GOST 24507-80

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  ГОСТ 24507-80

GOST 24507−80 nondestructive testing. Forgings of ferrous and non-ferrous metals. Methods of ultrasonic flaw detection (with Change No. 1)

GOST 24507−80

Group B09

STATE STANDARD OF THE USSR

NONDESTRUCTIVE TESTING.
FORGINGS OF FERROUS AND NON-FERROUS METALS
Methods of ultrasonic flaw detection
Non-destructive Testing.
Forgings from ferrous and non-ferrous metals.
Ultrasonic methods of slow defection

Date of introduction 1982−01−01

APPROVED AND put INTO EFFECT by decision of the USSR State Committee for standards from December 30, 1980, No. 6178

REPRINT (March 1993) Change 1, approved in may 1986 (IUS 8−86).

This standard applies to forgings made from ferrous and nonferrous metals with a thickness of 10 mm or more, and establishes methods of ultrasonic testing continuity of the metal, providing the detection of defects, such as shells, sunsets, cracks, placenow, bundles, non-metallic inclusions, without determining their nature and actual sizes.

The need for ultrasonic testing, the volume and standards of unacceptable defects should be installed in the technical documentation for forgings.
General requirements for methods of ultrasonic testing — GOST 20415−82.

Terms used in the standard given in the Appendix.

1. APPARATUS AND TEST SPECIMENS

1.1. When control should be used: a pulsed ultrasonic flaw detector, transducers, test or standard samples or DGS diagrams, accessories and fixtures, to provide permanent control settings and check results.

1.2. When control is used flaw detectors and transducers that have passed certification, state testing and periodic verification in the prescribed manner.

1.3. At contact control of cylindrical forgings with a diameter of 150 mm and less inclined transducers in the direction perpendicular to the generatrix of the working surface of the transducer rubbed over the surface of the forging.

Under the control of forgings with a diameter of over 150 mm can be used attachments and supports for fixing the angle of entry.

1.4. Test and standard samples used in large-scale production of forgings uniform in attenuation of the ultrasound when fluctuations in the amplitude of the bottom signal inside a separate forgings does not exceed 4 dB, and from forging to forging — 6 dB (with equal thickness and the same surface treatment) .

1.5. DGS diagrams are used in small batch production or when inspection of large forgings, as well as in the case when fluctuations of bottom signal exceed the values specified in claim 1.4.

1.6. DGS diagrams used in the control for flat surfaces, concave cylindrical surfaces with a diameter of 1 m or more and a convex cylindrical surfaces with a diameter of 500 mm or more for the direct Converter, and a diameter of 150 mm and for angle beam transducer.

1.7. Test specimens shall be made of metal of the same brand and structure and have the same surface treatment, forging and controlled. In the test samples must be free of defects detectable by the methods of ultrasonic testing.

1.8. The amplitude of the bottom signal in the test sample should be not less than the amplitude of the bottom signal in the forging (at equal thickness and equal to the surface) and should not exceed it by more than 6 dB.

1.9. Use test samples of the closest types of alloy (for example, of carbon steel of various grades), subject to the requirements of claim 1.8.

1.10. The shape and dimensions of the reference reflectors in the samples are specified in the normative-technical documentation. It is recommended to use reflectors in the form of a flat bottomed hole oriented along the axis of the ultrasonic beam.

1.11. A set of reflectors in the test sample should consist of reflectors, made at different depths, of which a minimum must be equal to the dead zone applied by the seeker, and the maximum thickness of forgings to be checked.

1.12. Stage depth should be such that the ratio of amplitudes of signals from the same security reflectors positioned on the surrounding depths was in the range of 2−4 dB.

1.13. At each step of the depth in the test specimen shall be made of the control reflectors that determine the level of fixation and the level of rejection. It is possible to manufacture the control reflectors of other sizes, but the ratio of amplitudes from the two closest sizes of reflectors shall not be less than 2 dB.

1.14. The distance between the reference reflectors in the test sample should be such that the influence of neighboring reflectors on the amplitude of the echo signal does not exceed 1 dB.

1.15. Distance from the reference reflector to the wall of the test specimen shall satisfy the condition: ,

where is the distance along the ray from the input point to the control of the reflecting surface of the reflector, mm;

is the wavelength of the ultrasonic vibrations.

(Changed edition, Rev. No. 1).

1.16. Square, flat-bottomed reflectors must be selected from a number (in parentheses are the diameters of the holes): 1 (1,1); 2 (1,6); 3 (1,9); 5 (2,5); 7 (3); 10 (3,6); 15 (4,3); 20 (5); 30 (6,2); 40 (7,2); 50 (8); 70 (9,6) mm.

1.17. Depth flat bottom reflector (distance from their ends to the input surface) must be selected from a number of: 2, 5, 10, 20, 50, 75, 100, 150, 200, 250, 325, 400, 500 mm and the 100 mm with an accuracy of ±2 mm.

1.18. Test samples for control of aluminum forgings are manufactured according to GOST 21397−81. Allowed the use of test samples-analogues of aluminium alloy D16T to control other materials using scalar devices.

1.19. Accuracy and the technology of manufacturing reflectors for the control of the direct Converter — GOST 21397−81, for an angle beam transducer — according to GOST 14782−76.

1.20. The radius of the test sample must be equal to , where is the radius of the forging.

Allowed to apply test samples of different radius when the relation of 0.9 <<img alt=«ГОСТ 24507-80 Контроль неразрушающий. Поковки из черных и цветных металлов. Методы ультразвуковой дефектоскопии (с Изменением N 1)» src=«data:image/jpeg;base64,R0lGODlhFQAYAIABAAAAAP///yH5BAEAAAEALAAAAAAVABgAAAIyjI+py+0Po1Sg1mnA0ZMHD4Hg442khXHi1ZTZ1sKfTCWaS6EZO3d0hJMEhTyM8YjEFAAAOw==»><1,2.

1.21. The use of test specimens with a flat surface input is allowed under the direct control of the combined transducer of cylindrical products with a diameter of over 500 mm and under direct control of dual inverter or Converter sloped cylindrical products with a diameter more than 150 mm.

1.22. DGS diagrams or counting device shall meet the following requirements:

the price of division of the scale «signal Amplitude» should be no more than 2 dB;

the price of division of the scale «Depth» should be not more than 10 mm;

distance on the ordinate between the curves corresponding to different dimensions of the reference reflectors shall be not more than 6 dB and not less than 2 dB.

2. PREPARATION FOR CONTROL

2.1. When the General technological preparation of production forgings that are subject to ultrasonic testing, are the routing of ultrasonic testing.

2.2. Technological chart is prepared for each size of forgings. In the map indicate the following information:

basic data of forgings (drawing, grade, if necessary — the speed of sound and attenuation coefficient);

volume control;

treatment of surfaces and allowances (if necessary, indicate on the sketch);

the main parameters of the control scheme (testing, types of probes, probe angle and operating frequency, the control sensitivity, speed and scanning step);

the quality requirements of the forgings.

Allowed preparation of standard check cards, combined with one or more of the listed parameters.

2.3. Routing controls shall be provided for inspection on the stage of the process when the forging has the most simple geometric form and the most allowance. Allowed control without allowance, if there is a full testing of the total metal. It is recommended to control after heat treatment forgings.

2.4. Before the control surface of the forgings from which to conduct testing (surface input) must be processed and having a parameter of surface roughness <10 µm according to GOST 2789-73.

The surface of the forging that is parallel to the input surface (bottom surface) must have a roughness of 40 µm according to GOST 2789−73.

May reduce requirements for surface roughness under the condition of detection of unacceptable defects.

3. CONTROL

3.1. Control of forgings is the echo method and the ultrasonic mirror-shadow method.

The use of other methods subject to the identification of unacceptable defects. Control mirror-shadow method is carried out by observing the attenuation of the amplitude of the bottom signal.

3.2. The schemes of forgings of different shapes are installed the technical documentation on the control.

3.3. The sounding scheme forgings in full set so that each elementary volume of metal was provoken in three mutually perpendicular directions or close to them. The forging of rectangular cross section prosvechivayut direct Converter with three perpendicular faces. Cylindrical forgings prosvechivayut direct transducer with end and side surfaces, and the inclined transducer with the lateral surface in two directions perpendicular to the generatrix (chordal testing).

3.4. If one of the dimensions of forging exceeds the other size or more then the direct Converter is replaced by oblique. Apply angle beam probes with the largest possible angle of incidence and the testing is conducted along the largest dimension in two opposite directions.

The value is determined by the expression

,

where the diameter of piezoplates Converter, mm;

is the ultrasound frequency, MHz;

 — the speed of longitudinal ultrasonic vibrations in the metal, m/s.

(Changed edition, Rev. No. 1).

3.5. The drawing shows examples of the testing schemes in full forging of simple geometric shapes, the sign indicates the direction of radiation is straight finder, a sign  — direction and the oblique orientation of the seeker.

Examples of testing of forgings of simple shape

3.6. Monitoring is carried out by scanning the transducer surfaces of forgings, defined by the given sounding scheme.

The speed and scanning step establishes the technical documentation on the control, based on reliable detection of unacceptable defects.

3.7. The ultrasound frequency is indicated in the technical documentation for the control. Massive and coarse-grained forgings, it is recommended to proslushivat at frequencies of 0.5−2.0 MHz, fine forgings with fine-grained structure at frequencies of 2.0 to 5.0 MHz.

3.8. The commit level and the acceptance level shall conform to the levels established in the technical documentation on forgings, with error not more than ±2 dB.

3.9. Search of defects is performed on the search sensitivity, which establish:

when manual control is 6 dB above the level of fixation;

when the automatic control is such that the defect is liable to commit, identified at least 9 times out of 10 experienced prosvechivanie.

3.10. When monitoring fixed stations which observed at least one of the following defects:

the reflected signal, the amplitude of which is equal to or greater than the specified commit level;

the weakening of bottom signal or the weakening of the last signal to or lower than a level of fixation.

4. PROCESSING AND PRESENTATION OF RESULTS CONTROL

4.1. Defects assess their main characteristics:

the distance to the transducer;

equivalent size or area;

the conventional boundaries and (or) conventional length.

If necessary, perform a classification of defects on the extended and unextended and determine their spatial location.

4.2. Testing results are fixed in certificate forging and recorded in a special register, which is made according to GOST 12503−75 with the following additional details:

commit level;

date control;

name or signature of the operator.

Defects in the journal captured their essential characteristics are in accordance with clause 4.1 and (or) defectogram.

4.3. Based on the comparison of testing results with the requirements of normative-technical documentation, make a conclusion of suitability or zabrakovanie forgings.

4.4. In the normative-technical documentation for forgings that are subject to ultrasonic testing shall contain the following information:

fixing levels, unacceptable levels of weakening of the backwall signal and the parameters of unacceptable defects (equivalent to the minimum size or area, the minimum conventional length, minimum number of defects in a certain volume), for example:

Fixing of defects shall be of equivalent area or more.

Not allowed defects with equivalent area and more.

Not permitted conditional defect length , and more.

Not allowed defects that cause for control of a direct Converter, the weakening of the bottom signal to a level and below.

Not allowed unextended defects with equivalent area from before , if they form a cluster of or more defects in the spatial distance between the outermost defects, equal to or less than the thickness of the forging .

Indicators the technical requirements of forgings for ultrasonic control

4.5. When recording regulatory quality requirements of the forgings is recommended to specify a group of quality forgings in accordance with the table. The table shows the values that are used to calculate the unacceptable number of defects in the cluster size according to the formula

.

In the calculation are rounded to the nearest whole number downwards.

(Changed edition, Rev. No. 1).

4.6. The forgings are classified as groups 1, 2 and 3 is not allowed no one an extensive defect and no defect with equivalent area and more. This condition is usually satisfied metals vacuum smelting. In forgings, assigned to groups 2, 3and 4, allowed small unextended defects (e.g. non-metallic inclusions present in some steel in open-hearth smelting). In forgings, classified in group 4, are allowed some extended defects, conditional length of which is less than 1.5.

5. SAFETY REQUIREMENTS

5.1. Ultrasonic flaw detectors are portable receivers, so their use must comply with the safety and industrial hygiene in accordance with the «Rules of technical operation of electrical installations» and «safety Rules at operation of electrical installations», approved by Gosenergonadzor in 1969 with additions and changes 1971

5.2. To work with ultrasonic devices are allowed persons who have passed the test of knowledge of «Rules of technical operation of electrical consumers». If necessary, a qualifying group of NDT inspectors is set by the company performing the control, depending on working conditions.

5.3. Measures of fire safety are carried out in accordance with the requirements of «Model regulations of fire safety for industry», approved supen MVD of the USSR in 1975 and GOST 12.1.004−91.

5.4. The control site should comply with the requirements of SN 245−71, approved by Gosstroy of the USSR, as well as GOST 12.1.005−88.

5.5. When used in the area of control of the lifting mechanisms must be taken into account the requirements of «Rules of arrangement and safe operation of cranes», approved by Gosgortekhnadzor of the USSR in 1969

5.6. Additional security requirements specified in the technical documentation that defines the specific control technology of forgings and approved in the prescribed manner.

5.7. During the inspection, must comply with the requirements of GOST 12.3.002−75 and GOST 12.1.003−83.

APPLICATION (reference). THE TERMS USED IN THE STANDARD

APP
Reference

The text of the document is verified by:
the official publication of the
M.: standards Publishing house, 1993