GOST 21639.4-93

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  ГОСТ 21639.4-93

GOST 21639.4−93 Fluxes for electroslag remelting. Methods of determining total iron

GOST 21639.4−93

Group B09

INTERSTATE STANDARD

Fluxes for electroslag remelting

METHODS OF DETERMINING TOTAL IRON

Fluxes for electroslag remelting.
Methods for determination of total iron

OKS 71.040.040*
AXTU 0709

________________

* In the index «National standards» 2006 ACS 25.160.20. -

Note the «CODE».

Date of introduction 1996−01−01

Preface

1 PREPARED by the Russian Federation — Technical Committee TC 145 «monitoring Methods of steel products"

SUBMITTED by the Technical Secretariat of the Interstate Council for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification 17 February 1993.

The adoption voted:

3 Decree of the Russian Federation Committee on standardization, Metrology and certification from 14.06.95 No. 299 of interstate standard GOST 21639.4−93 introduced directly as state standard of the Russian Federation from January 1, 1996

4 REPLACE GOST 21639.4−76

1 SCOPE

This standard specifies the photometric (with mass fraction of total iron from 0.05 to 1.0%) and atomic absorption (at a mass fraction of total iron from 0.10 to 1.0%) methods for determination of total iron in fluxes for electroslag remelting.

2 NORMATIVE REFERENCES

The present standard features references to the following standards:

GOST 199−78 Sodium acetate 3-water. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5456−79 of Hydroxylamine hydrochloride. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 7172−76 Potassium preservatory. Specifications

GOST 10484−78 hydrofluoric Acid. Specifications

GOST 21639.0−93 Fluxes for electroslag remelting. General requirements for methods of analysis

3 GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 21639.0.

4 PHOTOMETRIC METHOD

4.1 the essence of the method

The method is based on formation of colored complex compounds of iron (N) ortofenantrolinom or 2,2-dipyridil. For reduction of iron using hydroxylamine hydrochloride.

4.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Hydrochloric acid according to GOST 3118, diluted 1:1.

Nitric acid according to GOST 4461.

Orthophenanthroline, a solution with a mass concentration of 2.5 g/DMcook in low heat.

2,2-dipyridyl, a solution with a mass concentration of 50 g/DM.

Hydroxylamine hydrochloride according to GOST 5456, solution with a mass concentration of 100 g/DM.

Sodium acetate 3-water according to GOST 199, a solution with a mass concentration of 500 g/DM.

Paper of the Congo.

Iron carbonyl.

Standard solutions

Solution a: 0.5 g of iron dissolved in 30 cmof hydrochloric acid. After complete dissolution of the sample solution is oxidized with a few drops of nitric acid. Then the solution was boiled to remove oxides of nitrogen, cooled, placed in a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

1 cmstandard solution A contains 0.0005 g of iron.

Solution B: 5 cmstandard solution And placed in a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmstandard solution B contains 0,00001 g YEL

ESA.

4.3 analysis

4.3.1 Aliquot part of the master solution prepared according to GOST 21639.2 in accordance with table 1 was placed in a volumetric flask with a capacity of 100 cm, pour 5 cmof a solution of hydroxylamine hydrochloride, neutralized with sodium acetate solution until slightly acid reaction on Congo paper. Then pour 10 cmof the solution orthophenanthroline or 2,2-dipyridyl, made up to the mark with water and mix. After 30 min, measure the optical density of the solution on the spectrophotometer at a wavelength of 516 nm or photoelectrocolorimeter at a wavelength range from 520 to 530 nm.


Table 1 — Volume aliquote part of the solution

After subtracting the value of optical density of the solution in the reference experiment from the value of the optical density of the analyzed solution find the mass of total iron in the calibration schedule.

4.3.2 Construction of calibration curve

To build a calibration curve in five of the six conical flasks with a capacity of 100 cmtaken 1; 2; 3; 4; 5 cmstandard solution B, which corresponds to the 0.00001; 0,00002; 0,00003; 0,00004; 0,00005 g total iron. In each flask pour 10−15 cmwater, 5 cmof hydroxylamine hydrochloride, neutralized with sodium acetate solution until slightly acid reaction «paper of the Congo». Then pour 10 cmof the solution orthophenanthroline or 2,2-dipyridyl, made up to the mark with water and mix.

After 30 min, measure the optical density of the solution as specified in 4.3.1. Solution comparison is the solution of the sixth flask containing a standard solution of iron.

According to the obtained values of optical densities and corresponding mass of total iron to build the calibration graph.

4.4 Processing of results

4.4.1 Mass fraction of total iron () in percent is calculated by the formula

, (1)

where is the mass of total iron was found in the calibration schedule g;

 — the weight of the portion corresponding to aliquote part of the solution,

4.4.2 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of total iron are shown in table 2.


Table 2 — Standards accuracy control

5 ATOMIC ABSORPTION METHOD

5.1 the essence of the method

The method is based on measuring the degree of absorption of resonance radiation by free atoms of iron formed as a result of spraying the test solution in a flame acetylene-air.

5.2 Equipment, reagents and solutions

Spectrophotometer atomic absorption of any kind with the radiation source for iron.

Muffle furnace with heating temperature up to 1000 °C.

Acetylene is dissolved according to GOST 5457.

The compressor supplying compressed air, or compressed air.

Hydrochloric acid according to GOST 3118 and dilute 2:100.

Nitric acid according to GOST 4461.

Perchloric acid, a solution with a mass concentration of 1510 g/DM.

Hydrofluoric acid according to GOST 10484.

Potassium preservatory according to GOST 7172.

A standard solution prepared at 4.2.

5.3 analysis

5.3.1 Sample the sample mass, depending on the mass fraction of iron in fluxes, determined by the table 3.


Table 3 — the weight of the portion of the sample

The linkage of flux is placed in a platinum or stekloproduct Cup, moisten with water, add 15 cmof perchloric acid, 5 cmnitrogen, 10 cmhydrofluoric acid and heat the solution to dissolve the sample. The solution was then heated until complete removal of vapors of perchloric acid, cooled, poured 15 cmof hydrochloric acid of 30 cmof water and heated to dissolve the salts. The solution is filtered through a dense filter, washed 3−4 times with hot hydrochloric acid (2:100), 3−5 times in hot water. The filter is placed in a platinum crucible, dried, calcined and goplast with 1.5−2.0 g of potassium peacemaking. The cooled crucible is placed in a beaker with a capacity of 250 cm, 50 cm pourhot water, 10 cmof hydrochloric acid and heated to dissolve the melt. The solution was combined with the main solution, evaporated to moist salts, pour 4 cmof hydrochloric acid, 15−20 cmof water and heated to dissolve the salts, transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Through the analysis of spend control experience.

Spray the solution in the reference experiment and the solution of the sample in order of increasing absorption to obtain stable readings for each solution. Before spraying each solution is sprayed water to wash the system and check the zero point.

After subtracting the atomic absorption of the solution in the reference experiment of the values of the atomic absorption of the sample solution find the mass of iron in a solution of a test portion for calibration gra

fico.

5.3.2 Construction of calibration curve

For construction of calibration curve six platinum or stekloproduct cups placed 0,5; 1,0; 1,5; 2,0; 2,5; 3,0 cmstandard solution A, which corresponds to 0,00025; 0,0005; 0,00075; 0,001; 0,00125; 0,0015 g of iron and then spend analysis 5.3.1.

5.4 processing of the results

5.4.1 Mass fraction of total iron () in percent is calculated by the formula

, (2)

where is the mass of iron in a solution of the sample, was found in the calibration schedule g;

 — the weight of the portion of the sample,

5.4.2 Norms of accuracy and norms control the accuracy of determining the mass fraction of total iron are shown in table.2.