Surface Layer Formation of a 12KH18N10T Stainless Steel Toothed Base During Wire Electrical Discharge Machining

Abstract

Wire Electrical Discharge Machining (WEDM) is an effective manufacturing process for producing complex-shaped components from difficult-to-machine materials. However, the thermal effect of electrical discharges alters the structure and condition of the surface layer. The aim of this study was to investigate the surface layer formation of a 12Kh18N10T stainless steel toothed base during WEDM. Machining was performed on a DK7745 wire EDM machine using a 0.18 mm brass wire electrode and deionized water as the dielectric medium. Two machining regimes with different pulse energies were investigated. Surface morphology, recast layer microstructure, and elemental composition were characterized using optical metallography, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), while the mechanical state of the surface layer was evaluated by Vickers microhardness measurements. The results showed that increasing the pulse energy promoted the formation of a more developed recast layer and a more heterogeneous surface morphology without significantly changing the concentrations of the principal alloying elements (Fe, Cr, and Ni). In addition, an increased oxygen content and a slight transfer of Cu and Zn from the brass wire electrode were observed in the near-surface region. Higher microhardness was obtained after finish machining. The practical significance of this study lies in the substantiation of WEDM regimes that ensure the required dimensional accuracy and surface integrity for manufacturing toothed components of high-precision medical positioning mechanisms.