Non-destructive evaluation of stainless steel bellows and POCO graphite by means of the scanning laser acoustic microscope (SLAM). Technical report

Technical Report · Mon Oct 01 04:00:00 EDT 1979

OSTI ID:5921003

Yuhas, D E; McGraw, T E; Kessler, L W

An ultrasonic imaging inspection technique was developed for intact inspection of welded seams on stainless steel bellows at a frequency of 100 MHz. Two cylindrical bellows (outside diameter 6.5 and 1.0 inches) consisting of a series of convoluted, welded, metal rings were investigated. The report describes the imaging method, instrumentation, and data obtained. High resolution, magnified, acoustic images of the welded zones were obtained using a new stage to fit a Scanning Laser Acoustic Microscope (SLAM) that employes 100 MHz acoustic waves to create images of the weldment elastic-microstructure. These acoustic micrographs, which contain 2 x 10/sup 4/ image points, are displayed on a real-time TV monitor. Fixturing modifications to the SONOMICROSCOPE 100 and special transducers were developed to accommodate the complex bellows geometry. Examination of more than 140 inches of welded seams revealed a variety of flaws. These anomalous zones are classified according to flaw size, morphology, and degree of acoustic contrast. Acoustic micrographs illustrating the various flaw tyes are compared with results obtained by metallographs. Ultrasonic investigation of POCO graphite showed that samples in excess of 1/4'' (6.25 mm) thick were found to be too attenuating for testing at 100 MHz. The results of this investigation indicate lower ultrasonic frequencies, in the 25 to 30 MHz range, will allow the required penetration of POCO graphite parts in this 1/4'' thickness range.

• Research Organization: Rutgers--the State Univ., New Brunswick, NJ (USA). Dept. of Mechanical and Aerospace Engineering
• DOE Contract Number: EY-76-C-04-0789
• OSTI ID: 5921003
• Report Number(s): SAND-79-7047
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420500* -- Engineering-- Materials Testing
ACOUSTIC TESTING
ALLOYS
BELLOWS
CARBON
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
ELEMENTS
GRAPHITE
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
LASERS
MATERIALS TESTING
MECHANICAL STRUCTURES
MICROSCOPES
NONDESTRUCTIVE TESTING
NONMETALS
STAINLESS STEELS
STEELS
TESTING
ULTRASONIC TESTING
WELDED JOINTS