JPH0545305A - Method for measuring alloying degree of alloyzinc-plated layer - Google Patents

Abstract

PURPOSE:To make it possible to measure the alloying degree of an alloyzinc- plated layer at excellent accuracy in a practical alloying region. CONSTITUTION:The strength of the diffraction line of the specified phase in a plated layer, whose crystal-face intervals correspond to 1.222+ or - 0-005Angstrom , 1.259+ or -0.005Angstrom A, 1.301+ or -0.005Angstrom 1.311+ or -0.005Angstrom and 1.598+ or - 0.005Angstrom , is measured. Thus, the relation curve (calibrating curve) having the excellent correlation with the alloying degree is obtained. The alloying degree of the alloy-zinc-plated layer is obtained based on the relation curve and the actually measured value of any of the following ratios: the ratio of the strength of the diffraction line of the specified alloy phase wherein the crystal-face intervals correspond to 1.222+ or -0.005Angstrom and 1.259+ or -0.005 Angstrom , the ratio of the strength of the diffraction line of the specified alloy layer wherein the intervals correspond to 1.301+ or -0.05Angstrom and 1.259+ or -0.05Angstrom and the ratio of the strength of the diffraction line of the specified alloy phase wherein the intervals correspond to 1.598+ or -0.005Angstrom or 1.311+ or -0.005Angstrom and the strength of the background.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the degree of alloying of an alloyed galvanized layer, and more particularly to the alloying of an alloyed galvanized layer used for on-line analysis required in the production of galvannealed steel sheet. Degree measuring method.

[0002]

2. Description of the Related Art The volume fraction of each alloy phase in an alloyed galvanized layer is shown in FIG. 6 (Kawasaki Steel Technical Report, 18 (1986) 2,
p. It is known that the degree of alloying has a good correlation as shown in 31). On the other hand, there is an analysis method called a so-called X-ray diffraction method in which a crystal phase in a sample is identified by utilizing a diffraction phenomenon that occurs when a crystal is irradiated with X-rays having good parallelism. This X-ray diffraction method is originally a means for structural analysis, but X-rays diffracted by the individual alloy phases in the alloyed galvanized layer are used.
Since the intensity of the line has a correlation with the volume fraction of the alloy phase, the degree of alloying can be known by measuring the diffraction line intensity of the specific alloy phase. However, since the diffraction line intensity is a function of not only the degree of alloying but also the coating weight, the effect of the coating weight should be corrected, or the relationship curve between the alloying power and the diffraction line intensity for each coating weight, that is, the calibration You have to use different lines (Kawasaki Steel Technical Report, 18 (1986) 2, p. 3)
1). Here, the degree of alloying and the amount of plating adhered are determined by a chemical analysis method such as atomic absorption and ICP emission spectroscopy in which the metal components contained in the plating layer such as Zn and Fe in this solution are dissolved by acid. Is obtained by doing.

However, since the diffraction lines of each alloy phase often overlap with each other, in order to analyze the alloying degree online by this method, the correlation between the alloying degree and the diffraction line intensity is good, and moreover, the measurement accuracy is improved. It is necessary to select a diffraction line with extremely high intensity from a practical diffraction angle range. The practical diffraction angle (2θ) range here means a range in which flapping of a steel sheet during rolling and thermal influence from the steel sheet are small, and 2θ> 80 ° (Cr tube as X-ray tube). When the crystal is used, the crystal plane spacing is d <1.78Å) (JP-A-52)
-21887).

Heretofore, as diffraction lines to be noted that satisfy the above conditions, the (633) plane of the Γ phase, the (103) plane of the δ ₁ phase, and d = of the ζ phase
Diffraction lines with a surface of 1.26Å have been reported (Kawasaki Steel Technical Report, 18 (1986) 2, p.31; Nisshin Steel Technical Report,
36 (1977), p. 40; Japanese Patent Publication No. 56-12314
Publication). Then, these Γ-phase (633) planes and δ _1- phase (1
In order to avoid the influences of flapping of the steel sheet and fluctuations of incident X-ray intensity, the alloying degree analysis of the plating layer using the diffraction line of the d = 1.26Å plane of the 03) plane and the ζ phase should be performed with these influences. The values shown in Formula 1, Formula 2 or Formula 3 that are hard to receive and have good correlation with the alloying degree, that is, the estimated intensity of the diffraction line intensity I _P and the background (hereinafter referred to as BG) at the diffraction line position, or The ratio with the BG measurement intensity I _B in the vicinity of the diffraction line position is used (Kawasaki Steel Technical Report, 18 (1986) 2,
p. 31; CAMP-ISIJ, 3 (1990) p. 1
570).

[0005]

[Number 1] _{{I P (Γ) -I B} (Γ)} / I B (Γ)

[0006]

[Number 2] gamma value _{≡1-I B (Γ) /} I P (Γ)

[0007]

Equation 3] zeta value _{≡1-I B (ζ) /} I P (ζ) alternative to such respective ratios, as further shown in expression 4 for improving the correlation between the alloying degree two The intensity ratio of the diffraction lines of the seeds, that is, the Z value is used for the alloying degree analysis (Nisshin Steel Technical Report, 36 (1977), p. 40;
-12314).

[0008]

Equation 4] Z value _{≡ {I P (ζ) -I} B (ζ)} / {I P (δ 1)
−I _B (δ ₁ )}

[0009]

However, among the conventional alloying degree measuring methods described above, in the method using the Γ value, the ζ value and the Z value shown in the equations (2), (3) and (4),
There is no report on the accuracy of analysis σ _d , which means the difference between the wet chemical analysis value (reference value) and the X-ray analysis value shown in the following formula 5, and the applicable alloying degree range is 8 It is estimated to be 0.5 to 17%, 8.5 to 11%, and 7 to 14%, and cannot be applied alone to the practical alloying degree range (7 to 14%) except the Z value.

Further, the intensity ratio {I _P (Γ) −I shown in the equation 1 is used.
_{B (Γ)} / I B} (Γ) measuring method according to the accuracy sigma _d While applying alloying gamut is wide are estimated to 4-15% 0.6
Since it is not a sufficiently small value such as%, it was not a satisfactory measurement method used for online alloying degree control. The reason why this accuracy σ _d is not good is that the rate of change in the volume fraction of the Γ phase with respect to the alloying degree (the slope of the curve in FIG. 6) is small, so that the Γ phase The sensitivity may be insufficient if the diffraction intensity of the Γ phase having a correlation with the volume fraction is used.

[0011]

[Equation 5]

The present invention has been made in view of the above problems, and can be applied to a practical alloying degree range of an alloyed galvanized steel sheet and has a good accuracy σ _d. It is intended to provide a method for measuring the degree of alloying of a plating layer.

[0013]

In order to achieve the above object, the method for measuring the degree of alloying of an alloyed zinc-plated layer according to the present invention is a method of applying X-rays to a galvanized steel sheet and then alloying the plated layer. In the method of irradiating to measure the alloying degree of the plating layer, crystal plane intervals of the alloy phases in the plating layer are 1.222 ± 0.005Å and 1.259 ± 0.0.
The ratio of the diffraction line intensities of the specific alloy phase corresponding to 05Å, or 1.301 ± 0.005Å and 1.259 ± 0.005
Å is characterized by calculating the degree of alloying using the ratio of the diffraction line intensity of a specific alloy phase, and the method for measuring the degree of alloying of an alloyed zinc-plated layer according to the present invention is a galvanized steel sheet. In the method of irradiating the plated layer which has been subjected to the alloying treatment with X-rays to measure the degree of alloying of the plated layer, the crystal plane spacing of the alloy phases in the plated layer is 1.598 ±
The alloying degree is calculated by using the ratio of the diffraction line intensity of the alloy phase corresponding to 0.005Å or 1.311 ± 0.005Å and the BG intensity.

[0014]

1 is a schematic view of a parallel beam optical system X-ray diffractometer used for carrying out the method for measuring the degree of alloying of an alloyed zinc plating layer according to the present invention.
Is a Cr tube, S ₁ and S ₂ are solar slits with an opening angle of 1.2 °, F is a V filter having a thickness of 20 μm, and 12 is a counter tube. As shown in FIG. 1, when the alloyed zinc-plated steel sheet 11 as a sample is irradiated with X-rays having good parallelism, alloy phases such as Γ, δ ₁ and ζ that form the plating layer of the alloyed zinc-plated steel sheet 11 are formed. The X-rays elastically scattered on the crystal plane inside are observed only in the direction 2θ peculiar to the alloy phase and the crystal plane with respect to the incident X-ray. This 2θ is given by the following equation 6 depending on the crystal plane spacing d and the type of tube target.

[0015]

2 dsin θ = λ where λ is the wavelength of the characteristic X-ray generated from the Cr tube S in FIG. 1, for example.

The X-ray diffraction line intensity observed as described above has a positive correlation with the volume fraction of each alloy phase in the galvannealed layer, and the volume fraction and alloying degree of each alloy phase. Has a correlation as shown in FIG. 6, the degree of alloying of the galvannealed layer can be estimated by measuring the diffraction line intensity. However, since the diffraction line intensity is also a function of the coating amount, the alloying degree can be obtained by properly using the relationship curve (calibration curve) between the alloying degree and the diffraction line intensity for each coating amount.

However, the measurement of the calculation of the alloying degree based on the Γ (633) diffraction line intensity is likely to involve an error as described above, and for the same reason, the alloying using the ζ value calculated from the diffraction line intensity of the ζ phase is performed. The degree calculation is also subject to errors. On the other hand, in the practical alloying degree region (7 to 14%), δ ₁ (103) peak and d = 1.268 ± 0.005Å seen near the high diffraction angle side
Since there is a large overlap with the peak of, the alloying degree calculation using the Z value calculated from the δ ₁ (103) diffraction line intensity is likely to involve an error. For this reason, a good correlation cannot be obtained between the diffraction line intensity ratio and the alloying degree expressed by the equations (1) to (4), which is one of the causes of lowering the measurement accuracy.

The present inventor has found that the rate of change of the diffraction line intensity ratio Γ / ζ with respect to the degree of alloying is large, and therefore the intensity ratio Γ / ζ is large.
Fig. 6 shows that the accuracy of alloying degree measurement is improved by using
1.15 to find the diffraction lines of the Γ phase and ζ phase.
The relationship between the intensities of 14 diffraction lines and the degree of alloying observed in the range of Å <d <1.78Å (the aforementioned practical d range) was investigated. As a result, the diffraction line corresponding to d = 1.301 ± 0.005Å was determined to be Γ (4
44) and the intensity ratio Γ (633) / ζ
(D = 1.259 ± 0.005Å), Γ (444) / ζ (d
It was found that = 1.259 ± 0.005Å) has a better correlation with the alloying degree than the conventional example. Furthermore, d =
1.598 ± 0.005Å, 1.311 ± 0.005Å
It has been found that the diffraction lines corresponding to (1) have a good correlation with the degree of alloying, as compared with the conventional example, because the diffraction lines of these two have a large overlap and a large intensity.

According to the method for measuring the degree of alloying of the alloyed galvanized layer according to the present invention, the diffraction line intensity I _P corresponding to Γ (633) or Γ (444) and d = 1.259 ± 0. 005
The values R ₃ and R ₄ defined by the following equations 7 and 8 are obtained as a ratio with the diffraction line intensity of the ζ phase having a crystal plane of Å, and R ₃ or R ₄ and the degree of alloying are calculated. A well-correlated relationship curve (calibration curve) can be obtained. Furthermore, the crystal plane spacing d is 1.59.
8 ± 0.005Å or 1.311 ± 0.005Å as the ratio of the diffraction line intensity I _P and the BG intensity I _B of the alloy phase, the value R ₁ defined by the following formulas 9 and 10 , R ₂ are obtained, and similarly, a calibration curve having a good correlation with the alloying degree is obtained. Therefore, the degree of alloying of the galvannealed layer can be obtained with good accuracy from the measured values of R ₃ , R ₄ , R ₁ and R ₂ . The BG intensity I _B is 2θ between the diffraction lines.
A value calculated by interpolating the BG intensity at the position into the diffraction line position,
Alternatively, any of the BG measurement intensities near the position of the diffraction line may be used.

[0020]

## EQU7 ## R ₃ ≡I _P (Γ (633)) / I _P (ζ (d = 1.25
9 ± 0.005Å))

[0021]

Equation 8] _{R 4 ≡ {I P (Γ} (444)) - I B (Γ (444))} /
_{{I P (ζ (d =} 1.259 ± 0.005Å) -I B (ζ (
d = 1.259 ± 0.005Å)}

[0022]

Equation 9] _{R 1 ≡1-I B (d} = 1.598 ± 0.00
5Å) / I _P (d = 1.598 ± 0.005Å)

[0023]

Equation 10] _{R 2 ≡1-I B (d} = 1.311 ± 0.00
5Å) / I _P (d = 1.331 ± 0.005Å)

[0024]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the method for measuring the degree of alloying of an alloyed zinc plated layer according to the present invention will be described below with reference to the drawings. Prior to determining the degree of alloying of the galvannealed layer, a calibration curve was first created using a sample for creating a calibration curve. As a sample for making a calibration curve, alloying degree 7-
A hot-dip galvanized steel sheet was used as a sample for preparing a calibration curve having 14% and a coating weight of 30 to 80 g / m ² (one side).
Heat treated in salt bath at ~ 500 ° C for various times 130
Points were used. As the X-ray diffractometer, the X-ray diffractometer of the parallel beam optical system shown in FIG. 1 was used, and the crystal plane spacing d was 1.222 ± 0.005Å under the conditions shown in Table 1.
1.259 ± 0.005Å, 1.301 ± 0.005
Å, 1.311 ± 0.005 Å, and 1.598 ± 0.
Diffraction line intensity I _{P of} alloy phase corresponding to 005Å and BG
The intensity I _B was measured. And the measured diffraction line intensity I _P
And BG intensity I _B , the ratios R ₃ and R _{4 of} the diffraction line intensities I _P shown in Eqs. 7 to 10 and I _P and BG.
The ratios R ₁ and R _{2 with} respect to the intensity I _B were obtained. Further, the chemical analysis values of the degree of alloying and the amount of plating deposited, which are necessary for calculating the accuracy σ _d of the degree of alloying analysis, were obtained under the conditions shown in Table 3.

[0025]

[Table 1]

[0026]

[Table 3]

FIGS. 2 and 3 are graphs showing the relationship between the degree of alloying obtained by the chemical analysis and the R ₃ and R ₄ values obtained by the above operation. The cases of 30 to 50 g / m ² and 50 to 80 g / m ² are shown by □ ...,-+-, respectively. As is clear from FIGS. 2 and 3, according to this measuring method, the applicable alloying degree range is as wide as 7 to 14%. Further, when the accuracy σ _d in the plating adhesion amount □ ...,-+-shown in FIG. 2 was calculated, it was 0.39% and 0.29%, respectively, and the plating adhesion amount □ ... shown in FIG. ,-+-, The accuracy σ _d was 0.49% and 0.47%, respectively. Therefore, no matter whether the R ₃ value or the R ₄ value is used,
It can be seen that the accuracy σ _d is about 0.3 to 0.5%, which is a better value than the conventional value, by properly using the calibration curve for each plating adhesion amount. Therefore, the crystal plane spacing d is 1.
222 ± 0.005Å, 1.259 ± 0.005Å, and 1.301 ± 0.005Å corresponding to the diffraction line intensities I _P and BG intensities I _B of the alloy phase were measured, and the R ₃ and R ₄ values were calculated. By the calculation, it is possible to obtain a calibration curve having a wide applicable alloying degree range and a good correlation with the alloying degree.

FIGS. 4 and 5 are graphs showing the relationship between the alloying degree obtained by the above chemical analysis and the R ₁ and R ₂ values obtained by the above operation. The cases of 30 to 50 g / m ² and 50 to 80 g / m ² are shown by □ ...,-+-, respectively. As is clear from FIGS. 4 and 5, according to this measuring method, the applicable alloying degree range is as wide as 7 to 14%. Further, when the accuracy σ _d in the plating adhesion amount □ ...,-+-shown in FIG. 4 was calculated, they were 0.50% and 0.53%, respectively, and the plating adhesion amount □ ... shown in FIG. ,-+-, The accuracy σ _d was 0.54% and 0.51%, respectively. Therefore, no matter whether the R ₁ value or the R ₂ value is used,
It can be seen that the accuracy σ _d is about 0.5%, which is a better value than the conventional value, by properly using the calibration curve for each coating amount. Therefore, the crystal plane spacing d is 1.598 ±
The diffraction line intensity I _P and the BG intensity I _B of the alloy phase corresponding to 0.005Å and 1.311 ± 0.005Å were measured, and R ₁
By calculating the values and R ₂ values, it is possible to obtain a calibration curve having a wide applicable alloying degree range and good correlation with the alloying degree.

Next, the degree of alloying when the conventional method is used is suitable.
Range and accuracy σ_d The result of the investigation will be described.
The diffraction line intensity I of each alloy phase at this time_P And BG strength
Degree I _B Is a sample for preparing a calibration curve and X-ray diffraction similar to the above
Measured according to the conditions shown in Table 2 using a device and alloyed
Similarly, the chemical analysis values of the degree and the coating amount are shown in Table 3.
Calculated under the conditions.

[0030]

[Table 2]

[0031] Figure 7 shows a relationship between the alloying degree determined by chemical analysis and the intensity ratio _{{I P (Γ) -I B} (Γ)} / I B (Γ), as above Plating coverage is 30 on one side
To 50 g / m ^2, when the respective ^{... □ ... 50~80g / m 2,} - + - shows in. As is clear from FIG. 7, according to this measuring method, the applicable alloying degree range is 7-14%.
However, the accuracy σ _d in the coating amount of coating □□,-+-is 0.64% and 0.59% respectively, and a calibration curve is used for each coating amount to improve the accuracy σ _d. However, the accuracy σ _d did not seem to be about 0.6%. Figure 8
Shows the relationship between the alloying degree and the Γ value obtained by chemical analysis, and it was found that the applicable range is as wide as 7 to 14%. However, the accuracy of plating adhesion ... □ ...,-+- σ
_d respectively 0.64% and 0.58% and by selectively using calibration curve coating weight for the sake of the same manner as described above accuracy sigma _d improvement, accuracy sigma _d is also approximately 0.6% I didn't feel like it.

FIG. 9 shows the alloying degree and ζ obtained by chemical analysis.
This shows the relationship with the value, and shows that it is difficult to analyze the alloying degree by the ζ value when the alloying degree is 11% or more. Deposition amount of plating when alloying degree is 7 to 14% ... □,-+
The accuracy σ _{d at-} is 0.88% and 0.78, respectively.
%, And the accuracy σ _d was 0.8 to 0.9% even if the calibration curve was properly used for each coating adhesion amount.

FIG. 10 shows the relationship between the alloying degree and Z value obtained by chemical analysis. Alloying degree 7-14%
Accumulation of plating on □□…, ＋＋ － Accuracy σ _d
Are 0.93% and 0.76%, respectively, and the accuracy σ _d is 0.8-
It was 0.9%.

From the above results, R ₃ , R ₄ , R ₁ and R
_It can be seen that the use of _two values is effective in obtaining a calibration curve having a wide applicable alloying degree range and a good correlation with the alloying degree. Next, the accuracy σ _d in the alloying degree measurement of the actual sample
The result of the investigation will be described. As an actual sample, the alloying degree is 4 to 15%, and the coating weight is 30 to 50 g / m on one side.
^2. Samples of 50 to 80 g / m ² were added for each coating amount
Five points, a total of 130 points, were used to examine the accuracy σ _d for each coating adhesion amount according to the conventional method and the method of the above embodiment. The results are shown in Table 4. As is clear from Table 4, R ₃ value, R ₄
The accuracy σ _d in the method of the present embodiment using the values, R ₁ value and R ₂ value was about 0.3 to 0.5%, which was a better value than before. In addition, X when obtaining the accuracy σ _d
As the line analysis value, the value read from the calibration curve (quartic function) obtained from FIGS. 2 to 5 and FIGS. 7 to 10 was used.

[0035]

[Table 4]

As is clear from the above, according to the above embodiment, the crystal plane spacing d is 1.222 ± 0.005Å,
1.259 ± 0.005Å, 1.301 ± 0.005
Å, 1.311 ± 0.005 Å, and 1.598 ± 0.
Since a calibration curve with a good correlation with the alloying degree can be created from the diffraction line intensity of the alloy phase corresponding to 005Å, the alloying degree of the galvannealed layer can be accurately measured in the practical alloying degree range. be able to. INDUSTRIAL APPLICABILITY The measuring method according to the present invention can be applied to on-line analysis required when manufacturing an alloyed galvanized steel sheet.

[0037]

As described in detail above, the method for measuring the degree of alloying of the galvannealed layer according to the present invention is performed by irradiating the steel sheet with a galvanized steel sheet and then alloying it with X-rays to perform the plating. When measuring the alloying degree of the layer, the crystal plane spacing of the alloy phases in the plating layer is 1.222 ± 0.0.
Ratio of diffraction line intensities of specific alloy phases corresponding to 05Å and 1.259 ± 0.005Å, or 1.301 ± 0.005
By calculating the alloying degree using the ratio of the diffraction line intensities of the specific alloy phases corresponding to Å and 1.259 ± 0.005Å, it is possible to obtain a very good accuracy σ in the practical alloying degree range. The alloying degree of the plating layer can be measured by _d .

In the method for measuring the degree of alloying of an alloyed zinc plating layer according to the present invention, the crystal plane spacing of the alloy phases in the plating layer is 1.598 ± 0.005Å or 1.311 ±.
By calculating the alloying degree using the ratio of the diffraction line intensity of the alloy phase corresponding to 0.005Å and the BG intensity, the plating layer with good accuracy σ _d can be obtained in a practical alloying degree range. The degree of alloying can be measured.

Therefore, the method for measuring the degree of alloying of the galvannealed layer according to the present invention can be applied to the on-line analysis required when manufacturing the galvannealed steel sheet.

[Brief description of drawings]

FIG. 1 is a parallel beam optical system X used for carrying out a method for measuring the degree of alloying of an alloyed zinc plating layer according to the present invention.
It is the block diagram which showed the line diffraction device roughly.

FIG. 2 is a graph showing the relationship between the degree of alloying obtained by chemical analysis and the R ₃ value.

FIG. 3 is a graph showing the relationship between the alloying degree obtained by chemical analysis and the R ₄ value.

FIG. 4 is a graph showing the relationship between the degree of alloying obtained by chemical analysis and the R ₁ value.

FIG. 5 is a graph showing the relationship between the degree of alloying obtained by chemical analysis and the R ₂ value.

FIG. 6 is a graph showing the relationship between the volume fraction and the degree of alloying of each alloy layer in the plating layer.

FIG. 7 shows the alloying degree and strength ratio {I obtained by chemical analysis.
Is a graph showing the relationship between _{P (Γ) -I B (Γ} )} / I B (Γ).

FIG. 8 is a graph showing the relationship between alloying degree and Γ value obtained by chemical analysis.

FIG. 9 is a graph showing the relationship between the alloying degree and the ζ value obtained by chemical analysis.

FIG. 10 is a graph showing the relationship between the alloying degree and Z value obtained by chemical analysis.

[Explanation of symbols]

 11 Galvanized steel sheet

Claims (2)

[Claims] 1. A method for measuring the degree of alloying of a plated layer, which is obtained by galvanizing a steel sheet and then alloying the same, to measure the degree of alloying of the plated layer. Is 1.222 ± 0.005Å and 1.259
Ratio of diffraction line intensities of specific alloy phase corresponding to ± 0.005Å, or 1.301 ± 0.005Å and 1.259 ±
A method for measuring the degree of alloying of an alloyed galvanized layer, which comprises calculating the degree of alloying by using a ratio of diffraction line intensities of a specific alloy phase corresponding to 0.005Å. 2. A method of measuring the degree of alloying of a plated layer by irradiating the plated layer, which has been galvanized on a steel sheet and then subjected to alloying treatment, with X-rays. Is 1.598 ± 0.005Å or 1.311
A method for measuring the degree of alloying of an alloyed zinc-plated layer, wherein the degree of alloying is calculated using the ratio of the diffraction line intensity of the alloy phase corresponding to ± 0.005Å and the background intensity.