GOST 17745-90

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  ГОСТ 17745-90

GOST 17745−90 of Steel and alloys. Methods for the determination of gases

GOST 17745−90

Group B09

STATE STANDARD OF THE USSR

STEELS AND ALLOYS

Methods for the determination of gases

Steels and alloys. Methods for determination of gases

AXTU 0809

Valid from 01.07.91
before 01.07.96*
________________________________
* Expiration removed by Protocol No. 5−94
The interstate Council for standardization,
Metrology and certification (I & C N 11/12, 1994). -
Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR

DEVELOPERS

V. P., Zamaraev, V. V. Pokidyshev, A. A. Ivanov, V. M., Skosyrev, V. T. Ababkov, A. A. Sakharnov, L. N. Dmitrov

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 27.04.90 N 1048

3. REPLACE GOST 17745−72

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies the method of reductive melting in a vacuum or in a stream of inert carrier gas to determine the oxygen (with mass fraction of from 0.0005 to 0.2%), nitrogen (in mass fraction from 0.0005% to 0.8%) and hydrogen (with mass fraction of 0.00005 to 0.01%) and the method of heating or melting under vacuum or in a stream of inert carrier gas to determine the hydrogen (with mass fraction of 0.00005 to 0.01%) in steels and alloys based on iron, Nickel, cobalt, iron-Nickel.

The method of reductive melting to determine the mass fraction of oxygen, nitrogen and hydrogen is based on the melting of the sample in a graphite crucible in a vacuum or in a stream of inert carrier gas, the extraction of the gases contained therein and subsequent analysis of oxygen, hydrogen and nitrogen in the extracted gas mixture by physical or physico-chemical methods.

A method of heating or melting to determine the mass fraction of hydrogen based on the heating or melting of the sample in a container of ceramic material in vacuum or in a stream of inert carrier gas, the extraction of hydrogen from a sample and determination of its physical or physico-chemical methods.

The method of reductive melting is used when disagreement in the evaluation of quality of steels and alloys.

Allowed by agreement of the parties to apply the methods for cast irons, ferro-alloys and alloys based on manganese.

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 28437.

1.2. Sampling for fabrication of specimens for analysis according to GOST 7565.

Allowed sampling using the quartz tube, the size of which provide dense samples without pores and shrinkage defects, and also special samplers. Cooling of the samples is carried out in air or in water.

2. APPARATUS, MATERIALS AND REAGENTS

2.1. For the determination of oxygen is a rapid analyzer of the type AK 7516 technical characteristics:

analysis time — 82;

maximum power — 11 kVA;

the flow rate of argon of 0.5 DM/min;

sensing element — cell coulometric titration.

2.2. For determination of nitrogen applied Express-analyzer of the type AM 7514 technical characteristics:

the analysis period is not more than 120 s;

maximum power — 11 kVA;

the consumption of helium — 1.02 DM/min;

the sensitive element of the detector of thermal conductivity.

2.3. For the determination of hydrogen used in the device type RH-2 of the firm «LECO» technical characteristics:

the gas flow rate is 0.26 and 0.30 DM/min;

the analysis period is not more than 420;

maximum capacity of 4.5 kVA;

the sensitive element of the detector of thermal conductivity.

2.4. Flowchart of analysis for measuring the mass fraction of gas in the General form shown in Fig.

Block diagrams of devices for measuring the mass fraction of gases

Block diagrams of devices for measuring the mass fraction of gases:

a method of melting (heating) the flow of inert carrier gas (1 — a source of inert carrier gas;
2 — reducer; 3 — extraction oven; 4 — reactivity; 5 — analytical unit;
6 — control unit; 7 — power supply furnace)
b — method of melting (heating) in vacuum (1 — forevacuum pump; 2 — extraction oven;
3 — gazosbrosnoe pump; 4 — reactivity; 5 — analytical unit; 6 — control unit;
7 — power supply furnace)

Allowed the use of other measuring instruments with the metrological characteristics are not worse than the above devices.

The list of devices given in the Appendix.

2.5. Scales for weighing of samples — all to ensure the required weighing accuracy, including automatic, which is equipped with instruments for gas analysis. Samples for analysis are weighed with the maximum permissible error not exceeding 0.001 g weight of the sample to 0.1 g and 0.002 g — weight of the samples over 0.1 g.

2.6. Materials

Helium gas with a purity not less than 99.99%.

Argon gas according to GOST 10157.

Nitrogen gas according to GOST 9293.

The hydrogen gas according to GOST 3022.

Carbon monoxide gas with a purity not less than 99.5%.

Carbon tetrachloride according to GOST 20288.

The technical rectified ethyl alcohol according to GOST 18300.

Ether sulfuric.

The aviation gasoline according to GOST 1012.

Angidro.

Askari.

Copper (II) oxide according to GOST 16539.

Phosphoric anhydride.

Nickel H1, H2 according to GOST 849*.
______________
* On the territory of the Russian Federation GOST 849−97. — Note the manufacturer’s database.

Tin 01, 02 GOST 860.

Cotton calico GOST 11680.

Graphite crucibles.

The use of other materials, including those supplied by the manufacturers of the instrument quality is not below specified in the standard.

3. PREPARATION FOR ASSAY

3.1. Sample preparation

3.1.1. Used for the analysis of compact samples with clean without tint surface, without pores, cavities and burrs treated cutting machines with a fine file (needle files) or with an abrasive that does not contain compounds analyzed (analyzed) gases.

When determining the mass fraction of nitrogen is allowed to use samples in the form of large chips.

In the manufacture of samples is not allowed the heating of the metal above 70 °C.

The mass of samples should amount to 0.05−2.0 g to determine the mass fraction of oxygen and nitrogen and 0.05−12.0 g, for determine the mass fraction of hydrogen.

3.1.2. For analysis made at least three compact designs.

3.1.3. Before analysis the samples are degreased by washing in alcohol (ether, aviation gasoline, or carbon tetrachloride). When determining the mass fraction of oxygen and nitrogen is allowed purification of samples before analysis of the physical or physico-chemical methods, including electrochemical polishing and etching in acid with ultrasound.

If you are using samples in the form of chips, that allowed analysis without washing.

3.2. Preparation of instruments for analysis

3.2.1. Preparation of instruments to be analyzed involves the heating of the device, the calibration of an instrument with standard samples or calibration gases, the definition of amendments the reference experiment.

3.2.2. When determining amendments the reference experiment perform the same operations as in the analysis of samples (see p.4.1), with the exception of loading samples into a ceramic container or a graphite crucible.

The definition of amendments the reference experiment carried out at least once per shift (preferably 10−15 analyses). If the analysis used different batches of ceramic containers or crucibles of graphite, the definition of amendments the reference experiment carried out before use each such party.

4. ANALYSIS

4.1. Analysis of samples includes mandatory steps: the installation of the crucible or ceramic container in a furnace, degassing of the crucible, heating the crucible to a predetermined temperature and holding at that temperature for a period of time, providing completeness of extraction sample gas (gases).

4.2. Recommended composition of unmarried baths and temperature tests for various classes of steels and alloys in determining the mass fraction of gases are given in table.1.

Table 1

Recommended operating conditions the analysis of gases in steels and alloys

________________
* Allowed the use of other compositions blanks baths, providing completeness of extraction sample gas. In the analysis of materials not listed in the table, the temperature and other conditions of the analysis choose the best for these materials.

** Permitted additive in the graphite crucible fine in the amount not exceeding the mass of the analyzed sample.

5. PROCESSING OF THE RESULTS OF THE ANALYSIS

5.1. Mass fraction of gas () in percent is calculated by the formula

,

where is the mass of gas detected by the instrument, µg;

 — amendment of the control of experience, mcg;

 — the mass of sample, g.

Allowed calculation of the results of measuring the mass fraction of gas carried on the formulas given in the reference document on the devices.

5.2. Norms of accuracy and norms of control of accuracy of measurement of mass fraction of gases and oxygen are given in table.2 and 3.

Table 2

Table 3

5.3. If the discrepancy between the results of two parallel measurements is greater than the value , then perform the third dimension. If the difference is extreme results of the three measurements does not exceed the permissible value given in table.2 and 3, the result of the analysis is calculated as the arithmetic mean of results of three parallel measurements.

5.4. If the difference is extreme results of the three measurements exceeds the allowable value , and the divergence of two close measurements does not exceed , then calculate the arithmetic average of the two measurements . To find the value of (table.2 and 3) and assess whether the result of the remaining measurements in the interval if he does not, the recognized penalty for the result of the analysis of the accepted value . If it does, then the result of the analysis recognize incorrect. The measurement or repeat or stop to ascertain and eliminate the causes of increased dispersion of measurement results.

By agreement of the parties in the absence of additional samples for repeat analysis allowed the result of the analysis to give the results of the three definitions.

6. CONTROL OF MEASUREMENT ACCURACY

6.1. Stability control calibration characteristics

6.1.1. Stability control calibration characteristics for the upper and lower limits of the measuring range is carried out at least once per shift by using standard samples or calibration gases.

You can control the stability of the calibration characteristics only for the upper bound or mid-range.

6.1.2. If the difference of values of two parallel measurements of the mass fraction of gas in the standard sample does not exceed , then calculate the arithmetic average of the measurement results and the difference between where the certified value of the mass fraction of gas in the standard sample.

If the difference exceeds the parallel dimensions , the measurement is repeated in accordance with clause 5.3.

The stability of the calibration characteristics is considered satisfactory if not exceed the permissible values (see table.2 and 3).

If exceeds , then carried out the calibration of an instrument in accordance with the instructions.

AI.

6.2. The control of correctness of analysis results

6.2.1. At least once per shift before the analyses carried out the verification of results by analysis of a standard sample with a certified mass fraction of the gas nearest to the interval of mass fraction of gas in the analyzed series of samples and similar type material.

Allowed to combine the control of the correctness of the measurement with stability control calibration characteristics.

6.2.2. If the difference of values of two parallel measurements of the mass fraction of gas in the standard sample does not exceed , calculate the arithmetic mean and the difference .

If the difference exceeds the parallel definitions , the definition is repeated in accordance with clause 5.3.

Measurement accuracy is considered satisfactory if not exceed (see table.2 and 3).

If exceeds , then carried out the calibration of an instrument according to the instruction manual and the measurement repeated. If in this case exceeds , the measurement is stopped until the reasons causing the increased variance.

APPLICATION (reference). The list of devices for measuring the mass fraction of gases

APP
Reference

Table 4