Warm forming simulation of Al–Mg sheet

The accuracy of warm forming simulations depends to a large extend on the description of the yield surface with temperature and strain-rate dependent hardening and on the modeling of friction. In this paper, the anisotropic behavior of the sheet is described by using the Vegter yield locus, which is purely based on experimental measurements. For work hardening, the dislocation based Nes model is used, in which the evolution of microstructure is defined by three internal state variables. The model incorporates the influence of the temperature and strain rate effect on the flow stress by means of the storage and dynamic recovery of dislocations. It is demonstrated that the Nes model is able to describe the flow stress of Al–Mg alloys up to 250 ° C at different strain rates. It also represents the negative strain rate sensitivity behavior of Al–Mg alloys at temperatures below 125 °C. The simulation of uniaxial tensile tests shows that the model is able to predict the strain localization. Cylindrical cup deep drawing simulations are presented using shell elements. Data from experimental deep drawing tests is used to validate the modeling approach, where the model parameters are determined from tensile tests.

[1]  Amit K. Ghosh,et al.  Biaxial warm forming behavior of aluminum sheet alloys , 2003 .

[2]  Ken-ichiro Mori,et al.  Finite element simulation of warm deep drawing of aluminium alloy sheet when accounting for heat conduction , 2002 .

[3]  E. Evangelista,et al.  Modelling grain boundary strengthening in ultra-fine grained aluminum alloys , 2005 .

[4]  A. H. van den Boogaard,et al.  Modeling of AlMg Sheet Forming at Elevated Temperatures , 2001 .

[5]  K. Marthinsen,et al.  Modelling strain hardening and steady state deformation of Al–Mg alloys , 2001 .

[6]  Robert A. Ayres,et al.  Alloying aluminum with magnesium for ductility at warm temperatures (25 to 250°C) , 1979 .

[7]  John E. Carsley,et al.  Forming of AA5182-O and AA5754-O at elevated temperatures using coupled thermo-mechanical finite element models , 2007 .

[8]  K. Marthinsen,et al.  Modeling the evolution in microstructure and properties during plastic deformation of f.c.c.-metals and alloys – an approach towards a unified model , 2002 .

[9]  van den,et al.  Thermally Enhanced Forming of Aluminium Sheet. Modelling and experiments , 2002 .

[10]  J. Huetink,et al.  Simulation of aluminium sheet forming at elevated temperatures , 2006 .

[11]  K. Marthinsen,et al.  A unified microstructural metal plasticity model applied in testing, processing, and forming of aluminium alloys , 2005 .

[12]  E. Nes,et al.  Modelling of work hardening and stress saturation in FCC metals , 1997 .

[13]  Y. Bréchet,et al.  On the mechanisms of dynamic recovery , 2002 .

[14]  van der Erik Giessen,et al.  SIMULATION OF MATERIALS PROCESSING: THEORY, METHODS AND APPLICATIONS , 1998 .

[15]  A. H. van den Boogaard,et al.  A plane stress yield function for anisotropic sheet material by interpolation of biaxial stress states , 2006 .