GOST 21132.0-75

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  ГОСТ 21132.0-75

GOST 21132.0−75 aluminum and aluminum alloys. Method for the determination of hydrogen content in liquid metal (with Amendments No. 1, 2, 3)

GOST 21132.0−75

Group B59

INTERSTATE STANDARD

ALUMINUM AND ALUMINUM ALLOYS

Method for the determination of hydrogen content in liquid metal

Aluminium alloys. Method for determination of hydrogen content in molten metal

ISS 77.120.10
AXTU 1709

Date of introduction 1977−01−01

The decision of the State standards Committee of the USSR Council of Ministers dated 11 September 1975, N 2380 date of introduction is established 01.01.77

Limitation of actions taken by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (ICS 4−94)

EDITION with Amendments No. 1, 2, 3, approved in February 1979, January 1982, June 1986 (IUS 4−79, 3−82, 9−86)


This standard specifies a method for determining hydrogen content in liquid metal on the allocation of the first bubble in aluminum and aluminum alloys (with a hydrogen content of from 0.05 to 1.0 cmper 100 g metal).

The essence of the method is depending on the amount of dissolved hydrogen in the liquid metal from the partial pressure of hydrogen in the gas phase over metal.

The standard fully complies ST SEV 2281−80.

(Changed the wording. Izm. N 1, 3).

1. APPARATUS, MATERIALS AND REAGENTS

Mercury Pl GOST 4658−73.

The slag wool.

The aviation gasoline according to GOST 1012−72.

Grease vacuum.

Vacuum oil VM-4.

Rectified ethyl alcohol of the highest purification.

Rubber vacuum.

Medical absorbent cotton wool GOST 5556−81.

Asbestos sheet and corded.

Installation (DWG.1) consists of a sealed vacuum chamber housing 7 and the cover 5 in which there is a sight glass 3; electric resistance with a thermostat 6 and 8 of the crucible 4 with a capacity from 30 to 50 cm, chromelalumel thermoelectric thermometer 2 with a wire diameter of 0.5 to 0.8 mm, which put the protective case with a diameter of 5 to 7 mm, length 50 mm, to measure the temperature of the melt in the range from 590 °C to 810 °C with a measurement error not more than 2,5 °C; roughing pump 1 type EXT-461, RVN-20 or HV-494; mechanical pressure gauge 11 with a scale from 0 to 101,08·10PA (0 to 760 mm Hg.St.) for rough pressure measurements; glass U-shaped 12 gauge with a scale from 0 to 26.6·10PA (0 to 200 mm Hg.St.) for a more accurate pressure measurement.

Damn.1

Allowed the use of other analytical equipment, providing the meteorological parameters specified in this standard. Shaft furnace (Fig.2) serves for pre-heating of the crucibles of installation and thermostat.

1 — metal frame; 2 — refractory brick; 3 — special ceramics of four sections; 4 — silicony pin; 5 — asbestos sheet; 6 — cover; 7 — lever; 8 — limit switch; 9 — casing heaters

Damn.2

Thermostat (Fig.3) serves to maintain the desired temperature of the metal during transportation of the sample from the oven, mixer or transfer the device into the crucible installation. The thermostat is placed in a ceramic crucible with a capacity of 320 to 350 cm, which is heated by an electric furnace of the resistance of the thermostat (Fig.4). Is applied if the pack is removed from the place of sampling. Spoon for sampling steel or cast iron with heat-resistant coating paint containing chalk or kaolin (the use of asbestos as a protective layer is not allowed), of a capacity:

not less than 100 cmin the case of one definition of the selected samples;

at least 250 cmin case of multiple definitions of the selected once in the sample, provided the sample transfer in the thermostat.

1 — body; 2 — PowerPoint; 3 — latch; 4 — heater; 5 — glass; 6 — flange; 7 — filling of asbestos; 8 — handle; 9 — hole; 10 — cover; 11 — axis; 12 — ring; 13 — outlet

Damn.3

Sec. 1. (Changed edition, Rev. N 3).

1 — furnace body; 2 — crucible; 3 — spiral; 4 — a lining; 5 — insulation; 6 — slag wool; 7 — pin screw; 8 — fastening bolt; 9 — leaf; 10 — tray; 11 — fastening screw

Damn.4

Special forceps are used for overflow from the crucible of the thermostat in the crucible installation.

3. SAMPLING METHOD

_______________
* Sec. 2. (Deleted, Rev. N 2).

3.1. Before sampling check equipment for analysis and set the stage for analysis in accordance with the description of the operation of the installation.

3.2. In selecting the sample it is necessary to keep the hydrogen content at the level at which it is analyzed melt. Sampling is carried out from the melt has been heated in the melt with a spoon. At the point of selection of a sample that is not identical with the place of the heated spoons, the metal surface is cleaned of slag and careful movement dipped the spoon into the melt at a distance of at least 10 cm from the surface of the metal. Approximately 1/3 of the sample was poured, and the analysis is carried out of the remaining part of the sample. Then immediately select a new sample for carrying out parallel analysis. The temperature of the sample melt should not decrease by more than 15 °C after putting it in the installation.

When using the thermostat the sample is taken with a spoon the increased capacity of the above method, is poured into the crucible of the thermostat, which is transferred to the installation, and the sample immediately one after another spend at least two parallel tests.

The change of metal temperature in the crucible of the thermostat relative to the temperature of the analyzed melt should not be more than minus 15 °C or + 10 °C. the Duration of stay of the metal in the crucible of the thermostat, from the moment of sampling until the end of the last analysis should be no more than 20 min.

(Changed edition, Rev. N 3).

4. ANALYSIS

4.1. A sample (or part of the sample from the thermostat) of a continuous jet is poured into heated to the temperature of the melt crucible installation, pre-placing it in a thermoelectric thermometer. The change of metal temperature in the crucible installation in relation to the analyzed temperature of the melt should not be more than minus 15 °C or + 10 °C.

Before overflow of the sample from the melt it is necessary to remove the oxide film; do not remove the oxide film from the surface of the melt in the crucible installation.

4.2. The lid 5 of the camera, turn on the pump 1. Pumping speed for U-shaped manometer at a pressure of from 26.6·10to 2.66 x 10PA (from 200 to 20 mm Hg.St.) should be no more of 6.65·10PA (5 mm Hg.St.). The pumping rate is controlled by valve 10.

(Changed edition, Rev. N 3).

4.3. Through the window, watching the illuminated metal surface. After the first bubble register values of metal temperature and the residual pressure above the melt.

For the first bubble take the small bubble that appears not at the wall of the crucible and which, as a rule, with a slight decrease of the pressure of 1.33·10-2,66·10PA (10−20 mm Hg.St.) are new bubbles.

In some cases, at low values of hydrogen content possible the appearance of only a single bubble, which is not followed by others.

4.4 Unloading and preparing installation to the next analysis is carried out in accordance with the description on its operation.

5. PROCESSING OF THE RESULTS

5.1 the hydrogen Content in the sample metal (a) in cmper 100 g of the metal calculated as the arithmetic mean of two parallel definitions using tables or nomograms obtained by the formula

,

where is the temperature of the melt, K, measured at the time of first appearance of bubbles on the surface of the melt;

 — pressure over the metal, Pas, measured at the time of first appearance of bubbles on the surface of the melt;

and the coefficients in the equation of solubility, specified for this alloy (table.1).

5.2. For aluminum and some binary alloys coefficients and are given in table.1.

Table 1

5.3 the Allowable discrepancy between independent parallel measurements at a confidence probability of 0.95, should not exceed the values given in table.2.