为了解决超高强铝、镁合金厚板搅拌摩擦焊（FSW）技术难题，本项目提出了差动双轴肩自支撑FSW（DDS-FSW）新技术。针对铝、镁厚板同种材料DDS-FSW和薄板异种材料常规FSW，在温度场、塑性流场和应力应变场表征、沉淀强化相和金属间化合物反应机理、接头组织性能预测和控制等方面开展系统研究。拟采用实验和数值模拟相结合的方法，利用逆问题求解算法建立摩擦系数与温度的函数关系，并采用自主开发的MSFESL有限元软件高精度模拟仿真温度场、塑性流场和应力应变场。在表征晶粒尺寸、晶粒取向、沉淀强化相和金属间化合物等本征结构基础上，系统评价接头静态拉伸、疲劳和应力腐蚀行为。通过上述研究，掌握铝、镁合金同种/异种材料FSW温度场、塑性流变和应力应变演变规律；揭示沉淀强化相和金属间化合物反应机理；阐明接头多场服役环境响应机制；建立晶粒取向与力学性能量化关系，从而实现对FSW接头组织性能的理论预测和主动控制。

In order to solve the technical problems of friction stir welding (FSW) similar thick plates of ultra-high strength aluminium and magnesium alloys, a new technique of differential double-shoulder FSW (DDS-FSW) is invented in this work. Several basic issues for DDS-FSW similar thick plates and traditional FSW dissimilar thin plates were systematically studied, including characterization of temperature, material flow, and stress-strain fields, reaction mechanism of precipitates and intermetallic compounds, and prediction and control of microstructure and properties of joints. In this study, the combination of experimental and numerical simulation methods is used. The relationship between friction coefficient and temperature is solved by the inverse solution algorithm, and the temperature, material flow and stress-strain fields are modeled by self-developed MSFESL software. Based on the characterization of grain size, grain orientation, precipitates and intermetallic compounds, the static tensile property, fatigue and stress corrosion behaviors are systematically evaluated. These investigations will clarify the evolutions of temperature, material flow, and stress-strain fields during FSW, indicate reaction mechanisms of precipitates and intermetallic compounds, elucidate the environmental response mechanism of the joints under complicated loading conditions, establish quantitative relations between grain orientation and mechanical properties, and thus achieve the effective prediction and control of the microstructure and mechanical properties of FSW joints.