The Practical Application of Grain Noise Models in Titanium Billets and Forgings

Ultrasonic Grain Noise Modeling: Recent Applications to Engine Titanium Inspections

“…The multi-phase microstructures of jet engine titanium alloys are quite complex, and tend to vary with position in billets and forgings [4]. It is unlikely that measurements [4] of noise Figures-of-Merit will become a routine part of industrial inspections in the near future.…”

“…The multi-phase microstructures of jet engine titanium alloys are quite complex, and tend to vary with position in billets and forgings [4]. It is unlikely that measurements [4] of noise Figures-of-Merit will become a routine part of industrial inspections in the near future. Without knowledge of FOM values, certain relative noise Ievels can still be predicted if: (1) any non-Gaussian behavior is neglected; and (2) the functional form of the dependence of FOM on frequency is known.…”

“…In analogy with Eq. (1) for the tonehurst case, the fourth central moment can be written in terms of microstructural (11 2 , T) 4 ) and non-microstructural factors: <v 4 (t)> = ( 11 2 ) 2 [system factor 1] + T) 4 [system factor 2] . (2) We use FOM' to denote the square root of the higher-order backscatter coefficient, 11 4 = n< I A 4 I >.…”

“…Under the sponsorship of the U.S. Air Force and the FAA Engine Titanium Consortium, models have been developed which endeavor to predict characteristics of the backscattered microstructural noise observed in focused-probe pulse/ echo inspections of titanium billets and forgings [1][2][3][4][5]. In this paper we briefly review the history of the model development work at Iowa State University, and then compare noise model predictions with experiment for several cases of interest.…”

Experimental Evidence of Single and Multiple Scattering in Polycrystalline Materials

“…Current methods for properly estimating 7](m) are lirnited to cases in which the single scattering assumption is valid. Many models for grain noise also rely upon the validity of the single scattering assumption [5][6][7][8][9]. When attempting to validate models based upon the single scattering assumption, one must frrst verify that the single scattering assumption is valid.…”