MICROSTRUCTURAL HETEROGENEITIES INDUCED BY DEFORMATION PRIOR TO THERMAL RECRYSTALLISATION IN POLYCRYSTALLINE AGGREGATES
Recrystallisation processes occur in materials with low stacking fault energies during or after thermo-mechanical processing.In these materials,dislocation climb and cross slip are hindered,thus inhibiting recovery processes and promoting recrystallisation.As recrystallisation processes depend primarily on the nature of the microstructural state,an accurate prediction of such phenomena requires that the microstructural heterogeneities which develop within grains just before recrystallization takes place be properly described.These heterogeneities may consist of structures such as dislocation cells and pile-ups,shear and twin bands.The aim of this work is to reproduce the microstructural conditions present in a polycrystal aggregate just before the onset of thermal recrystallization.To that purpose,the constitutive behaviour of each grain is described using a dislocation mechanics-based crystallographic formulation.It accounts for non-local effects through the introduction of geometrically necessary dislocations (GND).The model is then implemented into the finite element method using a finite-strain kinematics framework.The deformation of a polycrystalline copper aggregate under plan strain conditions is then studied numerically.The fractions of edge and screw dislocations in the aggregate are obtained and used to predict the distribution of the stored intemal strain energy in the aggregate.A comparison between different stored energy measures is made and the implications discussed.
E.P.Busso G.Abrivard G.Cailletaud S.Forest
Centre des Matériaux,Mines Paris-ParisTech,CNRS-UMR 7633,B.P.87,F-91003 Evry,France Centre des Matériaux,Mines aris-ParisTech,CNRS-UMR 7633,B.P.87,F-91003 Evry,France
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
66
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）