Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Jfe Steel Corporation

The Japan Steel Works, Ltd.

Ken Yamashita

Atsushi Takada

Hidenori Nako

Rinzo Kayano

Minoru Otsu

Yoshitomi Okazaki

Hideaki Takauchi

Genichi Taniguchi

Mikihiro Sakata

Akinobu Goto

Hirohisa Watanabe

Tsuneshi Ogawa

Tsuyoshi Kurokawa

Kazuya Ikai

Hitoshi Hatano

Naoya Hayakawa

Yutaka Nishikawa

Daichi Izumi

Koichi Hosoi

Haruya Kozuki

Noriyuki Hara

Ryo Arao

Keiji Ueda

Liang Chen

Peng Han

Yuta Honma

Shohei Kozuki

Hayato Koike

This welded structure comprises a weld metal which contains C, Si, Mn, Cr, Mo, V, Nb, N and O in prescribed amounts respectively with the balance being Fe and unavoidable impurities and which exhibits an A value of 200 or more and a Z value of 0.05 or more. The A value is calculated from the element contents of the weld metal according to the formula: A value=([V]/51+[Nb]/93)/{[V]&#xd7;([Cr]/5+[Mo]/2)}&#xd7;10. The Z value is calculated according to the formula: Z value=N&#xd7;[insol. V] [wherein N (particles/&#x3bc;m) is the number density of carbide particles present in a prior austenite grain boundary per unit grain boundary in the stress-relief annealed weld metal, and [insol. V] is the concentration of compound-type V as determined by analyzing an extraction residue of the stress-relief annealed weld metal].

Weld metal and welded structure

A weld metal according to the present invention has a specific chemical composition, contains carbide particles each having an equivalent circle diameter of greater than 0.5 &#x3bc;m in a number of 0.25 or less per micrometer of grain boundary length, and has an A-value as specified by Formula (1) of 0.12 or more, Formula (1) expressed as follows:-value=([V]/51+[Nb]/93)/([Cr]/52+[Mo]/96) &#x2003;&#x2003;(1)where [V], [Nb], [Cr], and [Mo] are contents (percent by mass) of V, Nb, Cr, and Mo, respectively, in the weld metal.

Weld metal having excellent temper embrittlement resistance

This weld metal has excellent creep characteristics and has a given chemical composition. In the weld metal, the value A defined by equation (1) is 200 or greater, and carbide particles each having an equivalent-circle diameter of 0.40 &#x3bc;m or more have an average equivalent-circle diameter less than 0.85 &#x3bc;m. In the segments that connect the centers of three or more carbide particles which are present on a 6-&#x3bc;m straight line and which each has an equivalent-circle diameter of 0.40 &#x3bc;m or more, the sum of the lengths of the portions where the segments intersect the carbide particles is 25% or more of the overall length of the segments.Value=([V]/51+[Nb]/93)/{[V]&#xd7;([Cr]/5+[Mo]/2)}&#xd7;10&#x2003;&#x2003;(1)In the equation, [V], [Nb], [Cr], and [Mo] respectively indicate the contents (mass %) of V, Nb, Cr, and Mo in the weld metal.

Weld metal with excellent creep characteristics

Provided is a welding metal in which the chemical component composition thereof is appropriately controlled; an A value that is specified by a predetermined relational expression satisfies the requirement of being 3.8% to 9.0%; an X value that is specified by a predetermined relational expression satisfies the requirement of being 0.5% or greater; the area percentage of carbide particles having a circle-equivalent diameter of 0.20 &#x3bc;m or greater in the welding metal is 4.0% or less; and the number of carbide particles having a circle-equivalent diameter of 1.0 &#x3bc;m or greater is 1000 particles/mmor less. This welding metal, which can exhibit not only high strength but also good low-temperature toughness and good drop-weight characteristics, is useful as a material for a pressure vessel in a nuclear power plant.

Welding metal having excellent low-temperature toughness and drop-weight characteristics

Provided is a welding metal in which a predetermined chemical component composition is satisfied, the A value as specified by formula (1) is 3.8% to 9.0%, and the surface area percentage of carbide having a circle-equivalent diameter of 0.20 &#x3bc;m or greater in the welding metal is 4.0% or less.value=0.8&#xd7;[C]&#x2212;0.05&#xd7;[Si]+0.5&#xd7;[Mn]+0.5&#xd7;[Cu]+[Ni]&#x2212;0.5&#xd7;[Mo]+0.2&#xd7;[Cr]&#x2003;&#x2003;(1)(Provided that [C], [Si], [Mn], [Cu], [Ni], [Mo] and [Cr] are the C, Si, Mn, Cu, Ni, Mo and Cr content (by mass percent), respectively) The welding metal is useful as a material for a pressure vessel of a nuclear power plant as the welding metal is high in strength and has good low-temperature toughness and drop-weight characteristics.

To provide weld metal that has a high strength and toughness in the as-welded condition or in the annealed condition. The weld metal of the present invention contains by weight %, C: 0.04-0.15%, Si: 0.50% or less, Mn: 1.0-1.9%, Ni: 1.0-4.0%, Cr: 0.10-1.0%, Mo: 0.20 to 1.2%, Ti: 0.010-0.060%, Al: 0.030% or less, O: 0.15-0.060%, N: 0.010% or less, Fe and inevitable impurities as the remaining contents. The weld metal is further characterized by the fact that the ratio of Ti content (%) to Si content (%) i.e., [compound type Ti]/[compound type Si] is more than 1.5, and the number A defined by the following formula is 0.50 or more, wherein A=[Ti]/([O]&#x2212;1.1&#xd7;[Al]+0.05&#xd7;[Si]).

Weld metal and welded structure having weld joints using the same

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

A flux-cored wire for gas-shielded arc welding comprises a steel sheath, and a flux filled in the steel sheath. The flux-cored wire has a C content of 0.20% by mass or below, a Si content in the range of 0.06 to 1.10% by mass, a Mn content in the range of 0.55 to 1.60% by mass, a Cr content of 2.60% by mass or below, a Mo content in the range of 0.30 to 1.50% by mass, a Mg content in the range of 0.20 to 1.50% by mass, a N content in the range of 0.005 to 0.035% by mass and a B content in the range of 0.001 to 0.020% by mass on the basis of the total mass of the flux-cored wire. The flux has a TiOcontent in the range of 4.2 to 8.2% by mass and a fluorine compound content in terms of F content in the range of 0.025 to 0.55% by mass on the basis of the total mass of the flux-cored wire, and the flux-cored wire has an Al content of 0.50% by mass or below, a Nb content of 0.015% by mass or below, and a V content of 0.015% by mass or below on the basis of the total mass of the flux-cored wire. The flux-cored wire forms a weld metal that is resistant to ferrite band maintains proper tensile strength and excellent toughness even if the weld metal is processed at high temperatures for a long time for PWHT. The flux-cored wire has satisfactory usability

Flux-cored wire for gas-shielded arc welding

A flux-cored wire for gas-shielded arc welding of heat-resisting steel in the form of a steel tube filled with a flux, which is characterized in that the content of slag-forming agent is 6.10-9.90 mass % (based on the total mass of the wire), said steel tube and said flux all together contain less than 0.20 mass % C., 0.06-1.40 mass % Si, 0.55-1.60 mass % Mn, 0.004-0.090 mass % Cu, 0.004-0.090 mass % Ni, less than 2.60 mass % Cr, and 0.3-1.20 mass % Mo (based on the total mass of the wire), and said flux contains 4.2-8.2 mass % TiO , 0.025-0.25 mass % of metal fluoride (in terms of fluorine), and 0.20-1.50 mass % Mg. The flux-cored wire has both good welding maneuverability and ability to give weld metal with good mechanical properties, such as strength and toughness.

Flux-cored wire for gas-shielded arc welding of heat resisting steel

Described is a flux cored wire for stainless steel which comprises a metal covering and flux filled inside of the metal covering. In the flux cored wire for stainless steel, the flux contains a slag forming agent in an amount of 6.0 wt. % to 13.0 wt. % based on the total weight of the wire and the metal covering is formed of an austenite-base stainless steel containing 0.003 wt. % to 0.090 wt. % of O, 0.0005 wt. % to 0.02 wt. % of S, 0.1 wt. % to 0.6 wt. % of Si and 0.005 wt. % to 0.2 wt. % of V, each based on the total weight of the metal covering.

Flux cored wire for stainless steel

A flux-cored wire for welding stainless steel, with the flux filled in the metal skin, which contains 5-30% (by weight) of flux, 10.5-27.0% of Cr, less than 2% of slag-forming constituents, 0.05-2.0% of Ti, 0.05-2.0% of Si, 0.01-0.1% of N, 0.01-1.0% of Al, 0.1-1.0% of Mn, and 0.003-0.5% of metal fluorides constituting the flux, in the total weight of the wire. The wire may optionally contain Ni, alkali metals, S, Nb, Zr, and V. The wire gives rise to only a small amount of slag.

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Fujisawa, Japan

Ken Yamashita