heat resistant austenitic stainless steel, having excellent thermal fatigue properties and exhaust components made from the same

摘要

The present invention relates to a heat resistant austenitic stainless steel having excellent thermal fatigue properties, characterized in that it comprises by mass 0.3-0.6% c, 0.5-3% Si. , 5-2% min, 15-30% cr, 6-30% ni, 0.6-5% nb, 0.01-0.5% n, and 0.01-0.5 % s, c / n being 4-7 and the remainder being fe and unavoidable impurities; and a ratio a / b of a carbide formation index a to a carbide formation index b of nb being from 0.6 to 1.7, where a and b are expressed by formula (1) of a = 8, 5c? nb + 0.05cr + 0.65 ni? 5 and formula (2) of b = 7.8nb.