JB/T 5000.15-2007General technical requirements for heavy machinery - Part 15: Non-destructive testing of steel forgings (English PDF)

3.1 Single defect

The defect which has a spacing of more than 50 mm and an equivalent diameter not less than the initially recorded equivalent.

3.2 A cluster of defects

There are five or more defect's reflection signals simultaneously in the range of the 50 mm sound-path of the screen's scanning line; or five or more defect's reflection signals in the same depth on a 50 mm x 50 mm detection surface.

3.3 Extended defect

The continuous echo height of the defect shall not be lower than the initially recorded equivalent in at least one direction, the extended length shall be greater than the maximum equivalent diameter allowed by the defect. The extension of the extended defect is determined by the half-wave height method (6 dB method). When determining the extension, it shall consider the sound-field characteristics of the probe for correction.

4.1 Principles of selection

4.1.1

The selection of testing method and quality acceptance level shall be determined according to the specific use and type of forgings, meet the requirements of the corresponding technical documents.

4.2 Documentation of testing

4.2.1

When forgings are tested in accordance with this Part, if necessary, it may follow the provisions of this Part to establish a non-destructive testing procedures which complies with the relevant specifications.

4.2.4

The performance of the instruments and equipment used for the testing shall be periodically calibrated and have calibration records, which can only be used after passing the calibration.

4.3 Testing personnel

4.3.1

Any person engaged in non-destructive testing shall hold the corresponding qualification certificate issued by the relevant state department.

4.3.3

All personnel engaged in non-destructive testing must meet the following requirements for vision in addition to good physical fitness.

4.3.3.1

Corrected visual acuity shall not be less than 5.0 (decimal record value is 1.0) and be checked once a year.

5.1 Basis of testing

5.1.1

Relevant requirements for ultrasonic testing of forgings by the user or the design and process department.

5.1.2

The method of establishing sensitivity, the selection of instruments and equipment, the test of performance shall be consistent with the provisions in this Part.

5.2 Instrument and equipment

5.3 Probe

5.3.1

Various probes shall be used at the calibrated frequency. In principle, it uses the straight probes at 2 MHz ~ 2.5 MHz which have a wafer diameter 10 mm ~ 30 mm. The refraction angle of the angle beam probe shall be 35° ~ 70°, the effective wafer area of the angle beam probe shall be 20 mm2 ~ 625 mm2.

5.3.2

The main beam of the probe shall have no obvious double peak, the beam's linear deflection shall be less than 2°.

5.3.3

It may replace it with other probes to assess defects and accurately locate defects.

5.3.4

Probe's performance test method is as specified in JB/T 10062.

5.4 Coupling agent

5.5 Test block

5.5.1

The test block shall be made of the same or approximate acoustic properties as the workpiece being tested. When the material is tested by a straight probe, there shall be no defects greater than the equivalent diameter of the Phi2 mm flat-bottom hole.

5.5.5

In case of field testing, it may also use other types of equivalent test blocks.

5.6 Test of system's combined performance

The test of the system's combined performance is as specified in JB/T 9214.

5.7 Preparation of forgings before testing

5.7.1

Unless otherwise specified in the order, in case of radial testing of shaft forgings, it shall machine a cylindrical surface. In case of axial testing, the both end faces shall be machined into surfaces axially perpendicular to the forgings.

The surfaces of the pie-shaped and rectangular forgings shall be machined into planes which are parallel to each other.

5.8 Testing procedures

5.8.1 General rules

5.8.1.1

Unless otherwise the testing cannot be performed due to the change of sectional and local shape of the forgings due to chamfering, drilling, etc., it shall carry out ultrasonic testing of the entire forging as much as possible.

5.8.1.4

It shall scan all the cross-sections of the forging as far as possible in two mutually perpendicular directions.

5.8.1.5

For pie-shaped forgings, in addition to scanning from at least one plane, it shall also carry out radial scanning from the circumferential surface as much as possible.

5.8.1.6

For the testing of cylindrical solid or hollow forgings, in addition to the radial scanning, it shall also carry out auxiliary scanning from the axial direction.

5.8.2 Sensitivity of testing

5.8.2.1

In principle, use the AVG method to determine the testing sensitivity. For forgings which is limited by its geometry and whose testing thickness approaches to the length of near-field, use the test block comparison method.

5.8.2.2

The testing sensitivity shall be based on the initially recorded equivalent value, the reference wave height shall not be less than 40% of the full screen height.

5.8.2.3

When assessing defects, it shall adjust the evaluation sensitivity in the intact part of the forging.

5.8.2.4

Re-verification of testing sensitivity.

6.1 Basis of testing

6.1.1

Relevant requirements of the user or design process department for the magnetic-powder testing for forged steel.

6.1.2

Methods for establishing sensitivity, selection of instruments and equipment, selection of magnetization methods, requirements for magnetic- field's strength shall be consistent with this Part.

6.2 Requirements of testing surface

6.2.1

The sensitivity of magnetic-powder testing is highly dependent on the surface condition of the forged part being tested. If the irregular surface condition affects the display or evaluation of the defect, the surface to be tested must be treated by grinding, machining or other means.

6.2.3

The removal of foreign matter can be carried out by any method that does not affect the magnetic-powder testing.

6.2.4

In order to test small defects, the roughness Ra of the surface of the forging is generally not more than 6.3 µm.

6.2.5 Temperature of the testing surface

It shall be less than 300 °C in case of dry method; it shall be less than 10 °C ~ 50 °C in case of wet method.

6.3 Testing period

6.3.1

Unless otherwise specified by the purchaser, the magnetic-powder acceptance test shall be carried out after the final heat-treatment and finishing of the forgings.

6.4 Equipment and magnetic-powder

6.4.1

Magnetic-powder testing equipment and special types of equipment must meet the requirements of JB/T 8290.

6.4.3.4

Wet-powder method shall use kerosene or water as the dispersion medium. When using water as a medium, it shall add appropriate rust inhibitors and surfactants. The viscosity of the magnetic suspension shall be controlled within 5000 Pa·s ~ 20000 Pa·s (25 °C).

6.4.3.5

The concentration of magnetic suspension shall be determined according to the type, particle size, application method and time of the magnetic-powder. Under normal circumstances, non-fluorescence. 10 g/L ~ 25 g/L. fluorescence. 1 g/L ~ 3 g/L, its dispersion medium shall not have fluorescent properties.

6.5.1 Methods and materials

6.5.1.1

The ferromagnetic-powder used as the test medium may be either dry or wet; it may be fluorescent or non-fluorescent.

6.7 Magnetic-field's strength

6.7.1

The minimum magnetic-field's strength used shall be able to show all dissenting defects and distinguish them. The maximum magnetic-field's strength shall be just below the critical point at which the magnetic-powder

7.1 Basis of testing

User or design process department's requirements for penetration testing of forged steel.

7.2 Requirements of testing surface

7.2.1

The surface of the testing area and the adjacent 25 mm shall be dry and free of dirt, grease, cotton fiber, oxide scale, oil or other foreign matter which

7.3 Testing materials

7.3.1

Penetration testing materials generally include penetrants, emulsifiers, cleaning agents, imaging agents.

7.3.2

The quality control of the penetration test material shall comply with the requirements of JB/T 9216.

7.4 Control test block

7.4.1

The control test block is mainly used to test the performance of the testing agent and the operation process.

7.4.2

The control test blocks are divided into aluminum-alloy test blocks and chrome-plated test blocks.

7.4.3

Production of control test blocks.

7.5 Classification and selection of penetration testing methods

7.5.1 Classification and code of penetration testing methods

7.6 Operating procedures

7.6.1 Pre-cleaning

7.6.1.1

All areas to be tested must be pre-cleaned as required by 7.2 before applying the penetrant.

7.6.1.2

Post-cleaning drying.

The cleaned workpieces shall be dried. Drying methods generally include heating the workpiece in a drying oven, baking it using an infrared lamp, drying it using hot compressed air, or drying it naturally at ambient temperature.

However, the temperature of the workpiece must not exceed 50 °C before applying the penetrant.

7.6.2 Applying penetrant

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