GB/T 36399-2018Continuously hot-dip aluminium-silicon alloy coated steel sheet and strip (English PDF)

3.1 Hot-dip Aluminum-silicon Alloy Coating

Hot-dip aluminum-silicon alloy coating refers to coating, which is obtained on the production line of hot-dip aluminum-silicon by immersing preprocessed steel strip into melt plating solution, whose silicon content is 5% ~ 11%, whose impurity element, excluding iron, is not more than 1%, whose margin is aluminum.

3.2 Passivation

Passivation refers to a technique of implementing chromic acid passivation or chromium-free passivation chemical treatment of the surface of steel sheet or strip to prevent it from generating white rust during the shipment, storage and transportation process.

3.3 Skin-passing

Skin-passing refers to a technique of implementing mild cold rolling of hot-dip aluminum-silicon sheet.

NOTE: skin-passing has several objectives as follows.

a) Improve surface smoothness and appearance, however, this process would have adverse influence on substrate's plasticity;

b) Temporarily reduce tensile deformation or wrinkles that would emerge during […]

5.1 Order Information

5.1.1 Contract and order that comply with this Standard shall include the following content.

a) Standard No.;

b) Product name (steel sheet or strip);

c) Nameplate;

d) Coating weight;

e) Surface quality;

f) Surface treatment;

g) Specification and dimensional accuracy;

h) Unevenness accuracy;

i) Internal diameter and maximum weight of steel coil;

j) Weight;

k) Mode of packaging;

l) Other special requirements.

5.1.2 If it is not indicated in order contract, deliver products in accordance with the ordinary dimension (thickness and width) and unevenness accuracy; surface quality grade FA; surface treatment. chromic acid passivation C; steel coil shall be delivered in accordance with the internal diameter of 610 mm. Package in accordance with the mode of packaging provided by the supply side.

5.2 Example of Marking

DX51D+AS steel strip provided in accordance with this Standard. coating weight code 150; surface quality FB; surface treatment. chromic acid passivation and oiling CO; thickness 1.0 mm; high-grade thickness accuracy PT.B; width 1,250 mm; ordinary grade width accuracy PW.A. […]

6.1 Nominal Dimension

Please refer to Table 4 for the general nominal dimension of steel sheet and strip.

Through the negotiation between the demand side and the supply side, other dimensions of steel sheet and strip can also be provided.

6.2 Dimension, Appearance, Weight and Allowable Deviation

The dimension, appearance, weight and allowable deviation of steel sheet and strip shall comply with the stipulation in GB/T 25052-2010. The allowable deviation of the thickness of hot stamping formed steel shall comply with the stipulation in Table 3 in […]

B.1 Overview

This method shall be adopted to measure the weight of alloy coating of aluminum-silicon coated steel sheet. Firstly, peel off the non-alloy coating. Then, comply with the method in Appendix C or Appendix D to peel off the alloy coating. Take sponge tin, which is generated through the reaction of aluminum and stannous chloride solution (II), as the foundation. This solution shall not trigger reaction with alloy or iron-based materials. Before and after eliminating the alloy coating, weigh the sample.

B.2 Reagents

B.2.1 Stannous chloride solution (II)

B.2.1.1 Weigh-take 1,000 g of chemically purity SnCl2-XH2O; dissolve it in 500 mL hydrochloric acid (1+1). Add 5 g ~ 10 g of metallic tin (>= 99.5%), then, heat it up till the solution becomes bright; dilute to 1,000 mL.

B.2.1.2 Transfer-take 20 mL of solution (B.2.1.1), place it into 200 mL distilled water or deionized water, then, prepare the working solution.

B.3 Procedure

B.3.1 Remove non-alloy coating

Use petroleum ether to clean the sample, which is taken in accordance with No. 6 in Table 12, then, impregnate it into 200 mL working solution (B.2.1.2), till the reaction stops. After taking the sample out of the solution, use small spatula to scrape the sponge tin. Next, repeat this process, till there is no reaction. Then, clean and dry the sample.

B.3.2 Determine alloy coating

In accordance with the stipulation in C.3.2 and D.3.2, handle the sample, which is prepared in accordance with B.3.1.

B.4 Evaluation

Before and after the test, calculate the weight difference of the sample in accordance with Formula (C.1) or Formula (D.1), obtain the weight of the alloy coating.

C.1 Principle

Dissolve aluminum-silicon alloy coating with already known surface area into a test solution that has effect of corrosion inhibition. Weigh the sample before and after the dissolution of the coating. In accordance with the weighed difference and the sample area, calculate the weight of aluminum-silicon alloy coating in a unit area.

C.2 Reagents

C.2.1 Hexamethylenetetramine hydrochloride solution. weigh-take 0.35 g of chemically pure hexamethylenetetramine, then, dissolve it into 50 mL hydrochloric acid (rho=1.19 g/mL). Use distilled water or deionized water to dilute it into 100 mL.

C.2.2 Sodium hydroxide solution, 20%. weigh-take 20 g of chemically pure sodium hydroxide, then, dissolve it into 80 mL distilled water or deionized water.

C.3 Test Procedure

C.3.1 Sample

In accordance with the requirement in No. 6 in Table 12, prepare analytical sample.

The sample shall be clean. If necessary, use appropriate solvent that would not corrode the coating to clean the sample. Immediately place it into chemically pure absolute ethanol to clean it, then, thoroughly dry it.

C.3.2 Test method

Weigh-take sample (C.3.1), accurate to 0.001 g, then, place it into sodium hydroxide solution (C.2.2) whose temperature is not lower than 85 °C, till the reaction stops. Then, take out the sample; use water to rinse it.

Immediately impregnate the wet sample into hexamethylenetetramine hydrochloride solution (C.2.1). After hydrogen is severely generated in the preliminary stage, when small bubbles began to emerge, take out the sample, then, use water to rinse it. After rinsing it, thoroughly dry it. Re-weigh the sample, accurate to 0.001 g.

C.4 Calculation of Analytical Result

The weight of product's double-sided coating shall be calculated in accordance with […]

D.1 Principle

Dissolve aluminum-silicon alloy coating with already known surface area into a test solution. Weigh the sample before and after the dissolution of the coating. In accordance with the weighed difference and the sample area, calculate the weight of aluminum-silicon alloy coating in a unit area.

D.2 Reagents

D.2.1 Hydrochloric acid (rho=1.19 g/mL).

D.2.2 Sodium hydroxide solution, 20%. weigh-take 20 g of chemically pure sodium hydroxide, then, dissolve it into 80 mL distilled water or deionized water.

D.3 Test Procedure

D.3.1 Sample

In accordance with the requirement in No. 6 in Table 12, prepare analytical sample.

The sample shall be clean. If necessary, use appropriate solvent that would not corrode the coating to clean the sample. Immediately place it into chemically pure absolute ethanol to clean it, then, thoroughly dry it.

D.3.2 Test method

Weigh-take sample (D.3.1), accurate to 0.001 g, then, place it into hot sodium hydroxide solution (D.2.2), till the reaction stops. Take out the sample, then, use water to rinse it. Use cloth to wipe it clean, then, place it into hydrochloric acid (D.2.1) at room temperature for 2 s ~ 3 s.

Continue to use water to rinse the sample, then, re-impregnate it into sodium hydroxide solution, till it is confirmed that there is no reaction.

Repeat the above procedure, till there is no visible reaction when the sample is impregnated in the sodium hydroxide solution. Clean the sample, then, thoroughly dry it. Re-weigh the sample, accurate to 0.001 g.

D.4 Calculation of Analytical Result

E.1 Scope of Application

This method of measurement specifies the principle, test instrument, calibration curve drawing, correction and the procedure of measuring the weight of surface aluminum-silicon alloy coating of steel sheet and strip through X-ray fluorescence.

E.2 Principle

Utilize primary ray that is emitted from a ray source (X-ray tube) to irradiate steel sheet sample that has metal coating. Under certain conditions, in metal coating, trigger iron fluorescent X-ray of the coating metal; detect the intensity of the sample's fluorescent X-ray. Compare the sample's X-ray intensity with a sample's X-ray intensity under another already known coating weight; determine the coating weight of the sample.

E.3 Test Instrument

E.3.1 Dispersive X-ray fluorescence spectrometer. X-ray fluorescence spectrometer shall manifest satisfying stability and sensitivity; it shall be able to distinguish fluorescent X-ray, which is generated from coating and matrix.

E.3.2 Instrument's working environment shall comply with the stipulation in GB/T 16597. It shall be placed in a place where there are no electromagnetic interference, vibration or gas corrosion. The control of temperature and humidity shall comply with the configuration requested by instrument. Generally speaking, within 8 h, temperature difference shall not exceed ± 2 °C; relative humidity shall be below 70%.

E.3.3 Fluorescent X-ray, which is to be tested, shall be the primary ray of FeKalpha (wavelength. 0.194 nm) or the primary ray of FeKbeta(wavelength. 0.176 nm).

E.4 Calibration Curve Drawing and Correction

E.4.1 Calibration curve drawing

Please see the drawing of working curve as follows. As an alternative plan of sampling, which is needed to determine the coating weight of X-ray measurement sample, coating weight can be determined through the sample after X-ray intensity measurement in accordance with Appendix C or Appendix D.

a) In order to draw the working curve, extract two groups of samples. […]