Vibration-assisted metal deformation technique is highly popular due to its ability to improve the material forming capability by plummeting the forming resistance and reducing the interfacial friction. For a long time, this method has been observed to possess a softening effect mechanism, which has been a topic of interest. Consequently, this technique has attracted much attention in the field of metal forming. However, the constantly increasing intricacy of parts and high forming pressure is threatening the applicability of this technique whatsoever. In addition, there are still several uncertainties regarding the mechanism of vibration-assisted forming due to the introduction of intense heat evolving processes that inhibit the study of other significant factors. Recent technological advances have seen the development of a mechanical servo press machine which has made it possible to run high-pressure and low-frequency vibration-assisted forming processes. Unfortunately, this direct action mechanism of low-frequency vibrations on the deformation behavior and microstructure has minimally been studied.
To this note, a team of researchers led by professor Xinyun Wang from the State Key Laboratory of Materials Processing and Die & Mould Technology at Huazhong University of Science and Technology in China, conducted study with the objective to empirically cross-examine the influence of low-frequency vibrations on the room-temperature compression behavior of T2 copper. In order to fulfill their study, the researchers hoped to employ various modern equipment and techniques such as metallurgical characterization, microscopy and eventually mechanical and kinematic analyses. Their work is published in the research journal, Materials Science & Engineering A.
The researchers begun the experimental procedure by utilizing a desktop servo press machine to conduct the low-frequency vibration-assisted compression tests. Commercially available T2 copper bars were subjected to a homogenizing annealing treatment before compression. The compression tests with low-frequency vibrations were then conducted at room temperature with no lubricant used. Finally, in order to comprehend the influence of vibration loading, the microstructures of the specimens compressed with and without vibrations were analyzed.
The authors observed that the deformation load reduced significantly under low-frequency vibration conditions and proposed a multiple loading induced stress wave superposition mechanism. At the same time, the research team also noted that grain refinement was induced due to the intensification in dislocation density when roused by cyclic impact loading. From the kinematic analysis undertaken, the team realized that by increasing the amplitude and frequency the actual strain rate increased whereas deformation load plummeted.
The Xinyun Wang and colleagues study has presented a detailed systematic investigation on the effects of low-frequency vibrations on the deformation behavior of T2 copper. The results obtained here suggest that increasing the amplitude is a better way to reduce the deformation load, instead of increasing the frequency. Altogether, the research work has shown that low-frequency vibration-assisted forming is an auspicious technique to obtain fine grains and decrease energy consumption.
Lei Deng, Pan Li, Xinyun Wang, Mao Zhang, Jianjun Li. Influence of low-frequency vibrations on the compression behavior and microstructure of T2 copper. Materials Science & Engineering A, volume 710 (2018) pages 129–135
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