GOST 28870-90

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  ГОСТ 28870-90

GOST 28870−90 Steel. Methods tensile tests of rolled plates in the thickness direction

GOST 28870−90
Group B09

INTERSTATE STANDARD

STEEL

Methods tensile tests of rolled plates
in the direction of thickness

Steel. Methods of tensile tests of rolled thick-plates in the thickness direction

AXTU 0909

Date of introduction 1992−01−01

INFORMATION DATA

1. DEVELOPED by the Ministry of metallurgy of the USSR

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 29.12.90 N 3700

3. This standard fully complies with ISO 7778−83

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Limitation of actions taken by Protocol No. 5−94 of the Interstate Council for standardization, Metrology and certification (ICS 11−95)

7. REISSUE


This standard specifies the methods of tensile testing in the thickness direction at a temperature of () °C plate with a normalized minimum yield strength not exceeding 600 N/mmand a thickness of from 15 to 160 mm for the characterization of mechanical properties:

elongation after rupture;

the relative constriction after rupture.

Define other characteristics (strength and yield strength) in accordance with GOST 1497.

Terms, definitions and symbols — according to GOST 1497.

1. SAMPLING METHODS

1.1. Sampling for sample making is carried out at a distance of half the width rolled from either end of the sheet or strip.

Further requirements for sampling — according to GOST 7564.

1.2. A sample cut from the sample by mechanical means so that its axis was perpendicular to the surface of rolled products.

1.3. The number of samples selected for testing, set in the normative-technical documentation for metal products. In the absence of instructions on the number of samples should be tested three samples from each of the tested sheet.

1.4. The shape and dimensions of samples are given in Appendix 1.

Allowed the use of samples of other types and sizes.

1.5. The diameter of the working part of the sample depending on the thickness of the hire should match the values shown in the table.1.

Table 1

The ratio of the length of the working part of the specimen to its diameter (the ratio of the sample) shall be not less than 1.5.

1.6. Requirements for the manufacturing samples, the limit deviations of dimensions and marking — according to GOST 1497.

1.7. Allowed the production of samples with the use of welding to join the working and gripping parts of the sample.

Recommendations for the production of samples by welding are given in Appendix 2.

1.8. For sheets with a thickness of 15 to 20 mm the method of manufacturing a samples set in the normative-technical documentation for metal products. The diameter of the working part of the specimen needs to be equal to 6 mm, working length not less than 9 mm.

2. EQUIPMENT

Apparatus — according to GOST 1497.

3. PREPARING FOR THE TEST

3.1. The initial estimated working length take the length of the sample .

To determine the relative lengthening of the working length limit cores, or other risk markers.

Measurement of the working length before the test and working length after rupture of the sample carried out with a caliper or other measuring tool with a measuring error of up to 0.1 mm.

3.2. Allowed to determine the absolute lengthening of the working part of the specimen to measure the distance between the heads of the sample.

3.3. Allowed to calculate the working length of the specimen (mm), according to the formula

,

where is the distance between the heads of the specimen, mm;

 — the radius of the transition from the working side to the head of the specimen, mm.

3.4. The initial diameter of the working part of the specimen is measured in three sections of a caliper or other measuring tool with a measuring error of up to 0.05 mm.

In diameter to accept the smallest value of the measured.

3.5. Other requirements for the measurement of the sample and the rounding — according to shost 1497.

4. TESTING AND PROCESSING OF RESULTS

4.1. When testing set the speed of the active capture of the testing machine where the loading rate before the flow should be from 3 to 30 N/mm·s.

4.2. The elongation of the specimen after rupture in percent is calculated by the formula

or ,

where is the length between the cores or other marks, mm;

 — the length between the heads of the sample after the breakup.

Note. Elongation can be determined with the help of special devices (microprocessors) without measuring and .

4.3. The amount of elongation must be specified along with the multiplicity of the sample, for example .

4.4. The relative contraction of the specimen after the rupture () in percent is calculated by the formula

,

where ;

 — the initial cross-sectional area of the specimen, mm;

 — the minimum cross-sectional area after rupture, mm;

and  — the measured values of the mutually perpendicular diameters in the largest contraction of the sample. If the cross-section surface of the sample after fracture has an elliptical shape, and should be measured along the axes of the ellipse.

In Annex 3 the classification of sheet metal, depending on the relative values narrowed

ia.

4.5. The tests results are invalid when the failure of the specimen outside of the working part of the specimen, as well as the destruction caused by manufacturing defects in welded samples.

4.6. Other requirements for testing, measuring samples and the evaluation of test results in accordance with GOST 1497.

ANNEX 1 (mandatory). SAMPLES FOR TESTING IN THE THICKNESS DIRECTION OF STEEL PLATE

ANNEX 1
Mandatory

1. The shape and size of the sample, made of solid or welded workpiece.

Damn.1

Damn.1

Table 2

Dimensions, mm

Notes:

1. The sizes of heads of the sample are recommended and are set depending on the size of the gripping devices of the testing machine. It is possible to manufacture the threaded heads of the sample.

2. For samples made from sheet steel, having a thickness within the limits specified in table.2, length is selected corresponding to the thickness closest to the thickness of the sheet. The size is increased or decreased by polprasert between the actual thickness and indicated in the table.

Examples:

Sheet thickness of 22 mm. Size =9 mm, =5 mm.

Sheet thickness of 23 mm. Size =12 mm, =4 mm.

3. In the manufacture of specimens from sheets of thickness up to 50 mm may be performed to machine the ends of the heads of the sample. The middle of the working part of the specimen should correspond to the middle of the thickness of the sheet.

APPENDIX 2 (recommended). RECOMMENDATIONS FOR THE PRODUCTION OF SAMPLES BY WELDING

ANNEX 2
Recommended

1. If the thickness of the sheet allows the production of sample from solid material, allowed the connection of the gripping part of the specimen with the working method of welding.

Welding can be carried out by any available method (welding, friction welding, contact welding, manual arc welded), excluding the change in the properties of the test material.

Two types of samples with the use of welding for attaching the gripping parts to the work presented in hell.2 (a, b).

Damn.2

 — the thickness of the sheet

Damn.2

2. In the manufacture of samples by welding of the workpiece for gripping pieces of samples must be made of the test material or other type of weldable steel with the strength not lower the strength characteristics of the material being tested.

3. Welding is carried out with full penetration (discontinuities allowed) by the technology adopted for specific steel grades providing a minimum width of HAZ.

4. Electrodes for surfacing and welding needs to provide a weld metal and metal of welds with the strength not lower the strength characteristics of the material being tested.

The use of electrodes for welding according to GOST 10051 is not allowed.

5. In the manufacture of samples with application of the welding workpiece using the subject material х100х200 mm — sheet thickness (Fig.3A)]. Multi-layer coating on one or both surfaces of the workpiece in its Central portion perform a narrow rollers with a thickness of 4 mm, superimposed in the direction along the long side of the workpiece. The total width and height of the surfacing must be able to produce samples of the gripping parts (DWG.3b).

Damn.3

Damn.3

Weld the workpiece, except remove the initial and end sections of a length of 30 mm each (start and end cylinders), method of mechanical cold processing is cut into template, of which after polishing, etching and marking manufacture the samples. The thickness of the templates must be at least the diameter of the gripping pieces of samples with an allowance for processing.

6. In the manufacture of samples with the use of friction welding or contact welding of the test material cut cylindrical workpiece for working and gripping parts of the sample (Fig.4A). Blanks working parts cut out in the direction of thickness of the rolled billet for gripping parts in the direction of the length or width of the sheet. The diameter of the blanks needs to be at least the diameter of the gripping parts of the sample with an allowance for processing; the length of the workpieces for gripping parts to be arbitrary.

Damn.4

Damn.4

After welding of the workpieces the gripper parts and the material of the working part (Fig.4B) carry out a connection processing on a lathe, grinding, etching (to expose the welds), layout and prototyping.

7. In the manufacture of samples with the use of manual arc welding perform cross connections (Fig.5A), which are used for one workpiece dimensions х100х200 mm of the test material and two billet sizes x100x200 mm from a sheet thickness of equal to or greater than the diameter of the gripping part of the specimen with allowance for processing.

Damn.5

Damn.5

The shape of edges welded blanks, the cross-sectional shape of the connection and completed welds shall meet the requirements for connections of type T8 GOST 5264.

Union, with the exception of the delete start and end sections of a length of 30 mm each (beginning and end of seams), a method of cold mechanical processing is cut into template (damn.5B), which after polishing, etching and marking produce samples (Fig.5B). The thickness of the templates must be at least the diameter of the gripping pieces of samples with an allowance for processing.

APPENDIX 3 (recommended). CLASSIFICATION OF SHEET METAL, DEPENDING ON THE VALUES OF RELATIVE NARROWING

APPENDIX 3
Recommended

Table 3

Notes:

1. If the determination of mechanical properties in the thickness direction is not attained the prescribed minimum average or if an individual test result is below specified for minimum, conduct tests on three new samples. The average results of six tests shall be not below the prescribed minimum average and no individual value of the three new results must not be lower than specified for the minimum value.

2. To develop a classification of sheet metal, depending on the relative elongation instead of the classification is recommended at the same time the definition and .

3. The leaves corresponding to that particular group should have a designation of this group, for example: Z25.



The text of the document is verified by:
the official publication of the
Rolled steel General purpose: the security Council. Standards. -
M.: IPK Publishing house of standards, 2003