Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Nippon Steel & Sumikin Stainless Steel Corporation

Manabu Mizumoto

Shinji Kodama

Kenichi Asai

Hiroshige Inoue

Hideki Hamatani

Shinji Tsuge

Ryuichi Honma

Yoshinari Ishida

Tadashi Kasuya

Yuusuke Oikawa

Nobuo Mizuhashi

Shigeo Fukumoto

Ryo Matsuhashi

Ryuichi Shimura

Yusuke Oikawa

Takashi Namekata

A method of production of a welded joint which enables improvement of the fatigue strength in the case where measures for improvement of the fatigue strength cannot be applied due to the presence of structurally sealed regions is provided. The method is provided with a first weld step which performs welding by forming an inside weld toe or root part by using a weld metal with a transformation start temperature of 175&#xb0; C. to 400&#xb0; C. in range, at least parts of the weld metal forming the inside weld toe or root part which was formed at the first weld step becoming unmelted parts, and a second weld step which performs welding for building up the weld metal by a single pass by a weld heat input by which all of the unmelted parts are retransformed to austenite so as to introduce compressive residual stress to the inside weld toe or root part.

Method of production of welded joint

The present invention provides flux cored wire for welding duplex stainless steel which refines the solidified crystal grains for obtaining weld metal superior in toughness and ductility, characterized by containing, as the chemical ingredients included in the steel sheath and flux, by mass % with respect to the mass of the wire as a whole, C: 0.001 to 0.1%, Si: 0.01 to 1.0%, Mn: 2.0 to 6.0%, Cr: 17.0 to 27.0%, Ni: 1.0 to 10.0%, Mo: 0.1 to 3.0%, Al: 0.002 to 0.05%, Mg: 0.0005 to 0.01%, Ti: 0.001 to 0.5%, and N: 0.10 to 0.30%, further limiting P to 0.03% or less and S to 0.01% or less, satisfying 0.73&#xd7;Cr equivalents&#x2212;Ni equivalents&#x2267;4.0 and Ti (mass %)&#xd7;N (mass %)&#x2267;0.0004, and having a balance of iron and unavoidable impurities.

Flux cored wire for welding duplex stainless steel which refines solidified crystal grains

A stainless steel flux-cored welding wire for zinc-coated steel sheet welding use which gives a weld zone where no zinc embrittlement cracking occurs and the corrosion resistance and ductility are excellent and which is good in weld work efficiency and a welding method using the same, the welding wire characterized in that total amounts of elements which are included as metals or alloy compositions in the sheath and flux are, by mass % with respect to a total mass of the welding wire, C: 0.01 to 0.05%, Si: 0.1 to 1.5%, Mn: 0.5 to 3.0%, Ni: 7.0 to 10.0%, and Cr: 26.0 to 30.0%, an F value is 30 to 50 in range, further, the wire contains, as slag forming agents, in the flux, by mass % with respect to the total mass of the wire, TiO: 3.8 to 6.8%, SiO: 1.8 to 3.2%, ZrO: 1.3% or less, and AlO: 0.5% or less, a total amount of the slag forming agent and other slag forming agents is 7.5 to 10.5%, furthermore, the TiOsatisfies, by mass % with respect to the total amount of slag forming agents, TiO: 50 to 65%, and a balance of the sheath and flux is Fe and unavoidable impurities.

Stainless steel flux-cored welding wire for welding of zinc-coated steel sheet and arc welding method of zinc-coated steel sheet using same

A welding wire for austenitic stainless steel welding contains, in percent by mass, C: 0.005 through 0.05%, Si: 0.1 through 1.0%, Mn: 1.0 through 3.5%, Cr: 25.0 through 28.0%, Ni: 16.0 through 23.9%, Mo: 1.6 through 3.0%, Cu: 0.1 through 0.5%, Al: 0.001 through 0.02%, and N: more than 0.30 through 0.50%, limiting O to 0.03% or less, P to 0.03% or less, and S to 0.005% or less, and having a ratio of a Cr equivalent to Ni equivalent (Cr equivalent/Ni equivalent) within a range between 0.85 and 1.2 and a PI value of 35 or more, the remainder being iron and unavoidable impurities.

Austenitic stainless steel welding wire and welding structure

A stainless steel wire having a flux core for welding zinc-based alloy coated steel sheet having an outer metal sheath coating a core of flux wherein in total having in mass (%) as percentage to the total mass of the wire: C: 0.01-0.05%, Si: 0.1-1.5%, Mn: 0.5-3.0%, Ni: 7.0-10.0%, Cr: 26.0-30.0%, wherein an F value defined as a function of the above components ranges from 30 to 50, the flux further having a slag formation agent in mass (%) as percentage to the total mass of the wire: TiO: 0.6-2.6%, SiO: 1.8-3.8%, ZrO: 1.0-3.5%, and optionally AlO: 0.1-1.0%, wherein the slag formation agent in total is less than 10%, and the wire further containing Fe and residual impurities.

Stainless steel wire with flux core for welding zinc coated steel sheets

Disclosed are a weld joint and a stainless steel-based weld metal composition for the weld joint. The composition and weld joint made therefrom are suitable for welding a zinc-based alloy coated steel sheet. The weld is excellent in corrosion resistance and liquid-metal embrittlement crack resistance. This is accomplished by inhibiting liquid-metal embrittlement cracks of the stainless-steel-based weld metal when the zinc-based alloy coating steel sheet is welded using the stainless-steel-based weld metal. The weld joint comprises a welded portion of weld metal made of stainless-steel-based components, the weld metal containing in mass percent (%): C: 0.01-0.1; Si: 0.1-1; Mn: 0.5-2.5; Ni: 5-11; and Cr: 17-25, and the balance being iron and residual impurities, wherein the following expression are met: &#x2212;0.81&#xd7;Cr equivalent+23.2&#x2266;Ni equivalent&#x2266;0.95&#xd7;Cr equivalent&#x2212;8.1 . . . (1); Ni equivalent=Ni+30&#xd7;C+0.5&#xd7;Mn+30&#xd7;N . . . (2); Cr equivalent=Cr+Mo+1.5&#xd7;Si . . . (3).

Weld joint formed with stainless steel-based weld metal for welding a zinc-based alloy coated steel sheet

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Tokyo, Japan

Manabu Mizumoto