	US 11,834,731 B2
	Method of producing ferritic heat-resistant steel welded joint
Hiroyuki Hirata, Tokyo (JP); Kana Jotoku, Tokyo (JP); Shinnosuke Kurihara, Tokyo (JP); and Katsuki Tanaka, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/298,678
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Dec. 5, 2019, PCT No. PCT/JP2019/047717 § 371(c)(1), (2) Date Jun. 1, 2021, PCT Pub. No. WO2020/116588, PCT Pub. Date Jun. 11, 2020.
Claims priority of application No. 2018-228314 (JP), filed on Dec. 5, 2018.
Prior Publication US 2022/0042150 A1, Feb. 10, 2022
Int. Cl. C22C 38/54 (2006.01); B23K 35/30 (2006.01); C22C 38/38 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/28 (2006.01); C22C 38/30 (2006.01); B23K 103/04 (2006.01); B23K 103/16 (2006.01)

CPC C22C 38/38 (2013.01) [B23K 35/3086 (2013.01); C22C 38/001 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/28 (2013.01); C22C 38/30 (2013.01); B23K 2103/04 (2018.08); B23K 2103/166 (2018.08); C21D 2211/005 (2013.01)]

6 Claims

1. A method of producing a ferritic heat-resistant steel welded joint, the method comprising:

a multi-layer welding step in which a ferritic heat-resistant steel base material comprising B at 0.006% by mass to 0.023% by mass is multi-layer welded using a Ni-based weld material for a heat-resistant alloy,

wherein root pass welding is performed under a welding condition such that a ratio of an area [S_BM] that has been melted of the ferritic heat-resistant steel base material to an area [S_WM] of a weld metal, in a transverse cross-section of a weldment after the root pass welding but before second pass welding in the multi-layer welding step, satisfies the following formula (1), with respect to a mass percent of B, [%_BBM], which is included in the ferritic heat-resistant steel base material:

0.1≤[S_BM]/[S_WM]≤−50×[% B_BM]+1.3 (1)