 claims description 7
- 230000007935 neutral effect Effects 0.000 claims description 4
- 239000000446 fuel Substances 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims 1
- 230000001131 transforming effect Effects 0.000 claims 1
- 239000007789 gas Substances 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
Classifications
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
-
- 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
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
Definitions
- the present invention relates to the heating of coated strips, for transformation of the structure of the coating. It is known that, in the field of the manufacture of galvanized sheets, it is desired, for certain applications, to transform the zinc of the coating into an iron-zinc alloy.
- the rate of diffusion of iron through the zinc coating depends on both the temperature of the metal and its coating, as well as the residence time at this temperature. In general, it suffices to bring the coated strip from 450 to 550 ° C. in approximately a few seconds, then to allow it to cool in ambient air for a few other seconds, to effect the diffusion of the iron in the zinc in the desired proportions.
- the heating of the strip is generally carried out by means of burners with direct impact of the flame on the strip, this flame being able to be cylindrical or planar.
- a high combustion temperature and, on the other hand, a heating carried out over a short length, the gases escaping from the heating installation are still very hot, and the thermal yield obtained is relatively low, between 10 and 20%.
- This result can be improved by providing, in the heating installation, a recovery zone which makes it possible both to exhaust the fumes and to add maintenance after heating. Under these conditions, heating can be done at a slightly lower temperature.
- the invention proposes to provide a method of heating coated strips making it possible to increase this thermal efficiency, to a significant extent.
- the heating method according to the invention is characterized in that it exclusively uses convective exchanges, the heating being carried out by blowing a gas at a temperature below 1000 ° C., preferably of the order from 800 to 1000 ° C.
- the hot gas is blown perpendicular to the strip, over the entire height of the heating installation.
- This produces heating by orthogonal convection which ensures very high heat exchange homogeneity, unlike the results obtained with certain heating systems using burners with direct cylindrical flame impact s.
- the method according to the invention also has the advantage of being able to operate in a closed neutral gas circuit, which makes it possible to implement it in galvanizing installations on a single face without risk of oxidation of the uncoated face. .
- the blowing of the gas onto the strip can advantageously be carried out through slots or sheets perforated with circular orifices, or a combination of the two, placed at a short distance from the strip.
- the blown gas after its exchange with the strip, is taken up by a recirculation fan at high temperature.
- a gas exchanger or heater which can be powered by energy from combustion or electrical energy.
- This exchanger provides the additional heat necessary to bring the temperature of the return gas, already hot, to that which it must have on blowing.
- Electrical energy can be supplied, for example, through resistors, or by a plasma torch.
- the combustion energy is released inside radiant tubes, swept externally by the recirculated gas.
- These radiant tubes can be supplied with any fuel (gas or fuel).
- the recirculated gas can be air, but also a neutral gas, providing protection of the strip against oxidation.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Crystallography & Structural Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Coating With Molten Metal (AREA)
Abstract
Description
La présente invention est relative au chauffage de bandes revêtues, pour transformation de la structure du revêtement. On sait que, dans le domaine de la fabrication des tôles galvanisées, il est recherché, pour certaines applications, de transformer le zinc du revêtement en un alliage fer-zinc.The present invention relates to the heating of coated strips, for transformation of the structure of the coating. It is known that, in the field of the manufacture of galvanized sheets, it is desired, for certain applications, to transform the zinc of the coating into an iron-zinc alloy.
Par ailleurs, il est connu que cette transformation s'effectue grâce à un phénomène de diffusion du fer, à partir du métal de base, à travers le revêtement.Furthermore, it is known that this transformation takes place thanks to a phenomenon of diffusion of iron, from the base metal, through the coating.
La vitesse de diffusion du fer à travers le revêtement de zinc dépend à la fois de la température du métal et de son revêtement, ainsi que du temps de séjour à cette température. Il suffit en général de porter la bande revêtue de 450 à 550°C environ en quelques secondes, puis de la laisser refroidir dans l'air ambiant pendant quelques autres secondes, pour réaliser la diffusion du fer dans le zinc dans les proportions désirées.The rate of diffusion of iron through the zinc coating depends on both the temperature of the metal and its coating, as well as the residence time at this temperature. In general, it suffices to bring the coated strip from 450 to 550 ° C. in approximately a few seconds, then to allow it to cool in ambient air for a few other seconds, to effect the diffusion of the iron in the zinc in the desired proportions.
Dans les procédés actuellement mis en oeuvre, le chauffage de la bande est généralement réalisé au moyen de brûleurs à impact direct de la flamme sur la bande, cette flamme pouvant être cylindrique ou plane. Compte tenu, d'une part, d'une température de combustion élevée, et, d'autre part, d'un chauffage réalisé sur une faible longueur, les gaz s'échappant de l'installation de chauffage sont encore très chauds, et le rendement thermique obtenu est relativement faible, compris entre 10 et 20 %. Ce résultat peut être amélioré en prévoyant, dans l'installation de chauffage, une zone de récupération qui permet à la fois d'épuiser les fumées et d'ajouter un maintien après chauffage. Dans ces conditions, le chauffage peut se faire à une température légèrement inférieure.In the methods currently implemented, the heating of the strip is generally carried out by means of burners with direct impact of the flame on the strip, this flame being able to be cylindrical or planar. Taking into account, on the one hand, a high combustion temperature, and, on the other hand, a heating carried out over a short length, the gases escaping from the heating installation are still very hot, and the thermal yield obtained is relatively low, between 10 and 20%. This result can be improved by providing, in the heating installation, a recovery zone which makes it possible both to exhaust the fumes and to add maintenance after heating. Under these conditions, heating can be done at a slightly lower temperature.
Il demeure cependant que, dans ces installations connues, le mode principal d'échange de chaleur est radiatif, et, comme les coëffi- cients d'absorption de la tôle revêtue sont très faibles, le rendement thermique d'ensemble reste très médiocre.The fact remains, however, that in these known installations, the main mode of heat exchange is radiative, and, since the absorption coefficients of the coated sheet are very low, the overall thermal efficiency remains very poor.
L'invention se propose d'apporter un procédé de chauffage de bandes revêtues permettant d'accroître ce rendement thermique, dans une mesure importante.The invention proposes to provide a method of heating coated strips making it possible to increase this thermal efficiency, to a significant extent.
A cet effet, le procédé de chauffage selon l'invention est caractérisé en ce qu'il utilise exclusivement les échanges convectifs, le chauffage étant réalisé par soufflage d'un gaz à une température inférieure à 1000°C, de préférence de l'ordre de 800 à 1000°C.To this end, the heating method according to the invention is characterized in that it exclusively uses convective exchanges, the heating being carried out by blowing a gas at a temperature below 1000 ° C., preferably of the order from 800 to 1000 ° C.
Selon une caractéristique de cette invention, le gaz chaud est soufflé perpendiculairement à la bande, sur toute la hauteur de l'installation de chauffage. On réalise ainsi un chauffage par convection orthogonale qui assure une très grande homogénéité d'échange thermique, contrairement aux résultats obtenus avec certains systèmes de chauffage mettant en oeuvre des brûleurs à impact direct de flammes cylindrique s.According to a characteristic of this invention, the hot gas is blown perpendicular to the strip, over the entire height of the heating installation. This produces heating by orthogonal convection which ensures very high heat exchange homogeneity, unlike the results obtained with certain heating systems using burners with direct cylindrical flame impact s.
Le fonctionnement à une température relativement basse, de l'ordre de 800 à 1000°C, permet d'obtenir des rendements thermiques supérieurs à 45 %, tout en réalisant des échanges thermiques intensifs dans tous les points de l'installation.Operating at a relatively low temperature, of the order of 800 to 1000 ° C., makes it possible to obtain thermal yields greater than 45%, while carrying out intensive heat exchanges in all the points of the installation.
Le procédé selon l'invention présente en outre l'avantage de pouvoir fonctionner dans un circuit fermé de gaz neutre, ce qui permet de le mettre en oeuvre dans les installations de galvanisation sur une seule face sans risque d'oxydation de la face non revêtue.The method according to the invention also has the advantage of being able to operate in a closed neutral gas circuit, which makes it possible to implement it in galvanizing installations on a single face without risk of oxidation of the uncoated face. .
Selon l'invention, le soufflage du gaz sur la bande peut avantageusement s'effectuer à travers des fentes ou des tôles perforées d'orifices circulaires, ou combinaison des deux, placées à faible distance de la bande.According to the invention, the blowing of the gas onto the strip can advantageously be carried out through slots or sheets perforated with circular orifices, or a combination of the two, placed at a short distance from the strip.
Selon une autre caractéristique de l'invention, le gaz soufflé, après son échange avec la bande, est repris par un ventilateur de recirculation à haute température. Dans ce circuit de recirculation est placé un échangeur ou un réchauffeur de gaz, qui peut être alimenté par l'énergie issue de la combustion ou l'énergie électrique.According to another characteristic of the invention, the blown gas, after its exchange with the strip, is taken up by a recirculation fan at high temperature. In this recirculation circuit is placed a gas exchanger or heater, which can be powered by energy from combustion or electrical energy.
Cet échangeur apporte le complément de chaleur nécessaire pour porter la température du gaz de retour, déjà chaud, à celle qu'il doit avoir au soufflage.This exchanger provides the additional heat necessary to bring the temperature of the return gas, already hot, to that which it must have on blowing.
L'énergie électrique peut être fournie, par exemple, à travers des résistances, ou par un chalumeau au plasma.Electrical energy can be supplied, for example, through resistors, or by a plasma torch.
L'énergie de combustion est dégagée à l'intérieur de tubes radiants, balayés extérieurement par le gaz recirculé. Ces tubes radiants peuvent être alimentés en combustible quelconque (gaz ou fuel). Le gaz recirculé peut être de l'air, mais aussi un gaz neutre, procurant une protection de la bande contre l'oxydation.The combustion energy is released inside radiant tubes, swept externally by the recirculated gas. These radiant tubes can be supplied with any fuel (gas or fuel). The recirculated gas can be air, but also a neutral gas, providing protection of the strip against oxidation.
Il demeure bien entendu que cette invention n'est pas limitée aux exemples de mise en oeuvre décrits ici, mais qu'elle en englobe toutes les variantes.It remains to be understood that this invention is not limited to the examples of implementation described here, but that it encompasses all variants thereof.
Claims (8)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8209250A FR2527638A1 (en) | 1982-05-27 | 1982-05-27 | METHOD FOR HEATING A COATED STRIP FOR TRANSFORMING THE COATING STRUCTURE, PARTICULARLY FOR PRODUCING SHEETS |
| FR8209250 | 1982-05-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0095953A1 true EP0095953A1 (en) | 1983-12-07 |
Family
ID=9274395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP83400920A Withdrawn EP0095953A1 (en) | 1982-05-27 | 1983-05-06 | Method of heating coated strips for the transformation of a coating structure, especially at the production of galvanized sheets |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0095953A1 (en) |
| FR (1) | FR2527638A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2128296A1 (en) * | 2008-05-26 | 2009-12-02 | Aga AB | Method for galvannealing steel materials |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1157834A (en) * | 1955-08-26 | 1958-06-04 | Stein & Roubaix | Convection heated oven |
| US3262688A (en) * | 1965-06-03 | 1966-07-26 | Midland Ross Corp | Jet convection heat transfer |
| US3322558A (en) * | 1963-06-14 | 1967-05-30 | Selas Corp Of America | Galvanizing |
| GB1232191A (en) * | 1969-01-06 | 1971-05-19 | ||
| GB2009248A (en) * | 1977-11-30 | 1979-06-13 | Inland Steel Co | Hot-dip galvanizing and alloying |
-
1982
- 1982-05-27 FR FR8209250A patent/FR2527638A1/en not_active Withdrawn
-
1983
- 1983-05-06 EP EP83400920A patent/EP0095953A1/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1157834A (en) * | 1955-08-26 | 1958-06-04 | Stein & Roubaix | Convection heated oven |
| US3322558A (en) * | 1963-06-14 | 1967-05-30 | Selas Corp Of America | Galvanizing |
| US3262688A (en) * | 1965-06-03 | 1966-07-26 | Midland Ross Corp | Jet convection heat transfer |
| GB1232191A (en) * | 1969-01-06 | 1971-05-19 | ||
| GB2009248A (en) * | 1977-11-30 | 1979-06-13 | Inland Steel Co | Hot-dip galvanizing and alloying |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2128296A1 (en) * | 2008-05-26 | 2009-12-02 | Aga AB | Method for galvannealing steel materials |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2527638A1 (en) | 1983-12-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Designated state(s): AT BE DE GB IT LU NL SE |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| 18D | Application deemed to be withdrawn |
Effective date: 19840808 |
|
| RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: WANG, ROBERT |