Application of the First Higher-Order (M21) Mode Rayleigh Wave to the Inspection of Stainless Steel Overlays

Abstract

Efficient inspection of stainless steel overlays appears to present a particularly challenging problem due to the anisotropy that is characteristic of that material. An improved inspection technique may be available, however, when the dissimilar properties of the overlay and the base material are utilized. Higher order mode Rayleigh waves which at high frequencies remain confined to the upper layer of the stainless steel material are demonstrated to be able to detect welding defects in the overlay material in a field some distance away from the probe. With this technique, a larger area may be scanned with each probe placement rather than the point contact probe inspection method that is typically used.