Thermal-mechanical modeling and experimental validation of weld solidification cracking in 6061-T6 aluminum

Abstract

Finite element simulations using an internal state variable constitutive model coupled with a void growth and damage model are used to study weld solidification cracking of 6061-T6 aluminum. Calculated results are compared with data from an experimental program determining the locations of failure as a function of weld process parameters and specimen geometry. Two types of weld solidification cracking specimen were studied. One specimen, in which cracking did not occur, was used to evaluate finite element simulations of the thermal response and calculations of average strain across the weld. The other specimen type was used to determine the location of crack initiation as a function of weld process parameters. This information was used to evaluate the finite element simulations of weld solidification cracking. A solidification model which includes dendrite tip and eutectic undercooling was used in both thermal and mechanical finite element analyses. A strain rate and temperature history dependent constitutive model is coupled with a ductile void growth damage model in the mechanical analyses. Stresses near the weld pool are examined to explain results obtained in the finite element analyses and correlated with experimental observations. Good agreement is obtained between simulation and experiment for locations of crack initiation and extent of cracking. Some effects of uncertainties in material parameters are discussed. DISCLAIMERThis rrpon was F p a r d as an aQx)uat of work spowrrcd by an agency of the United States Gownmat Neither the Unitat Stam Government nor any agency &emf. nor any of their employes, mnkcr any #uranty, express or implied. or fuincss of m y information, apparatus, pmducr, or procar disciosai, or rrpraents that its w would not infringe privately owned igbu Rcfuencc herein to any rpafic c o m m d pmduct, proccu or wwice by trade rumt, tradmmk tnonufac-tu=. or otherwise docs not nccessoriiy QlLIttitlltc or impiy its atdorsrment. m mmend;ruon. or fawring by the United States Gonernmmt or any agency thereof. The views and Opinions of authors arprrued h d do not n d y state or rrfim those of the United States Government or any agency thereof. ==CS my legal linbility Or rrzp~art'bility for the -CY, C O m p i ~a l ~ OT W -DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

An extended mechanical threshold stress plasticity model: modeling 6061-T6 aluminum alloy

“…Adiabatic heat is assumed for the high strain rate calculations. [Green and Babcock 1966;Eleiche 1972]; [Dike et al 1997]; [Rosenberg et al 1986]; [Ogawa 2001]. …”