Kobe Steel, Ltd.

Yoshitomi Okazaki

Hidenori Nako

Ken Yamashita

Minoru Otsu

Hideaki Takauchi

Koichi Hosoi

Tomoko Sugimura

Hirohisa Watanabe

Hiroyuki Takeda

Keito Ishizaki

Munenobu Sato

Masafumi Yamakami

Yimin Yuan

Kazuyuki Suenaga

Kohjiroh Nakanishi

Disclosed herein is an electroslag welding wire containing, by mass % based on total mass of the wire: C: more than 0% and 0.07% or less; Si: more than 0% and 0.50% or less; Mn: more than 0% and 1.0% or less; Ni: 6.0 to 15.0%; and Fe: 79% or more. The electroslag welding wire satisfies the following relationship (1): 0.150&#x2264;C+Si/30+Mn/20+Ni/60&#x2264;0.300 (1).

Wire for electroslag welding, flux for electroslag welding and welded joint

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.

Welding solid wire and weld metal

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

It is an object of the present invention to provide a similar composition metal type welding solid wire capable of forming a welded joint having excellent cryogenic characteristics, such as ensuring a low-temperature toughness equivalent to that of the cryogenic base metal, and in addition, further having a high crack initiation resistance, and a weld metal thereof. The welding solid wire of the present invention is an iron base welding solid wire including carbon: 0.10 mass % or less (not inclusive of 0%), silicon: 0.15 mass % or less (not inclusive of 0%), nickel: 8.0 to 15.0 mass %, manganese: 0.10 to 0.80 mass %, and Al: 0.1 mass % or less (not inclusive of 0%), and oxygen in an amount of 150 ppm or less (inclusive of 0), characterized by including: a REM: 0.005 to 0.040 mass %, or chromium: 4.0 mass % or less (not inclusive of 0%).

Welding solid wire

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.

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Kobe, Japan

Yoshitomi Okazaki