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An Automated Imaging Scheme for Quantitative Non-Destructive Evaluation of Stainless Steel Plates and Welds

: Rao, B.; Raj, B.; Jayakumar, T.; Kalyanasundaram, P.; Arnold, W.; Kröning, M.

Raj, B.:
Materials Ageing and Life Management. Vol. 2
New Delhi: Allied Publishers, 2000
ISBN: 81-7764-087-9
International Symposium on Materials Ageing and Life Management (ISOMALM) <2000, Kalpakkam, Indien>
Fraunhofer IZFP ()
nondestructive evaluation; stainless steel; weld; plate structure

Eddy current test is a simple, versatile, fast and high sensitivity non-destructive evaluation technique widely used for detection and characterisation of surface and sub-surface defects in austentic stainless steels. Fracture mechanics based approaches for structural integrity assessment demand NDE data such as length, width, shape, orientation, and distribution of defects. In EC test situations, this data can only be obtained by raster-scan imaging of eddy current probe on the material surface. Three major problems noticed during EC imaging of stainless steel plates and welds are the influence of disturbing variables, the blurring of images due to convolution of point spread function of probe with defects, and the lager imaging times.
In this contribution, a new imaging scheme is presented for automated eddy current nondestructive evaluation of austentic stainless steel plates and welds. This scheme uses artifical neural networks and imaging methods to identify all the defective regions quickly and then to automatically examine the defective regions in more detail to ultimately produce 3-dimensional picture of defects. Experimental studies on stainless steel plates and welds confirm that the automated scheme is capable of detecting defects quickly and characterising them accurately besides reducing the memory requirements for storage of inspection data.