GOST 22706-77

• gost-22706-77.pdf (629.21 KiB)
  ГОСТ 22706-77

GOST 22706−77 Metals. Method of tensile testing at temperatures from minus 100 to minus 269 °C (Change No. 1)

GOST 22706−77

Group B09

INTERSTATE STANDARD

METALS

Method of tensile testing at temperatures from minus 100 to minus 269 °C

Metals. Method for tension tests at the temperature — 100 up to — 269 °C

AXTU 1909

Date of introduction 1979−01−01

INFORMATION DATA

1. DEVELOPED by the Central research Institute of ferrous metallurgy them. I. P. Bardin (TSNIICHM), Institute of problems of strength, Academy of Sciences of the Ukrainian SSR (IPP an UkrSSR), the State Institute of applied chemistry (gipkh)

INTRODUCED by the Ministry of ferrous metallurgy of the USSR

DEVELOPERS

S. A. Golovanenko, V. D. Lebedev, R. I. L. Kolesnikova, V. M. Postnov, N. In. Novikov, N. And. Gorodyskii, N. P. Antropov, I. L. Terushkin

2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from 23.09.77 N 2296

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

5. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)

6. EDITION (August 2000) with amendment No. 1, approved in April 1988 (I & C 7−88)


This standard applies to ferrous and nonferrous metals, alloys and their products and establishes the method of static tensile tests to determine temperatures from minus 100 to minus 269 °C following mechanical characteristics:

— limit of proportionality;

— the limit of elasticity;

— yield strength of the physical;

— the yield strength conditional;

— temporary resistance;

relative uniform elongation;

— the elongation after rupture;

the relative narrowing of the cross section after the break.

The standard does not specify the method of static tensile testing of wire, pipes, sheet metal or strips of thickness less than 0.5 mm.

Notation, concepts and definitions is given in Appendix 1.

(Changed edition, Rev. N 1).

1. SAMPLING AND PREPARATION OF SAMPLES

1.1. Sample for samples cut in any way, providing allowances on the metal area with the changed properties when heated or sticker.

The location and direction of the fillet samples (blanks) for samples, the number and magnitude of allowances when cutting needs to be specified in normative and technical documentation on the rules of sampling or steel.

1.2. For tensile tests used cylindrical specimens with an initial diameter of the working part 3 mm or more and flat samples with an initial thickness of 0.5 mm or more and with an initial estimated length =5,65or =11,3. Dimensions of samples are given in appendices 2 and 3.

Samples with an initial estimated length * called short, samples =11,3 — long. The use of short samples, it is preferable.
_____________

* The text of the document matches the original. — Note the manufacturer’s database.

1.1, 1.2. (Changed edition, Rev. N 1).

1.3. The shape and size of the heads flat and cylindrical specimens, as well as the size of the transition parts from the heads of the sample to its working parts are optional and are determined by the method of mounting the samples in the grips of the machine and the properties of the test material (Fig.1−3, tab.1−3 of Annex 2 to hell.1−3
Annex 3). The shape of the head model and the design of the gripper should ensure a centering of the specimen during testing and to prevent collapse of the support surface, slippage, deformation, and destruction of the heads, to prevent the destruction of the sample in places of transition from the working side to the heads.

1.4. Samples must be processed on machine tools. Depth of cut in the last passage of the working part should not exceed 0.1 mm. the roughness of the working part of the cylindrical specimen should be =0,63−0,32 µm and flat samples — =2,5−1,25 µm according to GOST 2789.

Allowed to test cylindrical samples with a roughness of the working part =2,5−1,25 µm and flat samples with roughness of the side surfaces of the working part is not more than =5 µm, provided that the norms of mechanical properties.

(Changed edition, Rev. N 1).

2. EQUIPMENT AND MATERIALS

2.1. As the testing machines used tensile testing machines and universal of all systems subject to their conformity to requirements of GOST 28840. The working space of the machine should allow you to install the cryostat and the extension rod.

2.2. The test machine must provide:

— centering the test sample;

— smooth increase of load when loading the sample;

— the speed of the movable gripper — less than 0.1 the estimated initial length of the specimen, expressed in millimetres per minute.

In the normative-technical documentation for specific products, the test speed can be specified and should be indicated in the test report.

For simultaneous cooling of the party samples it is recommended to apply mnogoobraznye cluster or rechargeable devices.

2.3. As coolers using liquid nitrogen (boiling point minus 196 °C), hydrogen (minus 253 °C) and helium (minus 269 °C). Intermediate temperatures were obtained through automatic metered flow liquid-vapor mixture of nitrogen in the temperature range from minus 100 to minus 196 °C, liquid-vapor mixture of hydrogen — from minus 100 to minus 253 °C and the liquid-vapor mixture of helium — from minus 196 to minus 269 °C. the Use of hydrogen is allowed in conditions that ensure full safety. It is recommended to choose the chiller based on the conditions of operation.

Not permitted for use:

— liquid oxygen and liquid air as a refrigerant;

— aggressive or toxic liquids in the mixture with a liquid cooler;

liquid technical nitrogen GOST 9293 containing oxygen in excess of 10%.

(Changed edition, Rev. N 1).

2.4. A cryostat must provide cooling of samples and the ability to maintain a constant set temperature of the specimen (s) under test. The lowest level of liquid coolant should not be below 15 mm from the end surface of the head sample. The cryostats in which to cool the specimen (s) used liquid helium should run in a closed cycle. A helium cryostat is evacuated; provides for the collection of gaseous helium. It is forbidden to carry out tests on machines not equipped with equipment to collect gaseous helium.

The cryostats in which to cool the specimen (s) used liquid hydrogen needs to ensure the safety of the work.

2.5. To measure the temperature of the sample used thermocouple and resistance thermometer with instruments of accuracy class not less than 0.5%. The level of liquid coolant measure semiconductor resistance, mechanical level gauges, float type and other devices. The permissible error of determining the level of liquid coolant in the cryostat — no more than ±5 mm.

(Changed edition, Rev. N 1).

2.6. Sprays vapor and liquid cooler to ensure uniform cooling of the entire working length of the sample to a predetermined temperature.

2.7. The devices measure the linear dimensions shall conform to the requirements of: calipers, GOST 166, micrometers, GOST 6507, strain gauges, rulers, metal -GOST 427.

(Added, Rev. N 1).

3. PREPARING FOR THE TEST

3.1. The initial estimated length defined by the formulas of 5.65and 11.3, rounded up to the nearest multiple of 5 or 10, respectively.

The initial gauge length is limited to marks on the sample surface with an accuracy of 1% from its value. It is recommended to apply the mark softer material without damaging the sample surface.

The initial and final estimated length is measured to 1 decimal places (mm) after decimal multiple of 1.

To translation elongation assigning the break to the middle it is recommended to apply along the entire working part of the specimen marker intervals of 5 or 10 mm.

3.2. Measurement of the transverse dimensions of the samples before the test is carried out in millimeters:

— up to 2nd decimal multiple of 1, — the measurement of the diameter of the cylindrical sample and the thickness to 2 mm flat sample;

— up to 2 decimal places after the decimal, a multiple of 5, — when measuring the thickness of flat sample over 2 mm and width of flat sample.

3.3. Each dimension is produced in three places (in the middle part and edges) the estimated length of the specimen.

According to the obtained sizes of the figure of square cross section on the calculated length of the sample and choose the smallest of them.

Rounding is produced within the limits specified in table.1.

Table 1

3.1−3.3. (Changed edition, Rev. N 1).

4. TESTING

4.1. When tested in liquid helium or its vapor after the installation of the sample helium (inner) Dewar seal and produce its evacuation.

Testing in liquid nitrogen can be carried out in open cryostats. Tests in liquid hydrogen and vapor must be conducted in a sealed cryostat.

4.2. The level of liquid coolers in the test process it is necessary to control the level and maintain within the specified values.

4.3. With the ambient temperature set by the temperature control of the sample located in the region of uniform cooling. The temperature deviation of the vapor of the cooling medium from the specified shall not exceed ±2 °C. When testing samples in liquid coolers, the temperature of the test sample shall be equal to the boiling point of liquid coolant.

4.4. While keeping the samples at a given temperature set point experimentally and in normative-technical documentation for specific products. If such an indication is missing, then extract the sample in the cooler after reaching the temperature set on the control sample should be:

— at intermediate temperatures — not less than 10 min. for cylindrical samples with a diameter of 6 mm or less, and for flat specimens of thickness 4 mm or less, and not less than 15 min for cylindrical samples with a diameter of more than 6 mm and for flat samples with thickness more than 4 mm;

— when testing the samples in liquid nitrogen 5 min after the rapid boiling of the liquid, and in liquid helium and hydrogen — 5 min after fixing the required level of fill of liquid coolant.

5. PROCESSING OF THE RESULTS

5.1. Measurement of samples after the test produce in millimetres to the first decimal multiple of 1.

5.2. The value of the load during the test count up to one smallest division of the scale siloizmeritelya. When the test chart recorded stretching. The scale of the chart must comply with the ordinate 1 mm is not more than 10 (1) N/mm(kgf/mm) stress in the sample. Along the axis of deformation (x-axis) scale of record of not less than 50:1.

In the absence of testing machines with a record of the chart of stretching of the specified scale is allowed to use machine diagrams tension scale on the axis of deformation of at least 10:1. Processing chart stretching to obtain a complex of mechanical characteristics when tested the same sample or statistical processing of test results of batch samples, we recommend use of the computer, asking for a certain step of deformation (see Annex 4).

5.3. The limits of proportionality, elasticity, strength (physical and symbolic), tensile strength, elongation (uniform and total), relative narrowing when tested cylindrical and flat specimens without stress concentrators (notches) in the test section is determined according to GOST 1497.

In the presence of serration on a plot of elastic-plastic deformation and physical conditional yield stress and tensile strength shall be determined in accordance with the recommendations given in Annex 5.

5.1−5.3. (Changed edition, Rev. N 1).

In the presence of jagged in the beginning of the segment of the elastic-plastic deformation yield strength is defined by the middle line between the extreme values of the peaks (see Appendix 5).

To determine the load in MN (kgf) by the tension diagram calculate the amount of residual elongation on the basis of the working length of the sample. The magnitude of increase is proportional to the scale of the graph and cut the resulting length of the FIRST lay on the x-axis to the right from point O (see drawing). The initial curvilinear portion of the graph is excluded. From point E draw ER, is parallel to the line OA. The ordinate of the point of intersection of a straight line EP with the tensile curve determines the load corresponding to the yield strength at a given tolerance on the magnitude of the residual elongation.

Yield strength (conditional) in MPa (kgf/mm) is calculated according to the formula

.

5.4. (Deleted, Rev. N 1).

5.5. The tensile strength of the specimen notched in N/mm(kgf/mm) is determined by the ratio of the maximum axial tensile load in N (kgf), previous fracture of the sample, the initial cross-sectional area of the specimen in the notch in mmand calculated by the formula

.

5.6. Allowed determination of relative uniform elongation or the tension diagram as corresponding to the highest load , previous fracture or decay to the first load at this stage of deformation in the case of multiple necks on the working part of the sample, either directly on the sample deformed before the advent of the cervix and removed from the testing machine without bringing him to destruction.

5.5, 5.6. (Changed edition, Rev. N 1).

5.7. (Deleted, Rev. N 1).

5.8. To determine the relative contraction of the cylindrical sample with a notch after the break to measure the sizes of the destroyed surface in two mutually perpendicular directions, calculate the cross sectional area of the sample with a notch after the break () and calculate percentage according to the formula

.

5.9. Rounding the calculated results are produced in accordance with the table.2.

Table 2

5.10. Tests are considered invalid:

— when rupture of the sample cores (risks) if any characterization of the mechanical properties does not meet the requirements of normative-technical documentation for metal products;

— when rupture of the sample outside of the working length of the sample;

— in case of violation of the temperature regime of the tests.

In such cases the test should be repeated on samples of the same melting or party metal. The number of samples for re-testing must match the number of invalid test results. A sample replacement and reasons for replacement should be indicated in the test report.

5.11. A proforma fill the magazine tests are given in Annex 6.

ANNEX 1 (reference). THE DESIGNATION, TERMS AND DEFINITIONS

ANNEX 1
Reference

1.1. In the tensile test are taken the symbols, concepts and definitions are given in the table.

Note. Subject to the availability of guidance in the normative-technical documentation on the products to determine the limit of proportionality, elastic limit, yield strength with other tolerances:

— the limit of proportionality from 10 to 50%;

— the limit of elasticity of from 0.005 to 0.05%;

— yield strength of from 0.1 to 1%.

APPENDIX 1. (Changed edition, Rev. N 1).

ANNEX 2 (mandatory). Proportional cylindrical specimens

ANNEX 2
Mandatory

Damn.1 Type 1

Type 1

Damn.1

Table 1

Dimensions, mm

Damn.2 Type 2

Type 2

Damn.2

Table 2

Dimensions, mm

Damn.3 Type 3

Type 3

Damn.3

Table 3

Dimensions, mm

Note. Other dimensions of notched specimens are accepted at the table.1 and 2.

Subject to the availability of guidance and regulatory technical documentation to test the samples with other values of the radius of the top of cut and depth of cut.


APPENDIX 2. (Changed edition, Rev. N 1).

APPENDIX 3 (obligatory). Flat samples

APPENDIX 3
Mandatory

Damn.1 Type 1

Type 1

Damn.1

Table 1

Dimensions, mm

Damn.2 Type 2

Type 2

Damn.2

Table 2

Dimensions, mm

Damn.3 Type 3

Type 3

Damn.3

Note. The shift of the notches relative to each other is not more than 0.1 mm.

Table 3

Dimensions, mm

Note. Other dimensions of notched specimens are accepted at the table.1 and 2.

Subject to the availability of guidance and regulatory technical documentation to test the samples with other values of the radius of the top of cut and depth of cut.


APPENDIX 3. (Changed edition, Rev. N 1).

ANNEX 4 (reference). Determination of residual deformations of the diagram of deformations and preparation of charts for processing on a computer

ANNEX 4
Reference

ANNEX 5 (reference). Determination of load and residual strain corresponding to the characteristic points of the chart of stretching in conditions of intermittent flow

ANNEX 5
Reference

ANNEX 6 (rekomenuem). Proforma journal entries testing

APPENDIX 6
Rekomenuem

Continued

ANNEX 6. (Changed edition, Rev. N 1).



The electronic text of the document
prepared by JSC «Code» and checked by:
the official publication of the

M.: IPK Publishing house of standards, 2000