Abstract
The ability to withstand corrosion and high temperature oxidation of the surface layer of workpiece produced by the electrical discharge machining has been studied. Electrical discharge machining was performed in hydrocarbon oil using copper and semi-metal silicon electrode on workpieces of carbon steel, aluminum, 13 chromium steel and SUS 304 stainless steel. In order to examine the machined surface characteristic, the susceptibility to corrosion or high temperature oxidation of the surface was evaluated. It has been revealed that the machined surfaces of SUS 304 stainless steel and 13 chromium steel produced by using of silicon electrode have remarkable corrosion and high temperature oxidation resistance respectively, while the behaviors of the machined surfaces of carbon steel workpiece produced by copper or silicon electrode were all similar to that of the carbon steel. Surface layers having remarkable corrosion or high temperature oxidation resistance were investigated by the electron-beam probe microanalyser and electron diffraction. The results showed that the surface region is implanted with silicon in the range of about 3 μm deep, and that an amorphous phase is produced on the machined surface of SUS 304 stainless steel. It was found, furthermore, that no damage of the surface layer occurred by cyclic plastic deformation or rapid heating and cooling.
