Surface strengthening and grain refinement of AZ31B magnesium alloy by ultrasonic cavitation modification

Ultrasonic cavitation modification (UCM) employs cavitation effect to induce strong plastic deformation on the material surface and improve surface properties. To explore the surface strengthening and grain refinement of materials by UCM, the UCM orthogonal experiments of AZ31B magnesium alloy were carried out in water and kerosene, respectively. The effects of ultrasonic amplitude, distance from the sample, and processing time on Vickers hardness and grain size of the material were studied. The results showed that the Vickers hardness of samples increased to 1.5 & ndash;3 times after UCM in water, which was 23.77 & ndash;48.19% higher than that in kerosene. The metallographic observation indicated the grains on the surface of AZ31B were refined after UCM. The maximum fluctuation of grain size on the material surface was not more than 10 & micro;m after UCM in water, and most of them were concentrated between 1.5 & micro;m and 2.5 & micro;m, while the former was more than 40 & micro;m and the latter were concentrated between 2 & micro;m and 10 & micro;m in kerosene. This reflected that the grain refinement effect of UCM in water was better than that in kerosene. Ultrasonic cavitation can be used as a benign means to improve the surface properties of materials. (c) 2020 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The research shows that ultrasonic cavitation modification can significantly enhance the surface hardness of materials and achieve grain refinement, with better effects achieved in water than in kerosene.