Patent ID: 11866814
Assignee: NIPPON STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  F | IPC C  F

Claim 0:
1. A heating furnace pipe made from an austenitic stainless steel, which consists of by mass percent, C: not more than 0.02%, Si: not more than 1.5%, Mn: not more than 2%, Cr: 17 to 25%, Ni: 9 to 13%, Cu: more than 0.26% to less than 2.95%, N: 0.06 to 0.35%, sol. Al: 0.008 to 0.03%, an amount of Co, the Co amount 0.03 to 1.0%, an amount of Ta, the Ta amount not more than 0.2%, an amount of Nb, the Nb amount not more than 0.5%, an amount of V, the amount of V not more than 0.4%, an amount of Ti, the amount of Ti not more than 0.4% and further contains one or more elements selected from Hf: not more than 0.2% and Zr: not more than 0.2%, with the balance being Fe and impurities, in which the contents of P, S, Sn, As, Zn, Pb and Sb among the impurities are P: up to 0.04%, S: up to 0.03%, Sn: up to 0.1%, As: not more than 0.01%, Zn: not more than 0.01%, Pb: not more than 0.01% and Sb: not more than 0.01%, and the values of F1 and F2 defined respectively by the following formula (1) and formula (2) satisfy the conditions F1≤0.075 and 0.05≤F2≤1.7-9×F1;

F1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5}  (1),

F2=Nb+Ta+Zr+Hf+2Ti+(V/10)  (2);, wherein each element symbol in the formulas (1) and (2) represents the content by mass percent of the element concerned.