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Title: Finite Element Modeling of Transition Zone in Friction Stir Welded Tailor-Made Blanks

Abstract

Finite element modeling of a prototype friction stir welded blank made of aluminum alloy 2024-T351 is considered in this paper. Feasibility of implementation of the experimentally-obtained mechanical properties of the weld nugget and heat-affected zones in FEM models is investigated. Limiting dome height test is considered as case of the study. Three different finite element models implementing different levels of the weld details are built and compared. It is shown that despite increased simulation time, implementation of the weld nugget and heat-affected zones is justified by significantly improved accuracy of the simulation results.

Authors:
 [1];  [2]; ;  [3]
  1. Netherlands Institute for Metals Research, Mekelweg 2, Delft 2628CD (Netherlands)
  2. (Netherlands)
  3. Faculty of Aerospace Engineering, Technical University of Delft, Kluyverweg 1, Delft 2629HS (Netherlands)
Publication Date:
OSTI Identifier:
21057370
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM '07: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2741014; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACCURACY; ALUMINIUM ALLOYS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; FINITE ELEMENT METHOD; FRICTION; HEAT AFFECTED ZONE; IMPLEMENTATION; MECHANICAL PROPERTIES; WELDED JOINTS; WELDING

Citation Formats

Zadpoor, Amir A., Faculty of Aerospace Engineering, Technical University of Delft, Kluyverweg 1, Delft 2629HS, Sinke, Jos, and Benedictus, Rinze. Finite Element Modeling of Transition Zone in Friction Stir Welded Tailor-Made Blanks. United States: N. p., 2007. Web. doi:10.1063/1.2741014.
Zadpoor, Amir A., Faculty of Aerospace Engineering, Technical University of Delft, Kluyverweg 1, Delft 2629HS, Sinke, Jos, & Benedictus, Rinze. Finite Element Modeling of Transition Zone in Friction Stir Welded Tailor-Made Blanks. United States. doi:10.1063/1.2741014.
Zadpoor, Amir A., Faculty of Aerospace Engineering, Technical University of Delft, Kluyverweg 1, Delft 2629HS, Sinke, Jos, and Benedictus, Rinze. Thu . "Finite Element Modeling of Transition Zone in Friction Stir Welded Tailor-Made Blanks". United States. doi:10.1063/1.2741014.
@article{osti_21057370,
title = {Finite Element Modeling of Transition Zone in Friction Stir Welded Tailor-Made Blanks},
author = {Zadpoor, Amir A. and Faculty of Aerospace Engineering, Technical University of Delft, Kluyverweg 1, Delft 2629HS and Sinke, Jos and Benedictus, Rinze},
abstractNote = {Finite element modeling of a prototype friction stir welded blank made of aluminum alloy 2024-T351 is considered in this paper. Feasibility of implementation of the experimentally-obtained mechanical properties of the weld nugget and heat-affected zones in FEM models is investigated. Limiting dome height test is considered as case of the study. Three different finite element models implementing different levels of the weld details are built and compared. It is shown that despite increased simulation time, implementation of the weld nugget and heat-affected zones is justified by significantly improved accuracy of the simulation results.},
doi = {10.1063/1.2741014},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}
  • A comparison of welding techniques was performed to determine the most effective method for producing aluminum tailor-welded blanks for high volume automotive applications. Aluminum sheet was joined with an emphasis on post weld formability, surface quality and weld speed. Comparative results from several laser based welding techniques along with friction stir welding are presented. The results of this study demonstrate a quantitative comparison of weld methodologies in preparing tailor-welded aluminum stampings for high volume production in the automotive industry. Evaluation of nearly a dozen welding variations ultimately led to down selecting a single process based on post-weld quality and performance.
  • Current joining technologies for automotive aluminum alloys are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding has been traditionally applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translatemore » to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum welded components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability utilizing a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.« less
  • Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminummore » alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.« less
  • Beginning in 1992, tailor-welded blanks (TWBs) were used in the US automotive industry to consolidate parts, reduce tolerances, save weight, and increase stiffness. This business is expanding rapidly; more than $500 million of annual TWB sales are expected by 1997. Welds in steel are generally stronger than the base material, such that weld failure by preferential localization is not a critical issue. However, the forming characteristics of TWBs must be understood in order to design and produce high-quality parts with reasonable production and tooling costs. Three formability issues were addressed in this study: the intrinsic ductility and relative formability ofmore » three weld types (CO{sub 2} and Nd:YAG laser welds and mash-seam welds with and without mechanical postweld processing); the value and correspondence of mechanical tests to each other and to press performance; and the prediction of the forming behavior using the finite element method (FEM). Two failure modes for TWBs were identified. While the local ductility of welds can differ greatly, little difference in press formability was measured among the weld types. More important than weld ductility are the changed deformation patterns which depend on the differential strength but depend little on local weld properties. Finite element method (FEM) simulations of dome tests and scale fender-forming operations show good agreement with measurements, as long as boundary conditions are known accurately. The importance of weld-line displacement is discussed and several simulations are compared with experiments.« less
  • The current trend in the automotive industry is to develop and apply technology to continually reduce and minimize the energy consumption and environmental impact of future vehicles. As a result, advanced materials and methods of material savings for the purpose of vehicle weight reduction are of interest to all major automotive manufacturers as reflected by the significant focus of the Partnership for New Generation Vehicles (PNGV) on materials issues. Aluminum sheet stampings are being increasingly applied in high volume hang-on applications including hoods, decklids and liftgates with considerable interest in door stampings as well. Automotive engineers have been successful inmore » reducing weight, reducing part count, streamlining the assembly process and reducing costs by taking advantage of singular steel tailored blanks to replace multiple blanks which would have to be separately stamped and assembled. The same opportunities exist for aluminum tailored blanks, with added weight savings. Potential applications of aluminum tailored blanks extend to body-in-white stampings.« less