GOST R 52764-2007

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  ГОСТ Р 52764-2007

GOST R 52764−2007 (ISO 7799:1985) Materials of metal. Test method for bending of sheets and strips of a thickness of 3 mm and less

GOST R 52764−2007
(ISO 7799:1985)

Group B09

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

MATERIALS METAL

Test method for bending of sheets and strips of a thickness of 3 mm and less

Metallic materials. Method of bend test for sheets and strips 3 mm thick and less

OKS 77.040.10
AXTU 0709

Date of introduction 2008−07−01

Preface

The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004"Standardization in the Russian Federation. The main provisions"

Data on standard

1 DEVELOPED AND SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products"

2 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology, dated 22 October 2007 N 268-St

3 this standard is modified in relation to the international standard ISO 7799:1985 «Materials metal. Sheet and strip 3 mm thick or less. Test bend with change of direction» (ISO 7799:1985 «Metallic materials — Sheet and strip 3 mm thick or less — Reverse bend test») by changing individual words, phrases of introduction and Annex A to reflect the needs of the national economy of the Russian Federation, which are shown in italics.

The name of this standard changed with respect to names specified international standard for compliance with GOST R 1.5−2004 (subsection 3.5)

4 INTRODUCED FOR THE FIRST TIME

Information about the changes to this standard is published in the annually issued reference index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet

1 Scope

This standard specifies the method of determining the ability of metallic sheets and strips of a thickness of 3 mm or less, to withstand plastic deformation at inflection.

For aluminum and its alloys, this method can only be applied after prior agreement between the manufacturer and the customer.

2 Normative references

This standard uses the regulatory references to the following standards:

GOST R 8.568−97 State system for ensuring the uniformity of measurements. Certification of testing equipment. The main provisions of the

GOST 2789−73 surface Roughness. Parameters and characteristics

Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.

3 the essence of the method

The bend test is repeated bends 90° in opposite directions of a rectangular sample, one end of which is secured in the device consisting of jaws with rollers installed size.

One inflection accept bending the sample 90° and returning it to its original position (figure 1).

Figure 1 — scheme of the test bend

Figure 1 — scheme of the test bend

4 Terms and symbols

Terms and symbols used in the test for inflection shown in table 1 and figure 2.


Table 1

Figure 2 — schematic structure of an apparatus for testing the bend

1 — the bending lever; 2 — lead and 3 — axis of rotation of the bending arm; 4 — roller; 5 — jaws

Figure 2 — schematic structure of an apparatus for testing the bend

5 Equipment

5.1 Test bend is carried out on the deviceshown in figure 2.

5.2 Rollers and sponge device

5.2.1 Rollers and sponge the device should be replaceable, sufficiently hard and wear-resistant.

5.2.2 the radius of the rollers is established by the normative documents for the products.

You can use cylinders with radii given in table 2.


Table 2

In millimeters

5.2.3 the axis of the rollers must be perpendicular to the plane of the bend, parallel to each other and lie in the same plane within 0.1 mm.

5.2.4 Between the sample fixed in the device in the initial position, and each roller should be a clearance not exceeding 0.1 mm.

5.2.5 the Upper edge of the jaws must be below the axes of the rollers at a distance equal to 1.5 mm for cylinders with a radius of 2.5 mm and less than 3 mm — for rollers of larger size.

5.2.6 Distance from the lower edge of the leash to the upper forming rollers should be 3 to 50 mm.

5.3 Bending lever

The distance from the axis of rotation of the bending arm to the upper forming rollers shall be 1.0 mm for rollers of all sizes.

Device for testing bend test equipment is and shall be subject to certification in GOST R 8.568.

6 Sample for test

6.1 sample Thickness should be equal to the thickness of the material being tested. The surface of the sheet and tape can’t handle.

6.2 the Width of the sample after processing it the sides should be 20 to 25 mm.the Specimen shall be rectangular in shape.

The width of the sample should not vary throughout the length of more than 0.5 mm.

When the width of the tape at least 20 mm sample width should equal the width of the material as supplied.

6.3 Sample should be made in any ways (by stamping, cutting machines, etc.), eliminating the possibility of changing the properties of the metal during heating and hardening.

The sample surface should not have cracks, scratches and burrs.

7 testing

7.1 Test bend shall be performed at ambient temperature from 10 °C to 35 °C. the differences in the assessment of the quality tests must be carried out at a temperature of (23±5) °C.

7.2 the Sample is clamped in the jaws of the device (figure 2). The upper end of the sample should pass through the groove in the leash, is fixed on the lever device (the original position). The length of the clamped end must be at least the height of the jaws.

When testing the movement of the specimen in the jaws is not permitted.

7.3 Sample bend through 90° from vertical in any direction and return to its original (vertical) position that is taken for a single fold.

Following the bending is carried out in the opposite direction (figure 1).

The test is carried out without interruption between the curves.

7.4 test Speed should be uniform, not exceeding one bend per second.

To heat did not affect the test results at the request of the consumerthe speed of bending can be reduced.

7.5 to ensure good contact between the sample and platens during the test, can be used the tension of the sample. At the same tensile stress from tension shall not exceed 2% of the nominal strength of the tested metal, unless otherwise indicated in the normative documents for the products.

7.6 the Test continues until, until it reaches a certain normative documents for the products the number of kinks or to the appearance of cracks, visible without the aid of magnifying means.

With the appropriate guidelines in the normative documents for products testing continues until the complete destruction of the sample.

7.7 Break, during which occurs the destruction of the sample or there is a crack, do not include in the total number of kinks .

The number of kinks is determined with an accuracy of up to 0.5.

7.8 In the absence of a criterion for evaluation of test results in the normative documents for the products the test is stopped at the crack.

8 test report

8.1 the test report shall contain:

— reference to this standard;

— sample identification (type of material, number of melt, the direction of the axis of the sample relative products, etc.);

— the size of the sample;

— test conditions (radius of the rollers , the distance , the applied tensile stress when using);

the criterion for the end of the test;

the results of the test.

Annex a (mandatory). Additional requirements that reflect the needs of the economy

Appendix A
(required)

A. 1 the place of cutting workpieces for the manufacture of samples, their number, the direction of the longitudinal axis of the sample relative to the workpiece is adjusted in accordance with the requirements of the normative documents on products.

A. 2 When cutting of rolled billets for samples of leave allowance to the processing from the cut line to the edge of the finished sample.

Work-hardened zone and subjected to heating, is removed by machining.

Allowed to sweep the sharp edges with a file.

A. 3 it is allowed to edit the sample before the test, unless otherwise indicated in the normative documents for the products.

A. 4 in the manufacture of samples keep rolling surface and surface treatment (Paluda, galvanizing, etc.).

A. 5 For the sheets and strips of electrical isotropic and anisotropic steel is allowed to carry out test on samples of width (30±0,2) mm.

A. 6 Sponges and rollers of the device shall have a hardness not lower than HRC 60. The surface roughness of the jaws and rollers should be of 1.25 µm according to GOST 2789.

A. 7 the Device has to provide the bend angle of the sample is 90°±3° right and left from the vertical.

A. 8 the Device must have a tensioner that provides tension force for less than 2% of the nominal value of the time resistance test of metal.

A. 9 the Device may be equipped with rollers, in addition to those in table 2, radii equal (2±0,1), (4±0,1), (6±0,1) and (8±0,2) mm.

A. 10 is allowed when using the device rollers with a radius not exceeding 6 mm distance is less than specified in 5.2.5, but not less than 0.5 .

A. 11 the Width of the groove in the leash of the bending arm must not exceed the thickness of the sample: more than 0.3 mm for samples with thickness up to 0.5 mm, inclusive; more than 0.6 mm for samples with thickness more than 0.5 to 1.5 mm, inclusive; more than 0.7 mm, for samples with thickness more than 1.5 mm.

12 A. in the absence of indications in regulatory documents for steel distanceset to 5, 10, 15 and 20 mm, respectively, for samples with thickness up to 0.3 mm, more than 0.3 to 0.5 mm, inclusive, more than 0.5 to 1.5 mm inclusive over 1.5 mm.

A. 13 Criterion for completion of the test can be a crack length equal to half the width of the specimen, if it is stipulated in the normative documents for the products.

A. 14 For the sheets and strips coated with the beginning of the destruction I think the appearance of cracks in the base metal or the coating, if the regulations are for steel not provided other requirement.



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

M.: STANDARTINFORM, 2007