GOST 30456-97

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  ГОСТ 30456-97

GOST 30456−97 metal Products. The rolled sheet and steel pipe. Methods of test for impact strength

GOST 30456−97

Group B09

INTERSTATE STANDARD

Steel products

THE ROLLED SHEET AND STEEL PIPES

Methods of test for impact strength

Metal production. Rolled steel and tubes. Methods of blow bending tests

ISS 77.040.10
AXTU 1309

Date of implementation 2000−01−01

Preface

1 DEVELOPED by the State scientific-research and design-technological Institute of pipe industry (GTI), the Interstate technical Committee for standardization MTK 7

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (minutes N 11 dated April 23, 1997)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated April 28, 1999 N 150 interstate standard GOST 30456−97 introduced directly as state standard of the Russian Federation from January 1, 2000

4 INTRODUCED FOR THE FIRST TIME

5 EDITION (October 2002) amended (ICS 9−2000)

1 Scope

This standard specifies test methods samples of the base metal of steel pipes with diameter of 508 mm and a wall thickness of 7.5 mm and sheet (hereinafter sheet) of the same thickness for their production.

The method is based on the destruction of the sample concentrator with one blow of the firing pin is free-falling dart vertical copra (VC) or a pendulum copra at room and low temperatures as specified in the normative documents for the products. The test drop-weight (IPG) determine the amount of a viscous component in the fractured sample in percent.

2 Normative references

The present standard features references to the following standards:

GOST 2789−73 surface Roughness. Parameters and characteristics

GOST 9293−74 (ISO 2435−73) Nitrogen gaseous and liquid. Specifications

GOST 12162−77 solid carbon Dioxide. Specifications

GOST 28498−90 Thermometers liquid-in-glass. General technical requirements. Test methods

3 sampling Methods and sample making

3.1 a Sample (billet) for producing samples of the pipe should be cut across the longitudinal axis of the pipe in accordance with figure 1.

Figure 1 — Scheme of cutting out of samples

 — longitudinally welded pipe with a seam; b — longitudinal welded pipe with two welds;
in — spiral-welded tube; the length of the sample

Figure 1 — Scheme of cutting out of samples

3.2 a Sample (billet) for producing samples from the sheet should be cut across the axis of the hire in the first quarter the width of the sheet.

3.3 the Number of pipes or sheets selected for the tests regulated by normative documents on specific products.

3.4 When cutting samples (blank) a way to fire the seam allowance from the cut line to the edge of the sample shall not be less than the thickness of the sheet or wall thickness of the pipe in order to protect the sample from the effect of heat, but not less than 15 mm.

3.5 On the surfaces and ends of the samples are not allowed influx and splashes of molten metal.

3.6 Cut out a sample label with sample identification.

3.7 Edit a sample from the pipe perform static load. Deflection after editing should be no more than 2 mm in length sample.

3.8 Out of samples are made at two samples per test temperature, unless otherwise indicated in the normative documents for the products.

3.9 it is possible to use samples with nevirapine the middle part on the length of 25−50 mm (nevirapine sample), while both ends of the sample are recommended to rectify at the same time.

When there is a discrepancy in the results obtained when testing samples of the rectified and nevirapine in arbitration trials, nevirapine samples are preferred.

3.10 Shapes and sizes of samples to IPG shall be as specified on figure 2.

Figure 2 — the Shape and size of the sample for IPG

 — wall thickness, mm

Figure 2 — the Shape and size of the sample for IPG

3.11 Hub on the sample perform the methods of pressing and cutting with the observance of the sizes indicated on the drawings 2 and 2b, respectively.

Method of application of the concentrator choose by agreement a consumer of metal products & manufacturer of sheet and pipes.

A schematic drawing of fixtures for the application of the hub by indentation and the dimensions of the working part of the blade is shown in figure 3.

Figure 3 — schematic diagram of the device for applying the hub to the sample

1, 2 — fixed and mobile traverses; 3 — knife; 4 — sample;
5 — pin pin; 6 — limit switch

Figure 3 — schematic diagram of the device for applying the hub to the sample

3.12 Thickness of samples from pipes and sheet corresponds to the full thickness of metal.

3.13 to agreement between the manufacturer and the consumer, of metal samples from a tube or sheet with a thickness more than 19 mm can be made reduced to 19 mm thickness by machining one or both sides of the sample.

The roughness of the processed surfaces to be no more than 20 µm according to GOST 2789.

Allowed reduction of the wall thickness 19 mm with boring or turning of the pipe to the cutting of the sample.

4 Equipment and materials

4.1 Pendulum and vertical copra with a freely falling weight with an energy sufficient to break the specimen in one blow.

4.1.1 sample set have to provide the location of the hub symmetrically with respect to the poles, and its axis must coincide with the centerline of the firing pin with an accuracy of ±2 mm.

4.1.2 the Specimen shall be placed on supports of copra and supported with special supports to prevent its lateral rotation during impact in the test.

4.1.3 the Speed of the striker at the moment of impact specimen shall be at least 5 m/s.

(Amendment).

4.1.4 Basic dimensions of the supports and striker shall be as specified on figure 2.

4.2 Thermostat, provides uniform cooling, no aggressive coolant environment on samples, and is equipped with a means of temperature control.

4.3 as the refrigerant is a mixture of liquid nitrogen according to GOST 9293 or solid carbon dioxide according to GOST 12162 with a non-freezing temperature testing non-toxic liquid (e.g. ethyl alcohol) or a pair of liquid nitrogen.

4.4 Thermometers accuracy up to ±1 °C for measuring the temperature of the cooling medium, liquid glass according to GOST 28498 or other devices with the same accuracy.

5 testing

5.1 Samples are placed in a bath thermostat with a gap between them and the walls of the bath not less than the thickness of the sample.

The height of coolant above the sample shall not be less than the sample thickness.

To ensure a uniform cooling it is recommended to use a mixing of the cooling medium.

In contact with the sample part of tools for extracting samples of the coolant must be cooled simultaneously with sample.

When extracting samples from the bath level of liquid above the remaining sample should be not less than the thickness of the samples.

5.2 the Temperature of the cooling medium bath must comply with the test temperature set of regulatory documents for products with an accuracy of ±2 °C.

5.3 samples with a thickness of 19 mm or less after reaching the temperature set is kept in the bath for at least 15 min. Samples of a thickness exceeding 19 mm stand at least 30 min.

If samples are constantly experience more than 10 s after removal from the bath, it is necessary to SuperCool them to the magnitude of the temperature to be determined experimentally.

5.4 Upon cooling the samples in liquid nitrogen vapor they stand in the thermostat bath for at least 1 h.

5.5, the Samples shall be removed from the bath thermostat and be destroyed for no more than 10 s. If cooled, the sample was placed outside the tub for more than 10 sec before the destruction, it should again be placed in a bath at the specified temperature for at least 10 min.

5.6 Samples of reduced thickness compared to the wall thickness of the pipe or the original sheet thickness should be tested at a temperature below the set value by the amount specified in table 1.


Table 1

5.7 Sample set on supports so that the impact hammer was struck on the side opposite to the hub.

5.8 After the destruction of the sample, the parts dry and they reach room temperature determine the amount of the viscous component.

6 processing of the results

6.1 While counting the number of the viscous component in the fracture samples with thickness up to 19 mm inclusive from consideration exclude portions of the fracture (sample thickness) adjacent to the hub and the point of impact of the striker (figure 4).

Figure 4 — Scheme of determining the percentage of a viscous component in the fractured sample

Figure 4 — Scheme of determining the percentage of a viscous component in the fractured sample

For samples with thickness more than 19 mm excludes areas in length , and 19 mm on each side.

(Amendment).

6.2 the Amount of the viscous component in the fracture , in %, is calculated by the formula

, (1)

where  — share fragile component in considering the area of the fracture.

6.3 Surface ductile fracture is characterized by a dull, gray appearance with a characteristic «fibers» and is usually located at an angle to the side surface of the sample.

The surface of brittle fracture in the form of a crystal, with no visible signs of plastic deformation at the failure surface. Areas of brittle fracture usually adjacent to the base of the hub and the point of impact.

6.4 the area of the fragile component is determined in the following ways:

6.4.1 Measurement area of brittle fracture by using a planimeter on a photograph or optical projection of the fracture surface.

6.4.2 Visual comparison of the fracture surface of the reference samples or photographs in which the share of the fragile component is pre-determined.

6.4.3 measurement of the dimensions of the zones of brittle fracture and calculate their total area.

6.5 Measurement of geometrical parameters of the plots of the fracture occupied by the fragile component is produced with a tolerance within ±0.1 mm.

6.6 in applying the method in 6.4.3 depending on the type of fracture can be used multiple ways of determining the amount of a viscous component (see figure 4).

6.6.1 If the break is fully viscous, except for the possible spots brittle fracture zones in length or 19 mm, adjacent to the incision and the point of impact of the striker, then it is determined at 100% viscous (figure 4).

6.6.2 If the fracture is completely brittle (crystalline lips of the slice is less than 0.5 mm), it is considered to have zero percent of a viscous component (figure 4b).

6.6.3 In case of a mixed fracture, when the fracture in the middle of the thickness of brittle and attached to the side surfaces of the sample lip cut more than 0.5 mm, the amount of viscous component count after defining three widths brittle zones of the fracture (figure 4in).

The amount of viscous component in the fracture, in %, is calculated by the formula

. (2)

(Amendment).

6.6.4 Mixed fracture with fragile component in the form of language with the base at the point of impact or at the bottom of the hub.

Measure the width of the brittle zone in the three sections at equal distances from the apex of the tongue (figure 4g).

The amount of the viscous component in the fracture, in %, is calculated by the formula

, (3)

where is the height of the tongue, mm.

 — the calculated height of sample, mm.

6.6.5 mixed fracture (figure 4d), with a separate fragile spots around the viscous cross-section design of the sample, the amount of the viscous component in the fracture, in %, is calculated by the formula

, (4)

where is the area of each spot, mm.

The fragile area of each spot is defined as half the sum of the squares inscribed and circumscribed basic geometric shapes (circle, rectangle, or triangle).

(Amendment).

6.7 the Accuracy of determining the share of the viscous component in the fracture under this standard is in the range of ±3% with a confidence level =95%.

6.8 Rounding of the calculated quantity of the viscous component produces up to 5%.

6.9 If the testing process found non-compliance with temperature regime, irregularity of alignment of the specimen on the supports of copra, the misalignment of load application relative to the axis of the hub and other violations of work copra, and if the sample has defects in the metal or poorly prepared, regardless of whether discovered before or after the destruction of the sample, the test results void and conduct re-testing on the same number of samples.

6.10 Initial data sample, all calculations regarding the amount of the viscous component in the fractured sample is recorded in a work log and keep it for three years. The test results recorded in the Protocol, the form of which is given in Appendix A.

Annex a (recommended). Form of test report

APPENDIX A
(recommended)

PROTOCOL N

Test specimens for impact bending of a freely falling load

Type copra

The maximum amount of impact energy when tested

Height lifting (women)

The speed of the pendulum (women) at the moment of impact

The form and dimensions of test of metal, the number and name of normative document on it

Mark the material under test

Date of test

Name of the organization performing the tests

Head of laboratory

The contractor



The text of the document is verified by:
the official publication of the
M.: IPK Publishing house of standards, 2003