Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Koichi Hosoi

Yoshitomi Okazaki

Ken Yamashita

Hirohisa Watanabe

Tsuyoshi Kurokawa

Kazuo Ikemoto

Yoshiya Sakai

Isao Aida

Shigeo Nagaoka

Tetsuya Hashimoto

A weld metal of a high-strength Cr&#x2014;Mo steel formed by shielded metal arc welding contains: 0.04 to 0.10% by mass C, 0.15 to 0.5% by mass Si, 0.5 to 1.0% by mass Mn, 2.00 to 3.25% by mass Cr, 0.9 to 1.2% by mass Mo, 0.01 to 0.03% by mass Nb, 0.2 to 0.7% by mass V, 0.003% by mass or below and above 0% by mass B, 0.02 to 0.05% by mass O, and the balance of Fe and inevitable impurities. A residual extracted by electrolytic extraction from only an unaffected zone of the weld metal contains precipitated Cr in a Cr content below 0.3% by mass, and precipitated Nb in a Nb content of 0.005% by mass or above.

Weld metal of high-strength Cr-Mo steel

Provided is a weld metal for Cr&#x2014;Mo steels which is suppressed in the formation of ferrite bands and therefore has heightened toughness and tensile strength and at the same time, good SR cracking resistance. The weld metal according to the present invention contains C: 0.02 to 0.06% (mass %, which will equally apply hereinafter), Si: 0.1 to 1.0%, Mn: 0.3 to 1.5%, Cr: 2.0 to 3.25%, Mo: 0.8 to 1.2%, Ti: 0.010 to 0.05%, B: 0.0005% or less (inclusive of 0%), N: 0.002 to 0.0120%, O: 0.03 to 0.07%, and the balance being Fe and inevitable impurities, wherein a ratio of the Ti content [Ti] to the N content [N] satisfies the following range: 2.00&#x3c;[Ti]/[N]&#x3c;6.25.

Weld metal excellent in toughness and SR cracking resistance

Disclosed is a flux-cored wire for gas shield arc welding comprising a mild steel sheath and a flux composition filled in the mild steel sheath, wherein the mild steel sheath is made of a mild steel containing, based on the total weight of the sheath, 0.02% or less of C, 0.01 to 0.20% of Ti, and 0.01 to 0.15% of Al, the contents of Ti and C satisfying a relation of (Ti/C.gtoreq.1.0) and the contents of Al and C satisfying a relation of (Al/C.gtoreq.1.5); and the flux composition contains, based on the weight of the total wire, 0.50 to 3.60% of Mn (including the Mn amount in the sheath), and 0.10 to 1.80% of Si (including the Si amount in the sheath).

Flux-cored wire for gas shield arc welding with low fume

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Fujisawa, Japan

Koichi Hosoi