skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Texture and grain evolutions in a 2195 friction stire weld

Abstract

Variations in microstructure, crystallographic texture, and grain distributions were determined in a conventional transverse cross section of the deposited weld and in a planview cross section around the embedded welding tool in an Al 2195 friction stir weld that had been prepared to preserve a static representation of the dynamic deformation field surrounding the tool. These results reveal important new details about the development of grain structure and crystallographic texture around the FSW tool that cannot be determined from observations on the transverse cross section alone. Two orthogonal views of a friction stir weld were analyzed to determine the microstructure, crystallographic texture, and grain structure of the deposited weld and how these characteristics initially developed in the vicinity of the weld tool. The transverse cross section reveals many interesting features. There is a complex precipitation sequence across the different weld regions. The strengthening precipitates from the matrix become coarsened across the HAZ, then are gradually replaced by a separate precipitate distribution, which forms during cooling of the weld, in the TMAZ. A third precipitate distribution that includes the equilibrium T{sub B} phase is observed in the weld nugget and is responsible for the lower microhardness of that region. A coarseningmore » of grains is observed in the TMAZ adjacent to the weld nugget, accompanied by an in-plane rotation of the grains towards <110>{parallel} welding direction. The latter observation suggests that this texture evolution is primarily in response to a simple-shear deformation field surrounding the tool. A plan-view section through the embedded FSW tool of this stop-action weld was prepared to reveal the initial development and evolution of the grain structure and crystallographic texture during friction stir welding. This analysis revealed bands of refined grains developing ahead of the fully refined region, likely reflecting different relative stabilities of the original grain orientations to the applied deformation. The initial development of the refined grain structure appears to occur by formation of fine subgrains induced by simple-shear deformation. These subgrains gradually develop greater misorientations with increased strain. The refined grains adjacent to the tool display a typical fcc shear texture after suitable rigid rotations are applied. As the material is swept around the welding tool, the texture of the refined grains evolves from the fcc shear texture to a modified texture principally consisting of two <111>{parallel}ND shear components. The primary mechanism of grain refinement in this weld therefore appears to be subdivision induced by deformation and dynamic recovery processes, with the possibility, but not necessity, of a concurrent dynamic recrystallization mechanism.« less

Authors:
 [1];  [2];  [3]
  1. Richard W.
  2. John F.
  3. Kevin J.
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
977840
Report Number(s):
LA-UR-04-6106
TRN: US201012%%759
Resource Type:
Conference
Resource Relation:
Conference: Submitted to: Proceedings of the 5th Intl. Friction Stire Welding Symposium, Metz, France, Sept. 14-16, 2004
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CROSS SECTIONS; DEFORMATION; DISTRIBUTION; FRICTION; GRAIN ORIENTATION; GRAIN REFINEMENT; MICROHARDNESS; MICROSTRUCTURE; PRECIPITATION; RECRYSTALLIZATION; ROTATION; SHEAR; TEXTURE; WELDING

Citation Formats

Fonda, R W, Bingert, J F, and Colligan, K J. Texture and grain evolutions in a 2195 friction stire weld. United States: N. p., 2004. Web.
Fonda, R W, Bingert, J F, & Colligan, K J. Texture and grain evolutions in a 2195 friction stire weld. United States.
Fonda, R W, Bingert, J F, and Colligan, K J. 2004. "Texture and grain evolutions in a 2195 friction stire weld". United States. https://www.osti.gov/servlets/purl/977840.
@article{osti_977840,
title = {Texture and grain evolutions in a 2195 friction stire weld},
author = {Fonda, R W and Bingert, J F and Colligan, K J},
abstractNote = {Variations in microstructure, crystallographic texture, and grain distributions were determined in a conventional transverse cross section of the deposited weld and in a planview cross section around the embedded welding tool in an Al 2195 friction stir weld that had been prepared to preserve a static representation of the dynamic deformation field surrounding the tool. These results reveal important new details about the development of grain structure and crystallographic texture around the FSW tool that cannot be determined from observations on the transverse cross section alone. Two orthogonal views of a friction stir weld were analyzed to determine the microstructure, crystallographic texture, and grain structure of the deposited weld and how these characteristics initially developed in the vicinity of the weld tool. The transverse cross section reveals many interesting features. There is a complex precipitation sequence across the different weld regions. The strengthening precipitates from the matrix become coarsened across the HAZ, then are gradually replaced by a separate precipitate distribution, which forms during cooling of the weld, in the TMAZ. A third precipitate distribution that includes the equilibrium T{sub B} phase is observed in the weld nugget and is responsible for the lower microhardness of that region. A coarsening of grains is observed in the TMAZ adjacent to the weld nugget, accompanied by an in-plane rotation of the grains towards <110>{parallel} welding direction. The latter observation suggests that this texture evolution is primarily in response to a simple-shear deformation field surrounding the tool. A plan-view section through the embedded FSW tool of this stop-action weld was prepared to reveal the initial development and evolution of the grain structure and crystallographic texture during friction stir welding. This analysis revealed bands of refined grains developing ahead of the fully refined region, likely reflecting different relative stabilities of the original grain orientations to the applied deformation. The initial development of the refined grain structure appears to occur by formation of fine subgrains induced by simple-shear deformation. These subgrains gradually develop greater misorientations with increased strain. The refined grains adjacent to the tool display a typical fcc shear texture after suitable rigid rotations are applied. As the material is swept around the welding tool, the texture of the refined grains evolves from the fcc shear texture to a modified texture principally consisting of two <111>{parallel}ND shear components. The primary mechanism of grain refinement in this weld therefore appears to be subdivision induced by deformation and dynamic recovery processes, with the possibility, but not necessity, of a concurrent dynamic recrystallization mechanism.},
doi = {},
url = {https://www.osti.gov/biblio/977840}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2004},
month = {1}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: