GB/T 29997-2013Eddy current testing method of copper and copper-alloys rods, bars and wires (English PDF)

3.3 SNR signaltonoiseratio

Noise ratio of signal amplitude and the maximum amplitude of the signal at the output of the eddy current flaw defect.

3.4 Zero potential

Differential detection coil induced voltage differential connection between the windings formed. Within the detection coil has zero potential for the load when the test piece.

In the detection coil when no test piece is unloaded zero potential.

3.5 Pass type eddy current method of feed-througheddycurrenttestingmethod

Through the use of eddy current detection coil eddy current testing methods.

3.6 Point eddy current testing method

Using point coil eddy current testing eddy current testing method.

3.7 Standard depth of penetration

Eddy current penetration depth of the conductivity in the subject bar and wire rod and wire, the detection frequency. Eddy Current Testing, Eddy Current density dropped to a sample

The depth of the surface vortex called density 1/e (about 37%), the standard depth of penetration, which are calculated in the formula (1).

delta = 503.3 rho/µrf =

503.3

µr. sigma. f (1)

Where.

[delta] --- standard penetration depth in millimeters (mm);

rho --- subject resistivity of the sample, ohms square millimeter per meter (ohm. mm2/m);

sigma --- conductivity of the test sample, in units of ohms per meter square millimeter [m/(ohm. mm2)] f --- detection frequency in hertz (Hz);

NOTE. rewrite GB/T 12604.6-2008, definitions 2.11.

3.8 Effective penetration depth

The ability to more than one standard depth of penetration by the eddy current test method will reduce the discontinuity defect, generally accepted testing or mechanical metallurgy

Limit the depth of defects is 3delta, and it is called the effective penetration depth.

NOTE. rewrite GB/T 12604.6-2008, definitions 2.12.

3.9 Excitation frequency

Excitation current nominal frequency.

[GB/T 12604.6-2008, definitions 2.16. ]

3.10 Probe

It comprises an eddy current sensor excitation and receiving unit.

[GB/T 12604.6-2008, definitions 4.1. ]

3.11 Detection coil fill factor

Through the outer coil, equal to the cross-sectional area than the outer diameter of the subject and the coil inner diameter of the cross-sectional area. Through to the inner coil, equal

The cross-sectional area than the coil outer diameter of the cross-sectional area of the subject member.

[GB/T 12604.6-2008, definitions 4.51. ]

3.12 End effect

Means that when the rod is in the detection coil wire ends, interfering signal distortion due to eddy currents flow path generated.

NOTE. rewrite GB/T 12604.6-2008, definitions 6.27.

3.13 Amplitude analysis

The amplitude of the signal evaluation techniques.

[GB/T 12604.6-2008, definitions 7.1. ]

3.14 Phase analysis

Eddy current testing phase angle signal measurement and analysis of the implementation of technology.

[GB/T 12604.6-2008, definitions 7.3. ]

3.15

j) the date of testing.

Appendix A (Normative)

Copper and copper alloy rod line automatic eddy current flaw detection device offline Comprehensive Performance Test Method

A.1 Scope

This appendix provides off-line testing of copper and copper alloy rod and wire automatic eddy current testing equipment comprehensive performance test conditions, methods and test items

Head and shall meet the minimum performance criteria.

A.2 Test conditions

A.2.1 eddy current flaw detectors and equipment should comply with this standard in Chapter 5.

When A.2.2 test should be carried out at 50m/min ~ 60m/min speed of testing. It should accurately record the excitation frequency, gain, phase and filter

Wave, testing speed, rod and wire diameter, the detection coil specifications and other parameters. Such as the use of saturation magnetization, but also record the magnetizing current, voltage magnetic remanence

Detection value.

A.3 standard artificial defects like rod (wire)

A.3.1 standard labor-like rod (wire) production shall comply with the provisions of Chapter 6 of the standard.

A.3.2 standard testing artificial defects like rod (wire) can be detected on the basis of the outer diameter of the device under test commonly used in the types of products and equipment

Rod and wire diameter size specifications for the upper limit.

A.4 Test items and methods

A.4.1 circumferential poor sensitivity

Adjust the detection sensitivity, the standard artificial defect rod (wire) in the circumferential direction 120 ° in the middle of three artificial defects just the alarm and continuous walking

Five were police. Gain value at that time write down.

Adjust the detection sensitivity, the standard rod-like artificial defects (line) to 120 ° circumferential middle three artificial defect is not just the police, and continuous

Walking 5 times without warning. Gain value at that time write down.

Z = Z1-Z2 (A.1)

Where.

Z --- circumferential sensitivity difference, in decibels (dB);

Gain value Z1 --- standard artificial defect rod (wire) in the middle of three artificial defects in alarm just in decibels (dB);

Gain value Z2 --- standard artificial defect rod (wire) in the middle of three artificial defects just not alarm, in decibels (dB).

A.4.2 SNR

DB value adjustment of detection sensitivity, continuous test five times, just to make noise alarm, note the time gain value.

S/N = Z3-Z1 (A.2)

Where.

S/N --- N ratio in decibels (dB);

Gain value Z1 --- standard artificial defect rod (wire) in the middle of three artificial defects in alarm just in decibels (dB);

Gain value Z3 --- just alert noise, in decibels (dB).

A.4.3 false negative rate

On the basis of Z1 improve detection sensitivity value on the amount of sensitivity 2dB, and walk for 50 times, note the omission of artificial defect frequency.

K1 = [N1/(N2 × 50)] × 100% (A.3)

Where.

K1 --- false negative rate,%;

N1 --- underreporting the number of artificial defects;

N2 --- standard artificial defect rod (wire) in the number of artificial defects.

A.4.4 false alarm rate

On the basis of the amount of 2dB increase the sensitivity of the detection sensitivity of the Z1, and walk for 50 times, more than a note of the number of artificial defects in alarm

The number of false alarms. Every time walking, appear more than once and once false positives were recorded as false positives 1 times.

K2 = (N3/50) × 100% (A.4)

Where.

K2 --- false positive rate,%;

N3 --- the number of false positives.

A.4.5 undetectable end zone (blind)

On the basis of Z1 2dB increase detection sensitivity value, under the effect of rod and wire ends are cut under the premise of continuous test five times,

So that the standard rod-like artificial defects (lines) 2 artificial defects both ends alarm.

From the artificial defect and the end of the line at both ends of the rod is the length between the non-detection zone.

A.4.6 artificial flaw size resolution

Artificial flaw size resolution in accordance with Figure A.1 production. Under the same conditions the dB value of the sensitivity, the test five times in a row, just alarm

The difference between the aperture and not just artificial defect aperture between the artificial defect alarm that is artificial defect size resolution.

gamma = d1-d2 (A.5)

Where.

gamma --- artificial flaw size resolution, millimeters (mm);

D1 --- just artificial defect alarm pore size in millimeters (mm);

Artificial defects d2 --- just no alarm aperture in millimeters (mm).