JPH0634352A - Fe-plated stainless steel plate and method for measuring attachment quantity of plating - Google Patents

Abstract

PURPOSE:To establish a method of measuring the Fe plating amount on an Fe-plated stainless steel plate in parallel with conducting the Fe plating process. CONSTITUTION:The procedures of measuring the attachment quantity of Fe plating on an Fe-plated stainless steel plate consists of analyzing the stainless steel plate before and after the Fe plating by means of fluorescent X-ray method and then determining two radios, i.e. the ratio Icr<b>/IFe<b> where Icr<b> is the fluorescent X-ray intensity of Cr before Fe-plating and IFe<b> is the corresponding value of Fe, and the ratio Ica<a>/IFe<a> where Icr<a> is the fluorescent X-ray intensity of Cr before Fe-plating and IFe<a> is the corresponding value of Fe. The obtained values are substituted into the following equation, and the Fe-plating attachment quantity W(g/m<2>) is calculated; W=(Icr<b>/IFe<b>-Icr<a>/IFe<a>)/C, where C is a proportional constant determined by the type of steel.

Description

Detailed Description of the Invention

[001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method capable of measuring the amount of Fe plating deposited on a Fe-plated stainless steel sheet in parallel with Fe plating.

[002]

2. Description of the Related Art Although stainless steel sheets are excellent in corrosion resistance and heat resistance, they can be further improved in corrosion resistance and heat resistance by subjecting stainless steel sheets to hot dip plating such as Al. However, the same process as this hot-dip galvanizing of a low carbon steel plating base plate, that is, the rolling oil or rust preventive oil first adhered to the plating base plate surface in the non-oxidizing furnace or degreasing equipment of the continuous hot-dip galvanizing line. the oil etc. is removed, then H ₂ -
The Fe-based oxide on the surface is reduced in an N ₂ atmosphere, and then A
In the process of performing hot dip coating such as l, Cr of the stainless steel sheet is preferentially oxidized at the time of gas reduction and concentrates on the surface, so that wettability with the molten metal is hindered and surface defects such as non-plating occur. Will end up.

Therefore, when hot-dip galvanizing a stainless steel sheet, Fe is previously added to 0.05 in a continuous electroplating line.
After pre-plating up to 5 g / m ² to make it have the same surface texture as the low carbon steel original plate, hot-dip galvanizing is performed in a continuous hot-dip galvanizing line. Since this Fe pre-plating improves the wettability of the stainless steel sheet with the molten metal, in order to inexpensively manufacture the hot-dip stainless steel sheet, the adhesion amount should be minimized within the range where surface defects do not occur. Is preferred.

There has been no conventional method for measuring the amount of adhesion in parallel with Fe plating on a continuous electroplating line. Therefore, a sample is sampled and the Fe plating layer is dissolved with an aqueous nitric acid solution or the like. The weight method was calculated from the weight difference before and after dissolution.

[0095]

However, according to this gravimetric method, the sampling of the sample is limited to the top end of the plating original plate coil, and the adhesion amount in the middle of the coil cannot be grasped. Therefore, safety is expected during plating. The amount of adhesion was large. Therefore, there is a problem that the Fe plating cost becomes high. In addition, since it takes time from the sampling to the determination of the measurement result, there is a problem that even if there is an excess or deficiency of the adhered amount, the adjustment cannot be performed immediately. further,
In this gravimetric method, a continuous electroplating line is arranged on the inlet side of the continuous hot-dip plating line in order to improve productivity, and when Fe pre-plating and hot-dip plating are performed simultaneously, a sample of only Fe pre-plating is sampled. There is also a problem that it cannot be applied because it cannot be done.

[0096]

In view of such a point, the present invention provides a method capable of measuring in parallel with Fe pre-plating, and analyzing a stainless steel plate before and after Fe plating by a fluorescent X-ray method. , of the fluorescent X-ray intensity I _cr ^b and Fe in Fe pre-plating of Cr fluorescent X-ray intensity I _Fe ^b ratio I _cr ^b / I _Fe ^b and after Fe plating of the fluorescent X-ray intensity I _cr ^a and Fe and Cr It is characterized in that the ratio I _cr ^a / I _Fe ^a of the fluorescent X-ray intensity I _Fe ^a is calculated, and these values are substituted into the following formula to calculate the Fe plating adhesion amount W (g / m ² ). W = (I _cr ^b / I _Fe ^b −I _cr ^a / I _Fe ^a ) / C Here, C is a proportional constant determined by the steel type.

[0097]

The fluorescent X-ray method is known as a method for continuously measuring the amount of the deposit while plating the steel plate. This method uses fluorescent X from the plating original plate of the plated steel plate.
When plating different kinds of metal on the plating original plate by the method of measuring the line intensity or the fluorescent X-ray intensity of the main elements that make up the plating layer and then substituting it into the fluorescent X-ray intensity formula to calculate the plating adhesion amount. However, when both the plating base plate and the plating layer contain Fe, such as the Fe-plated stainless steel plate, the fluorescent X-ray intensities from both Fes cannot be separated, so the amount of plating adhesion Cannot be measured.

However, the present inventors have adopted the fluorescent X-ray method for F
The fluorescent X-ray intensities of Fe and Cr were investigated to be applied to the measurement of the amount of Fe plating deposited on the e-plated stainless steel sheet.
It has been found that the fluorescent X-ray intensity of Fe monotonically increases and conversely the fluorescent X-ray intensity of Cr monotonically decreases with an increase in the Fe plating deposition amount. Then, when the fluorescent X-ray intensity ratio of Cr and Fe is examined, it decreases linearly as the Fe plating deposition amount increases, and the relationship can be approximated by a linear expression. It was found that the X-ray method can be applied to the measurement of the amount of Fe plating deposited on the Fe-plated stainless steel plate. The present invention will be specifically described below.

When an Fe-plated stainless steel plate is irradiated with X-rays 1, fluorescent X-rays 2 of Fe and fluorescent X-rays 3 of Cr are generated as shown in FIG.
Is the total of the original stainless steel plate 4 and the Fe plating layer 5 as described above. On the other hand, the fluorescent X-ray 3 of Cr detected is only from the stainless steel plate 4.

However, the relationship between the total of the fluorescent X-ray intensity I _Fe ^a of Fe and the amount of Fe plating deposited and the fluorescent X of Cr
When the relationship between the line strength I _cr ^a and the amount of Fe plating deposited is investigated for each stainless steel sheet type and manufacturing lot,
As shown in FIG. 2, in the production lot, the former monotonically increases as the Fe plating deposition amount increases, and conversely, the latter shows
As shown in (4), it decreases monotonically with an increase in the Fe plating deposition amount. 2 and 3, graphs 6 and 6a
Is SUH409 with 10.5 mass% Cr, graphs 7 and 7a
Is SUH409 of 12 mass% Cr, graphs 8 and 8a are 1
8mass% Cr-8mass% Ni SUS304, Graphs 9 and 9a are 20mass% Cr-10.5mass% Ni SU
S304, the intensity of Fe and Cr X-ray fluorescence I _Fe ^a ,
I _cr ^a is the intensity of Kα rays.

Therefore, if the relations shown in FIGS. 2 and 3 are created for each Fe concentration and Cr concentration of each steel type and made into a calibration curve formula, it is possible to measure the Fe plating deposition amount. is there. However, in order to create a calibration curve formula for each Fe concentration and Cr concentration of the steel type, the Fe concentration and Cr concentration of the stainless steel plate must be individually measured by the chemical analysis method, and the work is enormous. Become.

Therefore, the present inventors newly added the fluorescent X of Cr.
The intensity ratio I _cr ^a / of the line intensity I _cr ^a and the fluorescent X-ray intensity I _Fe ^a of _Fe
Focusing on I _Fe ^a , the data in FIGS. 2 and 3 are arranged, and as shown in FIG. 4, the intensity ratio I _cr ^a / I _Fe ^a is Fe.
Corresponding to an increase in the coating weight, it decreases linearly, and the gradient becomes constant depending on the steel type regardless of the production lot.
That is, if the steel types are the same, the Fe of the stainless steel plate
It was found that the gradient becomes constant regardless of the concentration and the Cr concentration. In addition, in FIG. 4, the graph 6b is 10.5 mas.
SUH409 of s% Cr, Graph 7b is 12 mass% Cr
SUH409, Graph 8b is 18 mass% Cr-8mass
% Ni SUS304, Graph 9b shows 20 mass% Cr-
It is that of SUS304 with 10.5 mass% Ni.

The difference in the gradient depending on the steel type in FIG. 4 is that the detected fluorescent X-ray intensity I _Fe ^a of _Fe is the total of the original plate and the plated layer.
When the Fe concentration of the plating original plate is low as in No. 4, the ratio of the Fe from the plating original plate to the fluorescent X-ray intensity I _Fe ^a is small and the ratio of the Fe plating layer is large. This is because the gradient becomes large when changes. Therefore, in the case of SUS304, the gradient becomes large as shown in graphs 8b and 9b. Conversely, SU
When the Fe concentration of the original plating plate is high as in H409, the proportion of the original plate from the original plating plate is small. Therefore, the gradient is small even if the Fe plating adhesion amount changes, and the gradient becomes small as shown in graphs 6b and 7b.

By the way, the graph of FIG. 4 has the same gradient in the case of the same steel type, and therefore can be expressed by the following regression linear equation for each steel type. In _{^{I cr a / I Fe a =}} I cr-0 / I Fe-0 -C · W ... (1) _{^{where, I cr a / I Fe a}} : after Fe plating Cr and Fe fluorescent X
_Linear intensity ratio I _cr-0 / I _Fe-0 : Fluorescent X-ray intensity ratio of Cr and Fe when Fe coating amount 0 g / m ² W: Fe plating amount by gravimetric method (g /
m ²⁾ C: proportionality constant depending steels

However, this regression linear equation is
The same steel type and the same F because it depends on e concentration and Cr concentration
The fluorescent X-ray intensity ratio I _cr ^a / I _Fe ^a of Cr and Fe also differs depending on the production lot even with the amount of e plating deposited. Therefore, when the Fe coating amount is measured by the calibration curve method using one regression linear equation for each steel type, an error occurs due to the Fe concentration and Cr concentration of the original plating plate.

In order to prevent this error, the fluorescent X-ray intensity ratio of Cr and Fe of the plating original plate before Fe plating is measured, and Cr when the Fe plating deposition amount of 0 g / m ² in the above formula (1) is measured. And the fluorescent X-ray intensity ratio I _cr-0 / I _Fe-0 of _Fe can be obtained, and the regression linear equation corresponding to the Fe concentration and Cr concentration of the plating original plate can be determined. For example, SUH with 10.5 mass% Cr
In the Fe plating using 409 as the plating base plate, the fluorescent X-ray intensity ratio of Cr and Fe before the Fe plating of the plating base plate is measured to be about 0.08, and thus the regression linear equation becomes the graph 6b in FIG.

Therefore, with the Cr of the plating original plate before Fe plating,
The fluorescence X-ray intensity ratio of Fe is I_cr ^b/ I _Fe ^bAs this
I in equation (1)_cr-0/ I_Fe-0Substitute in and arrange about W
Then, the Fe plating adhesion amount W can be measured by the following equation. W = (I_cr ^b/ I_Fe ^b-I_cr ^a/ I_Fe ^a) / C (2)

Next, an example of the case where the continuous Fe plating line is carried out in parallel with the Fe plating will be described. First, the fluorescent X-rays of Fe and Cr to be measured are not particularly limited, but Kα-rays, which have high intensity and are hardly absorbed by a substance, are preferable. The fluorescent X-ray spectroscopic method includes an energy-dispersion method and a wavelength-dispersion method, but the latter method which is excellent in resolution is preferable. The excitation source is also not particularly limited, but X-rays that are easy to handle are preferable.

Fluorescent X-ray intensity ratio I of Cr and Fe of the plated original plate I
Measurement of _cr ^b / I _Fe ^b or Fe fluorescent X-ray intensity ratio after plating of Cr and _Fe I _cr ^a / I Fe ^a, as shown in FIG. 5, the measuring head 11 disposed above the measuring steel 10 Then, the X-ray tube 12 emits the X-ray 1 of the excitation source to the measurement steel plate 10, and the generated fluorescent X-rays (Kα) 13 of Cr and fluorescent X-rays (Kα) of Fe.
14 after being dispersed by the dispersive crystal 15, fluorescence X of Cr and Fe
The line intensity is measured by the detector 16.

As shown in FIG. 6, the measurement heads 11 are arranged on the front and back sides of the continuous electroplating line on the inlet side and the outlet side, respectively.
e The fluorescent X-ray intensities of Cr and Fe before and after the plating are measured.
The measurement is performed by arranging the measurement head 11 so that the measurement positions on the front and back sides are the same before and after Fe plating and traversing it in the plate width direction. Reference numeral 17 is an electrolytic degreasing tank, and 18 is an Fe electroplating tank.

The measuring head 11 is preliminarily input with a proportional constant C of plating base plates of various steel types, a calibration curve formula based on the fluorescent X-ray intensity ratio I _cr ^b / I _Fe ^b of Cr and Fe of the plating base plates, and the like. By connecting to the device 19, the Fe plating adhesion amount is calculated and fed back to the plating condition. It is also possible to continuously arrange a continuous molten metal plating line on the outlet side of the continuous electroplating line.

The stainless steel plate as the plating base plate contains various additive elements and unavoidable impurities in addition to Cr and Fe depending on the steel type, but these do not hinder the measurement except in very special cases. Further, in Fe plating, in order to improve wettability with molten metal during hot dipping, 0.001 to
B may be added in an amount of 0.3 mass% in some cases, and this is also the same.

[0233]

EXAMPLE The measurement head 11 of FIG. 5 was arranged as shown in FIG. 6, and the Fe plating adhesion amount was measured while performing Fe plating on various stainless steel plates under the following conditions, and compared with the measurement value by the gravimetric method. . Samples by the gravimetric method were sampled from random positions in the line direction on both sides and the center part. Table 1 shows the amount of Fe plating deposited by the method of the present invention and the gravimetric method. (1) Plated original plate (A) Steel type SUS304 (18 to 20 mass% Cr, 8 to 10.5 mas)
s% Ni) SUS316 (16-18 mass% Cr, 10-14 mass)
% Ni) SUH409 (10.5 to 12 mass% Cr) SUS444 (18 to 20 mass% Cr) (B) Plate thickness 1.0 mm (C) Plate width 1,000 mm (D) Number of coils Different manufacturing lots for each steel type 5 coils

(2) Fe plating conditions (A) Plating solution composition Ferrous sulfate 300 g / l, sodium sulfate 70 g / l, tartaric acid
1 g / l, boric acid 5 to 50 g / l (B) pH 1.5 to 2.0 (C) Liquid temperature 50 ° C. (D) Current density 5,000 A / m²  (E) Fe plating adhesion amount 0.38 to 5.78 g / m²(Communication
(F) B concentration in the Fe plating layer 0.001 to 0.3 ma
ss% (adjusted by the amount of boric acid added)

(3) Fe plating deposition amount measuring condition (A) X-ray tube tungsten (B) tube voltage 50 kV (C) tube current 40 mA (D) dispersive crystal LiF (E) detector proportional counter (F) measurement Target Cr-Kα ray, Fe-Kα ray (G) Incident angle of excitation X-ray and extraction angle of fluorescent X-ray 6
0 ° (H) Measuring time 1 sec (I) Traversing method While reciprocating the measuring head once every 1 minute in the width direction, measure both sides and the center part (F
e The measurement heads are tuned so that the measurement points on the front and back are the same before and after plating)

[026]

[Table 1]

[027]

As described above, according to the method of the present invention, the amount of Fe plating deposited on the entire length of the stainless steel plate can be measured in parallel with the plating. Even if there is a shortage, it can be adjusted immediately. Therefore, the quality is improved and the Fe plating cost is reduced. Further, it can be applied even when the continuous electroplating line for Fe plating and the continuous hot dip plating line are combined to perform the Fe plating and the hot dip plating at the same time.

[Brief description of drawings]

FIG. 1 shows fluorescent X-rays of Fe and Cr generated when an Fe-plated stainless steel plate is irradiated with X-rays.

FIG. 2 is a graph showing the relationship between the amount of Fe plating deposited on an Fe-plated stainless steel plate and the fluorescent X-ray intensity of Fe for each steel type and manufacturing lot.

FIG. 3 is a graph showing the relationship between the amount of Fe plating deposited on an Fe-plated stainless steel plate and the fluorescent X-ray intensity of Cr for each steel type and manufacturing lot.

FIG. 4 is a graph showing the relationship between the amount of Fe plating deposited on an Fe-plated stainless steel plate and the fluorescent X-ray intensity ratio of Cr and Fe for each steel type and manufacturing lot.

FIG. 5 is a diagram showing a fluorescent X-ray intensity measurement method for a stainless steel plate as an original plating plate and an Fe-plated stainless steel plate.

FIG. 6 is a diagram showing a method for measuring the amount of Fe plating deposited by the method of the present invention on a continuous Fe plating line.

[Explanation of symbols]

1 ... X-ray, 2 ... Fe fluorescent X-ray, 3 ... Cr fluorescent X-ray,
4 ... Stainless steel plate, 5 ... Fe plating layer, 10 ... Measuring steel plate, 11 ... Measuring head, 12 ... X-ray tube, 13 ... Cr fluorescent X-ray, 14 ... Fe fluorescent X-ray, 15 ... Spectroscopic crystal, 1
6 ... Detector, 17 ... Electrolytic degreasing tank, 18 ... Fe electroplating tank, 19 ... Arithmetic processing device,

Claims (1)

[Claims] 1. A fluorescent X-ray of Cr before Fe plating is analyzed by analyzing a stainless steel plate before and after Fe plating by a fluorescent X-ray method.
Ratio I _cr ^b / I _{Fe of the} line intensity I _cr ^b and the fluorescent X-ray intensity I _Fe ^b of _Fe
^b and Fe fluorescence Cr X-ray intensity I _cr ^a and Fe after plating
The ratio I _cr ^a / I _Fe ^a of the fluorescent X-ray intensity I _Fe ^a is calculated, and these values are substituted into the following formula to calculate the Fe plating adhesion amount W (g / m ² ). Method for measuring the amount of Fe plating deposited on an Fe-plated stainless steel sheet. W = (I _cr ^b / I _Fe ^b −I _cr ^a / I _Fe ^a ) / C Here, C is a proportional constant determined by the steel type.