Jfe Steel Corporation

National Institute for Materials Science

Yasushi Morikage

Keniti Amano

Fumimaru Kawabata

Tatsumi Kimura

Takahiro Kubo

Hironori Miura

Chiaki Shiga

Kazuo Hiraoka

Takanori Okui

Akihiko Ohta

Keizou Taoka

Koich Yasuda

Hiroyuki Ookubo

In the present invention, an iron based alloy which contains by mass %: 0.20% or less of C; 6.0 to 16.0% of Cr; 6.0 to 16.0% of Ni and whose martensitic transformation starting temperature (Ms point temperature) is in the range of 0-170&#xb0; C., inclusive of 0&#xb0; C. and exclusive of 170&#xb0; C., is used as a welding material. With respect to a weld metal, the weld metal has a iron alloy composition which contains by mass %: 0.20% or less of C; 3.0 to 13.0% of Cr; 3.0 to 13.0% of Ni and whose martensitic transformation starting temperature (Ms point temperature) is in the range of 50-360&#xb0; C., inclusive of both 50&#xb0; C. and 360&#xb0; C.

Welding material and a method of producing welded joint

When manufacturing a straight steel section having a joint comprising a ball claw and a curved claw by hot-rolling a bloom vertically symmetrically to make a section blank having a flange A at a web end (first step), vertically asymmetrically hot-rolling the section blank to adjust the size of the web and form the flange into a rough joint B including a projection A (second step), and subjecting the projection to hot bend rolling into a curved claw (third step), wherein the bloom has a chemical composition comprising, in mass percentage, from 0.01 to 0.20% C, up to 0.8% Si, up to 1.8% Mn, up to 0.030% P, and up to 0.020% S; and therein the claw bending start temperature in the third step is a temperature of over Ar or up to Ar -50&deg; C., thereby achieving a depth of wrinkle flaws present on the inner surface side of the curved claw of up to 0.5 mm.

Linear shape steel excellent in joint fatigue characteristics and production method therefor

Growing community of inventors

Chiba, Japan

Yasushi Morikage