Systems and processes for treating surfaces of metal components are provided. The systems can include a container for containing a metal workpiece having a surface with a complex external geometry and for containing a solution that has electrolytes at a flow rate that varies according to a local shape of the surface to thereby treat the surface of the metal workpiece; optionally one or more electrodes for creating an electrical field; and optionally a temperature control device configured to provide a predetermined temperature or range of temperatures. The processes can include providing a metal workpiece having a surface with a complex external geometry; and contacting the workpiece in the presence of a predetermined electrical field at a predetermined temperature with a solution containing electrolytes at a flow rate that varies according to a local shape of the surface to thereby treat the surface of the metal workpiece.