A new etchant for the chemical machining of St304

The present work is an investigation aimed at reducing pitting problem and obtaining better surface finish in chemical machining of St304. A new etchant is introduced for chemical machining of St304. Results present good surface finish without any pitting while high machining rate is achieved. The etchant tested in several temperatures and different depths of machining and the results are compared with other etchants, which are introduced in some references [Chemical Milling Nontraditional Machining Process, Machining ASM Handbook, 1994; Chemical Machining, Metals Handbook, vol. 3, Machining, 8th ed., American Society for Metals, Metals Park, OH, pp. 240–248; Fontana, Mars, G., Corrosion Engineering, 30th ed., 1986]. New etchant is a mixture of H 2O+HCl+HNO 3+HF+H 2COOH+TEA. Scan electron microscope (SEM) and roughness tests were employed to observe the surface topography.