Patent ID: 8034198
Filing Date: 2011-10-11
Classification: C21D,Y10S,Y10T

Abstract:
1. An austenitic stainless steel tube for boiler, comprising 16 to 20% Cr by weight, being formed by cold-working at an inner surface of the tube after solution heat treatment followed by descaling in an acid solution to eliminate both an oxide scale formed on the inner surface of the tube and a part of the mother material at the inner surface of the tube, the Cr concentration at the 5 μm position from the inner surface of the tube being in the range of 14% by weight or larger and not exceeding a Cr content of the mother material being 16 to 20% by weight, and the hardness at 100 μm depth from the inner surface of the tube being 1.5 times or larger the average hardness of the mother material or being HV 300 or larger.