GOST 21639.9-93

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  ГОСТ 21639.9-93

GOST 21639.9−93 Fluxes for electroslag remelting. Method for determination of carbon

GOST 21639.9−93

Group B09

INTERSTATE STANDARD

Fluxes for electroslag remelting

METHOD FOR DETERMINATION OF CARBON

Fluxes for electroslag remelting.
Method for determination of carbon

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. Resolution of the Committee of the Russian Federation for standardization, Metrology and certification from 14.06.95 No. 304 interstate standard GOST 21639.9−93 introduced directly as state standard of the Russian Federation from January 1, 1996

4 REPLACE GOST 21639.9−76

1 SCOPE

This standard sets the coulometric method for determining carbon mass fraction from 0.01 to 0.1% in fluxes for electroslag remelting.

2 NORMATIVE REFERENCES

The present standard features references to the following standards:

GOST 4140−74 Strontium chloride 6-water. Specifications

GOST 4207−75 Potassium ferrocyanide 3-aqueous. Specifications

GOST 4234−77 Potassium chloride. Specifications

GOST 5583−78 the Oxygen. Specifications

GOST 9147−80 Glassware and equipment lab porcelain. Specifications

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

3 GENERAL REQUIREMENTS

General requirements for method of analysis according to GOST 21639.0.

4 COULOMETRIC METHOD

4.1 the essence of the method

The method is based on the combustion of the flux linkage in a current of oxygen in presence of flux at a temperature of 1300−1400 °C, with subsequent absorption of the formed carbon dioxide absorption by a solution with a particular initial pH value and the measurement (in the apparatus for coulometric titration) the amount of electricity spent to restore the original pH value.

4.2 Equipment, reagents and solutions

Installation for the determination of carbon (figure 1) consists of the oxygen cylinder 1 according to GOST 5583, equipped with a pressure reducing valve start-up and adjustment of a current of oxygen; the reducer, manometer 2, fine adjustment of oxygen; absorber 3filled with Astarita; tubular furnace 4, which provides heating to 1400 °C, porcelain boats N 2 according to GOST 9147, calcined at 1300 °C in flowing oxygen 5; a porcelain tube with an inner diameter of 20−22 mm, a length of 650−750 mm 6; vessel-sink 7with a diameter of 25 mm and height 150 mm with spikes for the supply of rubber tubes filled with wet anionite resin EDE-10P. This sink allows you to spend 15−20 definitions of carbon. Then it should be replaced or recharged. At the top and bottom of the container put pieces of paper of the Congo. The blue paper at the top of the absorber indicates that the hydrofluoric acid is in a cell and need to change the absorber; Express analyzer 8 type an-7560 (it is allowed to use the same analyzers of other types).

Figure 1 — Installation for determination of carbon

Figure 1 — Installation for determination of carbon

The hook with which the boat was placed in a tube and extracted from it, is made of heat-resistant wire with a diameter of 3−5 mm and a length of 500−600 mm.

Potassium ferrocyanide 3-water according to GOST 4207.

Potassium chloride according to GOST 4234.

Strontium chloride 6-water according to GOST 4140.

Askari.

Copper oxide according to GOST 16539, calcined at 800 °C for 4−5 h.

Anionity resin EDE-10P. The resin was pre-flooded with distilled water for 24 h, and then washed with water several times.

The absorption solution: 50 g of potassium chloride and 50 g of strontium chloride is dissolved in 1 DMdistilled water.

Auxiliary solution: 50 g of potassium chloride and 50 g potassium ferrocyanide dissolved in 1 DMdistilled water.

4.3 analysis

Weighed flux of 0.5 g was placed in a porcelain boat, add 0.5 g of copper oxide and stirred. A boat with linkage and flux are placed in the most heated portion of the porcelain tube, the end of which is immediately closed with shutter. Burning is carried out for 2 min.

4.4 Processing of results

4.4.1 Mass fraction of carbon in percent with the sample of 0.5 g corresponds to the indication of the digital display device.

4.4.2 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of carbon is given in table 1.


Table 1 — Standards of accuracy control