STAINLESS STEEL MINIMIZED IN DEFECT OR SURFACE COATING LAYER OF STAINLESS STEEL MINIMIZED IN DEFECT AND FORMED ON SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To improve the pitting corrosion resistance and cracking resistance and to prolong the service life of the material by forming stainless steel or a coating layer on the surface by stainless steel in which the density of micro-defects as the specified surface opening diameter is extremely low, being equal to or below the specified one.;SOLUTION: The density of micro-defects of 0.6 to 1000 nm surface opening diameter is ≤60 pieces/μm2. As one method for prolonging the service life of the material, before the generation of big defects, the repair of the micro-defects of nanometer scale causing big defects is more effective. The repair of micro-defects is composed of each stage of mechanical polishing, cleaning treatment for the surfaces of defects, passivating treatment and the growth of oxidized coating films. In the final growth of oxidized coating films, after the passivating treatment, the surface is washed away by distilled water or ion exchange water, the water is blown off, and, after that, it is held in the air or in gas contg. ≥20% oxygen. The granular or beltlike structure of the oxide formed by the passivation grows, and in this process, micro-defects are covered and repaired.;COPYRIGHT: (C)2001,JPO