A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both sta...A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.展开更多
Micro-bending tests were performed to investigate effects of thickness and grain size on material behavior in sheet metal forming.The rolling brass C2680 foil was selected as the experimental material,and it was annea...Micro-bending tests were performed to investigate effects of thickness and grain size on material behavior in sheet metal forming.The rolling brass C2680 foil was selected as the experimental material,and it was annealed to eliminate the work-hardening and get different grain sizes.A device was specially designed for three-point bending with two load sensors.The results show that the bending force increases with increasing the punch displacement.With the foil of same thickness,a smaller punch radius leads to a larger bending force.When the grain size increases,the bending force becomes smaller.Size effects are observed obviously.These results have been analyzed by work-hardening,Hall-Petch equation and free surface effect.展开更多
基金Projects(50835002,50821003,50975174,51275297)supported by the National Natural Science Foundation of ChinaProjects(200802480053,20100073110044)supported by the PhD Programs Foundation of Ministry of Education of China
文摘A non-local dislocation density based crystal plasticity model, which takes account of the microstrncture inhomogeneity, was used to investigate the micro-bending of metallic crystalline foils. In this model, both statistically stored dislocations （SSDs） and geometrically necessary dislocations （GNDs） are taken as the internal state variables. The strain gradient hardening in micro-bending of single-grained metal foils was predicted by evolution of GNDs. The predicted results were compared with the micro-hardness distribution of the previous micro-bending experiments of CuZn37 a-brass foils with coarse grains and fine grains. Comparison of the simulated dislocation densities distribution of SSDs and GNDs with the experimental results shows that different micro-hardness distribution patterns of the coarse and fine grain foils can be attributed to the corresponding SSDs and GNDs distributions. The present model provides a physical insight into the deformation mechanism and dislocation densities evolution of the micro-bending process.
基金Project(2006AA04Z316)supported by the High-tech Research and Development Program of ChinaProject(2008RFQXG041)supported by the Foundation for Innovation Scholars of Harbin City,ChinaProject(50805035)supported by the National Natural Science Foundation for Young Scholars of China。
文摘Micro-bending tests were performed to investigate effects of thickness and grain size on material behavior in sheet metal forming.The rolling brass C2680 foil was selected as the experimental material,and it was annealed to eliminate the work-hardening and get different grain sizes.A device was specially designed for three-point bending with two load sensors.The results show that the bending force increases with increasing the punch displacement.With the foil of same thickness,a smaller punch radius leads to a larger bending force.When the grain size increases,the bending force becomes smaller.Size effects are observed obviously.These results have been analyzed by work-hardening,Hall-Petch equation and free surface effect.
