GOST 3565-80

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  ГОСТ 3565-80

GOST 3565−80 Metals. Test method for torsion (Change No. 1)

GOST 3565−80
Group B09

STATE STANDARD OF THE USSR

METALS

Test method for torsion

Metals. Method of torsion test

The validity 01.07.81
to 01.07.91*
____________________________________________
* Expiration removed by resolution
Gosstandart of the USSR No. 464 from 09.04.91.
(IUS N 7, 1991). — Note the CODE.

APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards, dated may 30, 1980 N 2445

REPLACE GOST 3565−58

REPRINT (February 1988) with amendment No. 1, approved in March 1982 (ICS 6−82).

This standard applies to ferrous and nonferrous metals and alloys, and their products and establishes methods of static tests in torsion at a temperature of 20°C to characterize the mechanical properties and character of fracture in torsion.

The standard does not specify test methods for torsion in conditions of high and low temperature, vacuum, chemically active media and radiation exposure.

1. GENERAL PROVISIONS

1.1. Terms, definitions and symbols used in this standard are shown in mandatory Appendix 1.

1.2. The results of the test samples in torsion produced a definition of the following mechanical characteristics:

the shear modulus,

the limit of proportionality,

yield strength

tensile strength (conditional),

the tensile strength (true),

maximum residual shear

the nature of the fracture (cut or separation).

2. TEST EQUIPMENT

2.1. For the torsion testing can be used testing machine, which provides:

free torsion of the samples without any additional stress on the sample throughout the testing process;

centering of the specimen in the grips with a misalignment less than 0.1 mm for every 100 mm;

smooth static load (without impacts);

free movement of one of the grippers along the axis of the sample;

load measurement error not exceeding ±1% of measured load from 0.2 maximum values of each range, but not below 0.04 limit load;

variation of readings siloizmeritelya with repeated loadings and load, not exceeding the permissible error of cylosporine;

the ability of loading with an accuracy of one smallest division of the scale siloizmeritelya testing machine;

the persistence of the readings siloizmeritelya for at least 30 s;

measurement of angle of twist with an error not exceeding 1°.

(Changed edition, Rev. N 1).

3. SAMPLES

3.1. For the torsion testing as a major use of cylindrical samples with diameter of the working part 10 mm and the estimated length of 100 and 50 mm, with the heads on the ends for fixation in the grips of the testing machine.

Note. The estimated length consider the length of the cylindrical part of the sample, which produces a measurement of angular deformation. The measuring base of the device should be placed in the middle part of the sample. Testing samples of steel with a diameter of less than 5 mm are only subject to the requirements of the standards for these types of products.

3.2. Allowed testing of samples and products, proportional normal, as well as tubular specimens.

Note. The results of the tests of tube samples can only be used with no loss of their stability.

3.3. The form and sizes of heads of the sample determined by the method of mounting the specimen in the grips of the testing machine.

3.4. The transition from the working part of the specimen to its heads should be smooth with radius not less than 3 mm.

3.5. The difference between the largest and smallest diameter of the working part of the main sample should not exceed 0.2% of the nominal value of the diameter.

3.6. The measurement of the diameter of the sample is carried out with an accuracy of at least 0,01 mm, and its length with an error of not more than 0.1 mm.

3.7. The test specimen dimensions is carried out to test the measurement tool for ensuring that the requirements of clause 3.6.

3.8. The technology of manufacturing the samples should not affect the mechanical properties of the starting material.

3.9. The surface roughness of the working part of the main cylindrical specimens must meet µm according to GOST 2789−73.

4. TESTING AND PROCESSING OF RESULTS

4.1. When tested in torsion the load count up to one scale siloizmeritelya. Precision measurement of angles corresponds to the price of division of the protractor. The calculation of the mechanical characteristics on the results of tests conducted with a precision of 1%.

4.2. Determination of the shear modulus in torsion.

4.2.1. Establish and fix the specimen in the grips of the testing machine. Load the sample torque, the corresponding initial shear stress of 10 per cent, the expected limit of proportionality of a material, fixed on the working part of the sample goniometer and note the initial reading of the protractor, is taken as zero.

4.2.2. Loading the sample torque is carried out in equal steps (at least three) so that the voltage in the sample did not exceed the limit of proportionality, and register at each stage of loading, the twist angles of the sample to its estimated length. Check angle of twist must not exceed 10 seconds.

4.2.3. The shear modulus in torsion in MPa (kgf/mm) is calculated according to the formula

where the level of loading, N·mm (kgf·mm);

 — gauge length of the specimen, mm;

 — the arithmetic average of the twist angles on the calculated length of a specimen per degree of loading, happy;

 — polar moment of inertia, mm.

Note. For the sample circular diameter of the polar moment of inertia is calculated by the formula

For sample tubular annular cross section with an outside diameter and a wall thickness of

.

4.2.4. Example determine the shear modulus in torsion is given in reference 2 below.

4.2.5. The shear modulus in torsion can also be determined by the tangent of the slope of the straight portion of the curves corresponding to the elastic deformation, if the scale of the diagram provides not more than 0.01% of the relative shift by 1 mm the x-axis and not more than 1 MPa (is 0.102 kgf/mm) shear stress at 1 mm in the y-axis.

4.3. The definition of the limit of proportionality torsional

4.3.1. Perform the operations specified in paragraph 4.2.1.

4.3.2. DeGroat sample at first large and then small steps, noting after each stage of loading, the angular deformation. Loading of the big steps is carried out to 80% of the expected limit of proportionality. Stages of small loadings are selected so that until the limit of proportionality was at least five stages of small loadings. The value of a small degree of loading must correspond to the increase in shear stress is not more than 10 MPa (1.02 kgf/mm).

4.3.3. The test is stopped when the angular deformation from loading on the small stage will exceed by not less than two times the average value of the angular deformation obtained in the previous stages of loading in the linear range.

4.3.4. Determine the increment value of the angle of twist at a low level of loading in the linear range. The resulting value increases in accordance with the permit. According to the results of the tests determine the load corresponding to the counted value of the increment of the angle of twist. If calculated in accordance with the tolerance value of angular deformation is repeated several times, the load take the first (smaller) value of the load.

Note. In cases where you need the updated value of the limit of proportionality, be allowed the use of linear interpolation.

4.3.5. The load may also be determined according to the strain diagram shown in hell.1, if the scale of the diagram provides not more than 0.05% of relative shift by 1 mm to the x-axis and not more than 5 MPa (0,51 kgf/mm) shear stress at 1 mm in the y-axis.

Damn.1 strain Diagram

Damn.1

4.3.5.1. To determine on the chart to draw , coincident with the initial straight-line portion of the curve deformation. Point hold the y-axis , then straight , parallel to the x-axis at an arbitrary level, and on this line lay the cut is equal to half cut . Through the point and the origin is carried out straight parallel to it and tangent to the curve deformation. The ordinate of the touch point .

uet .

4.3.6. The limit of proportionality in torsion in MPa (kgf/mm) is calculated according to the formula

where is the polar moment of resistance, mm.

Note. For a specimen of circular cross-section moment resistance is calculated by the formula

For tubular specimen of annular section —

.

4.3.7. An example of determining the limit of proportionality in torsion in the reference enclosure 3.

4.4. Determination of the yield strength in torsion

4.4.1. Perform the operations specified in the claims. 4.2.1 and 4.3.2 — 4.3.4. Deformation to the limit of proportionality, elastic think, and the limit of proportionality residual.

4.4.2. Calculate the relative shift in percent by the formula

,

where is the angle of twist of the sample to its estimated length, corresponding to the limit of proportionality in torsion, glad;

 — diameter of the working part of the specimen, mm;

 — gauge length of the specimen, mm.

4.4.3. Added to the relative shift in the tolerance on the residual shear 0.3% and largest find the corresponding yield stress angle of twist calculated length of a specimen.

4.4.4. Continue loading the sample beyond the limit of proportionality until then, until you reach the angle of twist corresponding to the value and record the load corresponding to the yield stress.

4.4.5. The load can also be determined by the graph deformations, shown on features.2, if the scale of the graph provides not more than 0.05% relative shift of 1 m to the x-axis and not more than 5 MPa (0,51 kgf/mm) shear stress at 1 mm in the y-axis.

Damn.2 Diagram of deformation

Damn.2

4.4.5.1. To determine the origin of the postpone on abscissa axis the segment corresponding to the residual shear . The initial curvilinear portion of the graph is excluded. From the point draw, a parallel line to the intersection with the curve (point ). The ordinate of the point of intersection of a straight line with the curve of the chart is the value of the load corresponding to the limit recuces

ti.

4.4.6. Yield strength in torsion in MPa (kgf/mm) is calculated according to the formula

.

4.4.7. An example of determining yield stress in the reference Appendix 4.

4.5. The definition of conditional tensile strength torsional

4.5.1. Establish and fix the specimen in the grips of the testing machine and loaded to failure, recording failure load . At the same time record the maximum angle of twist on the calculated length of the sample used in the calculation (see section 4.7).

4.5.2. Conditional ultimate strength in torsion in MPa (kgf/mm) is calculated according to the formula

.

4.6. The determination of true tensile strength torsional

4.6.1. Establish and fix the specimen in the grips of the testing machine and loaded until the appearance of plastic deformations.

4.6.2. Speed zagrujat the specimen to failure, recording the load and corresponding twist angles on the calculated length of the sample during a monotonous deformation of the sample at a specified rate.

4.6.3. Calculate the relative angles of twist in rad/mm by the formula

.

4.6.4. According to calculated values of loads and build the final segment of the curve coordinates (you can also use the chart that was in the process of testing). For points of the curve corresponding to the time of the destruction of a sample, graphically determine the magnitude equal to the tangent of the angle between the tangent to the curve at that point and the x-axis (considering the scale). The dimension of the indicated value .

4.6.5. An ultimate strength in torsion in MPa (kgf/mm) is calculated according to the formula

,

where 's the torque at fracture of the sample, kgf·mm;

 — relative angle of torsion at failure of the specimen, rad/mm;

 — the amount determined graphically in accordance with paragraph 4.6.4.

4.7. The maximum residual torsional shear () is calculated by the formula

,

if the shift amount does not exceed 0.1 rad. At higher deformation the maximum residual shift is determined by the formula

,

where  — the maximum angle of twist on the calculated length of the sample, good (item 4.5.1).

Allowed to Express in percentage, by multiplying the calculated value by 100.

Note. For ductile metals, in which the amount of elastic deformation is relatively small (not more than 10% of the total deformation), is allowed to take a total shift of the residual. For low-plasticity of metals, in which the elastic deformation is relatively large, to define the maximum residual shear should be subtracted from the total shear elastic shear calculated according to formula

,

where is the conventional ultimate strength in torsion of the material, MPa (kgf/mm);

 — the shear modulus of the material, MPa (kgs/mm).

4.8. Specified in section 1.2 mechanical properties can be determined by the results of the torsion testing of one sample by combining the relevant operations specified in PP. 4.2−4.7.

4.9. Proforma of test report torsion of cylindrical specimens is given in reference 5.

ANNEX 1 (mandatory). TERMS, DEFINITIONS AND SYMBOLS

ANNEX 1
Mandatory

1. Terms, definitions and symbols common to all test methods specified in GOST 16504−81.

2. Terms, definitions and designations related to testing in torsion are given in the table.

ANNEX 2 (informative). AN EXAMPLE OF DETERMINING THE SHEAR MODULUS TORSIONAL

ANNEX 2
Reference

The subject material — carbon steel.

The size of the sample:

=10 mm;

the moment of inertia of the cross section mm;

drag torque mm;

the estimated length and base of protractor mm;

the price of division of the scale angle — of 0.00025 rad.

The expected limit of proportionality, MPa

Initial tension MPa, which corresponds to the moment N·mm, rounded accept N·mm.

Maximum load in N·mm, corresponding to 80% load the expected limit of proportionality, equal to N·mm Accept N·mm.

To obtain the three stages in the interval of the load step of loading , in N·mm calculated according to the formula

N·mm.

Accept N·mm.

The test results recorded in the table.

The average difference between the readings on the level of loading: N·mm — 55 divisions, which corresponds to the angle of twist.

happy.

The shear modulus

MPa.

APPENDIX 3 (reference). AN EXAMPLE OF DETERMINING THE LIMIT OF PROPORTIONALITY TORSIONAL

APPENDIX 3
Reference

The test material, specimen dimensions and calculate the first three steps of loading are given in reference Appendix 2 of this standard.

Accept N·mm, carry out the loading of three steps and the test results recorded in the table.

Further loading hold small steps N·mm (which corresponds to the increment of stress MPa) to noticeable deviations from the law of proportionality, taking readings of the inclinometer. The test results recorded in the table.

The average value of the increment of the readings of the protractor on the small stage of loading N·mm in the linear range is

scale divisions.

Since the definition of limit of proportionality allowance is made 50% increase in the tangent of the angle between the tangent to the curve of deformation and axis loads, the value increased by 50% and the desired increment readings on the goniometer stage of loading N·mm, corresponding to the limit of proportionality is

scale divisions.

Table approximate value is 50000 N-mm.

The updated value of the load can be obtained by applying a method of linear interpolation

52000 N·mm to 50,000 N·mm = 2000 N·mm.

17 points — 13 divisions = 4 division.

Incremental load is determined from the proportion

where 2.5 dividing the difference between the nominal increment of reference (15.5 points) and the received increments of 13 points (in N·mm).

Incremental load in N·mm equal

N·mm.

The updated value of the load corresponding to the limit of proportionality, is equal to

N·mm.

The limit of proportionality , to meet an estimated load equal to

MPa.

ANNEX 4 (reference). EXAMPLE OF DETERMINATION OF YIELD STRENGTH IN TORSION

ANNEX 4
Reference

Consistently performed all the operations described in the informational Annex 3 of this standard, except for the counting .

Using a proportion, determine the increment of indications of the scale of the protractor, corresponding to the incremental load, N·mm.

hence, divisions.

The reading of the protractor, corresponding to the limit of proportionality, is equal to

232 cases. + 11. = 243 cases.

Angle of torsion wounded

happy.

The relative shift is equal to

.

The number of divisions of the scale of the protractor, corresponding to the shift determined by the formula

Affairs.

The scale of the protractor, which achieved load yield stress equal to

243 cases.+240 cases. = 483 cases.

Smoothly manually load the specimen and record the load at the time of the readings of the protractor on 483 division.

Get N·mm.

The yield strength corresponding to , is equal to

MPa

ANNEX 5 (reference). A PROFORMA TEST REPORT TORSION OF CYLINDRICAL SPECIMENS

ANNEX 5
Reference

PROFORMA OF TEST REPORT TORSION OF CYLINDRICAL SPECIMENS

PROTOCOL N_______

twist testing of cylindrical specimens ________ by car ____

The text of the document is verified by:
the official publication of the
M.: Publishing house of standards, 1988