Nippon Steel & Sumikin Stainless Steel Corporation

Ryo Matsuhashi

Hiroshige Inoue

Shinji Tsuge

Yuusuke Oikawa

Shigeo Fukumoto

Kazuhiro Suetsugu

Ryuichi Honma

Manabu Mizumoto

Hiroshi Urashima

Yusuke Oikawa

A nitrogen-rich two-phase stainless steel that has corrosion resistance equal to that of standard type of two-phase stainless steel and is not susceptible to corrosion in a welding heat-affected part, wherein the austenite phase area ratio is 40-70%, the PI value expressed by formula (1) is 30-38, the NI value expressed by formula (2) is 100-140, and the &#x3b3;pre expressed by formula (3) is 1350-1450. (1) PI=Cr+3.3Mo+16N (2) NI=(Cr+Mo)/N.

Duplex stainless steel superior in corrosion resistance of weld

The present invention provides a lean duplex stainless steel able to suppress the drop in corrosion resistance and toughness of a weld heat affected zone comprising, by mass %, C: 0.06% or less, Si: 0.1 to 1.5%, Mn: 2.0 to 4.0%, P: 0.05% or less, S: 0.005% or less, Cr: 19.0 to 23.0%, Ni: 1.0 to 4.0%, Mo: 1.0% or less, Cu: 0.1 to 3.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25%, and Ti: 0.05% or less, having a balance of Fe and unavoidable impurities. An Md30 value is 80 or less, an Ni-bal is &#x2212;7.1 to 4, an austenite phase area percentage is 40 to 70%, and a 2&#xd7;Ni+Cu is 3.5 or more: Md30=551&#x2212;462&#xd7;(C+N)&#x2212;9.2&#xd7;Si&#x2212;8.1&#xd7;Mn&#x2212;29&#xd7;(Ni+Cu)&#x2212;13.7&#xd7;Cr&#x2212;18.5&#xd7;Mo&#x2212;68&#xd7;Nb; Ni-bal=(Ni+0.5Mn+0.5Cu+30C+30N)&#x2212;1.1(Cr+1.5Si+Mo+W)+8.2 and N(%)&#x2266;0.37+0.03&#xd7;(Ni-bal).

Lean duplex stainless steel excellent in corrosion resistance and toughness of weld heat affected zone

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

An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, &#x3b4; cal [=2.9 (Cr+0.3Si+Mo+0.5W)&#x2212;2.6 (Ni+0.3Mn+0.25Cu+35C+20N)&#x2212;18] ranges from &#x2212;6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at &#x2212;40&#xb0; C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50&#xb0; C. (Vc'100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Austenite-type stainless steel hot-rolling steel material with excellent corrosion resistance, proof-stress, and low-temperature toughness and production method thereof

An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, &#x3b4; cal [=2.9(Cr+0.3Si+Mo+0.5W)&#x2212;2.6(Ni+0.3Mn+0.25Cu+35C+20N)&#x2212;18] ranges from &#x2212;6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at &#x2212;40&#xb0; C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50&#xb0; C. (Vc'100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Growing community of inventors

Tokyo, Japan

Ryo Matsuhashi