GOST 24956-81

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  ГОСТ 24956-81

GOST 24956−81 Titanium and titanium alloys. Method for the determination of hydrogen (with Amendments No. 1, 2, 3)

GOST 24956−81

Group B59

STATE STANDARD OF THE USSR

TITANIUM AND TITANIUM ALLOYS

Method for the determination of hydrogen

Titanium and titanium alloys. Method for the determination of hydrogen

AXTU 1809

Date of introduction 1983−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR

DEVELOPERS

V. I. Dobatkin, V. A. Danilkin, L. I. Vorobyova

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 28.09.81 N 4404

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

_________________
* On the territory of the Russian Federation GOST R 51652−2000. — Note the manufacturer’s database.

5. Resolution of the state standard from 07.09.92 N 1122 removed the limitation of the validity period

6. REPRINT (February 1997) with Amendments No. 1, 2 approved in June 1987, September 1992 (IUS 9−87, 12−92)

AMENDED N 3 adopted by the Interstate Council for standardization, Metrology and certification (minutes N 11 dated 25.04.97). The state developed by Russia. By the resolution of Gosstandart of Russia from 23.09.97 N 340 was put into effect in the territory of the Russian Federation with 01.01.98

Change No. 3 made by the manufacturer of the database in the text IUS N 12, 1997


This standard specifies a method of vacuum heating for the determination of hydrogen in titanium and titanium alloys (in mass fraction of hydrogen is from about 0.0006 to 0.05%).

The method is based on extraction of hydrogen from a test sample of the alloy, is heated below the melting point (usually at a temperature of from 880 °C to 920 °C), in vacuum under residual pressure (1,33-of 6.65)·10PA [(1−5)·10] mm Hg.St.

The hydrogen produced is collected in a calibrated volume, the pressure change determines the amount.

(Changed edition, Rev. N 1, 2, 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 25086 with the Supplement.

1.1.1. Mass fraction of hydrogen in the analyzed alloys are determined on two samples one sample, weighted with the error not more than 0.01 g For the result of the analysis be the arithmetic mean of results of two parallel measurements.

1.1, 1.1.1. (Changed edition, Rev. N 2).

2. SAMPLING AND PREPARATION OF SAMPLES FOR ANALYSIS

2.1. Sampling for analysis is carried out according to normative-technical documentation.

2.2. From the sample and cut the workpiece width, and thickness 6 mm, length 20 to 25 mm. From the resulting billets are machined two samples with a diameter of (4±0,1) mm and length (6±0,2) mm;

the workpiece is clamped in the Chuck of the lathe, grind the face surface and along the length of a diameter of 4.5 mm;

carried out final truing of the end face and the surface of the sample power feed caliper.

The cutting edge of the cutter is polished on a diamond lap. The turning is carried out without cooling the emulsion.

The roughness parameter samples should be not more than 2.5 µm reference length of 0.8 mm according to GOST 2789;

cut samples in length (6±0,2) mm each;

each sample is clamped in a metal collet Chuck, pre-fat-free gasoline, and grind the second side.

On the surface of the sample is not allowed to have tint.

Depending on the equipment allowed the use of samples of large dimensions.

When determining the content of hydrogen in thin sheets or wire samples for analysis by mass from 0.2 to 0.3 g every cut directly from the intermediate product.

(Changed edition, Rev. N 2).

2.3. The samples are weighed, then degreased with benzene and alcohol. All operations are performed clean grease-free tools.

3. EQUIPMENT AND REAGENTS

3.1. The device for determination of hydrogen content (Fig.1) with remote control consists of main units and elements:

electric resistance furnace 15, which provides heating temperature from 800 to 1000 °C, equipped with chromelalumel thermoelectric thermometer according to GOST 1790 and potentiometer type KSP-4 to measure and record temperature;

vacuum system with which to install create vacuum (1,33-of 6.65)·10PA; this includes the roughing pump 13 of the type VN-461М, prototy diffusion pump 12of the type Н50Р, glass prototy pump 6 and the glass tubing;

glass extraction Assembly consisting of a replacement extraction tube 1 (Fig.2) connected with a water-cooled cone 2 with a feed tube 3;

analytical system consisting of:

calibrated vessel, bounded on one side of the conditional median line of the glass protochnogo pump, on the other hand, mercury gate 10. Extracted from the sample gas is pumped into a calibrated container, comprising a cylinder 8, of glass prostudnym pump 6;

compression gauge Mac-Leod 9 with a measurement range from 1.33·10to 79.8 per PA (1·10to 6·10mm Hg.St.) for measuring the pressure collected in the analytical system hydrogen;

cranes and with which carried out the lifting and lowering of the mercury in the manometer Mak-Lead 9 and the shutter 10 when connecting them alternately with the atmosphere or a backing cylinder 11;

cranes , , , , , which shall prepustanje extracted from a sample of hydrogen from an extraction site in the analytical system;

capillary trap 5 and trap 7cooled with liquid nitrogen; are used for freezing the water vapors in the installation;

gauge lamp 17 of the type PMT-2 for vacuum control.

Damn.1.- The device for determination of hydrogen content with remote control

Damn.1

Damn.2. Glass extraction node

Damn.2

Allowed the use of other analytical equipment, providing the meteorological parameters specified in this standard.

Mercury metal according to GOST 4658.

Hydrochloric acid according to GOST 3118, a solution of 1:9.

Sulfuric acid according to GOST 4204.

Potassium dichromate according to GOST 4220.

The aviation gasoline according to GOST 1012.

The technical rectified ethyl alcohol according to GOST 18300.

Oil vacuum.

Grease vacuum.

Liquid nitrogen according to GOST 9293.

Medical absorbent cotton wool GOST 5556.

Baptiste.

Rubber vacuum.

(Changed edition, Rev. N 3).

4. ANALYSIS

4.1. Check the vacuum valves, which should be free with no effort to rotate. All the cranes need not less than two times per month to replace the vacuum grease, applying it with a thin layer. The lubricant must not get into the vacuum of communication.

4.2. Download the analyzed samples in the feeder tube 3 and grind the glass cap. In one series do not download more than 30 samples.

4.3. Applied vacuum grease to the cone of the extraction tube 1 and grind it to a water cooled cone 2. Do not allow any lubricant on the inner surface of the quartz tube.

4.4. For pre-evacuating throughout the unit should:

close all the taps;

enable the roughing pump 13;

tap to combine with a backing cylinder 11 and to pump the air for 15−20 minutes;

close the faucet and the taps , and connect with high-vacuum pumping line (paritally through a diffusion pump 12).

In this position of the valves the air is pumped out of the extraction tube and the diffusion protochnogo pump 12 to generate a vacuum less than 1.33 PA (1·10mm Hg.St.). The vacuum control lamp 17;

close all the taps, tap to connect with the trunk of the faucet and gently open the tap , combining analytical system with a backing pump. The mercury in the manometer Mak-Lead 9 and mercury gate 10 will rise. The mercury must be lowered by connecting the taps and with the backing cylinder 11. Pumping is carried out to generate a vacuum less than 1.33 PA (1·10mm Hg

.St.).

4.5. To create throughout the system a high vacuum is necessary:

to include water cooling of the diffusion pumps and prostudnyh section 2;

to enable heating of the diffusion prostudnyh pumps 6 and 12;

cranes , , to connect with parachute diffusion pump 12 and after 10 minutes, turn on the pump, the trap 7 pour liquid nitrogen. Pumping is carried out to create in the vacuum system not less than 1.33·10PA (1·10mm Hg.St.). The vacuum control lamp 17 and a pressure gauge Mack-Leod 9.

4.6. Conduct decontamination of the extraction tube 1. To do this, pull the electric resistance furnace to the tube and turn it. The temperature of degassing from 880 to 920 °C, duration 1−1,5 hours.

4.7. Determine the correction control of the experience, which should not exceed 3·10% of hydrogen at 1 g sample for 15 min at assay temperature from 880 to 920 °C.

Pour liquid nitrogen in the capillary trap 5, a faucet connected to the analytical system through a diffusion prototy pump 6, raises the mercury in the bolt 10. After 15 min measure the pressure in the analytical system.

(Changed edition, Rev. N 3).

4.8. After the correction of the reference experiment, the mercury in the stopper 10 is omitted and analytical system and an extraction tube, a high vacuum.

(Changed edition, Rev. N 1).

4.9. For analysis of the sample raise the mercury in the gate 10, and then discard the test sample in the extraction tube 1 steel pusher with a magnet.

Raise one half of the split resistance furnace 15 and the second pusher 14is transferred the sample into a heating zone, and then are transferred pusher into the cold zone and close the oven. Include a recording pressure measurement in the analytical system on the potentiometer. Potentiometer with millivoltage scale is used for registration of pressure change in the test system installation.

The end of the extraction is determined by the kinetic curve of pressure change in the analytical system. When the kinetic curve goes to a straight line segment measured by the pressure gauge Mack-Leod 9. The extraction is complete, if two or three subsequent measurements of pressure or change to match the correction in the reference experiment.

The duration of the extraction of hydrogen from a sample taken size is 15−20 min. pressure Value of the last measurement recorded in the work log.

The crane is connected to the line protochnogo pumping the diffusion pump 12. At the same time remove the sample from the hot zone, which raises one half of electric resistance 15, steel pusher 14 is transferred to the sample used in the receiver samples 16 of the extraction tube 1, and then return the pusher into the cold zone and close the oven 15.

4.10. The crane is connected to the analytical system, and lower the mercury in the gate 10 and create the analytical system of high vacuum.

4.9, 4.10. (Changed edition, Rev. N 3).

4.11. The analysis of other samples of the series is carried out, as indicated in the claims.4.9, 4.10.

During the analysis in the traps 5 and 7 maintain a constant level of liquid nitrogen, which should not exceed 15 mm.

4.12. For analysis the next series of samples will carry out the following operations.

4.12.1. Turn off the electric resistance furnace 15 and after 20 minutes close the taps and .

Off glass prototy pump 6 and vaporize liquid nitrogen, compressed air from his traps 7. Vacuum in the analytical system is reduced due to the evaporation of moisture condensed on the trap. Pumped to the analytical system through diffusion prototy pump 12 to create a high vacuum, and then close the valve .

Prototy turn off the diffusion pump 12 and after 10 min to evaporate the liquid nitrogen from the trap 7. After 15 minutes close the valve . After 30 min after switching off the diffusion pump protochnogo shut off the water.

4.12.2. Turn off the roughing pump 13 and the pump letting in air through the valve , connecting it with the atmosphere.

4.12.3. In the low vacuum, the highway through the faucet to let the air of the atmosphere.

Taps and connect the extraction tube 1 with the low vacuum line and disconnect it from the water-cooled section 2.

Remove the cap from the tube 3 and load a new batch of samples.

4.12.4. Cap the extraction tube 1 to a water-cooled grind the socket 2, close the valve , include a roughing pump 13 and create a backing pump in an extraction tube 1by connecting it through the valves , and a pump 13.

4.13. When the machine is switched off, if the series of samples analyzed is loaded not completely, carry out the operations specified in the PP.4.12.1, 4.12.2.

4.14. When you download a new series of samples per period of operation (during working days) carry out the activities specified in paragraphs.4.12.2, 4.12.3, 4.12.4.

4.15. The air in the analytical system and prototy diffusion pump 12 is admitted only when the total preventive maintenance installation and Troubleshooting.

4.16. After a series of tests on the walls of the quartz extraction tube 1 may form a dark coating that must be removed before reuse of the tube. This tube filled with 10% solution of hydrochloric acid or a mixture consisting of one part of potassium dichromate and five parts of concentrated sulphuric acid (in the case of stubborn plaque), and incubated for 20 min, after which the acid was discarded and the tube washed with first water and then with distilled water. Washed up is calcined in an electric furnace of the resistance at a temperature of from 880 to 920 °C for 1 h.

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of hydrogen in the analyzed sample (), in percent, is calculated by the formula

,

where  — volume of the analytical system, cm;

 — temperature coefficient;

 — indoor temperature, °C;

 — pressure in the analysis, PA;

 — pressure when control experience, PA;

1,13·10 — coefficient, PA.

 — the mass of sample, g.

(Changed edition, Rev. N 3).

5.2. Discrepancies in the results must not exceed the values given in the table.