25 Cr-28 Niオーステナイト耐熱鋼について

抄録

In order to develop high strength austenitic heat resisting steel, the creep-rupture and metallo graphia data are presented on 25% Cr-28% Ni steels. The individual and combined effects of C, N, Mo, W, V, and B have been studied in detail. Some of the steels tested with high N content are prepared using a melting and casting technique under high-pressure nitrogen atmosphere. Of the 25% Cr-28% Ni steels tested two compositions 2 Mo-5.7 W-0.6 N-0.05 B and 1.6 Mo-2.2 W-0.3N are shown to give good combination of properties. The former possesses very high 1000hr creep rupture strength, that is 26.5kg/mm² at 700°C. The latter possesses strength of 23.0kg/ mm², and shows no abnormal drop in the rupture strength even after the test period of 20000hr at 700°C. This property together with ease of hot-rolling and forging make this steel very attractive for high strength applications at elevated temperature.