Investigations on the pH value of corrosion-sensitive steels after PECM

The increasing use of unconventional manufacturing technologies favors a spread of high-performance steels for product manufacture. In particular, the properties of high tensile strength of over 1200 MPa and low ductility are used to develop lighter components that save resources. Low-alloyed high-performance steels often have a lower Cr content, which have a substantial influence on corrosion resistance. When machining using PECM, unwanted corrosion occurs due to the salty working medium, which negatively affects the component dimensions as well as the microstructure. An approach to chemical corrosion protection takes place in an alkaline environment. In this context, exceeding a certain pH value leads to the formation of a passivation layer. The present investigation is focused on the change of pH under variation of PECM process parameters such as current density and duty cycle at the fixture output for a low-alloyed, corrosion-sensitive steel. The electrolyte solution provided by the machine remains unchanged.