Investigation the Grain-Boundary Corrosion and Cracking on Stainless Steel A316 Processed by Edm Die-Sinker for the Food and Medicines Industry

Stainless-steel A316 is widely utilized in the medicine and food industry not only because of its excellent material characteristics: hard, high fatigue strength, wear-resistance and corrosion-resistance but also because it meets health standards. However, due to the complicated forms of dies and punches, a conventional machining is limited to process this material. To tackle the limitation of the conventional machine, the sinker EDM (electrical discharge machining) which uses spark energy with a large electric current density can be used. Strongly influenced by the process parameters, including discharge current, pulse-on-time, servo sensitivity, and electrode material, EDM brought some disadvantages such that the surface and it's below are susceptible to the grain boundaries corrosion and crack. Grain boundary corrosion and cracking on A316 processed by EDM has not been further explored yet. This research aims to investigate the corrosion and crack form in dies and punches of stainless steel A316 processed by EDM. Based on the result, the grain boundary corrosion and cracking appeared in both surface and recast layer of A316, which processed by the EDM with 6A and copper electrode. This corrosion and cracking can reduce the lifetime and health considered of punch and dies.