Research On Electrochemical Machining Of Holes In Nickel-based Superalloy

As a non-magnetic Ni-Cu superalloy,Monel has many advantages such as strong toughness,high hardness,high performance of anti-fatigue and corrosion resistance,because of which Monel is widely used in marine,aviation and other industries,especially in fasteners on ship,aviation engine turbines and gas turbine blade fields.The processing of holes in Monel materials has been a problem for a long time.The machining methods and conditions are continuously improved from the traditional drilling process to electrolysis,ultrasonic and other non-traditional processing technologies to drilling holes with high forming precision and good surface quality.Electrochemical Machining(ECM),as a kind of non-traditional machining method,has its unique advantages in the processing of holes with good quality of machined surface,no tool wear,and materials' mechanical properties independence.Shaped Tube Electrochemical Machining(STEM)have become a research hotspot.Based on the previous STEM,this paper focuses on using a new type of grooved electrode to carry out researches on hole-machining in Monel K500.Considering machining precision,efficiency and cost,electrolyte is optimized by testing anodic polarization curves under different concentrations of NaCl ?NaNO3 and NaClO3 solutions combined with machining experiments.Then studies the effect of electrolyte flow rate,depth of processing,inter-electrode gap(IEG)size and the side gap(SG)size on the separation phenomenon and cavitation phenomenon in electrochemical machining through the flow field simulation by CFX software.The insulation of electrode's sidewall is of great importance for ECM.Insulating effect and service life of different insulation coating are investigated and experiments are carried out using the best insulating coating,which verified the superiority of grooved electrode compared to the shaped tube electrode.Finally,influences on machining by the power parameters,the feeding speed of cathode and electrolyte flow rate are studied by single-factor experiments,and verifies the simulation results to select the optimal machining parameters in order to achieve the electrolytic machining of high precision and high stability.