Spatial averaging algorithms for ultrasonic inspection of austenitic stainless steel welds

Conference · Mon Apr 07 04:00:00 EST 1980

OSTI ID:5342685

Horn, J. E.; Cooper, C. S.; Michaels, T. E.

Interpretation of ultrasonic inspection data from stainless steel welds is difficult because the signal-to-noise ratio is very low. The three main reasons for this are the granular structure of the weld, the high attenuation of stainless steel, and electronic noise. Averaging in time at the same position in space reduces electronic noise, but does not reduce ultrasonic noise from grain boundary scattering. Averaging wave-forms from different spatial positions helps reduce grain noise, but desired signals can destructively interfere if they shift in time. If the defect geometry is known, the ultrasonic waveforms can be shifted before averaging, ensuring signal reinforcement. The simplest geometry results in a linear time shift. An averaging algorithm has been developed which finds the optimum shift. This algorithm computes the averaged, or composite waveform as a function of the time shift. The optimum occurs when signals from a reflector become aligned in time, producing a large amplitude composite waveform. This algorithm works very well, but requires significant computer time and storage. This paper discusses this linear shift averaging algorithm, and considers an implementation using frequency domain techniques. Also, data from several weld defects are presented and analyzed.

• Research Organization: Hanford Engineering Development Lab., Richland, WA (USA)
• DOE Contract Number: AC14-76FF02170
• OSTI ID: 5342685
• Report Number(s): HEDL-SA-1913; CONF-800668-1
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420500* -- Engineering-- Materials Testing
ACOUSTIC TESTING
ALGORITHMS
ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
DATA PROCESSING
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS TESTING
MATHEMATICAL LOGIC
NONDESTRUCTIVE TESTING
PROCESSING
STAINLESS STEELS
STEELS
TESTING
ULTRASONIC TESTING
WELDED JOINTS