Ultrasonic sonotrodes play an essential role in transmitting power ultrasound into the large-scale metallic casting. However, cavitation erosion considerably impairs the in-service performance of ultrasonic sonotrodes, leading to marginal microstructural refinement. In this work, the cavitation erosion behaviour of ultrasonic sonotrodes in large-scale castings was explored using the industry-level experiments of Al alloy cylindrical ingots (i.e. 630 mm in diameter and 6000 mm in length). When introducing power ultrasound, severe cavitation erosion was found to reproducibly occur at some specific positions on ultrasonic sonotrodes. However, there is no cavitation erosion present on the ultrasonic sonotrodes that were not driven by electric generator. Vibratory examination showed cavitation erosion depended on the vibration state of ultrasonic sonotrodes. Moreover, a finite element (FE) model was developed to simulate the evolution and distribution of acoustic pressure in 3-D solidification volume. FE simulation results confirmed that significant dynamic interaction between sonotrodes and melts only happened at some specific positions corresponding to severe cavitation erosion. This work will allow for developing more advanced ultrasonic sonotrodes with better cavitation erosion-resistance, in particular for large-scale castings, from the perspectives of ultrasonic physics and mechanical design.

超声波超声焊棒在将功率超声传输到大型金属铸件中起着至关重要的作用。但是，气蚀会极大地损害超声焊极的使用性能，从而导致微结构的细化。在这项工作中，使用铝合金圆柱铸锭（直径630毫米，长度6000毫米）的工业水平实验探索了超声焊棒在大型铸件中的空化腐蚀行为。当引入功率超声时，发现在超声焊棒的某些特定位置可重复发生严重的气蚀。但是，在没有由发电机驱动的超声波超声焊极上不存在气蚀现象。振动检查表明空化腐蚀取决于超声焊极的振动状态。此外，开发了一个有限元（FE）模型来模拟3D凝固体积中声压的演变和分布。有限元模拟结果证实，超声波和熔体之间的显着动态相互作用仅发生在与严重空化侵蚀相对应的某些特定位置。从超声物理学和机械设计的角度来看，这项工作将允许开发出具有更好的抗气蚀侵蚀能力的更先进的超声波焊条，特别是对于大型铸件。有限元模拟结果证实，超声波和熔体之间的显着动态相互作用仅发生在与严重空化侵蚀相对应的某些特定位置。从超声物理学和机械设计的角度来看，这项工作将允许开发出具有更好的抗气蚀侵蚀能力的更先进的超声波焊条，特别是对于大型铸件。有限元模拟结果证实，超声波和熔体之间的显着动态相互作用仅发生在与严重空化侵蚀相对应的某些特定位置。从超声物理学和机械设计的角度来看，这项工作将允许开发出具有更好的抗气蚀侵蚀能力的更先进的超声波焊条，特别是对于大型铸件。