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Quality of surface and subsurface layers after WEDM aluminum alloy 7475-T7351 including analysis of TEM lamella


Wire electrical discharge machining (WEDM) is an unconventional machining method indispensable especially for the aeronautical and automotive industries. In this context, the effective manufacturing of high surface quality components from aluminum alloy 7475-T7351 requires comprehensive knowledge of the applied production procedures. We therefore performed a designed experiment comprising 33 cycles (with systematic alteration of machine setting parameters such as gap voltage, pulse on time, pulse off time, discharge current, and wire feed), enabling us to evaluate systematically the cutting speeds in the relevant samples. The machined areas were subjected to a thorough analysis involving both the surface and the subsurface layers. The actual topography was assessed using a non-contact profiler, and the entire operation concentrated on 12 parameters within the areal, profile, and basic and bearing profile categories. To observe the surface relief, we employed several instruments, including the semi-contact atomic force microscopy (AFM) technique, a digital microscope, and a non-contact 3D profiler. Another major step then consisted in examining the morphology and surface defects, a process suitably complemented with a chemical composition analysis (EDX). The distribution of individual elements within the material was investigated in detail using a lamella, whose subsequent inspection relied on a transmission electron microscope (TEM) as the principal tool. To study the subsurface layer and its defects, we prepared metallographic specimens (cross-sections) of the samples and observed them by means of light and electron microscopes.

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Part of the work was carried out with the support of CEITEC Nano Research Infrastructure (ID LM2015041, MEYS CR, 2016–2019), CEITEC Brno University of Technology.

This paper is an output of the research and scientific activities of NETME Centre, supported through project NETME CENTRE PLUS (LO1202) from funds of the Ministry of Education, Youth and Sports under “National Sustainability Programme I.”

This work was supported by BUT grant FSI-S-17-4785 “Engineering Applications of Artificial Intelligence.”

The article was supported from project no. FEKT-S-17-3934, utilization of novel findings in micro and nanotechnologies for complex electronic circuits and sensor applications.

This research was supported by the BUT, Faculty of Mechanical Engineering, Brno, Specific research 2016, with the grant “Research of modern production technologies for specific applications,” FSI-S-16-3717 and technical support of Intemac Solutions, Ltd., Kurim.

This work was supported through an internal grant provided by Jan Evangelista Purkyně University in Ústí nad Labem, titled SGS (Student Grant Competition), No. 0004/2015, and also in part by the Ministry of Education, Youth and Sport of the Czech Republic, programme NPU1, project No. LO1207.

This research has been financially supported by the Specific University Research grant of Brno University of Technology, FEKT/STI-J-18-5354.

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Correspondence to K. Mouralova.

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Mouralova, K., Benes, L., Zahradnicek, R. et al. Quality of surface and subsurface layers after WEDM aluminum alloy 7475-T7351 including analysis of TEM lamella. Int J Adv Manuf Technol 99, 2309–2326 (2018).

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  • WEDM
  • Electrical discharge machining
  • Aluminum alloy 7475-T7351
  • Morphology
  • Topography
  • TEM lamella
  • Design of experiment