In a global scenario, the high strength lightweight dissimilar aluminium alloy 7075 and 2014 joining delivers a new opportunity to reduce weight in aerospace vehicles. The dissimilar aluminium alloy joining faces a technical challenge during fusion welding, due to the difference in thermo-mechanical properties. In this present work, the temperature distribution and grain size effects on dissimilar friction stir welded aerospace-grade aluminium alloy 7075 and 2014 was studied numerically and verified experimentally. The 3D integrated multiphysics model, coupled with a moving coordinate system, was simulated with the frictional effects of tool shoulder, pin to the workpiece and stick-slip mechanism. The dissimilar numerical model predicts the temperature and grain size changes across the weld zone. To verify the numerical model, two experiments T9 and T11 welded with a specimen size of 200 × 100 × 3 mm by the FSW-3T-CNC machine. The high-temperature computerized compact DAQ® 9212 and Lab VIEW© software interfaced with K-type thermocouple to measure the temperature. The measured temperature and grain size across the weld are in good agreement with simulated values. Optical microstructure and SEM micrographs illustrate T9 and T11 dissimilar joint with a clear onion pattern in the stir zone, which ensures the proper mixing of material with dynamically recrystallized fine equiaxed grains. The variation in hardness value observed from stir zone to base metal region and the average hardness in stir zone as 139 HV and 133 HV for T9 and T11 specimen, respectively.

在全球范围内，高强度轻质异种铝合金7075和2014年的加入为减轻航空航天器的重量提供了新的机会。由于热机械性能的差异，异种铝合金连接在熔焊期间面临技术挑战。在本工作中，数值研究了不同摩擦搅拌焊接航空级铝合金7075和2014的温度分布和晶粒尺寸的影响，并进行了实验验证。利用刀肩，销钉到工件和粘滑机构的摩擦效应，模拟了3D集成多物理场模型以及运动坐标系。不同的数值模型预测了整个焊接区域的温度和晶粒尺寸的变化。为了验证数值模型，用FSW-3T-CNC机将两个实验T9和T11焊接成200×100×3 mm的试样尺寸。高温计算机紧凑型DAQ®9212和Lab VIEW©软件与K型热电偶连接以测量温度。整个焊缝上测得的温度和晶粒尺寸与模拟值非常吻合。光学显微结构和SEM显微照片显示，T9和T11异种接头在搅拌区具有清晰的洋葱图案，从而确保了材料与动态重结晶的细等轴晶粒的正确混合。对于T9和T11试样，从搅拌区到母材区域观察到的硬度值变化以及搅拌区的平均硬度分别为139 HV和133 HV。高温计算机紧凑型DAQ®9212和Lab VIEW©软件与K型热电偶连接以测量温度。整个焊缝上测得的温度和晶粒尺寸与模拟值非常吻合。光学显微结构和SEM显微照片显示，T9和T11异种接头在搅拌区具有清晰的洋葱图案，从而确保了材料与动态重结晶的细等轴晶粒的正确混合。对于T9和T11试样，从搅拌区到母材区域观察到的硬度值变化以及搅拌区的平均硬度分别为139 HV和133 HV。高温计算机紧凑型DAQ®9212和Lab VIEW©软件与K型热电偶连接以测量温度。整个焊缝上测得的温度和晶粒尺寸与模拟值非常吻合。光学显微结构和SEM显微照片显示，T9和T11异种接头在搅拌区具有清晰的洋葱图案，从而确保了材料与动态重结晶的细等轴晶粒的正确混合。对于T9和T11试样，从搅拌区到母材区域观察到的硬度值变化以及搅拌区的平均硬度分别为139 HV和133 HV。光学显微结构和SEM显微照片显示，T9和T11异种接头在搅拌区具有清晰的洋葱图案，从而确保了材料与动态重结晶的细等轴晶粒的正确混合。对于T9和T11试样，从搅拌区到母材区域观察到的硬度值变化以及搅拌区的平均硬度分别为139 HV和133 HV。光学显微结构和SEM显微照片显示，T9和T11异种接头在搅拌区具有清晰的洋葱图案，从而确保了材料与动态重结晶的细等轴晶粒的正确混合。对于T9和T11试样，从搅拌区到母材区域观察到的硬度值变化以及搅拌区的平均硬度分别为139 HV和133 HV。