A system for high-resolution, nondestructive, ultrasonic imaging of weld grains

The purpose of nondestructive evaluation is to detect degradation so that corrective action can be taken before the degradation challenges the structural integrity of an industrial system or one of its components. Accurate characterization is required to distinguish progressive degradation from benign material conditions. In nondestructive evaluation, characterization includes quantification and description of location, dimensions, shape, orientation, and composition of an indication of degradation. An imaging system that uses synthetic aperture focusing is one choice for detection and characterization of degradation in welded assemblies. In this paper, the ultrasonic imaging of the intended weld microstructure is reported. New technology invented for this purpose is described. This paper reviews how an ultrasonic imaging system that uses a synthetic lens can have a resolution that approaches the diffraction limit. A constrained solution to the coherent summation problem is presented for near real-time performance in high-resolution synthetic aperture focusing. Data are included to show that nondestructive, ultrasonic imaging of weld grains is practical.