1 Description of the inspection
For the system calibration, a test block was used, manufactured from a real chain link prior the thermal treatment (Fig 1). The test block has three flat bottom holes with different deeps in the welding zone.
Configuration parameters of the SITAU phased-array system are summarized in the following table:
|
Phased array probe |
|
|
Nº of elements |
32 elements |
|
Pitch |
0.5 mm |
|
Frequency |
5 MHZ |
|
Angular Scan |
|
|
Active aperture |
32 elements |
|
Start angle |
30º |
|
Final angle |
70º |
|
Angular step |
2º |
|
Acquisition |
|
|
Sound velocity |
3.200 m/s |
|
Initial range |
0 mm |
|
Final range |
650 mm |
|
Reception focus |
Dynamic focusing (DDF) |
|
Emission focus |
Emission Auto-focus |
2 Measurements over the calibration block
Fig. 2.- Original image of the test block (without GNR filter)
Fig. 3.- Image of the test block filtered with GNR.
3 Measurements over a real chain link prior the thermal treatment.
Fig. 4.- Original image of a real chain-link prior the thermal treatment (without GNR filter).
Fig. 5.- image of a real chain-link prior the thermal treatment after applying the GNR filter.
4 Conclusions
In the analyzed cases, the GNR filter reduces the grain-noise level about 6 times while maintaining the reflectors amplitudes. Hence, signal to noise ratio is improved about 16 dB.