Comparison of Experimental Measurements of Material Grain Size Using Ultrasound

Abstract

Material grain size is related to metallic material properties and its elastic behaviour. Measuring and monitoring material grain size in material manufacturing and service is an important topic in measurement field. In this paper, three materials, i.e., aluminium 2014 T6, steel BS970 and copper EN1652, were chosen to represent materials with small, medium and large grain size, respectively. Various techniques of measuring material grain size were demonstrated and compared. These techniques include the measurements from material microstructure images, backscattered ultrasonic grain noise using a conventional transducer, longitudinal wave attenuation using ultrasonic arrays and shear wave attenuation using a lead zirconate titanate (PZT) plate. It is shown that the backscattered ultrasonic noise measurement and material attenuation measurement are complementary. The former is pretty good for weak scattering materials, e.g., aluminium, while the latter for materials with large grains, e.g., steel and copper. Consistent measured grain size from longitudinal and shear wave attenuations in steel and copper suggests that shear wave attenuation can be calculated from the measured longitudinal wave attenuation integrated with Stanke-Kino's model or Weaver's model, if there is a difficulty to either excite or capture shear waves in practice. The outcome of the paper expects to provide a further step towards the industrial uptake of these techniques.

Elastic and thermodynamic properties of cerium‐doped yttrium aluminum garnets

“…Even though the magnitudes of C 11 and C 12 are significantly lower for 1Ce:YAG, its longitudinal component of sound velocity (V 11 ) is largely preserved, whereas the transverse component of sound velocity (V 44 ) is significantly reduced (Table 2). V 44 is more sensitive to microstructural variations than V 11 , 54,55 thus a reduction in V 44 may again reflect the presence of micropores and anisotropic grain size distributions in 1Ce:YAG 56‐58 . This is consistent with lower magnitudes in the elastic moduli of 1Ce:YAG compared to 0.025Ce:YAG and 0.1Ce:YAG (Table 2).…”

“…The elastic moduli of 1Ce:YAG differ 2). V 44 is more sensitive to microstructural variations than V 11 , 54,55 thus a reduction in V 44 may again reflect the presence of micropores and anisotropic grain size distributions in 1Ce:YAG. [56][57][58] This is consistent with lower magnitudes in the elastic moduli of 1Ce:YAG compared to 0.025Ce:YAG and 0.1Ce:YAG (Table 2).…”

Comparison of Time Domain and Frequency-Wavenumber Domain Ultrasonic Array Imaging Algorithms for Non-Destructive Evaluation

“…A 2-D linear systems modelling approach [ 21 , 24 ] is used to simulate the FMC data set from a defect and hence produce noise-free images for comparison purposes. In the frequency domain, for a wave path from transmitter element at to a defect at and back to a receiver element at , the received signal can be expressed as [ 21 , 24 ], where, is the signal spectrum of the transmitted signal, B is the directivity function of an array element [ 25 ], is the measured material attenuation coefficient as shown in Figure 3 [ 26 ], is the scattering matrix [ 27 ] of the defect at the wave incident angle of and scattering angle of .…”

Characterization of Grain Size in 316L Stainless Steel Using the Attenuation of Rayleigh Wave Measured by Air-Coupled Transducer

“…Traditionally, a small piece of specimen is taken from material and polished for microstructure imaging with optical and electron microscopy [ 3 ]. Though this method provides extensive and accurate details, it is constrained by their destructive nature, as well as laboratory confinement and time-consuming procedures for specimen preparation [ 4 ].…”