The effect of ultrasonic treatment on the microstructural evolution and the related softening process in tensile pre-deformed 316 stainless steel was studied by means of electron backscatter diffraction method, optical microscopy, and microhardness measurement. It was observed that different levels of ultrasonic energy induced complex microstructural changes in the treated samples. A large decrease in twin boundaries was observed, which is an indication of the de-twinning process under ultrasonic treatment. A new mechanism for the de-twinning process under oscillatory stress of ultrasonic vibration was proposed. It was shown that de-twinning under ultrasonic treatment led to dislocation production from twin boundaries. Inverse pole figures investigation revealed strong grain rotation following ultrasonic treatment in tensile pre-deformed samples. Subgrain formation in the ultrasonic treated austenitic stainless steel samples indicated that considerable ultrasonic energy was induced by the ultrasonic vibration, which provided the activation energy needed for dislocation climb and cross-slip. The ultrasonic induced subgrain formation, dislocation annihilation, and de-twinning, which resulted in a decrease of the microhardness in the samples, can be considered as possible mechanisms for the acoustic softening in the austenitic stainless steels.

采用电子背散射衍射法、光学显微镜和显微硬度测量方法，研究了超声波处理对拉伸预变形316不锈钢组织演变及相关软化过程的影响。据观察，不同水平的超声波能量会引起处理过的样品复杂的微观结构变化。观察到孪晶边界大幅减少，这表明超声波处理下发生了去孪晶过程。提出了超声振动振荡应力下的去孪生过程的新机制。结果表明，超声波处理下的去孪晶导致孪晶界产生位错。反极图研究显示，拉伸预变形样品在超声处理后出现强烈的晶粒旋转。超声波处理的奥氏体不锈钢样品中的亚晶粒形成表明，超声波振动产生了相当大的超声波能量，为位错攀爬和横向滑移提供了所需的活化能。超声波诱导的亚晶形成、位错湮灭和去孪晶导致样品显微硬度降低，可以被认为是奥氏体不锈钢声软化的可能机制。