目的 获得二维超声挤压最优工艺参数，并研究工艺参数以及其交互作用对工件表面质量的影响。方法 采用正交试验法对7075-T651铝合金进行二维超声挤压加工试验，运用熵权法确定表面粗糙度和显微硬度的影响权重，结合灰色关联法和TOPSIS法构建最优表面质量评价模型，以此获得最佳表面质量时的最优工艺参数，并基于极差分析获得工艺参数以及其交互作用对工件表面质量的影响结果。结果 经二维超声挤压加工后，零件表面粗糙度值显著降低，表层显微硬度大幅提高，建立的评价模型可准确获得最优工艺参数。结论 最优工艺参数为：静压力300 N，挤压速度30 m/min，进给量0.1 mm/r。此时表面粗糙度Ra值约为0.41 μm，显微硬度约为378HV。工艺参数间的交互作用对零件表面粗糙度、显微硬度和表面综合质量的影响远大于主效应，对表面综合质量起主要影响作用的是挤压速度分别与静压力、进给量间的交互作用。

The work aims to obtain optimal process parameters, and study effects of process parameters and their interactions on surface quality of workpieces. 2D ultrasonic extrusion processing test was performed to 7075 aluminum alloy in the method of orthogonal test. Influence weight of surface roughness and microhardness was determined in entropy weight method. Optimal evaluation model of surface quality was built by combining grey correlation method and TOPSIS method. Optimal process parameters for the best surface quality were obtained. The effects of process parameters and their interactions on the surface quality were studied based upon range analysis. The surface roughness values decreased substantially and the surface microhardness increased significantly after 2D ultrasonic extrusion processing. The optimal process parameters could be obtained accurately by the as-built evaluation model. Provided with static force of 300 N, extrusion speed of 30 m/min and feed-rate of 0.1 mm/r, the optimal surface quality may be obtained with surface roughness Ra of 0.41 μm and microhardness of nearly 378HV. The effect of interactions among processing parameters on surface roughness, microhardness and surface quality is far greater than the main effect. The interaction between static force and extrusion speed as well as the interaction between extrusion speed and feed-rate play a major role on surface overall quality.