A new technique using digital speckle correlation for nondestructive testing of corrosion

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Materials Evaluation

OSTI ID:562046

Jin, F; Chiang, F P ^[1]

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1. State Univ. of New York, Stony Brook, NY (United States). Dept. of Mechanical Engineering

When the speckle pattern (laser or white light) of a corroded specimen surface is compared to that of a virgin surface, the difference can be quickly and clearly revealed by the cross-correlation coefficient of the two speckle patterns. This technique can reveal pitting corrosion areas as small as 5 x 5 mm (0.2 x 0.2 in) wherein exists a cluster of pits of 0.3 mm (0.012 in.) in diameter and 0.1 mm (0.004 in.) in depth. An artificial stress corrosion crack was used to demonstrate the validation of this method for detection of stress corrosion cracking. For detection of crevice corrosion, laser illumination must be applied. Digital speckle correlation takes the advantage of laser speckle properties. The speckle decorrelation caused by out-of-plane displacement in the region with a crevice corrosion under the specimen`s surface is bigger than that without defects. This difference is calculated by a digital correlation algorithm, which reveals the crevice corrosion.

• OSTI ID: 562046
• Journal Information: Materials Evaluation, Journal Name: Materials Evaluation Journal Issue: 7 Vol. 55; ISSN MAEVAD; ISSN 0025-5327
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
ALLOYS
CRACK PROPAGATION
LASER RADIATION
NONDESTRUCTIVE TESTING
STRESS CORROSION