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Title: An experimental statistical analysis of stress projection factors in BCC tantalum

Abstract

Crystallographic slip planes in body centered cubic (BCC) metals are not fully understood. In polycrystals, there are additional confounding effects from grain interactions. This paper describes an experimental investigation into the effects of grain orientation and neighbors on elastic–plastic strain accumulation. In situ strain fields were obtained by performing digital image correlation (DIC) on images from a scanning electron microscope (SEM) and from optical microscopy. These strain fields were statistically compared to the grain structure measured by electron backscatter diffraction (EBSD). Spearman rank correlations were performed between effective strain and six microstructural factors including four Schmid factors associated with the <111> slip direction, grain size, and Taylor factor. Modest correlations (~10%) were found for a polycrystal tension specimen. The influence of grain neighbors was first investigated by re-correlating the polycrystal data using clusters of similarly-oriented grains identified by low grain boundary misorientation angles. Second, the experiment was repeated on a tantalum oligocrystal, with through-thickness grains. Much larger correlation coefficients were found in this multicrystal due to the dearth of grain neighbors and subsurface microstructure. Finally, a slip trace analysis indicated (in agreement with statistical correlations) that macroscopic slip often occurs on {110}<111> slip systems and sometimes by pencil glide onmore » maximum resolved shear stress planes (MRSSP). These results suggest that Schmid factors are suitable for room temperature, quasistatic, tensile deformation in tantalum as long as grain neighbor effects are accounted for.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1063327
Report Number(s):
SAND2013-1358J
Journal ID: ISSN 0921-5093
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
Additional Journal Information:
Journal Volume: 581; Journal Issue: C; Journal ID: ISSN 0921-5093
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Carroll, J. D., Clark, B. G., Buchheit, T. E., Boyce, B. L., and Weinberger, C. R. An experimental statistical analysis of stress projection factors in BCC tantalum. United States: N. p., 2013. Web. doi:10.1016/j.msea.2013.05.085.
Carroll, J. D., Clark, B. G., Buchheit, T. E., Boyce, B. L., & Weinberger, C. R. An experimental statistical analysis of stress projection factors in BCC tantalum. United States. https://doi.org/10.1016/j.msea.2013.05.085
Carroll, J. D., Clark, B. G., Buchheit, T. E., Boyce, B. L., and Weinberger, C. R. 2013. "An experimental statistical analysis of stress projection factors in BCC tantalum". United States. https://doi.org/10.1016/j.msea.2013.05.085.
@article{osti_1063327,
title = {An experimental statistical analysis of stress projection factors in BCC tantalum},
author = {Carroll, J. D. and Clark, B. G. and Buchheit, T. E. and Boyce, B. L. and Weinberger, C. R.},
abstractNote = {Crystallographic slip planes in body centered cubic (BCC) metals are not fully understood. In polycrystals, there are additional confounding effects from grain interactions. This paper describes an experimental investigation into the effects of grain orientation and neighbors on elastic–plastic strain accumulation. In situ strain fields were obtained by performing digital image correlation (DIC) on images from a scanning electron microscope (SEM) and from optical microscopy. These strain fields were statistically compared to the grain structure measured by electron backscatter diffraction (EBSD). Spearman rank correlations were performed between effective strain and six microstructural factors including four Schmid factors associated with the <111> slip direction, grain size, and Taylor factor. Modest correlations (~10%) were found for a polycrystal tension specimen. The influence of grain neighbors was first investigated by re-correlating the polycrystal data using clusters of similarly-oriented grains identified by low grain boundary misorientation angles. Second, the experiment was repeated on a tantalum oligocrystal, with through-thickness grains. Much larger correlation coefficients were found in this multicrystal due to the dearth of grain neighbors and subsurface microstructure. Finally, a slip trace analysis indicated (in agreement with statistical correlations) that macroscopic slip often occurs on {110}<111> slip systems and sometimes by pencil glide on maximum resolved shear stress planes (MRSSP). These results suggest that Schmid factors are suitable for room temperature, quasistatic, tensile deformation in tantalum as long as grain neighbor effects are accounted for.},
doi = {10.1016/j.msea.2013.05.085},
url = {https://www.osti.gov/biblio/1063327}, journal = {Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing},
issn = {0921-5093},
number = C,
volume = 581,
place = {United States},
year = {2013},
month = {10}
}