Cr-CONTAINING STEEL EXCELLENT IN THERMAL FATIGUE CHARACTERISTICS

摘要

A Cr-containing steel excellent in thermal fatigue characteristics which contains by mass C: 0.01% or below, N: 0.015% or below, Si: 0.8 to 1.0%, Mn: 0.2 to 1.5%, P: 0.03% or below, S: 0.01% or below, Ni: 0.2% or below, Cu: 0.2% or below, Cr: 13 to 15%, Mo: 0.1% or below, Nb: 0.3 to 0.5%, Ti: 0.05 to 0.2%, V: 0.01 to 0.2%, Al: 0.015 to 1.0%, and B: 0.0002 to 0.0010% in such a way as to satisfy the relationship: (Nb + 1.9 x Ti)/(C + N) = 50 with the balance consisting of Fe and unavoidable impurities, characterized by exhibiting a 0.2% proof stress of 20MPa or above at 800°C after the aging at 800°C for at least 10 hours, a reduction of area of 35% or above at 200°C, and a total content of solid-dissolved Nb and solid-dissolved Ti of 0.08% or above after the aging at 800°C for at least 100 hours.