The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX a...The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX are determined by the grain level deformation and sequentially coupled.In order to fully capture the microstructure and mechanical property evolution,a crystal plasticity finite element based modelling method for DRX and SRX is proposed in the current work.The grain level deformation is calculated with crystal plasticity which is coupled with the recrystallization model straightforwardly,and both the grain deformation and microstructure evolution are updated simultaneously.The proposed method is validated with discontinuous DRX experiments and the effects of initial deformation conditions are well-captured.Two controversial mechanisms for recrystallization microstructure evolution,i.e.oriented nucleation and growth selection,are discussed in the current framework with the advantages of accurate grain level deformation and interaction predictions.Furthermore,the sequentially coupled DRX and SRX are modelled seamlessly in the current work which provides a critical method for fully integrated thermo-mechanical processes analysis.展开更多
Grain scale plasticity of NiTi shape memory alloy(SMA)during uniaxial compression deformation at 400℃was investigated through two-dimensional crystal plasticity finite element simulation and corresponding analysis ba...Grain scale plasticity of NiTi shape memory alloy(SMA)during uniaxial compression deformation at 400℃was investigated through two-dimensional crystal plasticity finite element simulation and corresponding analysis based on the obtained orientation data.Stress and strain distributions of the deformed NiTi SMA samples confirm that there exhibits a heterogeneous plastic deformation at grain scale.Statistically stored dislocation(SSD)density and geometrically necessary dislocation(GND)density were further used in order to illuminate the microstructure evolution during uniaxial compression.SSD is responsible for sustaining plastic deformation and it increases along with the increase of plastic strain.GND plays an important role in accommodating compatible deformation between individual grains and thus it is correlated with the misorientation between neighboring grains,namely,a high GND density corresponds to large misorientation between grains and a low GND density corresponds to small misorientation between grains.展开更多
A dynamic compression test was performed on α+β dual-phase titanium alloy Ti20C using a split Hopkinson pressure bar.The formation of adiabatic shear bands generated during the compression process was studied by com...A dynamic compression test was performed on α+β dual-phase titanium alloy Ti20C using a split Hopkinson pressure bar.The formation of adiabatic shear bands generated during the compression process was studied by combining the proposed multi-scale crystal plasticity finite element method with experimental measurements.The complex local micro region load was progressively extracted from the simulation results of a macro model and applied to an established three-dimensional multi-grain microstructure model.Subsequently,the evolution histories of the grain shape,size,and orientation inside the adiabatic shear band were quantitatively simulated.The results corresponded closely to the experimental results obtained via transmission electron microscopy and precession electron diffraction.Furthermore,by calculating the grain rotation and temperature rise inside the adiabatic shear band,the microstructural softening and thermal softening effects of typical heavily-deformed α grains were successfully decoupled.The results revealed that the microstructural softening stress was triggered and then stabilized(in general)at a relatively high value.This indicated that the mechanical strength was lowered mainly by the grain orientation evolution or dynamic recrystallization occurring during early plastic deformation.Subsequently,thermal softening increased linearly and became the main softening mechanism.Noticeably,in the final stage,the thermal softening stress accounted for 78.4% of the total softening stress due to the sharp temperature increase,which inevitably leads to the stress collapse and potential failure of the alloy.展开更多
Microstructure-based numerical modeling of the deformation heterogeneity and ferrite recrystallization in a cold-rolled dual-phase(DP)steel has been performed by using the crystal plasticity finite element method(CPFE...Microstructure-based numerical modeling of the deformation heterogeneity and ferrite recrystallization in a cold-rolled dual-phase(DP)steel has been performed by using the crystal plasticity finite element method(CPFEM)coupled with a mesoscale cellular automaton(CA)model.The microstructural response of subsequent primary recrystallization with the deformation heterogeneity in two-phase microstructures is studied.The simulations demonstrate that the deformation of multi-phase structures leads to highly strained shear bands formed in the soft ferrite matrix,which produces grain clusters in subsequent primary recrystallization.The early impingement of recrystallization fronts among the clustered grains causes mode conversions in the recrystallization kinetics.Reliable predictions regarding the grain size,microstructure morphology and kinetics can be made by comparison with the experimental results.The influence of initial strains on the recrystallization is also obtained by the simulation approach.展开更多
We present the formulation and applications of JAX-CPFEM,an open-source,GPU-accelerated,and differentiable 3-D crystal plasticity finite element method(CPFEM)software package.Leveraging the modern computing architectu...We present the formulation and applications of JAX-CPFEM,an open-source,GPU-accelerated,and differentiable 3-D crystal plasticity finite element method(CPFEM)software package.Leveraging the modern computing architecture JAX,JAX-CPFEM features high performance through array programming and GPU acceleration,achieving a 39×speedup in a polycrystal case with~52,000 degrees of freedom compared to MOOSE with MPI(8 cores).Furthermore,JAX-CPFEM utilizes the automatic differentiation technique,enabling users to handle complex,non-linear constitutive materials laws without manually deriving the case-specific Jacobian matrix.Beyond solving forward problems,JAX-CPFEM demonstrates its potential in an inverse design pipeline,where initial crystallographic orientations of polycrystal copper are optimized to achieve targeted mechanical properties under deformations.The end-to-end differentiability of JAX-CPFEM allows automatic sensitivity calculations and high-dimensional inverse design using gradient-based optimization.The concept of differentiable JAX-CPFEM provides an affordable,flexible,and multi-purpose tool,advancing efficient and accessible computational tools for inverse design in smart manufacturing.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52105384 and U2141215).
文摘The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX are determined by the grain level deformation and sequentially coupled.In order to fully capture the microstructure and mechanical property evolution,a crystal plasticity finite element based modelling method for DRX and SRX is proposed in the current work.The grain level deformation is calculated with crystal plasticity which is coupled with the recrystallization model straightforwardly,and both the grain deformation and microstructure evolution are updated simultaneously.The proposed method is validated with discontinuous DRX experiments and the effects of initial deformation conditions are well-captured.Two controversial mechanisms for recrystallization microstructure evolution,i.e.oriented nucleation and growth selection,are discussed in the current framework with the advantages of accurate grain level deformation and interaction predictions.Furthermore,the sequentially coupled DRX and SRX are modelled seamlessly in the current work which provides a critical method for fully integrated thermo-mechanical processes analysis.
基金Projects(51475101,51305091,51305092)supported by the National Natural Science Foundation of China
文摘Grain scale plasticity of NiTi shape memory alloy(SMA)during uniaxial compression deformation at 400℃was investigated through two-dimensional crystal plasticity finite element simulation and corresponding analysis based on the obtained orientation data.Stress and strain distributions of the deformed NiTi SMA samples confirm that there exhibits a heterogeneous plastic deformation at grain scale.Statistically stored dislocation(SSD)density and geometrically necessary dislocation(GND)density were further used in order to illuminate the microstructure evolution during uniaxial compression.SSD is responsible for sustaining plastic deformation and it increases along with the increase of plastic strain.GND plays an important role in accommodating compatible deformation between individual grains and thus it is correlated with the misorientation between neighboring grains,namely,a high GND density corresponds to large misorientation between grains and a low GND density corresponds to small misorientation between grains.
基金financially supported by the National Natural Science Foundation of China(No.51571031)。
文摘A dynamic compression test was performed on α+β dual-phase titanium alloy Ti20C using a split Hopkinson pressure bar.The formation of adiabatic shear bands generated during the compression process was studied by combining the proposed multi-scale crystal plasticity finite element method with experimental measurements.The complex local micro region load was progressively extracted from the simulation results of a macro model and applied to an established three-dimensional multi-grain microstructure model.Subsequently,the evolution histories of the grain shape,size,and orientation inside the adiabatic shear band were quantitatively simulated.The results corresponded closely to the experimental results obtained via transmission electron microscopy and precession electron diffraction.Furthermore,by calculating the grain rotation and temperature rise inside the adiabatic shear band,the microstructural softening and thermal softening effects of typical heavily-deformed α grains were successfully decoupled.The results revealed that the microstructural softening stress was triggered and then stabilized(in general)at a relatively high value.This indicated that the mechanical strength was lowered mainly by the grain orientation evolution or dynamic recrystallization occurring during early plastic deformation.Subsequently,thermal softening increased linearly and became the main softening mechanism.Noticeably,in the final stage,the thermal softening stress accounted for 78.4% of the total softening stress due to the sharp temperature increase,which inevitably leads to the stress collapse and potential failure of the alloy.
基金financially supported by the National Science Foundation of China under Grant Nos. 51771192, 51371169 and U1708252。
文摘Microstructure-based numerical modeling of the deformation heterogeneity and ferrite recrystallization in a cold-rolled dual-phase(DP)steel has been performed by using the crystal plasticity finite element method(CPFEM)coupled with a mesoscale cellular automaton(CA)model.The microstructural response of subsequent primary recrystallization with the deformation heterogeneity in two-phase microstructures is studied.The simulations demonstrate that the deformation of multi-phase structures leads to highly strained shear bands formed in the soft ferrite matrix,which produces grain clusters in subsequent primary recrystallization.The early impingement of recrystallization fronts among the clustered grains causes mode conversions in the recrystallization kinetics.Reliable predictions regarding the grain size,microstructure morphology and kinetics can be made by comparison with the experimental results.The influence of initial strains on the recrystallization is also obtained by the simulation approach.
基金support from the Department of Defense Vannevar Bush Faculty Fellowship,USA N00014-19-1-2642from the NSF Engineering Research Center for Hybrid Autonomous Manufacturing Moving from Evolution to Revolution(ERC‐HAMMER)under Award Number EEC-2133630.
文摘We present the formulation and applications of JAX-CPFEM,an open-source,GPU-accelerated,and differentiable 3-D crystal plasticity finite element method(CPFEM)software package.Leveraging the modern computing architecture JAX,JAX-CPFEM features high performance through array programming and GPU acceleration,achieving a 39×speedup in a polycrystal case with~52,000 degrees of freedom compared to MOOSE with MPI(8 cores).Furthermore,JAX-CPFEM utilizes the automatic differentiation technique,enabling users to handle complex,non-linear constitutive materials laws without manually deriving the case-specific Jacobian matrix.Beyond solving forward problems,JAX-CPFEM demonstrates its potential in an inverse design pipeline,where initial crystallographic orientations of polycrystal copper are optimized to achieve targeted mechanical properties under deformations.The end-to-end differentiability of JAX-CPFEM allows automatic sensitivity calculations and high-dimensional inverse design using gradient-based optimization.The concept of differentiable JAX-CPFEM provides an affordable,flexible,and multi-purpose tool,advancing efficient and accessible computational tools for inverse design in smart manufacturing.
