Mischa Crumbach

Through-process texture modelling of aluminium alloys

The complete through-process modelling of crystallographic texture evolution during aluminium sheet production is addressed. The texture determining processes deformation and recrystallization are analysed with respect to the underlying mechanisms. The advanced deformation texture model grain interaction (GIA) is coupled to a statistical analytical recrystallization texture model (StaRT). New concepts are described to model nucleation spectra for recrystallization with the GIA model and with a new model for the prediction of in grain orientation gradients. Orientation dependent recovery of the deformed structure is reflected based on substructure information extracted from the GIA model. A finite element (FE) model incorporating dislocation density based work hardening as well as texture serves as a process model to describe the macroscopic production parameters based on microstructural information. More detailed information on this integrative FE model can be found in a second paper presented at this symposium by Neumann et al. The excellent performance of the outlined through-process texture modelling concept is demonstrated in applications for two different aluminium sheet production lines?one laboratory and one industrial process?and displays for the first time the possibility of modelling texture evolution throughout various consecutive processing steps.

Through-process modelling of texture and anisotropy in AA5182

A through-process texture and anisotropy prediction for AA5182 sheet production from hot rolling through cold rolling and annealing is reported. Thermo-mechanical process data predicted by the finite element method (FEM) package T-Pack based on the software LARSTRAN were fed into a combination of physics based microstructure models for deformation texture (GIA), work hardening (3IVM), nucleation texture (ReNuc), and recrystallization texture (StaRT). The final simulated sheet texture was fed into a FEM simulation of cup drawing employing a new concept of interactively updated texture based yield locus predictions. The modelling results of texture development and anisotropy were compared to experimental data. The applicability to other alloys and processes is discussed.

Simulation of casting, homogenization, and hot rolling: consecutive process and microstructure modelling for aluminium sheet production

An overview of simulation of casting, homogenization, and hot rolling of an aluminium alloy is addressed in this paper. The microstructure models used to describe casting, solidification, precipitation (growth and coarsening) during homogenization, deformation texture evolution, and the work hardening behaviour are presented as well as their respective theoretical backgrounds. Emphasis is placed on interfacing the microstructure models with each other between the processing steps. This makes it possible to take into account microstructural changes that occur early during processing during later production steps. Along with this overview, reference will be made to previously presented simulation and experimental results—for validation—where appropriate.

Recent Advances in the Simulation of Recrystallization and Grain Growth

Modeling and simulation of recrystallization, grain growth, and related phenomena are important tools for the fundamental understanding of microstructural evolution and prediction of engineering properties. In particular for ultra fine grained and nanocrystalline materials proper account of microstructural evolution is essential for the optimal processing of these materials. It is shown that for modeling of softening phenomena it is important to discriminate between discontinuous primary recrystallization and discontinuous grain growth owing to their quite different underlying physics. Recent developments in recrystallization modeling and simulation of grain growth are addressed, in particular nucleation of recrystallization and junction effects in grain growth. Major progress is also expected from atomistic modeling and quantum-mechanical computations for making available specific material properties.

Through-process texture simulation for aluminum sheet fabrication

We introduce a simulation procedure for through-process texture and anisotropy prediction, in particular for AA5182 sheet production from hot rolling through cold rolling and annealing. The FEM package ‘T-Pack’ based on the software LARSTRAN served as a process model. It was combined with physics based microstructure models for deformation texture (GIA), work hardening (3IVM), nucleation texture (ReNuc), and recrystallization texture (StaRT). The terminal sheet texture was used for a FEM simulation of cup drawing. A new concept of interactively updated texture based yield locus predictions was employed. The simulation predictions were compared to experimental data. The procedure can be applied to a wide variety of Aluminum alloys.

Modelling Set Up for Through‐Process Simulation of Aluminium Cup Production

In order to enable metal forming process optimisation through numerical simulation rather than trial and error, it is necessary to develop plasticity models of predictive character. The major disadvantage of frequently used phenomenological plasticity models lies in their limited validity which is defined by the experimental data ranges to which these models are fitted. The concept of phenomenological models may, however, be very successful if the plastic strains are small and if the strain path is not complex. This is often the case in sheet metal forming. Physical plasticity models, on the other hand, capture not only the true physical phenomena occuring during plastic deformation but also have the benefit of a ‘self evolutionary character’ which means that they are able to describe a considered phenomenon even outside of the experimental data range to which they have been adjusted. However, setting up physical models requires a significant amount of research and their adaptation to a specific alloy mak...

Integral Modelling of Texture Evolution in Multiple Pass Hot Rolling of Aluminium Alloys

The interaction of several physically based models for the development of crystallographic texture and microstructure during deformation and recrystallisation is exemplified in two cases of multiple pass hot rolling of commercial aluminium alloys. In this study streamlines output by the FE-code LARSTRAN/SHAPE and a model based on elementary rolling theory have been used respectively to calculate the evolution of material properties during deformation with a dislocation density based flow stress model and a Taylor type deformation texture model which considers grain interaction. To model the texture development during the interpass times between the rolling passes, an analytical recrystallisation model has been applied .

Modelling Nucleation of Recrystallisation in Aluminium Alloys

The predictions from a grain cluster deformation texture model, GIA, are utilized to study the nucleation texture of recrystallisation of aluminium alloys. In combination with a dislocation based work hardening model, the propensity of specific grains in their granular environment for select nucleation mechanisms is investigated. Quantitative criteria for the nucleation events can be formulated. The results can be fed into a growth model of recrystallisation to predict recrystallisation textures and lend themselves to through-process modelling.

Modeling of Nucleation Spectra for Primary Recrystallization and Application to Through-Process Texture Modeling

Schemes to model deformation inhomogeneities and nuclei distributions based on the grain cluster model for deformation texture simulation GIA are presented. The orientation distributions of nuclei in stable orientations, nuclei in grains with orientation gradients and nuclei due to subgrain growth at grain boundaries are predicted. Additionally, nuclei with a random orientation distribution are considered, reflecting nucleation at shear bands or large constituent particles. Furthermore, models for a quantitative assessment of the participating nucleation mechanisms are proposed. The resulting nucleation texture was input to the static recrystallization texture model StaRT. The through-process texture development during a sequence of several hot rolling, cold rolling and annealing steps in industrial production of the aluminum alloy AA5182 is presented.

Industrial Application of Through-Process Modelling II: Microstructural Models and Descriptors Required for Thermo-Mechanical Processing

Through-Process modelling (TPM) of microstructure evolution during thermomechanical processing of sheet produced from direct chill (DC) cast non-heat treatable aluminium alloys is discussed. In a companion paper [1] the upstream processes of casting and homogenisation were dealt with, whereas the present paper focuses on the downstream deformation and annealing steps. Some recent advances in relevant model development are reviewed, and the important microstructural descriptors and their interactions are outlined. Together with two application examples – coiling of hot strip, and cold rolling of foil – current knowledge gaps in theory and modelling capability are highlighted.