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Title: Using Scattering Theory to Determine Orientation Distribution Coefficients of Polycrystals with Preferred Grain Orientations

Abstract

The mechanical behavior of single-phase polycrystalline materials depend on the elastic constants of individual grains. Most engineering metals are polycrystalline aggregates possess macroscopic texture resulting from preferential grain orientations. Accurate knowledge of texture is important for a number of engineering applications. For example, it plays an important role in determining their subsequent formability into finished parts of complex shape by deep drawing. Textural information can also be exploited to assess plastic damage in a component due to fatigue or external impact. Current ultrasonic methods are based on the relationship between ultrasonic phase velocities and the low-order orientation distribution coefficients (ODCs); a consequence of the application of Voigt averaging method to infer aggregate elastic properties. Thus, such techniques provide only a partial description of texture. It is well-known from the scattering theories that while phase velocity of acoustic waves is controlled primarily by averages of single grain elastic constant fluctuations, redirection of their energy by scattering at the grain boundaries are controlled primarily by two-point averages of these fluctuations. Since these two-point averages depend on higher order ODCs, a more complete and accurate description of texture can be obtained from the measurement of scattered acoustic energy. In this paper, however, wemore » will present a methodology to determine the three low-order ODCs from L-wave and two S-waves propagating only in the normal direction in steel with rolling symmetry. This methodology appears more attractive than that using ultrasonic phase velocities since that requires measurements in three mutually orthogonal directions. In particular, in cases where wave characteristics measurements can be made only in one direction, only the proposed method will be able to yield the lowest three ODCs.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1000839
Report Number(s):
PNNL-SA-46364
TRN: US201101%%576
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Ultrasonics: Proceedings of the Indian Society for Non-Destructive Testing, Kolkata Chatper, National Seminar on NDT (NDE-2005)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACOUSTICS; DISTRIBUTION; ELASTICITY; FLUCTUATIONS; GRAIN BOUNDARIES; GRAIN ORIENTATION; NONDESTRUCTIVE TESTING; ORIENTATION; PHASE VELOCITY; PLASTICS; POLYCRYSTALS; ROLLING; S WAVES; SCATTERING; SHAPE; STEELS; SYMMETRY; TEXTURE; ULTRASONIC WAVES; Scattering; Texture; Grains; Polycrystals; ODC

Citation Formats

Ahmed, Salahuddin, and Taylor, Tom T. Using Scattering Theory to Determine Orientation Distribution Coefficients of Polycrystals with Preferred Grain Orientations. United States: N. p., 2006. Web.
Ahmed, Salahuddin, & Taylor, Tom T. Using Scattering Theory to Determine Orientation Distribution Coefficients of Polycrystals with Preferred Grain Orientations. United States.
Ahmed, Salahuddin, and Taylor, Tom T. 2006. "Using Scattering Theory to Determine Orientation Distribution Coefficients of Polycrystals with Preferred Grain Orientations". United States.
@article{osti_1000839,
title = {Using Scattering Theory to Determine Orientation Distribution Coefficients of Polycrystals with Preferred Grain Orientations},
author = {Ahmed, Salahuddin and Taylor, Tom T},
abstractNote = {The mechanical behavior of single-phase polycrystalline materials depend on the elastic constants of individual grains. Most engineering metals are polycrystalline aggregates possess macroscopic texture resulting from preferential grain orientations. Accurate knowledge of texture is important for a number of engineering applications. For example, it plays an important role in determining their subsequent formability into finished parts of complex shape by deep drawing. Textural information can also be exploited to assess plastic damage in a component due to fatigue or external impact. Current ultrasonic methods are based on the relationship between ultrasonic phase velocities and the low-order orientation distribution coefficients (ODCs); a consequence of the application of Voigt averaging method to infer aggregate elastic properties. Thus, such techniques provide only a partial description of texture. It is well-known from the scattering theories that while phase velocity of acoustic waves is controlled primarily by averages of single grain elastic constant fluctuations, redirection of their energy by scattering at the grain boundaries are controlled primarily by two-point averages of these fluctuations. Since these two-point averages depend on higher order ODCs, a more complete and accurate description of texture can be obtained from the measurement of scattered acoustic energy. In this paper, however, we will present a methodology to determine the three low-order ODCs from L-wave and two S-waves propagating only in the normal direction in steel with rolling symmetry. This methodology appears more attractive than that using ultrasonic phase velocities since that requires measurements in three mutually orthogonal directions. In particular, in cases where wave characteristics measurements can be made only in one direction, only the proposed method will be able to yield the lowest three ODCs.},
doi = {},
url = {https://www.osti.gov/biblio/1000839}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2006},
month = {1}
}

Conference:
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