Comparison of Realistic Artificial Cracks and In-Service Cracks

In-service inspection qualification needs representative defects to be used in qualification mockups. Present defect production techniques have weaknesses, which are not acceptable, such as not representative defects or additional alterations induced in the surrounding material. Hence qualification...

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Bibliographic Details
Published in:E-journal of Nondestructive Testing 2003-03, Vol.8 (3), p.1-6
Main Authors: Kemppainen, M, Virkkunen, I, Pitkanen, J, Paussu, R, Hanninen, H
Format: Article
Language:English
Online Access:Get full text
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Summary:In-service inspection qualification needs representative defects to be used in qualification mockups. Present defect production techniques have weaknesses, which are not acceptable, such as not representative defects or additional alterations induced in the surrounding material. Hence qualification bodies are still searching for better defect production techniques. It is commonly understood that best representativeness is achieved with realistic defects. A new method has been developed, which enables artificial production of realistic thermal fatigue cracks. This presentation introduces artificially made controlled thermal fatigue cracks. Cracks have been induced without any artificial initiator such as a notch or a precrack and without any preliminary surface treatment. Results of characterisation of cracks with non-destructive ultrasonic methods and destructive metallography are presented. Ultrasonic response as well as metallographic properties of artificial cracks is compared to properties of real, in-service induced cracks. It is shown that artificially produced thermal fatigue cracks compare favourably with the real, inservice induced ones.
ISSN:1435-4934
1435-4934