Ultrasonic-assisted microforming of superalloy capillary: Modeling and experimental investigation
Ultrasonic-assisted microforming of superalloy capillary: Modeling and experimental investigation
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DOI：
10.1016/j.jmapro.2020.07.015
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发表时间：
2020-09
影响因子：
6.2
通讯作者：
B. Meng;B. Cao;M. Wan;J. Xu;D. Shan
中科院分区：
文献类型：
--
作者：
B. Meng;B. Cao;M. Wan;J. Xu;D. Shan
超声振动（UV）辅助成形技术对于降低金属制品的制造问题、提高成形质量具有重要意义。然而，由于声软化和尺寸效应的耦合作用，超薄壁微管在紫外光作用下的变形行为尚未得到清晰的揭示。本文通过对不同晶粒尺寸的高温合金板材进行紫外光辅助拉伸实验，建立了高温合金板材的本构模型。实验结果表明，晶粒尺寸不改变超声波辅助微成形过程中的软化机制。而最大声软化值随晶粒尺寸的增大而下移，表明超声能量吸收阈值受晶粒尺寸效应的影响。建立了一个考虑超声软化和晶粒尺寸耦合效应的本构模型，并在声学项中引入了Logistic函数来描述超声能量吸收的饱和度。基于实验和模拟结果，对超声波辅助下超薄毛细管的微拉深过程进行了探索。随着紫外光幅值的增加，微成形毛细管的尺寸精度和表面形貌得到了显著提高，在适当的幅值下，微成形毛细管的拉伸强度没有降低，拉伸后的延展性得到了改善。因此，超声辅助微成形技术为难变形管状微零件成形质量和力学性能的协调调控提供了一种有效的途径。
Ultrasonic vibration (UV) assisted forming technology has been proved beneficial for lowering manufacturing issues and improving the forming qualities of metallic products. However, the deformation behavior of ultrathin-walled microtube under the assistance of UV has not been clearly revealed due to the coupling effect of acoustic softening and size effect. In this research, UV assisted tensile test was performed on ultrathin superalloy sheets with different grain sizes to construct the constitutive model. The experimental results revealed that the grain size does not change the softening mechanism in ultrasonic-assisted microforming of ultrathin superalloy sheet. Whereas, the maximum acoustic softening value is shifted down with increasing grain size, indicating that the threshold of ultrasonic energy absorption is affected by grain size effect. A constitutive model considering the coupled effects of ultrasonic softening and crystal size was developed, and the logistic function is introduced into the acoustic term to describe the saturation of ultrasonic energy absorption. Based on the experimental and modeling results, the ultrasonic-assisted microdrawing process of the ultrathin-walled capillary was explored. The dimensional accuracy and surface appearance of the microformed capillary were significantly enhanced with increasing UV amplitude, and the ductility of capillaries after the UV assisted drawing is improved without loss of tensile strength under appropriate amplitude. Therefore, the ultrasonic-assisted microforming technology provides an efficient way for the coordinated regulation of forming quality and mechanical property of difficult-to-deform tubular micropart.