目的 研究AZ31B镁合金在超声表面滚压处理后，表面微观结构、显微硬度和表面粗糙度的变化及其在拉伸试验过程中对AZ31B镁合金内部组织的影响。方法 利用超声表面滚压处理在AZ31B镁合金表面制备梯度变形层。利用X射线衍射仪、EBSD、显微硬度仪和表面粗糙度仪，分析试样表面的微观结构、显微硬度和表面粗糙度。对超声表面滚压处理前后试样进行拉伸试验，分析其拉伸性能和微观组织变形。结果 经过9道超声表面滚压处理后，样品表层形成了厚约600 μm的变形层。变形层组织呈梯度分布，分别为超细晶粒层、细粒过渡层和母材组织。随着与试样表面距离的增加，试样表面的显微硬度值为84~52HV10g。USRP试样的表面粗糙度Ra达到0.140 μm。在拉伸过程中，相对于母材，超声表面滚压处理试样微观组织的变化量较少。结论 相对于未处理试样，超声表面滚压处理试样的屈服强度提高了28%，显微硬度提高了40%，表面粗糙度降低了96.4%。同时，超声表面滚压处理在镁合金试样表层形成的梯度结构，在拉伸过程中降低了中心微观组织的变形。

The changes of microstructure, microhardness and surface roughness of AZ31B magnesium alloy after ultrasonic surface rolling process (USRP) were investigated. And their effecton the internal microstructure of AZ31B magnesium alloy in the process of tensile test. A gradient deformation layer was generated on the surface of AZ31B magnesium alloy by USRP. The microstructure, microhardness and surface roughness of the samples were analyzed by X-ray diffractometer, EBSD, microhardness tester and surface roughness tester. Tensile tests were carried out on the untreated and USRPed samples to analyze the tensile properties and microstructure deformation. After 9 passes of USRP, a deformation layer about 200 μm was formed on the surface of the sample. The microstructure of the deformed layer is gradient distribution:ultrafine grain layer, fine grain transition layer and base material. With the increase of the distance from surface of the sample, the microhardness of the sample surface is between 84HV10g and 52HV10g. The surface roughness of USRP specimen reaches Ra 0.140 μm. Compared with the untreated sample, the microstructure changes of the USRPed sample are less. Compared with untreated samples, the yield strength and microhardness of the samples treated by ultrasonic surface rolling are increased by 28% and 40%. The surface roughness was reduced by 96.4%. And, the gradient structure formed by USRP on the surface of the magnesium alloy sample can reduce the deformation of the central microstructure during the tensile test.