Abstract
Pitting corrosion of SUS 316L stainless steel pipe was investigated on its application to high purity gas supply equipments in semiconductor manufacturing. Two types of 316L were used: a conventional one and a purified one by vacuum induction melting and vacuum arc remelting. The pipes were seamless pipe of 6.35mm outer diameter and 1.0mm wall thickness and their inner surfaces were finished with bright annealing (BA) and electro-polishing (EP). Those pipes were exposed to moist Cl2 at 30 degree C for 24h. After the test the dissolved Fe from the pipes was measured by dissolving the corrosion product with 30%HNO3. The dissolved Fe amount gave following ranking as the pitting resistance: purified EP>conventional EP=purified BA>conventional BA. The ranking suggested that the dissolved Fe, namely corrosion amount, was dependent on the amount of defects such as inclusions and scratches on the inner surface of the pipes.
