Sarafoglou Panagiota I, Serafeim Alexandros, Fanikos Ioannis A, Aristeidakis John S, Haidemenopoulos Gregory N
Department of Mechanical Engineering, University of Thessaly, 38334 Volos, Greece.
RWTH Aachen, Institut für Eisenhüttenkunde, Intzestrasse 1, 52072 Aachen, Germany.
Materials (Basel). 2019 May 1;12(9):1421. doi: 10.3390/ma12091421.
Control of the homogenization process is important in obtaining high extrudability and desirable properties in 6xxx aluminum alloys. Three consecutive steps of the process chain were modeled. Microsegregation arising from solidification was described with the Scheil-Gulliver model. Dissolution of MgSi, Si (diamond) and β-AlFeSi (β-AlFeSi) to α-AlFeSi (α-Al(FeMn)Si) transformation during homogenization have been described with a CALPHAD-based multicomponent diffusion Dual-Grain Model (DGM), accounting for grain size inhomogeneity. MgSi precipitation and associated strengthening during homogenization cooling were modeled with the Kampmann-Wagner Numerical (KWN) precipitation framework. The DGM model indicated that the fractions of β-AlFeSi and α-AlFeSi exhibit an exact spatial and temporal correspondence during transformation. The predictions are in good agreement with experimental data. The KWN model indicated the development of a bimodal particle size distribution during homogenization cooling, arising from corresponding nucleation events. The associated strengthening, arising from solid solution and precipitation strengthening, was in good agreement with experimental results. The proposed modeling approach is a valuable tool for the prediction of microstructure evolution during the homogenization of 6xxx aluminum alloys, including the often-neglected part of homogenization cooling.
在6xxx铝合金中，控制均匀化过程对于获得高挤出性和理想性能至关重要。对该工艺链的三个连续步骤进行了建模。用Scheil-Gulliver模型描述了凝固产生的微观偏析。在均匀化过程中，MgSi、Si（金刚石）和β-AlFeSi向α-AlFeSi（α-Al(FeMn)Si）的转变用基于CALPHAD的多组分扩散双晶粒模型（DGM）进行了描述，该模型考虑了晶粒尺寸的不均匀性。用Kampmann-Wagner数值（KWN）析出框架对均匀化冷却过程中的MgSi析出和相关强化进行了建模。DGM模型表明，在转变过程中，β-AlFeSi和α-AlFeSi的分数呈现出精确的空间和时间对应关系。预测结果与实验数据吻合良好。KWN模型表明，在均匀化冷却过程中，由于相应的形核事件，出现了双峰粒度分布。由固溶强化和析出强化引起的相关强化与实验结果吻合良好。所提出的建模方法是预测6xxx铝合金均匀化过程中微观结构演变的宝贵工具，包括均匀化冷却中经常被忽视的部分。
