GOST 14019-2003

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  ГОСТ 14019-2003

GOST 14019−2003 (ISO 7438:1985) Materials of metal. Method of bend test

GOST 14019−2003
(ISO 7438:1985)
Group B09

INTERSTATE STANDARD

MATERIALS METAL

Method of bend test

Metallic materials. Bend test method

ISS 77.040.10
AXTU 0709

Date of introduction 2004−09−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 145 «monitoring Methods of steel products"

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 23 dated 22 may 2003)

The adoption voted:

3 this standard is modified in relation to the international standard ISO 7438:1985 «Materials metal. The bend test». The sections are identical, and the application And supplements these with the needs of national economy the above States

4 Resolution of the State Committee of the Russian Federation for standardization and Metrology on January 20, 2004 N 23 St interstate standard GOST 14019−2003 introduced as a national standard of the Russian Federation from September 1, 2004

5 REPLACE GOST 14019−80

6 REISSUE. March 2006

1 Scope

This standard specifies a method for determining the ability of metallic materials to withstand plastic deformation in bending.

Additional requirements that reflect the needs of the economy, is given in Appendix A.

2 Normative references

The present standard features references to the following standards:

GOST 2789−73 surface Roughness. Parameters and characteristics

GOST 7564−97 hire. General rules of sample, blanks collection for mechanical and technological tests

GOST 28840−90 Machine for testing materials in tension, compression and bending. General technical requirements

GOST 30893.1−2002 (ISO 2768−1-89) Basic norms of interchangeability. The total tolerance. Limit deviations of linear and angular dimensions with unspecified tolerance

3 Symbols and definitions

Symbols (figures 1 and 2) and the names of the parameters are given in table 1.

Figure 1

Figure 2

Table 1

4 the essence of the method

The bend test consists in plastic deformation of round, square, rectangular or polygonal cross section by bending without changing the direction of the force to achieve a given bending angle.

The axis of the two supports during bending of the sample must remain in a plane perpendicular to the direction of the force. When bending by 180°, the two lateral surfaces may, depending on the requirements of the standard for steel to touch each other or be parallel, while one from the other at a specified distance, for controlling this distance, apply the gasket.

5 Instrument

5.1 bend Test shall be carried out on universal testing machines or presses (GOST 28840), equipped with the following devices:

— bending device with two supports and a mandrel (figure 1);

— bending device with a V-shaped notch and a mandrel (figure 2);

— bending device with a vise (figure 3).

1 — grip; 2 — mandrel

Figure 3

5.2 bending device with supports and a mandrel

5.2.1 the anchorage Length and the width of the mandrel must exceed the width or diameter of the specimen. The diameter of the mandrel is determined by the normative document for the products. Support for the specimen and the mandrel shall be rigid enough.

Additional requirements to the mandrel and the supports given in Appendix A.

5.2.2 Unless otherwise specified, the distance between the supports is determined by the formula

, (1)

where is the diameter of the mandrel, mm;

 — the thickness (diameter) of specimen, mm.

This distance must not change during the bend test.

5.3 bending device with a V-shaped notch and the bar

The inclined planes of the V-shaped notch form an angle of 180°-(figure 2). The angle is established by the normative documents for the products.

Edge V-shaped notches must have a radius of curvature, in 1−10 times the thickness of the sample, and should be quite firm.

Additional requirements for the bending device is given in Appendix A.

5.4 the bending device grip

The device consists of a vise and a mandrel of sufficient hardness; it may be provided with a lever for applying a force to the sample (figure 3).

Additional requirements for the bending device is given in Appendix A.

6 Preparation for testing

6.1 Sampling, blanks and samples — according to the normative documents for the products.

Additional requirements for the selection of blanks and samples is given in Appendix A.

6.2 For the test used samples of round, square, rectangular or polygonal cross-section. Any areas of the material subjected to cutting with shears, flame cutting or similar operations during sampling should be removed. If such sites cannot be removed and allowed to test samples in bending, provided that the test results are to comply with regulations for steel products.

6.3 Edges of specimens of rectangular section shall be rounded with a radius not more than 0.1 of the thickness of the sample. Rounding should be performed so that it did not result in the formation of cross-section of burrs, scratches or dents that may affect the test results.

Allowed to conduct tests on the specimen with chamfered edges, provided that the test results are to comply with regulations for steel products.

6.4 If the regulations for metal products not specified otherwise, the specimen width shall be as follows:

— when the width of the product is not more than 20 mm sample width equal to the width of the product;

— when the width of the product more than 20 mm sample width is (20±5) mm for products of thickness less than 3 mm and from 20 to 50 mm for products of a thickness of 3 mm or more.

6.5 the Thickness of the specimens taken from sheets, strips and shaped sections, must be equal to the thickness of the test items. If the thickness more than 25 mm, it can be reduced by machining one side to obtain a thickness of not less than 25 mm When the bending of the raw surface should be on the stretch side of the specimen.

6.6 Samples of round, square, rectangular or polygonal cross section experiencing bending with a cross-section equal to the cross section of the product, provided if the diameter of the specimen with round cross section or inscribed circle diameter (for polygonal cross section) does not exceed 50 mm. If the diameter of the sample or the inscribed circle diameter of over 30 mm but not more than 50 mm, inclusive, then the sample can be reduced to a diameter of not less than 25 mm. If the diameter of the sample or the inscribed circle diameter exceeds 50 mm, the sample should be reduced to a diameter of not less than 25 mm (figure 4).

Figure 4

Bending the raw surface should be on the stretch side of the specimen. Additional requirements to the dimensions of samples are given in Appendix A.

6.7 When testing forgings, castings and semi-finished dimensions of samples and location sampling set by agreement between the consumer and the manufacturer.

6.8 as agreed between the consumer and the manufacturer of the bend test may be performed on samples of greater thickness and width than specified in 6.4 to 6.6.

6.9 Length of sample depends on the sample thickness and used test equipment.

7 testing

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

7.2 bending Test carried out in accordance with the requirements of one of the following methods specified in the normative documents for the products:

— to achieve a given bending angle under the action of stress (figures 1, 2 and 3);

— to achieve the parallel sides of the sample, spaced from each other at a predetermined distance under the action of stress (figure 5);

— to contact the sample under the action of forces (figure 6).

Figure 5

Figure 6

7.3 When tested in bending until the preset bending angle of the specimen mounted on supports (figure 1) or to the bending device with a V-shaped notch (figure 2) and bent in the middle between the supports under the action of a continuously increasing effort.

When tested in all ways (figures 1, 2 and 3), the bending force shall be applied gradually to permit free plastic flow of the metal.

If the above is impossible to bend the sample directly to the specified angle, then dahib produced by compression of the ends of the specimen (figure 7).

Figure 7

7.4 When tested in bending parallel to the sides of the sample first curve, as specified in 7.3, and it was then placed between two parallel surfaces of the press (figure 5) and with ever-increasing force to bend until parallel to sides of the sample. This test may be done with strip or without strip. The gasket thickness should be equal to the diameter of the mandrel.

7.5 When tested in bending to the contact side of the specimen (figure 6) the sample is then pre-bend is subjected to further bending between two parallel surfaces of the press with ever-increasing force.

8 Handling of test results

8.1 the results of the bending test was evaluated in accordance with the regulations for steel products. If such instructions are absent, then the absence of cracks visible to the naked eye, is proof that the sample withstood the bending test.

8.2 bending Angle specified in the regulations for steel products is always considered to be minimal. If you specify the inner radius of the bend, he will always be at its peak.

9 test report

The test report must contain the following information:

— reference to this standard;

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

the form and size of the sample;

test method;

the results of the test.

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

APPENDIX A
(required)

A. 1 in the absence of indications in regulatory documents for the products the place cutting blanks for samples, their number, the direction of the longitudinal axis of the sample relative to the blank margins when cutting out and machining establish on GOST 7564 or other normative document on the rules of sampling, blanks and samples in agreement between consumer and manufacturer.

A. 2 in the absence of indications in regulatory documents for steel mandrel diameter must be equal to two thicknesses (diameters) of the sample, and the radius of curvature of supports must be not less than thickness (diameter) of the sample.

A. 3 the Working surface of the mandrel and the supports of the bending device, clamping device and a bending device with a V-shaped notch should not be crushed. The hardness of these surfaces must be not less than 50 HRC.

A. 4 Testing of steel products of a thickness exceeding 30 mm may be performed on cylindrical samples with a diameter of (25±0,5) mm.

A. 5 Approximate length of the sample , mm, is determined by the formula

, (A. 1)

where  — the thickness (diameter) of specimen, mm;

 — mandrel diameter, mm;

 — coefficient, equal to 100−150 mm.

A. 6 surface Roughness of specimens after machining must be no more than 40 µm according to GOST 2789.

A. 7 If there are indications in regulatory documents for products testing is carried out before the appearance of the first cracks in the stretched area of sample with the definition of the bending angle.

8 A. Before the test is allowed to edit the sample at a temperature of from 10 °C to 35 °C.

A. 9 When tested up to the contact Pets clearance equal to the inner radius of the bend.

A. 10 the bend Test to the first appearance of cracks is carried out according to the same method as bending to a predetermined angle. With any method of testing the bending velocity of the mandrel or of the supports should not exceed 15 mm/min.

The moment of occurrence of cracks establish to the naked eye. The bending angle is measured without removing the force.

A. 11 it is allowed to measure the bend angle after the removal efforts.

A. 12 Limit deviation for diameter and width of samples in accordance with GOST 30893.1 for accuracy class rude.

A. 13 In the test report should specify the thickness or diameter (or the diameter of the inscribed circle to the polygonal cross-section) of steel products.

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

M.: STANDARTINFORM, 2006