Effect of pulsed electric current on electrically assisted indentation for surface texturing
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ORIGINAL ARTICLE
Effect of pulsed electric current on electrically assisted indentation for surface texturing Oyunchimeg Erdene-Ochir 1 & Jing Liu 1 & Doo-Man Chun 1 Received: 4 February 2020 / Accepted: 14 September 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract Electrically assisted manufacturing has been widely studied for controlling material properties during the forming process and reducing flow stress and springback. In electrically assisted manufacturing, an electric current is applied during forming to improve the conventional forming process, and the type of electric current can be continuous or pulsed. Pulsed current has been widely applied today because of its high peak power and short processing time. In this study, the effects of pulsed electric current on electrically assisted indentation were examined on stainless steel 304, stainless steel 316, and titanium substrates. The electrically assisted indentation process consisted of a Vickers hardness tester, a power supply, and a controller. The effects of timing, amplitude, duty cycle, and frequency for electric current were examined. The experimental results showed that the timing of the electric current is important and there is an optimal preheating and total electric current time to achieve a large hardness reduction, which represents increased indentation depth and width at a constant load. The decrease in hardness clearly increased as the amplitude of the electric current increased. Finally, it was found that there is a close relationship between maximum temperature difference and hardness. This study provides guidelines for selecting process parameters in electrically assisted indentation using pulsed electric current for surface texturing. Keywords Electrically assisted manufacturing . Electrically assisted indentation . Pulsed electric current . Hardness . Surface texturing
1 Introduction Electrically assisted manufacturing (EAM) is a hybrid manufacturing process to improve the quality of a product or to enhance the productivity of the process [1]. EAM has been developed by applying electric currents to forming processes for enhancing the formability of metals and their alloys during plastic deformation [2]. Additionally, EAM has been used to enhance the manufacturing process through the application of electricity in the form of direct current or electric fields. Studies have shown that EAM provides advantages of flow stress and forming force reduction, increased formability, decreased elastic recovery, fracture mode transformation from brittle to ductile, decreased overall process energy, and decreased cutting forces in
* Doo-Man Chun [email protected] 1
School of Mechanical Engineering, University of Ulsan, Ulsan 44610, Republic of Korea
machining [3]. Also, the EAM technique improves the material behavior of most metals by reducing the material flow stress and increasing its achievable elongation [4]. In the 1960s, Troitskii et al. reported a phenomenon in which applying an electric current during deformati
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