CN107532269A - Continuous molten metal method for plating and continuous molten metal plating apparatus - Google Patents

Continuous molten metal method for plating and continuous molten metal plating apparatus Download PDF

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Publication number
CN107532269A
CN107532269A CN201680022565.7A CN201680022565A CN107532269A CN 107532269 A CN107532269 A CN 107532269A CN 201680022565 A CN201680022565 A CN 201680022565A CN 107532269 A CN107532269 A CN 107532269A
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China
Prior art keywords
nose
molten metal
plating
bath
steel band
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CN201680022565.7A
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CN107532269B (en
Inventor
高桥秀行
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JFE Steel Corp
JFE Engineering Corp
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NKK Corp
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Priority claimed from PCT/JP2016/001013 external-priority patent/WO2016170720A1/en
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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
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C23C2/003—Apparatus
    • C23C2/0032—Apparatus specially adapted for batch coating of substrate
    • C23C2/00322—Details of mechanisms for immersing or removing substrate from molten liquid bath, e.g. basket or lifting mechanism
    • 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
    • C23C2/003—Apparatus
    • C23C2/0034—Details related to elements immersed in bath
    • C23C2/00342—Moving elements, e.g. pumps or mixers
    • C23C2/00344—Means for moving substrates, e.g. immersed rollers or immersed bearings
    • 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
    • C23C2/003—Apparatus
    • C23C2/0035—Means for continuously moving substrate through, into or out of the bath
    • 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
    • C23C2/003—Apparatus
    • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
    • 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
    • C23C2/003—Apparatus
    • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
    • C23C2/004—Snouts
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • 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
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0224—Two or more thermal pretreatments
    • 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
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • 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
    • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
    • C23C2/36—Elongated material
    • C23C2/40—Plates; Strips

Abstract

A kind of can suppress in the lump using non-plating of the caused metal vapors as the non-plating of cause and using the oxide-film in the bath of molten metal face in nose as cause in nose is provided, and then it can stablize and promptly change the continuous molten metal method for plating of the oxidizing force of the atmosphere in nose.The continuous molten metal method for plating of the present invention is characterised by, supply oxidizing gas in nose (14), and make the temperature of the internal face of the nose for more than (150 DEG C of plating bath temperature), and make the atmosphere temperature on the top in the nose for more than (100 DEG C of plating bath temperature).

Description

Continuous molten metal method for plating and continuous molten metal plating apparatus
Technical field
The present invention relates to the continuous molten metal plating side used for example in order to be continuously manufactured by fused zinc plated steel sheet Method and continuous molten metal plating apparatus.
Background technology
In the continuous fusion zinc plating wiring of steel band, generally, the steel band cleaned to surface is connected using annealing furnace Annealed, be cooled to after set point of temperature continuously, bathed into fused zinc, fused zinc plating is implemented to steel band.Generally, annealing furnace Interior annealing/refrigerating work procedure is carried out under reducing atmosphere.Also, it is expelled in steel band from annealing furnace into the bath of fused zinc plating and is During only, steel band is led into plate path from big gas barrier, steel band can be in reducing atmosphere by therefore in annealing furnace with being formed Have fused zinc bathe plating coating groove between be provided be referred to as nose square-section path.Sinking roller is provided with fused zinc bath, Steel band into fused zinc bath is changed direct of travel by sinking roller and risen along vertical.From fused zinc bath pull-up steel band by Gas wiping nozzle is adjusted to after defined plating thickness, is cooled and is oriented to subsequent handling.
Nose is connected with the cooling zone (steel band outlet side) of annealing furnace, therefore it is usually reducing atmosphere that it is internal.Therefore, exist Fused zinc bath face in nose is difficult to form oxide-film, only forms thin oxide-film.So, it is formed at fused zinc bath in nose The oxide-film in face is insecure, therefore when steel band enters fused zinc and bathed, because of vibration etc., fused zinc is showed out to bath, and zinc is from there Evaporated into nose.In this case, fused zinc is evaporated to the saturated vapour pressure under the atmosphere temperature inside nose.
Zinc fume with reducing atmosphere gas micro existing oxygen react and form oxide.Moreover, even in In the case that zinc fume is not oxidized, when the vapour pressure of zinc fume turns into more than saturated vapour pressure, a part for zinc fume Meeting phase transformation turns to the zinc of liquid phase or solid phase.Especially nose is only made up of thin heat proof material, therefore the temperature of nose internal face Influenceed by extraneous gas, the temperature below the saturation temperature for the vapour pressure for easily becoming zinc fume, as the temperature with Under position, zinc fume turn into zinc powder and be attached to nose inner surface.
When oxide, attachment (so-called ash) are attached to steel band as more than, there are the product such as the generation of non-plating portion Matter defect.After, in this manual, by so using the ash generated due to the zinc fume in nose as caused by cause The quality defects such as non-plating portion are referred to as " the defects of being caused by ash ".
As technology the defects of suppressing to be caused by ash, following technology be present.Recorded in patent document 1 as follows Technology：Nose is heated using heater, and then, using heat-barrier material to being thermally shielded on the outside of the heater, by making The temperature difference of atmosphere temperature and inner wall temperature and plating bath temperature in nose is less than 150 DEG C, to prevent ash to nose inwall Attachment.Following technology has been recorded in patent document 2：Suction blower is set in plating bath, in the suction blower Attractive side be linked with suction tube, the high position in bath face of the suction tube in than nose has suction port, by the zinc in nose Steam is discharged to outside system.Following technology has been recorded in patent document 3：It is non-oxide for steel plate to make the atmosphere in nose Property and for fused zinc be oxidisability gas, thus suppress flue gas (zinc fume) generation.
Citation
Patent document
Patent document 1：Japanese Unexamined Patent Publication 8-176773 publications
Patent document 2：Japanese Unexamined Patent Publication 8-302453 publications
Patent document 3：Japanese Unexamined Patent Publication 6-330271 publications
The content of the invention
The invention problem to be solved
The technology of patent document 1 is steamed by the zinc heated to nose can suppress in certain degree in nose inwall The crystallization of gas, i.e. grey generation.However, because the generation itself of the zinc fume from fused zinc bath face can not prevent, therefore The grey generation at unheated position is inevitable, can not exclude the potential danger that ash is attached to steel band.
In the technology of patent document 2, the zinc fume in nose can not be reliably discharged, therefore undischarged zinc fume is attached The effect for the defects of in nose inwall, generation ash, therefore preventing from being caused by ash is insufficient.Moreover, the situation of discharge zinc fume The aspect for the evaporation for promoting fused zinc on the contrary be present, therefore not effective situation is more.
In the technology of patent document 3, the convection current of quite rapid gas in nose be present.Therefore, input is most Several oxidizing gas do not stay in bath face and released to outside system.Therefore, can not shape if not putting into very more gas Into appropriate oxide-film, it is difficult to prevent the evaporation of fused zinc.
So, in the technology of patent document 1~3, suppress insufficient by the effect of grey the defects of causing.In addition, according to The investigation of present inventor, distinguish in the case where oxide-film is blocked up, when steel band enters fused zinc and bathed, oxide-film is attached to steel Belt surface, this also turns into the reason for producing the quality defects such as non-plating portion.After, in this manual, will be so with nose Fused zinc bath face oxide-film be thus the quality defect such as caused non-plating portion referred to as " the defects of being caused by oxide-film ".
In addition, the technology of patent document 1~3 there is also it is following the problem of.That is, (especially near bath face) in nose The preferable oxidizing force of atmosphere forms according to the composition of steel band, the composition of the annealing conditions in annealing operation, bath of molten metal etc. Operating condition and change.Therefore, in the case of handover operation condition, it is desirable to which the oxidizing force of the atmosphere in nose is also promptly cut Change.However, in the technology of patent document 1~3, the oxidizing force for the atmosphere that can not stably and promptly change in nose be present Problem.Especially in patent document 3, larger free convection in nose be present, therefore can not stablize and promptly change The oxidizing force of atmosphere in nose.
These problems are not limited to fused zinc plating, are also generally applicable in the case of molten metal plating.
Therefore, the present invention in view of above-mentioned problem and make, its object is to provide one kind in the lump to suppress with nose Metal vapors caused by interior is the non-plating of cause and the non-plating using the oxide-film in the bath of molten metal face in nose as cause, And then it can stablize and promptly change the continuous molten metal method for plating and continuous fusion of the oxidizing force of the atmosphere in nose Metal-plated equipment.
For solving the scheme of problem
In order to solve above-mentioned problem, the result of present inventor's investigation is to have obtained following opinion.
(A) the defects of suppressing to be caused by ash to suppress the evaporation of fused zinc (generation of zinc fume) is, it is necessary in bath face The upper oxide-film formed more than certain certain thickness.On the other hand, in order to suppress to be caused by oxide-film the defects of, is, it is necessary to by oxide-film Suppress into below certain certain thickness.I.e., in order to suppress to be caused by ash the defects of and this two side the defects of caused by oxide-film, it is necessary to Form the oxide-film of most suitable thickness.
(B) in order to so form the oxide-film of most suitable thickness, it is necessary to by the convection current for inhibiting the atmosphere in nose On the basis of, oxidizing gas is supplied into nose, and strictly manage the dew point of the atmosphere near the fused zinc bath face in nose. Therefore, in the state of the thermal convection current for inhibiting the atmosphere in nose, by necessary minimal oxidizing gas into nose Supply to be best.Because like this, it can make to be supplied to the oxidizing gas near bath face and substantially be stranded in as former state Near bath face.
(C) as a result, can also obtain stablizing and promptly change the such effect of oxidizing force of the atmosphere in nose Fruit.Therefore, in handover operation condition, the atmosphere in nose can promptly be switched corresponding to the operating condition after change Oxidizing force.
The present invention is completed based on above-mentioned opinion, and its purport structure is as described below.
(1) a kind of continuous molten metal method for plating, there is following process：
The process that steel band is continuously annealed in annealing furnace；
To collecting molten metal and the plating coating groove formed with bath of molten metal continuously feeds the steel band after annealing, right The process that the steel band implements metal-plated,
The continuous molten metal method for plating is characterised by,
Nose is arranged on the steel band outlet side of the annealing furnace and set in a manner of end is impregnated in the bath of molten metal Put, at the space that the steel band is divided from the annealing furnace towards the bath of molten metal by the nose, to the nose Oxidizing gas is supplied in portion, and the temperature of the internal face of the nose is turned into more than (- 150 DEG C of plating bath temperature), makes institute Stating the atmosphere temperature on the top in nose turns into more than (- 100 DEG C of plating bath temperature).
(2) the continuous molten metal method for plating recorded according to above-mentioned (1), wherein, the oxidizing gas is to include water The nitrogen or the steam-laden nitrogen/hydrogen mixed gas of bag of steam.
(3) according to above-mentioned (1) record continuous molten metal method for plating, wherein, changed according to operating condition described in The oxidizing force of oxidizing gas.
(4) according to above-mentioned (2) record continuous molten metal method for plating, wherein, changed according to operating condition described in Steam vapour amount in oxidizing gas.
(5) the continuous molten metal method for plating recorded according to above-mentioned (2), wherein, the continuous molten metal plating side Method also has following process：Study the dew point in the nose and reality under this operating condition in advance for each operating condition The relation between the defect level as caused by non-plating of the steel band of metal-plated is applied, and is determined described under the operating condition Target dew point in nose,
Based on the target dew point determined for each operating condition, to determine that the water in the oxidizing gas steams Tolerance.
(6) according to above-mentioned (5) record continuous molten metal method for plating, wherein, when operating condition switches, based on Target dew point corresponding to operating condition after change, to change the steam vapour amount in the oxidizing gas.
(7) the continuous molten metal method for plating recorded according to any one of above-mentioned (3)~(6), wherein, the operation bar Part be the composition composition of the steel band, the annealing conditions in the annealing operation and the bath of molten metal composition at least One.
(8) the continuous molten metal method for plating recorded according to any one of above-mentioned (3)~(6), wherein, the operation bar Part is the composition composition of the steel band.
(9) the continuous molten metal method for plating recorded according to any one of above-mentioned (1)~(8), wherein, from width of steel band The both ends of the nose on direction supply the oxidizing gas.
(10) a kind of continuous molten metal plating apparatus, it is characterised in that have：
Annealing furnace, steel band is continuously annealed；
Plating coating groove, house molten metal and formed with bath of molten metal；
Nose, the steel band outlet side of the annealing furnace is arranged on, is set in a manner of end is impregnated in the bath of molten metal Put, and divide the space that the steel band continuously fed from the annealing furnace into the bath of molten metal passes through；
Calandria, the top being arranged in the outer wall and the nose of the nose；
Gas supply mechanism, link with the nose；And
Control unit, the calandria and the gas supply mechanism are controlled, oxidizing gas is supplied into the nose, and Make the temperature of the internal face of the nose for more than (- 150 DEG C of plating bath temperature), and make the atmosphere temperature on the top in the nose Spend for more than (- 100 DEG C of plating bath temperature).
Invention effect
According to the present invention continuous molten metal method for plating and continuous molten metal plating apparatus, can suppress in the lump with Caused metal vapors is the non-plating of cause and using the oxide-film in the bath of molten metal face in nose as cause in nose Non- plating, and then, it can stablize and promptly change the oxidizing force of the atmosphere in nose.
Brief description of the drawings
Fig. 1 is the schematic diagram of the continuous fusion zinc plating apparatus 100 of one embodiment of the present invention.
Fig. 2 is the figure of the half of the width center from steel band P in the inside for the nose 14 for only showing Fig. 1.
Fig. 3 is the enlarged diagram of Fig. 1 nose 14.
Fig. 4 is the coordinate diagram for representing the relation between the oxidizing force of bath face atmosphere and ratio of defects.
Fig. 5 (A) is on representing the pass between the oxidizing force of bath face atmosphere and ratio of defects containing high Si steel and containing low Si steel The coordinate diagram of system, Fig. 5 (B) be on being bathed containing high Al and bathing containing low Al and represent the oxidizing force of bath face atmosphere and oxide thickness it Between relation coordinate diagram.
Fig. 6 (A), (B) are the coordinate diagram of the relation between dew point and ratio of defects in the nose for represent steel grade A, B respectively.
Fig. 7 is the coordinate diagram that the dew point in the nose for represent example 1~3 and comparative example 1,2 changes.
Embodiment
Hereinafter, illustrate the continuous fusion zinc plating apparatus 100 of one embodiment of the present invention and use the continuous fusion zinc The continuous fusion zinc method for plating of plating apparatus 100.
Reference picture 1, continuous fusion zinc plating apparatus 100 have annealing furnace 10, plating coating groove 12, nose 14.
Annealing furnace 10 is the device continuously annealed for the steel band P passed through inside it, is arranged in parallel with successively Heating tape, soaking zone and cooling zone.Fig. 1 only illustrates cooling zone.As annealing furnace, known or arbitrary structure can be used Annealing furnace.Generally reducibility gas or non-oxidizing gas are supplied to the inside of annealing furnace.As reducibility gas, generally make Use H2-N2Mixed gas, the H for example with 1~20 volume % can be enumerated2And remainder is by N2And inevitable impurity structure Into composition gas (dew point：- 60 DEG C or so).Moreover, as non-oxidizing gas, can enumerate with by N2It is and inevitable Impurity form composition gas (dew point：- 60 DEG C or so).Steel band P after annealing is cooled to 470~500 DEG C in cooling zone Left and right.
Fused zinc is housed in plating coating groove 12, forms fused zinc bath 12A.Nose 14 annealing furnace 10 steel band outlet side, Link in present embodiment with cooling zone and set.The end 14A of nose is set in a manner of being impregnated in fused zinc bath 12A.Nose 14 be the component divided for the steel band P being continuously fed to from annealing furnace 10 in the fused zinc bath 12A spaces passed through. The top of nose 14 is configured with the regulating roller 26 that steel band P direct of travel is changed to obliquely downward from horizontal direction.For passing through Seen in the section view vertical with steel band P direct of travel the part that the space that steel band P after regulating roller 26 is passed through is divided Examining down turns into rectangle.
Steel band P bathes 12A by the inside of nose 14 continuously into fused zinc.It is provided among fused zinc bathes 12A Sinking roller 28 and backing roll 30, enter fused zinc bath 12A among steel band P logical plate direction is changed to upwards by sinking roller 28 Afterwards, guided by backing roll 30 and discharged from fused zinc bath 12A.So, fused zinc plating is implemented to steel band P.
Reference picture 2, continuous fusion zinc plating apparatus 100 have the gas supply mechanism 20 linked with nose 14.Gas supplies Include to mechanism 20：The first pipe arrangement 22A that hydrogen passes through；The second pipe arrangement 22B that nitrogen passes through；Water as oxidizing gas steams The 3rd pipe arrangement 22C that gas passes through；It is installed on the valve 24 of the flow adjustment of these pipe arrangements；From the gas mixing of these pipe arrangements supply And the 4th pipe arrangement 22D that the mixed gas formed passes through；And it is located at the inside of nose 14 with the 4th pipe arrangement 22D links and front end The 5th pipe arrangement 22E.First pipe arrangement 22A and the 3rd pipe arrangement 22C are linked to the second pipe arrangement 22B, by valve 24 is adjusted and Hydrogen, nitrogen and vapor can be made to be mixed with arbitrary flow-rate ratio.
As oxidizing gas, the gas containing vapor, oxygen, carbon dioxide etc. can be enumerated, is not particularly limited.So And from not too high due to oxidizing force and hold the low situation of manageable situation, cost, oxygen can be easily determined using dew point instrument The situation for changing power is set out, and is preferably set to wrap steam-laden gas.
Reference picture 3, there is the heater 16 as calandria in the outer wall configurations of nose 14, and then heater 16 is by heat-insulated material The covering of material 18.It should be noted that heater 16 covers the whole of the outer wall in addition to the leading section (near bath face) of nose 14 Face.Moreover, the top in nose is also configured with the heater 17 as calandria.Nose top is as described later for thermal convection current Generation influence it is big, therefore by setting heater 17, the atmosphere temperature on nose top is increased.
In the present embodiment, heater 16,17 and gas supply mechanism 20 are controlled by control unit (not shown), to Supply oxidizing gas in nose 14, and by the temperature treatment of the internal face of nose 14 into more than (- 150 DEG C of plating bath temperature) and The atmosphere temperature management on the top in nose 14 is most important into the situation more than (- 100 DEG C of plating bath temperature).Hereinafter, in detail Describe its bright technical meaning in detail.
As has been described, in the atmosphere in nose, on its oxidisability exist most just when.Fig. 4 is to show its concept Figure.When oxidisability is low, oxide-film will not be generated in bath face, even if or generation it is also very thin, therefore caused by oxide-film The defects of be difficult to occur, but the evaporation of zinc is actively producing, therefore is increased the defects of caused by ash.It is otherwise high in oxidisability In the case of, thick oxide-film turns into diaphragm, and the defects of hardly causing the evaporation of zinc, therefore being caused by ash is difficult to produce, But the defects of being caused by oxide-film, more produces.
Therefore, it is necessary to which the oxidizing force of the atmosphere near the evaporation/oxidating bath face of zinc is strictly controlled into optimum level (figure 4 middle body).The inventors have found that steam-laden gas for example is being wrapped to control the bath face attached by being supplied into nose In the case of the oxidizing force of near atmosphere, if the dew point of the atmosphere near bath face is strictly controlled into established practice fixed point, (target is revealed Point) ± 4 DEG C or so of scope, then the defects of being caused by ash and the defects of caused by oxide-film this two side be suppressed to it is relatively low Level.If it should be noted that the operating condition beyond the target dew point target dew point determines, pass through method described later It can determine.
Here, the dew point management near bath face is set to become it is difficult to the convection current of the atmosphere in nose.As in nose Convection current, can mainly enumerate due to the movement of steel band and it is caused with stream, the thermal convection current associated with the temperature difference in nose and with Pressure differential in nose is the pressure current of cause, but under the conditions of common nose, influences to be to dominate as caused by thermal convection current Property.For example, in the case where temperature of steel strips is 500 DEG C, plating bath temperature is 450 DEG C, with existing outside nose inside nose More than 400 DEG C of temperature difference.Moreover, generally, nose top links with cooling zone, therefore the atmosphere temperature on nose top turns into 200~300 DEG C of situation is more.In this case, wind speed turns into 4~5m/s or so as caused by thermal convection current, and as steel band Compared with the 1m/s of the representative value of stream quite big.
Even if input promotes the gas of bath face oxidation, such as input to wrap steam-laden gas, its big portion in this condition Divide the bath face that also do not stay in, therefore in order to generate the oxide-film of the appropriate thickness for the defects of suppressing to be caused by ash, it has to throw Enter substantial amounts of vapor.In addition, in order to suppress to be caused by oxide-film the defects of, the very thin situation of oxide-film is favourable, therefore Result is to need to make the concentration distribution minimization of the oxidizing gas near bath face.However, under conditions of thermal convection current is big, face is bathed The concentration distribution of neighbouring oxidizing gas becomes big (that is, concentration becomes heterogeneity in face), therefore the dew point pipe near bath face Manage extremely difficult.
Based on above-mentioned opinion, present inventor has obtained following conclusion：In order to strictly manage the dew point near bath face And this two side of the defects of suppressing the defects of being caused by ash and being caused by oxide-film, suppressing the evaporation of zinc, itself is most effective, therefore, On the basis of the thermal convection current in nose is inhibited, necessary minimal oxidizing gas is supplied into nose to be best.
Therefore, present inventor intends to reduce the temperature difference as in nose the reason for causing such thermal convection current.In nose Inside portion, temperature highest is steel band, but generally only 10 DEG C higher than bath temperature or so, therefore in the present invention of steel band, by temperature Benchmark be set to plating bath temperature.Moreover, thermal convection current is opposite direction with stream with steel band, so if can make thermal convection current Size is less than 2 times of the size of the adjoint stream of steel band, then can significantly suppress the convection current in nose.
The result that various investigations are repeated is to be found that, if the temperature of the internal face of nose is set as into (plating is bathed - 150 DEG C of temperature) more than, then the convection current of the atmosphere in nose can be suppressed to the flow regime degree for ignoring temperature influence. But the atmosphere temperature on the top in nose influenceed to caused by thermal convection current it is bigger, it is therefore desirable to be set as (plating bath temperature- 100 DEG C) more than.Because when the big gas of the density of density current is present in higher position, flow velocity becomes much larger.(with density It is proportional to Δ ρ gh for the flowing of cause.H is the difference of height and position, if highdensity gas be present in higher position, Flow velocity accelerates.)
It should be noted that the atmosphere temperature on top in nose be preferably (+100 DEG C of plating bath temperature) below.This is Because the atmosphere temperature on top is higher, then the convection current in nose more stabilizes that (state that top has materials of low density is stable Property), but if its stabilization effect exceedes (+100 DEG C of plating bath temperature), then culminate.Moreover, the internal face of nose Temperature be preferably (+0 DEG C of plating bath temperature) below.When the temperature of internal face is higher than plating bath temperature, the side in nose Wall is nearby produced in rising, and sinking is generated in central portion due to its influence.The flowing with by steel band with stream and generate Flow for equidirectional, therefore big flowing is produced in nose.Therefore, it can be said that it is that the temperature for not making internal face exceedes plating The certainty of bath temperature is applied, the possibility for increasing flowing on the contrary is high.
It should be noted that in the present invention, " top in nose " is that the surface of span regulating roller is the nose within 1m Region in portion.In figure 3, the surface away from the regulating roller 26 in nose 14 is turned into as in the range of 1m.
So, by the state of the atmosphere temperature for having managed the top in the temperature of internal face of nose and nose, Oxidizing gas is supplied into nose, so as to make the major part of the oxidizing gas near arrival bath face stay in bath in advance Face, therefore the generation of zinc fume can be suppressed with less gas flow.Moreover, the gas componant supplied into nose is substantially former It is present near bath face, therefore control climate becomes easy sample, the variation of the dew point of atmosphere near bath face can be suppressed.Its As a result, the defects of also can suppressing to be caused by oxide-film.So, the state of oxidation in the bath face in nose is ideally kept, because This two side of the defects of this can almost eliminate the defects of being caused by ash and be caused by oxide-film.It is further possible to obtain stablizing And promptly change effect as the oxidizing force of the atmosphere in nose.Therefore, in handover operation condition, it can correspond to and become Operating condition after more and promptly switch the oxidizing force of the atmosphere in nose.
The oxidizing gas supplied into nose is preferably to wrap steam-laden nitrogen or the steam-laden nitrogen/hydrogen of bag Mixed gas, if composition or the steel grade of manufacture that dew point is bathed according to plating, other operating conditions and suitably set, but It is more as good situation substantially in the range of -20~-35 DEG C.Moreover, the quantity delivered of oxidizing gas is by various The influence of operating condition, but beyond the atmosphere temperature on the top in the temperature of the internal face of nose and nose it is identical conditions When, compared with the condition outside the present invention, same dew point can be realized with 1/4 or so quantity delivered.Therefore, it is possible to make oxidisability gas The quantity delivered of body turns into the necessary minimal amount for being used for forming appropriate oxide-film.
As shown in Fig. 2 oxidizing gas preferably supplies from the both ends of the nose on width of steel band direction into nose 14. Because if the 5th pipe arrangement 22E with gas input port is arranged at into the side of nose 12, near the side in nose Temperature situation about reducing it is more, therefore turn into sinking generally near side, therefore efficiently can arrive oxidizing gas Near up to bath face.The height away from bath face of gas input port can be set to 100~3000mm or so.If 100mm, gas The possibility height in bath face is directly reached, result is that the concentration distribution of the oxidizing gas near bath face becomes big.Moreover, exceed If 3000mm, away from the in larger distance of bath face, therefore gas concentration declines, as a result, needing substantial amounts of gas.
Here, the preferable oxidizing force of the atmosphere near bath face in nose is according to the composition of steel band composition, annealing operation In annealing conditions, fused zinc bath the operating condition such as composition and change.That is, 2 curves shown in Fig. 4 can be according to operation bar Part and move left and right.Hereinafter, such case is illustrated by taking Fig. 5 (A), (B) as an example.
First, as has been described, the defects of being caused by ash, oxidation all with being formed at bath face of the defects of being caused by oxide-film Film thickness is related.Specifically, the defects of being caused by ash is related to grey growing amount and its adhesive rate, the defects of being caused by oxide-film Dependent on oxide-film amount and its adhesive rate.
Fig. 5 (A) shows that the composition of steel band is formed to caused by the preferable oxidizing force of the atmosphere near the bath face in nose One influenceed.When containing the so-called easily oxidizable element such as more Si, Mn, Al in steel band, enter plating bath it is tight before steel Belt surface generates the more dense compound in surface.When carrying out plating with such surface denseization state, oxide-film becomes easily attached In steel band, i.e. the adhesive rate of oxide-film rises, therefore easily produces the defects of being caused by oxide-film.On the other hand, ash generation Amount is hardly dependent on the surface denseization state of steel band, therefore the composition of steel band the defects of forming for being caused by ash is hardly Impact.
In addition, the surface denseization state difference of steel band according to annealing conditions such as dew points in annealing temperature or stove, therefore move back The generation easness for the defects of fiery condition also can be for being caused by oxide-film impacts, but several the defects of for being caused by ash It will not impact.
Fig. 5 (B) shows that the composition of fused zinc bath causes for the preferable oxidizing force of the atmosphere near the bath face in nose One of influence.As shown in Fig. 5 (B), the Al concentration in bath is higher, then in the bath easier formation oxide-film in face.Therefore, Bathed containing high Al, then the defects of being caused by ash is more difficult to produce, the defects of being caused by oxide-film easier generation.That is, the 2 of Fig. 4 Curve is moved to the left.
It is therefore preferable that the oxidizing force of oxidizing gas is changed according to operating condition.That is, steamed in oxidizing gas comprising water During gas, the preferable dew point of the atmosphere near bath face, i.e. target dew point is different according to operating condition, as long as therefore according to operation Condition changes the steam vapour amount in oxidizing gas.It should be noted that the steam vapour amount in oxidizing gas is usual As more than 100ppm.
In this case, study the dew point in nose in advance for each operating condition and the defects of caused by ash and by Relation (that is, Fig. 4 information) between the defects of the defects of oxide-film causes rate, can be determined in the nose under the operating condition Target dew point.Also, based on the target dew point determined for each operating condition, the water in oxidizing gas can be determined Vapor volume.When operating condition switches, as long as changing oxidisability based on target dew point corresponding with the operating condition after change Steam vapour amount in gas.
Here, in past operation, rate the defects of by grasping dew point in nose and each defect now in advance Tendency, and the dew point in nose as shown in Figure 4 can be obtained and the defects of caused by ash and the defects of being caused by oxide-film The defects of rate between relation.The presence or absence of each defect can determine that by visual observation.The size for the defects of can differentiating by visual observation For more than 100 μm or so.Also, the incorporation rate of the defects of by length per 0.5m is defined as " ratio of defects ".Ratio of defects 1% is equivalent to 1 Individual/50m.
It should be noted that the dew point in above-mentioned nose is needed for the dew point in bath face (near bath face) immediately above.In reality When the position of border measure dew point is not that bath face is immediately above, following consideration is carried out.First, if being applicable the present invention and eliminating nose The state of thermal convection current in portion, then hardly it is distributed in nose with dew point, therefore can be directly using actual measurement dew point.So And when thermal convection current in nose be present, actual measurement dew point is corrected to dew point near bath face.The correction can be used according to flow solution The dew point analysed and predicted is distributed to carry out.It is that dew point at 500mm height is -35 away from bath face for example, in flowing parses DEG C, when dew point near bath face is -30 DEG C, both differences are+5 DEG C, and moisture poor turns into 150ppm than it.It is therefore possible to use Dew point value at the 500mm of actual measurement height is showed a little plus dew point obtained from 150ppm amounts as bath all the time.
(vapor is included as the preferable oxidizing force for the atmosphere near the bath face in nose in oxidizing gas When, for the target dew point of the atmosphere near bath face) operating condition that impacts, can enumerate steel grade (steel band into packet Into), the composition of the annealing conditions in annealing operation and fused zinc bath.It is therefore preferable that consider at least one in these and ask in advance Go out Fig. 4 information.For example, in specific continuous fusion zinc plating apparatus, do not have in the composition that annealing conditions and fused zinc are bathed When known to the situation of change, if the pre research Fig. 4 information according to the predetermined steel grade for leading to plate to the equipment, and determine mesh Mark dew point.Also, when switching steel grade, as long as being changed in a manner of as target dew point corresponding with the steel grade after change Steam vapour amount in oxidizing gas.
The present invention is not defined to above-mentioned embodiment, in the case where steel band continuously is carried out into molten metal plating Similarly.
Embodiment
<Embodiment 1>
The continuous fusion zinc plating apparatus recorded using Fig. 1~Fig. 3, make composition composition in terms of quality % and comprising C： 0.001%th, Si：0.01%th, Mn：0.1%th, P：0.003%th, S：0.005%th, Al：0.03% and remainder by Fe and can not The impurity that avoids is formed, make thickness of slab be 0.6~1.2mm, steel band that a width of 900~1250mm of plate, tensile strength are 270MPa (with Under, referred to as steel grade A) with 60~100mpm of plate speed enter fused zinc bath, manufactured fused zinc plated steel sheet.Such as Fig. 2 institutes Show, the 5th pipe arrangement with gas input port is arranged at the side of nose, and the height away from bath face of gas input port is 500mm. According to past operation data, the defects of have studied the dew point in nose in advance and being caused by ash and the defects of caused by oxide-film The defects of rate between relation.As a result as shown in Fig. 6 (A).Based on Fig. 6 (A), the target dew point in nose is determined as -30 DEG C.And And understand, if it is possible to by the dew point control in nose into -30 DEG C ± 4 DEG C or so of scope, then will can be lacked as caused by ash Fall into and suppress into relatively low level with this two side the defects of being caused by oxide-film.
When steel band is by nose, in test example No.1~5, the nitrogen containing vapor/hydrogen mixed gas (table is supplied Mark is the supply of vapor in 1, is existed ".), in test example No.6,7, from gas input port, supply does not contain vapor Nitrogen/hydrogen mixed gas (in table 1 mark for vapor supply, in the absence of ".).The input gas of test example No.1~5 The dew point instrument that dew point determines 32A settings in hole by the dew point in Fig. 2 the 5th pipe arrangement is measured, as shown in table 1.
The temperature of nose internal face when steel band is by nose and the atmosphere temperature management on the top in nose are into the institute of table 1 The value shown.In test example No.6, without the heating of the heater based on the top being arranged in nose outer wall and nose.
Each test example all determines hole by the dew point in the back side of nose center, height 500mm position shown in Fig. 2 The dew point instrument that 32B is set, determine the dew point of the atmosphere in nose with lasting.Also, in each test example No.1~7, based on survey Determine the difference of dew point and target dew point (- 30 DEG C), the stream of input gas is changed in a manner of making measure dew point close to target dew point Amount.The control is carried out by general PID control logic.Table 2 shows the column of the measure dew point of each test example No.1~7 Figure.Moreover, in test example No.1~5, the volume of vapor relative to the whole volume of the input gas in experiment ratio It is shown in Table 1 below as " amount of moisture ", by whole input flows of the gas in experiment by being shown by 1 index of No.5 And it is shown in Table 1 below.
It should be noted that when being bath face dew point immediately above in view of the dew point that should be managed, the position of dew point instrument is original It should be near lower bath face, but according to the present invention, be hardly distributed in nose with dew point, therefore even in height 500mm position finding dew point, it also can accurately grasp the dew point near bath face.It should be noted that steamed producing zinc In the case of the comparative example of gas, in the relatively low position for being 100mm or so away from bath face, the biography that zinc fume is attached to dew point instrument be present The danger in sensor portion, therefore in nose bottom the situation of dew point instrument can not be set more.It should be noted that in example of the present invention In, oxidizing gas uses vapor, therefore apparatus for determination of gas is set to dew point instrument, but is using the oxidisability beyond vapor In the case of gas, need to set the analyzer for detecting the gas certainly.
(evaluation of ratio of defects)
In following method, the defects of have rated the defects of being caused by ash and being caused by oxide-film respective ratio of defects. The presence or absence of each defect judges by visual observation.The size for the defects of can differentiating by visual observation is more than 100 μm or so.Also, By length per 0.5m the defects of incorporation rate be defined as " ratio of defects ", as shown in table 1.Ratio of defects 1% is equivalent to 1/50m.
(evaluation result)
With reference to table 1,2, illustrate evaluation result.No.1 (example) be bath temperature, wall surface temperature and upper temp without The example of temperature difference, dew point, which changes, also there's almost no, as a result, the defects of being caused by ash and the defects of caused by oxide-film All almost do not occur.No.2 (example) is the relatively low example of wall surface temperature, and No.3 (example) is the atmosphere temperature on nose top Relatively low example is spent, but the dew point of the atmosphere in nose can be suppressed into range of management (- 30 DEG C ± 4 DEG C), each ratio of defects Also relatively low state is kept.Moreover, in No.1~3, the input flow of gas can be fully reduced compared with No.5.
In contrast, No.4 (comparative example) is the example that wall surface temperature departs from the scope of the invention, No.5 (comparative example) is nose The atmosphere temperature on portion top departs from the example of the scope of the invention, the dew point of the atmosphere in nose can not be suppressed into range of management (- 30℃±4℃).As a result, the defects of being caused by ash or more producing the defects of caused by oxide-film.No.6 (comparative example) It is not carry out the input of vapor and do not carry out the example of the heating based on heater.In this case, dew point is before and after -40 DEG C The defects of reducing, therefore do not produce the defects of being caused by oxide-film, but being caused by ash very acred life.(compare in No.7 Example) in, without temperature difference, therefore dew point is stable, but is reduced before and after -40 DEG C, therefore is still the defects of being caused by ash Very acred is given birth to.
[table 1]
Table 1
[table 2]
Table 2
<Embodiment 2>
Steel band except substituting steel grade A, composition composition has been used in terms of quality % and comprising C：0.12%th, Si：1.0%th, Mn：1.7%th, P：0.006%th, S：0.006%th, Al：0.03%, remainder is made up of Fe and inevitable impurity, thickness of slab Steel band (the hereinafter referred to as steel grade B for being 780MPa for 0.6~1.2mm, a width of 900~1250mm of plate, tensile strength.), except this with Outside, similarly to Example 1, the defects of having obtained dew point in nose and having been caused by ash and the defects of the defects of caused by oxide-film Relation between rate.As a result as shown in Fig. 6 (B).
Reference picture 6 (A), (B) understand that steel grade A, B all presence can be adequately suppressed the defects of being caused by ash and by aoxidizing The dew point of this two side of the defects of film causes, but steel grade B's is most relatively low just when i.e. target dew point, and also rate is abundant the defects of two sides The dew point of reduction also narrows.It follows that for example when switching to B from steel grade A, it is necessary to accurately become in a short time More dew point of atmosphere.
<Embodiment 3>
It has studied and bath temperature, wall surface temperature and upper temp are set to No.1~5 that table 1 records (example 1~3 and compared Example 1,2) when nitrogen/hydrogen mixed gas containing vapor dew point switching rapid degree.As shown in fig. 7, at 50 minutes Time point switches to -20 DEG C by dew point is put into from -35 DEG C.
Bath temperature, wall surface temperature and upper temp are all set to 450 DEG C by example 1, therefore almost do not produce thermal convection current. Therefore, the variation for determining dew point shows the trace roughly the same with the dew point variation of input gas.Therefore, supply gas is utilized Dew point can directly control dew point in nose, it is therefore very excellent in qualitative control.Example 2,3 and and example 1 compares, and can be changed to turn into by dew point although confirming the In trace delays to the dew point after switching, at 30 minutes or so Dew point is put into, therefore in qualitative control fully.
On the other hand, in comparative example 1,2, after it have switched input dew point, the dew point in nose is also while become Move while continuing gentle rising, even if also being difficult to realize stabilisation after 1 hour.In such a state, it is difficult to should The change of target dew point during to for example switching to B from steel grade A.
Industrial applicibility
According to the present invention continuous molten metal method for plating and continuous molten metal plating apparatus, can suppress in the lump with Caused metal vapors is the non-plating of cause and using the oxide-film in the bath of molten metal face in nose as cause in nose Non- plating.
Label declaration
100 continuous fusion zinc plating apparatus
10 annealing furnaces
12 plating coating grooves
12A fused zincs are bathed
14 noses
The end of 14A noses
16th, 17 heater
18 heat-barrier materials
20 gas supply mechanisms
22A, 22B, 22C, 22D, 22E pipe arrangement
24 valves
26 regulating rollers
28 sinking rollers
30 backing rolls
32A, 32B dew point determine hole
P steel bands

Claims (10)

1. a kind of continuous molten metal method for plating, there is following process：
The process that steel band is continuously annealed in annealing furnace；
To collecting molten metal and the plating coating groove formed with bath of molten metal continuously feeds the steel band after annealing, to described The process that steel band implements metal-plated,
The continuous molten metal method for plating is characterised by,
Nose is arranged on the steel band outlet side of the annealing furnace and set in a manner of end is impregnated in the bath of molten metal, During the space that the steel band is divided from the annealing furnace towards the bath of molten metal by the nose, supplied into the nose Oxidizing gas, and the temperature of the internal face of the nose is turned into more than (- 150 DEG C of plating bath temperature), make the nose The atmosphere temperature on interior top turns into more than (- 100 DEG C of plating bath temperature).
2. continuous molten metal method for plating according to claim 1, wherein,
The oxidizing gas is the steam-laden nitrogen of bag or the steam-laden nitrogen/hydrogen mixed gas of bag.
3. continuous molten metal method for plating according to claim 1, wherein,
The oxidizing force of the oxidizing gas is changed according to operating condition.
4. continuous molten metal method for plating according to claim 2, wherein,
The steam vapour amount in the oxidizing gas is changed according to operating condition.
5. continuous molten metal method for plating according to claim 2, wherein,
The continuous molten metal method for plating also has following process：The nose is studied in advance for each operating condition Pass between interior dew point and the defect level as caused by non-plating for the steel band for implementing metal-plated under this operating condition System, and the target dew point in the nose under the operating condition is determined,
Based on the target dew point determined for each operating condition, to determine the vapor in the oxidizing gas Amount.
6. continuous molten metal method for plating according to claim 5, wherein,
When operating condition switches, based on target dew point corresponding with the operating condition after change, to change the oxidisability gas Steam vapour amount in body.
7. the continuous molten metal method for plating according to any one of claim 3~6, wherein,
The operating condition is composition composition, the annealing conditions in the annealing operation and the bath of molten metal of the steel band Composition in it is at least one.
8. the continuous molten metal method for plating according to any one of claim 3~6, wherein,
The operating condition is the composition composition of the steel band.
9. according to continuous molten metal method for plating according to any one of claims 1 to 8, wherein,
The oxidizing gas is supplied from the both ends of the nose on width of steel band direction.
10. a kind of continuous molten metal plating apparatus, it is characterised in that have：
Annealing furnace, steel band is continuously annealed；
Plating coating groove, house molten metal and formed with bath of molten metal；
Nose, the steel band outlet side of the annealing furnace is arranged on, is set in a manner of end is impregnated in the bath of molten metal, and Divide the space that the steel band continuously fed from the annealing furnace into the bath of molten metal passes through；
Calandria, the top being arranged in the outer wall and the nose of the nose；
Gas supply mechanism, link with the nose；And
Control unit, the calandria and the gas supply mechanism are controlled, oxidizing gas is supplied into the nose, and make institute The temperature of the internal face of nose is stated as more than (- 150 DEG C of plating bath temperature), and makes the atmosphere temperature on the top in the nose be More than (- 100 DEG C of plating bath temperature).
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