Ferritic heat-resistant steel and method for producing it

(19)

(11)

EP 1 329 532 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	30.07.2003 Bulletin 2003/31

(43)	Date of publication A2:
	23.07.2003 Bulletin 2003/30

(21)	Application number: 03007333.2

(22)	Date of filing: 21.09.1998

(51)	International Patent Classification (IPC)⁷: C22C 38/24, C22C 38/26, C22C 38/22

(84)	Designated Contracting States:
	BE DE

(30)

Priority:

22.09.1997 JP 25647997
22.09.1997 JP 25648097
22.09.1997 JP 25648197

(62)	Application number of the earlier application in accordance with Art. 76 EPC:
	98307629.0 / 0903421

(71)	Applicant: NATIONAL RESEARCH INSTITUTE FOR METALS
	Tsukuba-shi, Ibaraki (JP)

(72)	Inventor:
	The designation of the inventor has not yet been filed ()

(74)	Representative: Matthews, Derek Peter
	Frank B. Dehn & Co., European Patent Attorneys, 179 Queen Victoria Street London EC4V 4EL London EC4V 4EL (GB)

(54)	Ferritic heat-resistant steel and method for producing it

(57) The invention provides a ferritic heat-resistant steel having excellent high-temperature oxidation resistance, especially excellent steam oxidation-resistant characteristics. In high-Cr ferritic heat-resistant steel, ultra-fine oxide particles having a size of not larger than 1 µm are formed just below the oxide films and formed on the steel base, whereby the adhesiveness between the films and the base is enhanced. The ferritic heat-resistant steel contains Cr in an amount of from 8.0 to 13.0 % by weight, and at least one of Rh and Ir in a total amount of from 0.3 to 5.0 % by weight.

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