This paper presents a novel technique to improve the machined surface of Al-Zn-Mg aluminum alloy by a combined machining process of electrical discharge machining (EDM) with ultrasonic machining (USM). In these experiments, SiC particles were added into the dielectric fluid to produce a particle-reinforced mechanism and solid solution strengthened structure to form a modified layer on the machined surface in a short working time. The experimental investigation also discusses the influence of machining polarity on the modified layer of aluminum alloy. Furthermore, quantitative analysis of element content has been carried out by electron probe micro-analyzer (EPMA) to determine the thickness of the modified layer and the distribution of silicon and carbon in the cross-section of the machined zone. Moreover, micro-hardness tests and wear tests were also conducted to evaluate the effects of surface modification by the combined process. From the experimental results, it can be seen that the combined process of EDM with USM can achieve an 80 μm deep modified layer on the machined surface of aluminum alloy in 240 s, and that such layer can significantly improve the hardness and wear resistance of the machined surface.
- Combined process
- Electrical discharge machining
- Surface modification
- Ultrasonic machining