JPH06207296A - Method and equipment for plating strip material with zinc - Google Patents

Abstract

PURPOSE: To stably and uniformly form a Zn-Fe layer on a strip material by measuring the radiation amount on the surface of the strip material on which a zinc layer is formed and executes its heat treatment in a furnace opened at both ends, and controlling calorific value in the heat treatment furnace and completing the reaction of the Zn-Fe layer.

CONSTITUTION: The strip 1 with the zinc layer formed by a zinc coating means (galvanizing means) 4 is carried out through a scraping-off means 7, the furnaces 10, 11 opened at both ends as the heat treatment means 13 and a cooling means 15. At this time, a pyrometer 14 is arranged between the heat treatment means 13 and the cooling means 15 and the radiation amount radiated from the surface (Zn-Fe layer) of the strip 1 is measured. The measured actual value is inputted into a process computer 18 and compared with a reference inputted value, and the calorific values in the furnaces 10, 11 opened at both ends, are adjusted through an automatic control means 19 to complete the reaction of the Zn-Fe layer. By this way, a galvanized strip excellent in the quality having always stable and uniform Zn-Fe layer, is obtd.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to continuous coating of a strip material, particularly a steel strip, with zinc by a continuous treatment with a zinc bath by an electrolytic method or a hot dip galvanizing method, and then Z coating.
Performing heat treatment in a double-ended open furnace to form an n-Fe layer, further on-line control of the zinc layer, and galvanizing strip for controlling the galvanizing process as a function of on-line control parameters and this galvanizing method The present invention relates to galvanizing equipment.

[0002]

2. Description of the Related Art A galvanizing process of this kind for the production of so-called heat treated (galvannealing) galvanized strips, i.e. steel strips coated with a thermally post-treated metal, is described, for example, in EP-A 473. , 154, the galvanized strip is continuously galvanized in a continuous process. Therefore, the strip is formed as a double-ended open furnace for galvannealing and soaking (soaking) after passing through the galvanizing section (zinc bath + extraction system of hot dip galvanizing plant, galvanizing cell of electrolytic galvanizing plant). Is guided into the furnace. This furnace can be, for example, an electric induction furnace or a gas furnace.

[0003]

The galvannealing process converts a pure zinc layer into a Zn-Fe layer by diffusion of iron. Products with different mechanical properties (toughness, strength, etc.) are manufactured depending on the amount of iron component of Zn-Fe alloy, and their application fields (wear resistance, weldability, paintability, corrosion resistance, deep drawing) Characteristic). For example, as described in the above-mentioned EP-A 473,154, the iron component is measured by an appropriate measuring means (for example, X-ray fluorescence, X
Continuous, ie online, by means of line diffraction or other similar technique) and the measurement result is Zn-F of the iron component.
The average value in the thickness direction of the e layer is given. For the quality of the product, it is very important that the Zn-Fe layer has completely finished the reaction, that is, that iron penetrates to the surface of the Zn-Fe layer and forms a stable phase with zinc. The present invention is
By further developing the above-mentioned galvanization method, it is possible to obtain a galvanized strip having a completely reacted layer structure, directly and immediately intervening in the manufacturing process, while minimizing the occurrence of defective products, The purpose is to provide a homogeneous galvanized strip.

[0004]

The process according to the invention, inter alia, automatically incorporates both planned changes in process parameters and unintended changes in these parameters, so that the manufacturing process does not require human intervention. It is always optimized without. According to the invention, the above-mentioned object is to determine the completion of the reaction of the Zn-Fe layer by measuring the radiation dose on the strip surface during or after the heat treatment with at least one pyrometer, To ensure that the reaction is complete at the meter position, it is ensured by varying the calorific value of the double-ended open furnace, which functions as a manipulated variable for the control process as a function of pyrometer power. Preferably,
By arranging a plurality of pyrometers continuously in the transport direction along the strip transport path and performing the measurement, the place (position) at which the reaction of the Zn-Fe layer was completely finished was determined, and By controlling the amount of heat generation, this position is set as a desired position on the strip transport path that functions as a reference input value. According to the preferred operating mode
The value of the iron component of the Zn-Fe layer is determined as another reference input value in addition to the completion position of the reaction.
The set value of the iron component of the bed is compared with the reference input value, and the deviation is compensated by automatic control by changing the calorific value of the double-ended open furnace as the manipulated variable. Temperature control in a double-ended open furnace is determined by the structure of the galvanile layer and thus the mechanical quality of the product, because the diffusion process of iron into the zinc layer (diffusion coefficient of iron) largely depends on the temperature and the heat treatment time in the furnace. Have a positive effect.

By the way, in the temperature detection of the strip in the area of the galvannealing furnace, there is no non-contact type inexpensive measuring means capable of detecting the temperature sufficiently accurately under the condition of the inside of the furnace. Above is impossible. In an embodiment of the invention, the temperature in the furnace is adjusted indirectly from the heating value, thereby ensuring a very uniform quality of the galvanized strip. Preferably, the control is performed by a computer that stores the control error and by a closed loop control circuit that executes various instructions to control the heating value of the double-ended open furnace. The computer measures the dimensions of the strip, the chemical composition and structure of the base material of the strip, the thickness of the zinc layer, the composition ratio of the zinc bath, such as the amount of aluminum component, the strip speed, and the strip temperature at the entrance of the double-ended furnace. Control is executed by inputting various parameters such as room temperature. In a preferred embodiment of the present invention, the calorific value of the double-ended opening furnace and the temperature inside the furnace are individually adjustable in each heating zone. Iron-
When the amount of iron component in the zinc alloy or the amount of surface radiation is different in the width direction of the strip, it is preferable to make the amount of heat generation different in each region in the width direction of the strip.

In another embodiment of the present invention, the heat generation amount can be adjusted differently in each heating zone continuously arranged in the strip conveying direction, and the heating rate of the strip and a predetermined temperature can be adjusted. The soaking time is variable to achieve optimum strip quality. More suitably, the radiation amount and / or the iron component amount may be measured at a plurality of positions in the strip width direction. The equipment for carrying out the production method according to the present invention comprises a strip transport means for continuously transporting the strip along the transport path, a heat treatment means for continuously arranging the strip constituted by a galvannealing furnace, and a strip transport path on the strip transport path. The measuring means is arranged in or downstream of the heat treatment means and comprises a measuring means for controlling the zinc layer, said measuring means comprising at least one pyrometer, the pyrometer being connected to the automatic control means, said automatic control means Is connected to the heating means of the heat treatment means via a control line. In a preferred embodiment, a plurality of pyrometers are arranged at appropriate intervals in the strip transport direction, the pyrometers are connected to automatic control means, and a plurality of measured values are input to the automatic control means. ing. The automatic control means is preferably connected to a process control computer in order to incorporate and control a plurality of parameters which influence the quality of the paint strip. In order to determine the iron content in the Zn-Fe layer, an additional measuring means for measuring the iron content in the Zn layer is provided for monitoring the heat treatment means and via the control line the heat treatment means Connected to the automatic control means connected to the heating means.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As is apparent from FIG. 1, a galvanized steel strip 1 has a strip transport path from a take-out station (not shown) to an take-in station by means of strip carrying means consisting of a plurality of strip guide rollers 2. 3 is continuously conveyed. Strip transport path 3
Along the way, the steel strip is first coated with zinc 4
Reach In the present embodiment, the zinc coating means 4 comprises hot dip galvanizing means. This galvanizing means comprises a zinc bath 5 and a zinc bath 5 in the strip transport direction 6.
And stripping means 7 for ensuring a constant zinc layer of uniform thickness across the width of the strip. Next, the steel strip 1 includes a thermal type thickness measuring device 8 and a temperature measuring means 9 for measuring the thickness of the zinc layer, and the heat treatment means 1 comprises two end-opening furnaces 10 and 11.
Introduced in 3. In a first double-ended furnace 10, the steel strip 1 is first heated to the required galvannealing temperature. The steel strip 1 is maintained at a constant galvanile temperature in another double-ended open furnace 11 arranged in the next stage.

Steel strip 1 from the second open-ended furnace 11
Then, the radiation amount of the completely galvannealed steel strip 1 is measured by the pyrometer 14. Subsequently, the cooling means 15 is arranged along the strip conveying means. The strip conveying path 3 downstream of the heat treatment means 13 is provided with another measuring means 16 for measuring the amount of iron component in the Zn-Fe layer. Preferably, this measuring means is a double arrow in the figure. As indicated at 17, the strip is displaceable in the width direction so that the measurement can be performed at various positions in the width direction. It is preferable that this measuring means be capable of performing measurement by a measuring method using X-rays. An automatic controller 19 in combination with a process control computer 18 cooperates with a heat treatment means 13 composed of two double-ended open furnaces 10 and 11, as shown by a double-headed arrow 20, to adjust the heat generation amount of each furnace.

The operation of the above equipment is as follows. Due to its high affinity for iron, the aluminum dissolved in the zinc bath 5 first forms an iron-aluminum layer (Fe ₂ Al ₅ ) on the steel strip, whereby the iron component of the steel strip 1 and the zinc Prevent layer reaction.
The system consisting of the steel strip 1, the Fe-Al layer and the liquid zinc layer enters the first double-ended open furnace 10, where there
It is heated to a temperature in the range of 700 ° C. In the second open-ended furnace 11, the steel strip 1 is maintained at a predetermined temperature or heated to a higher temperature. The pure zinc layer is converted into a zinc-iron layer in the process of diffusion of iron into the zinc layer induced thereby. As a result, the Fe-Al barrier layer formed first in the zinc bath is destroyed by Zn-Fe growth at the grain boundaries of the substrate, and Zn-F
Initiate mushroom-shaped growth of the e-complex. Depending on the iron content, different metallographic phases with different properties are formed.

The most important phases are listed in the table below. ─────────────────────────────────── Phase% Fe Crystal structure Hardness (MPa) η <0.03 Hexagonal system 300-500 ζ 5-6 Monoclinic system 1800-2700 δ 7-12 Hexagonal system 2500-4500 γ 21-28 Cubic system 4500-5500 ────────────── ────────────────────── As is clear from the above table, as the iron content increases, the phases become harder and brittle. This means that a larger amount of wear is generated in the subsequent deformation (for example, deep drawing), which means that the adhesive force of the Zn—Fe layer is significantly weakened. In the case of electrolytic galvanizing equipment, the treatment process is the same, but the amount of aluminum component is not important. For product quality, Zn-F
It is of utmost importance that the e-layer is completely reacted, ie the zinc forms a stable phase with iron at the surface of the steel strip 1 coated by iron infiltration during the diffusion process described above.

Since the Zn-Fe layer rapidly changes as soon as the Zn-Fe layer contains iron as the zinc layer is converted into the Zn-Fe layer, the radiation dose of the pyrometer 14 cannot be measured. It is necessary for the evaluation of the galvanized layer. Pyrometer 1
4 is within the range of the heat treatment means 13 (for example, the galvanizing furnace 1
(Between 0 and the soaking furnace 11) or in the subsequent stage. This measurement is based on the surface of the steel strip 1, namely its Zn--F.
It serves to give information about the radiant energy emitted from the e-layer, which is a function of temperature and the radiative coefficient of the surface layer. The emission coefficient of pure zinc surface is less than 0.2, while that of fully reacted Fe-Zn surface is about 0.6. If the Zn-Fe layer has not completely reacted at the position of the pyrometer 14, the furnace 1 with open ends is shown.
The calorific values of 0 and 11 are connected to the process control computer 18, and the measured value of the pyrometer is input to the automatic control means 1.
The pyrometer is controlled by 9 to increase until it detects a complete reaction. In this case, the calorific value is an operation variable amount of the control process. When the complete reaction takes place, that is, when the iron penetrates into the surface of the zinc layer, the strip transport direction 6 in which the complete reaction is realized due to the large change in the radiation amount.
Can recognize the site. This is possible, for example, by arranging two or more pyrometers in the strip transport direction 6 at suitable intervals. Zn-F
By knowing the sudden rise in the radiation dose due to the complete reaction of the e-layer, and by measuring the radiation intensity with the pyrometer 14,
In the strip transport path 3, the position where the Zn-Fe layer has completely reacted can be detected.

The calorific values of the double-ended open furnaces 10 and 11 are controlled by the automatic control means 19 so that a complete reaction is realized at a predetermined preferable position. Another method of recognizing the position where a complete reaction has occurred in the strip transport direction may be to compare the pyrometer measurements with some thermal model calculations. For this reason, the pyrometer measurement was performed the first time based on the empirically determined degree of change in the radiation amount of the pure zinc layer, and the second time on the empirically determined completely reacted Zn-F.
It is performed based on the degree of change in the radiation amount of the e layer. The result of this calculation gives two different pyrometer temperature values for the strip running according to different radiation coefficients. By comparing these two values obtained by a model calculation of the temperature at the time of entry of the steel strip into the heat treatment means and the temperature which can be calculated from the calorific value of the heat treatment means in parallel for the strip part in question It can be found which of the pyrometer temperature values corresponds to the calculated temperature. This temperature value is regarded as the correct temperature of the running steel strip 1. The associated radiation dose will indicate whether the steel strip is still in the pure zinc layer or the layer has completed the reaction. The heat generation amount of the heat treatment means is controlled at the position of the pyrometer 14 so that the reaction is completed.

Although the iron component of the Zn-Fe layer cannot be directly and immediately derived only by information on the complete reaction of the Zn-Fe layer, the amount of iron component is nevertheless very important for the properties of the product, Two information quantities, namely
It is effective to adjust the calorific value distribution over the entire length of the heat treatment means based on the combination of the iron content of the Zn-Fe layer and the determined emissivity. In order to adjust the optimum iron content, ie the iron content which allows the deformation of the galvanized steel strip 1 without any problems, the iron content of the Fe-Zn layer is in addition to the complete reaction control and determination. Therefore, it is advantageous to determine by an on-line X-ray fluorescence measurement with the measuring means 16, which is preferably done over the entire width and the entire length of the strip. The actual value of the iron content of the Zn-Fe layer is the Zn-Fe preset as the reference input.
The iron component value of the layer is compared with the automatic control means 19.
The deviation that may occur is compensated for by the automatic control means 19 by changing the amount of heat generation as the operating variable of the first and second double-ended open furnaces 10, 11. For example, when the measured amount of iron component is less than the desired value, the calorific value of the double-ended open furnace becomes zero or falls below a preset value (dead zone), as described below with reference to FIG. Will be increased up to.

Curve I in FIG. 2 shows the relationship between the iron component of the Zn--Fe layer and the amount of heat generation. This is determined empirically and is applied to the control computer (automatic control means 19), for example as a formula in the form of internal correlations or tables. If the steel strip 1 behaves to exactly match curve I,
The preferred value of the iron component Fe ₁ (point A) is achieved by adjusting the heating value to P ₁ . If the steel strip 1 behaves a little differently as shown by the curve II due to, for example, fluctuations in ambient temperature, fluctuations in the transformer output for electric heating of a double-ended furnace, and other external factors, the iron content is set to the set value Fe. _The value Fe ₂ (point B) deviates from ₁ . Therefore, the calorific value can be calculated, for example, as a function of the degree of increase dp / dFe at the point A ′ of the curve I by the equation k × (dp / d
Fe) × ΔFe. Gain factor k
When is 1, the changed calorific value is input at P ₂ in the figure. As a result, the iron component has a more preferable value (point C)
Becomes The control is (Fe component ≠
Fe ₁ ) is performed.

Irregular iron profile in the strip width direction is caused by various causes: 1) uneven feed thickness 2) strip lateral bulge 3) strip profile 4) strip width direction Non-uniform heat generation 5) Non-uniform temperature distribution in the strip width direction at the strip entrance to the galvanizing furnace. First, the coating thickness is adjusted uniformly within a narrow tolerance in the strip width direction (known layer thickness control process). Despite the uniform layer thickness in the strip width direction, the non-uniform distribution of the iron component in the strip width direction is caused by the causes 2) to 5). The uneven heat input to the steel strip 1 results in an iron component distribution as shown in FIG. 3, for example, even if the coating thickness is uniform in the strip width direction. What is required is a coating thickness and iron component distribution that are as uniform as possible in the strip width direction (and length direction).

Mainly by reducing the heating value of the double-ended opening furnaces 10, 11 in the heating zone 12 acting in the width direction of the strip, or by increasing the heating value in the heating zone 12 'mainly acting on the edge of the strip. Thereby, the uniformity of the iron component in the width direction of the strip can be improved and a complete reaction over the entire width of the strip can be guaranteed. Several further factors are taken into account by the process according to the invention: 6) Zinc layer thickness The diffusion path and the structure of the coating also change with the layer thickness. Under equal furnace calorific conditions, thinner layer thickness (thinner coating layer) results in higher iron content. This is also seen at the edges of the strip, which may have different layer thicknesses than the central region of the strip. 7) Aluminum component in the zinc bath The aluminum dissolved in the zinc bath 5 adheres, inter alia, to the following two layers: a) The boundary layer between the iron substrate and the zinc layer: its high affinity for iron. Due to its properties, in a zinc bath the aluminum first forms a Fe ₂ Al ₅ barrier layer, which is a brittle Z
Prevents premature growth of the n-Fe phase. This barrier layer must be destroyed in the galvanizing process to initiate zinc-iron growth. b) Surface oxide layer: Most of the aluminum is present as Al ₂ O _{3 on} the surface of the zinc layer.

8) The speed at which the steel strip 1 is moved in the installation: this is the end opening furnace 11, 12 of the steel strip 1.
Influences the time of presence (soaking time) within and thus the temperature control of the steel strip 1. Therefore, the reaction time changes, which in turn affects the iron content. 9) Chemical composition and structure of steel strip 1: Zn-F
Since the growth of the e-composite first begins at grain boundaries, the reactivity depends on the composition and structure of the substrate. 10) Additionally, the strip dimensional parameters influence the heat input and thus the diffusion conditions. According to the present invention, all the factors that affect the iron component amount as described above can be taken into consideration by inputting all the data that determines these factors into the control computer 18, and the automatic control means 19 causes the heat treatment means. Thirteen
These factors are taken into account by connecting an automatic control means 19 to the control computer 18 in determining the heating value of the.

Intentional changes in the process parameters, such as changes in the dimensions of the steel strip 1, changes in the chemical composition of the steel strip 1, changes in the thickness of the zinc layer, changes in the transport speed of the steel strip 1, etc. , Is output to the control computer 18 in order to consider (determine) the heat generation amount of the heat treatment means.
Each of the control methods described above is operable within a closed control circuit. Operable variables of the heat treatment means 13 are calculated by the computer of the automatic control means 19 from the deviation between the measured value, the set value for the radiation amount and the actual value, and further, if desired, the iron content. In the calculation, high temperature measurement (layer thickness measurement) and / or temperature measurement downstream of the double-ended opening furnace 10, strip speed, heat treatment means 13
Various measurement values from the heat input in each zone of
Required to increase the accuracy of the control process, as indicated by 0,21. The calculation of the manipulated variable is performed using a certain control model, and the model can be changed according to the measuring device and control means used in each facility. In a specific configuration of an equipment, the control model is described by model parameters. These model parameters differ depending on different base materials, strip size specifications, the amount of aluminum components in the zinc bath, etc. These base material, strip size specifications, and the amount of Al component in the zinc bath are transmitted to the control computer 18 by a superset computer (for example, a production planning computer) or an external input unit. These data are transmitted to the computer of the automatic control means 19 together with the set values applied to the product to be manufactured (see arrow 22). The computer of the automatic control means 19 calculates each control command by considering these model parameters of the control model. Opening furnace at both ends 1
Depending on the structure of 0 and 11, the total calorific value, the calorific value in each furnace part (zone in the length direction of the strip),
It is adjusted within a predetermined limit range. As shown in FIG. 3, F that may be generated despite the uniform thickness of the Zn--Fe layer.
Since it is possible to compensate for the deviation of the e component, if the distribution of the heat input of the strip, that is, the calorific value of the double-ended open furnaces 10, 11 in the strip width direction can be adjusted within a predetermined control range, it is It is advantageous.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a facility for galvanizing a strip.

FIG. 2 is a graph showing the dependence of iron components on the amount of heat generation.

FIG. 3 is a graph showing changes in the iron component in the Zn—Fe layer in the strip width direction.

FIG. 4 is a graph showing the dependence of the radiation dose on the soaking time.

[Explanation of symbols]

1 ... Strip, 5 ... Zinc bath, 7 ... Scraping means, 8 ...
Heat thickness measuring means, 10, 11 ... Both end opening furnace, 13 ... Heat treatment means, 14 ... Pyrometer, 15 ... Cooling means, 19 ... Automatic control means, 18 ... Process computer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Josef Fadel Austria, Ar-4493 Wolfern, Stifterstraße No. 6 (72) Inventor Alois Stattlebauer Austria, Ar-4040 Linz, Asan Gerweg 20 (72) ) Inventor Klaus Zemann Austria, Ar-4020 Linz, Croatengasse No. 33

Claims (14)

[Claims] 1. A method of galvanizing a strip material such as a steel strip having a strip surface and conveyed along a strip conveying path, the strip surface being formed by a zinc bath used in an electrolytic method or a hot dip galvanizing method. Is continuously coated with zinc to form a zinc layer on the strip, the strip having the zinc layer is heat-treated in a double-ended open furnace having a heating means, and the zinc layer is controlled by online control to perform the galvanizing process. At least one pyrometer for measuring the amount of radiation emitted on the strip surface during or after the heat treatment and providing an output for determining the completion of the reaction of the Zn--Fe layer in an on-line controllable system. Is set as a function of the pyrometer output, and the calorific value of the double-ended opening furnace is adopted as the manipulated variable in the control process. Gyoshi, zinc plating of the strip material, characterized in that the reaction of the Zn-Fe layer is to be completed at the pyrometer position. 2. A plurality of pyrometers are continuously arranged along the strip conveying direction to identify the reaction completion position of the Zn—Fe layer and control the calorific value of the double-ended furnace. 2. The galvanizing method for strip material according to claim 1, wherein the specified reaction completion position is set as a desired position on the strip transport path with the first reference input value. 3. The Zn—Fe layer has a certain actual iron content, and the Zn—Fe layer has a second reference input value to be compared with the actual iron content. The value of a certain iron content is determined, the deviation between the actual iron content and the reference input value of the iron content is detected, and the above-mentioned deviation is obtained by changing the calorific value of the double-ended open furnace as the manipulated variable. The method of galvanizing a strip material according to claim 1, further comprising an automatic control means for compensating for the above. 4. A closed control circuit and a computer for performing the control are further provided, and the computer stores the deviation and executes a command to control the heat generation amount of the double-ended open furnace. The galvanizing method of the strip material according to claim 3. 5. The computer includes data on dimensions of the strip material, data on at least one of the chemical composition and structure of the base material of the strip, thickness of zinc layer, composition of zinc bath, etc. of zinc component. 5. The galvanizing method for strip material according to claim 4, wherein the strip transport speed is used as a control factor. 6. The zinc plating of strip material according to claim 5, wherein additional parameters such as strip temperature and room temperature at the inlet of the double-ended opening furnace are input to the computer as control factors. Law. 7. The double-ended open furnace comprises a plurality of heating zones, and the calorific value of the double-ended open furnace and the temperature inside the furnace are adjusted differently for each individual heating zone.
Zinc plating method for strip material described in. 8. The galvanizing method for a strip material according to claim 7, wherein the heating zones are arranged adjacent to each other in the width direction of the strip material. 9. The galvanizing method for a strip material according to claim 7, wherein the plurality of heating zones are continuously arranged in a transport direction of the strip. 10. The galvanized strip material according to claim 7, wherein the radiation amount and the iron component are measured at a plurality of locations arranged at intervals in the width direction of the strip. Law. 11. A facility for galvanizing a strip material such as a steel strip having a strip surface, the strip transport means for guiding the strip along the strip transport path, and the strip disposed on the strip transport path. It consists of a zinc coating means for continuously coating the strip surface with zinc to form a zinc layer on it, and a double-ended opening furnace located downstream of the zinc coating means and designed as a galvannealing furnace, including a heating means. In a galvanizing installation of the type including means and a first measuring means for measuring the zinc layer, which is arranged inside or downstream of the heat treatment means and on the strip transport path, at least one high temperature constituting the measuring means Meter and at least one pyrometer connected to the automatic control means, and the automatic control means is a heating means of the heat treatment means. Galvanizing equipment and a control line connected to. 12. The galvanizing facility according to claim 11, wherein a plurality of pyrometers are continuously arranged in the strip transport direction and are connected to the automatic control means. 13. The galvanizing facility according to claim 11, further comprising a process computer connected to the automatic control means. 14. Further comprising second measuring means arranged downstream of said heat treatment means for measuring the amount of iron component of the zinc layer, said second measurement means heating said heat treatment means via a control line. The galvanizing equipment according to claim 11, wherein the galvanizing equipment is connected to an automatic control means connected to the means.