为了研究铝在非等温退火过程中的组织演变和流动应力,分别采用2、4和6道次多向锻造工艺,使试样应变量为1、2和3.然后,在150、200、250、300和350℃ 下对试样进行非等温退火.通过对变形阶段和退火阶段的模拟,研究位错密度和流动应力的演化规律.结果发现,经2、4和6道次多向锻造的试样在温度分别达到250、250和300℃ 时其热稳定性仍然较好.模拟结果与实验数据吻合较好.与模拟得到的流动应力值相比,经2道次和4道次多向锻造的样品在350℃ 非等温退火后的实验流动应力值偏低.其根本原因在于,模拟所用非等温退火模型仅是基于晶内位错密度演化,只考虑了回复和再结晶现象;然而,在350℃ 退火后,除了回复和再结晶外,还会发生晶粒长大现象,这使得模拟和实验得到的流动应力值出现偏差.%In order to investigate the evolution of microstructure and flow stress during non-isothermal annealing, aluminum samples were subjected to strain magnitudes of 1, 2 and 3 by performing 2, 4 and 6 passes of multi-directional forging. Then, the samples were non-isothermally annealed up to 150, 200, 250, 300 and 350 ℃. The evolution of dislocation density and flow stress was studied via modeling of deformation and annealing stages. It was found that 2, 4 and 6 passes multi-directionally forged samples show thermal stability up to temperatures of 250, 250 and 300 ℃, respectively. Modeling results and experimental data were compared and a reasonable agreement was observed. It was noticed that 2 and 4 passes multi-directionally forged samples annealed non-isothermally up to 350 ℃ have a lower experimental flow stress in comparison with the flow stress achieved from the model. The underlying reason is that the proposed non-isothermal annealing model is based only on the intragranular dislocation density evolution, which only takes into account recovery and recrystallization phenomena. However, at 350 ℃ grain growth takes place in addition to recovery and recrystallization, which is the source of discrepancy between the modeling and experimental flow stress.
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