[6A6] Investigation into metallic material grain size measurement from ultrasound backscattering using ultrasonic arrays
W Wang, J Zhang and P Wilcox
University of Bristol, UK
Material grain size is a key factor influencing material properties. Ultrasound backscattering from material microstructures can be used to evaluate the material grain size using a conventional ultrasound transducer. However, it requires a large number of accurate immersion measurements and this restricts its use in some applications, for example online measurements in manufacturing or in service. The main benefit of using ultrasonic phased arrays is that one array probe at one position can focus an ultrasound beam on multiple points using different focal laws. This has the potential to replace multiple measurements using a conventional transducer. In this paper, the classic Margetan’s backscattering method was adapted to be used with full matrix capture data from an ultrasonic array, either by simulating A-scans from focused transducers or by using the total focusing method of imaging. It is shown that only a single full matrix capture dataset is required to measure material grain size, which increases measurement efficiency significantly and makes online measurements possible. The experimental validation is performed on three metallic materials: aluminium, steel and copper. A good agreement is shown between the experimentally measured grain sizes from ultrasonic arrays and metallography.
Keywords: material grain size, ultrasonic phased array, wave backscattering, FMC.
Keywords: material grain size, ultrasonic phased array, wave backscattering, FMC.
