Electrochemical surface modification-assisted machining strategy for GH4698 nickel-based superalloy

GH4698, a nickel-based wrought superalloy, serves as a primary material for hot-end components of aero engines. However, its inherent properties result in accelerated tool wear and inferior machined surface quality, posing significant challenges to precision machining. Herein, we propose an Electrochemical surface modification-assisted machining (ECMAM) approach which leverages the synergistic effects of Cl - -pitting corrosion and C 6 H 5 O 7 3- -Complexation to selectively remove Cr-rich γ matrix, thereby forming an electrochemically modified layer on GH4698 surface. Further characterization reveals that the modified layer exhibits uniform thickness, significantly reduced hardness, and markedly enhanced hydrophilicity, facilitating easier mechanical removal. To evaluate the practical applicability of this approach, ECMAM feasibility experiments were conducted on GH4698 using an ultra-precision lathe, with assessments of cutting forces, surface integrity, and tool wear. Compared with conventional machining (CM), ECMAM reduced the thrust force, feed force, and principal cutting force by 84%, 87.5%, and 58.7%, respectively. Moreover, it achieved a 31.6% reduction in surface roughness and an 88.9% reduction in work hardening. Tool flank wear was also significantly mitigated under ECMAM. These results demonstrate that ECMAM substantially enhances various aspects of GH4698 machining performance, presenting a promising approach for the precision machining of nickel-based wrought superalloys.