Research on the surface characteristics of 42CrMo alloy steel pulse electrochemical machining

Electrochemical processing, due to its unique material removal mechanism compared to mechanical processing, often results in significantly different micro-morphologies. It is widely used in areas such as aerospace component processing, surface finishing, passivation, micro-structure mold processing, etc. The complexity of alloy steel composition makes uniform etching difficult to achieve, and the post-etch micro-morphology is also complex, making it challenging to describe and analyze. Therefore, it is difficult to analyze the surface morphology of electrochemical etching under different parameters. In this study, a self-developed electrochemical etching device with adjustable DC voltage, pulse width voltage, and pulse width positive and negative voltage output was used. Different parameters of pulse voltage were used to etch the surface of 42CrMo alloy steel. Due to the strong relationship between surface roughness parameters and the chosen measurement scale, as well as the surface morphology and waviness errors introduced by specimen preparation and etching processes, a wavelet filtering method was used to remove the low frequency components in the surface morphology, and only the surface roughness part was retained for fractal parameter calculation and analysis. The research showed that fractal analysis can also be applied to analyze the surface morphology after electrochemical etching. Pulse voltages with characteristic voltages, characteristic pulse frequencies, and duty ratios can achieve better surface quality during positive pulse etching. Positive and negative pulse etching can obtain better surface morphology than positive pulse etching, but the etching amount is lower, making it suitable for precision finishing.