Improving peening efficacy through high-amplitude short duration pulsed current

The efficacy of peening treatment depends on the plasticity of the target metal. In this study, the effec-tiveness of high-amplitude short duration pulsed current in improving the peening efficacy was examined in a process called electropulsing-assisted ultrasonic nanocrystal surface modification (EP-UNSM). During the EP-UNSM process, the target metal, i.e., Ti64, is subjected to simultaneous ultrasonic peening and electropulsing. The high energy pulsed current can generate a critical magnetic field that can induce the transition of the radical pairs formed by dislocations and the pinning obstacles from the singlet state to the triplet state. This leads to higher dislocation mobility and thus higher plasticity for more effective peening treatment. The results show that the sample treated with EP-UNSM had a deeper plastically deformed layer than that for samples subjected to UNSM and continuous current-assisted UNSM (CC-UNSM), and the maximum depth of plastic deformation was obtained when using the highest peak current density. Due to microstructure refinement, work hardening, and dynamic strain aging, the EP-UNSM sample had a 50% higher surface hardness compared with the control sample. Moreover, the compressive residual stresses generated by EP-UNSM were higher in magnitude and greater in depth compared to those generated by traditional UNSM. These results demonstrate that pulsed current can effectively improve the peening ef-ficacy and EP-UNSM is an effective method for strengthening Ti64. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The efficacy of peening treatment can be improved by using high-amplitude short duration pulsed current, as demonstrated in the study of electropulsing-assisted ultrasonic nanocrystal surface modification (EP-UNSM). EP-UNSM process combines ultrasonic peening and electropulsing to enhance the plasticity of the target metal Ti64, resulting in deeper plastic deformation layer, higher surface hardness, and greater compressive residual stresses. The pulsed current effectively improves the peening efficacy, making EP-UNSM an effective method for strengthening Ti64.