ABSTRACT Numerical investigation on dynamic recrystallization in friction stir welds is of great significance to control the microstructure evolution and grains size in joints. The recrystallization and grain growth in the nugget centre of friction stir welded 6061 aluminium alloy are numerically simulated by combining the multiphase-field model with Kocks–Mecking dislocation model and employing the calculated temperature and strain rate variations with time in FSW process. The reliability of the model is verified by electron backscattered diffraction measurement results of grains size distribution at the same position. The specific reasons for different grain sizes under different levels of welding speed are quantitatively analysed. The ratios of recrystallization duration to deformation period and incubation period to deformation time are determined.

中文翻译：

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铝合金搅拌摩擦焊动态再结晶过程的相场模拟

摘要 搅拌摩擦焊动态再结晶的数值研究对于控制接头的微观结构演变和晶粒尺寸具有重要意义。通过将多相场模型与 Kocks-Mecking 位错模型相结合，并采用 FSW 过程中计算的温度和应变率随时间的变化，对搅拌摩擦焊 6061 铝合金熔核中心的再结晶和晶粒长大进行了数值模拟。通过对同一位置晶粒尺寸分布的电子背散射衍射测量结果验证了模型的可靠性。定量分析了不同焊接速度水平下晶粒尺寸不同的具体原因。