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Proceedings Paper

EMAT-generated Lamb waves for volumetric inspection of strip steel
Author(s): Wayne M. Latham; P. Jerry Latimer; Daniel T. MacLauchlan; Kenneth R. Camplin; Dennis D. Lang
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Paper Abstract

The detection of longitudinally oriented defects in steel plate using ultrasonics has been widely reported. Ultrasonic methods are capable of detecting extremely small volume flaws in strip steel, but are limited because of the need to maintain fluid couplant between the transducer and steel strip. At a minimum, this couplant requirement slows the test speeds considerably, can introduce errors in test results, and, in many cases, prevents the test from being performed at all. The purpose of this paper is to present the results of the investigation of EMAT generated Lamb waves for the volumetric inspection of steel strip and subsequent on-line system performance. The strip steel industry has described a manufacturing problem of internal inclusions in their strip steel product for use in the automotive/appliance industry which is manifested after the rolling operation. The 'pencil pipe', a non-metallic inclusion introduced during the continuous casting process, is not detected prior to the roll, and after rolling it is too late to recover. A major midwestern US steel company considers this defect to be their number one quality problem. A method of detecting these inclusions prior to rolling was needed and is the basis of this development. The objective of this evaluation was the selection and implementation of EMAT generated Lamb wave modes that could be used for on-line detection of pencil pipe defects in strip steel before the strip is rolled to its final thickness. In addition, different Lamb waves modes were used to discriminate between the internal pencil pipe and non- deleterious surface scratches.

Paper Details

Date Published: 15 March 1998
PDF: 12 pages
Proc. SPIE 3399, Process Control and Sensors for Manufacturing, (15 March 1998); doi: 10.1117/12.302547
Show Author Affiliations
Wayne M. Latham, MAST Automation, Inc. (United States)
P. Jerry Latimer, MAST Automation, Inc. (United States)
Daniel T. MacLauchlan, MAST Automation, Inc. (United States)
Kenneth R. Camplin, Innerspec Technologies (United States)
Dennis D. Lang, Innerspec Technologies (United States)

Published in SPIE Proceedings Vol. 3399:
Process Control and Sensors for Manufacturing
Richard H. Bossi; David M. Pepper, Editor(s)

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