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Title: In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy

Abstract

The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in situ, time resolved neutron diffraction technique. A method was developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [2];  [2];  [1]
  1. ORNL
  2. Los Alamos National Laboratory (LANL)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
931709
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Science and Technology of Welding and Joining; Journal Volume: 12; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; FRICTION; NEUTRON DIFFRACTION; NEUTRONS; STRESSES; THERMAL STRESSES; WELDING

Citation Formats

Feng, Zhili, Wang, Xun-Li, David, Stan A, Choo, Hahn, Hubbard, Camden R, Woo, Wan Chuck, Brown, D. W., Clausen, B, and An, Ke. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy. United States: N. p., 2007. Web.
Feng, Zhili, Wang, Xun-Li, David, Stan A, Choo, Hahn, Hubbard, Camden R, Woo, Wan Chuck, Brown, D. W., Clausen, B, & An, Ke. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy. United States.
Feng, Zhili, Wang, Xun-Li, David, Stan A, Choo, Hahn, Hubbard, Camden R, Woo, Wan Chuck, Brown, D. W., Clausen, B, and An, Ke. Mon . "In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy". United States. doi:.
@article{osti_931709,
title = {In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy},
author = {Feng, Zhili and Wang, Xun-Li and David, Stan A and Choo, Hahn and Hubbard, Camden R and Woo, Wan Chuck and Brown, D. W. and Clausen, B and An, Ke},
abstractNote = {The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in situ, time resolved neutron diffraction technique. A method was developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.},
doi = {},
journal = {Science and Technology of Welding and Joining},
number = 4,
volume = 12,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in-situ, time-resolved neutron diffraction technique. A method is developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.
  • The microstructure change is one of the most important research areas in the friction stir welding (FSW). However, direct observation of microstructure changes during FSW has been extremely challenging because many measurement techniques are inapplicable. Recently developed in-situ time-resolved neutron diffraction methodology, which drastically improves the temporal resolution of neutron diffraction, enables to observe the transient microstructure changes during FSW. We installed a portable FSW system in the Spectrometer for MAterials Research at Temperature and Stress (SMARTS) at Los Alamos Neutron Science Center and the FSW was made on 6.35mm-thickness 6061-T6 Al alloy plate. At the same time, the neutronmore » beam was centered on the mid-plane of the Al plate at 8 mm from the tool center (underneath the tool shoulder) and the diffraction peak was continuously measured during welding. The peak broadening analysis has been performed using the Williamson-Hall Method. The result shows that the dislocation density of about 3.2 x 10^15 m-2 duing FSW, which is the significant increse compared to the before (4.5 x 10^14 m-2) and after (4.0 x 10^14 m-2) the FSW. The quantitatively analysis of the grain structure can provide an insight to understand the transient variation of the microstructure during FSW.« less
  • An integrated thermal-metallurgical-mechanical model is used to analyze and provide insights into the formation of the residual stress and the changes in microstructure and property of Al6061-T6 friction stir welds. The simulations were conducted by means of a three-dimensional finite element model that accounts for the phenomena of frictional heating, weld microstructure and strength changes due to dissolution and reprecipitation of the hardening precipitate particles, and the mechanical workpiece/tool contact during the friction stir welding (FSW) process. The model predictions were confirmed by experimental measurement data from previous studies. For the friction stir welds investigated, it was found that themore » residual stress distribution is strongly dependent on the welding process parameters and the degree of material softening caused by welding. The recovery of material strength from natural aging does not increase the residual stress in the weld. The failure of friction stir weld under tensile load is controlled by the combination of the reduction in strength and the residual stresses in the heat affected zone (HAZ).« less