Kobe Steel, Ltd.

Masafumi Yamakami

Masayuki Nagami

Yoshihiko Kitagawa

Hidenori Nako

Yoshitomi Okazaki

Munenobu Sato

Hiroyuki Kawasaki

A flux-cored wire for gas-shielded arc welding has a steel outer sheath filled with a flux. The flux-cored wire includes specific amounts, relative to a total mass of the wire, of TiO, at least one of Si, an Si oxide and an Si compound, C, Mn, Mo, Ni, at least one of metal Mg and an Mg alloy, an F compound, a K compound, an Na compound, B and a B compound, and Fe, respectively. A total content of each of Ti and a Ti alloy, metal Al and an Al alloy, and V is restricted to the specific range, respectively. A content of Ti is also restricted to the specific range relative to the total mass of the steel outer sheath.

Wire containing flux for gas shield arc welding

Provided is a flux-cored wire for gas-shielded arc welding that contains specific amounts of C, Mn, TiO, and Ni and specific amounts or less of P and S. The TiOhas a ratio (&#x3b1;1/&#x3b1;2) of 0.90-1.50 when &#x3b1;1 (mass %) is the content per wire total mass of particles having a size of 106 &#x3bc;m or smaller and &#x3b1;2 (mass %) is the content per wire total mass of particles having a size exceeding 106 &#x3bc;m.

Flux-cored wire for gas-shielded arc welding

Provided is a flux-cored wire for gas-shielded arc welding that contains, per wire total mass, specific amounts of C, Mn, TiOand specific amounts or less of P and S, and contains, in the flux, a specific amount of Ni per wire total mass. The Ni has a ratio (&#x3b1;1/&#x3b1;2) of 0.50-1.00 when &#x3b1;1 (mass %) is the content per wire total mass of particles having a size of 106 &#x3bc;m or less and &#x3b1;2 (mass %) is the content per wire total mass of particles having a size exceeding 106 &#x3bc;m.

The objective of the present invention is to provide a similar-metal-composition welding solid wire, and weld metals therefor, with which both excellent bead shape and high ultralow-temperature toughness for the weld joints can be achieved when welding 9% Ni steels together by means of a high-efficiency MIG welding method. A fixed ratio of a REM and O are included in a similar-metal-composition welding solid wire of a 9% NI steel base material, and oxygen is supplied in a trace amount in a range that does not hinder the ultralow-temperature toughness of the weld joint () but that is capable of forming fine REM oxides in the weld metal () and of controlling the weld metal to produce an excellent bead shape. In addition, both Al and Ti are regulated and an argon gas that contains little or no carbon dioxide gas is used as the shield gas in the MIG welding method. Thus, both an excellent bead shape and high ultralow-temperature toughness for the weld joint () can be achieved.

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Kanagawa, Japan

Masafumi Yamakami