Surface characteristics investigation of EDM-fabricated maraging steel post-processed by organic acid-based electropolishing

Abstract

The key processing issue with EDM of maraging steel is the formation of defective surfaces, including cracks, craters, voids, and globules, along with a recast layer. These defects degrade surface characteristics, leading to premature failure of EDM-fabricated critical components like aerospace landing gear and gyroscope flexures. To address this, the present study explores the effectiveness of organic-electrolyte-based electropolishing (EP) as a post-processing technique, replacing traditional sulfuric acid-based methods. The present research compares EDM and EP surfaces in terms of surface quality, morphology, phase composition, crystallite size, hardness, reflectance, wettability, and tribological performance. The EP process eliminates all the surface defects, enhancing surface quality. Peak broadening in EDM is attributed to micro-strain, which EP alleviates, aligning with the base material's strain levels. Hardness measurements show EDMed surfaces at 7.78 GPa, the base material at 4.11 GPa, and EP surfaces at 4.02 GPa. Reflectance increases from 12% to 78% post-EP, and wettability improves with a reduced contact angle. EP significantly enhances tribological performance by lowering friction, wear, and adhesion, making EDMed components more suitable for aviation applications like landing gear. These findings demonstrate significant improvement in surface characteristics after EP, offering a cost-effective, promising solution for EDMed maraging steel components.