Nippon Steel Corporation

Nippon Steel & Sumitomo Metal Corporation

Sumitomo Metal Industries, Inc.

Nippon Steel Stainless Steel Corporation

Takahiro Osuki

Kazuhiro Ogawa

Hirokazu Okada

Hiroyuki Hirata

Yoshitaka Nishiyama

Kana Jotoku

Tomohiko Omura

Jun Nakamura

Shohgo Aota

Masayuki Sagara

Shinnosuke Kurihara

Kenta Yamada

Yuhei Suzuki

Masahiro Seto

Etsuo Dan

Masaaki Igarashi

Satoshi Matsumoto

Tetsuo Yokoyama

Hiroyuki Semba

Shinji Tsuge

Yasuhiro Masaki

Kiyoko Takeda

Masaki Ueyama

Masaaki Terunuma

Yukihiro Nishida

Mitsuru Yoshizawa

Hiroyuki Anada

Masatoshi Toyoda

An austenitic stainless steel material is provided that has high creep strength even when used at an average operation temperature of more than 600 to 750° C. after welding with higher heat input, and furthermore, has excellent stress relaxation cracking resistance even after use for a long time period at the average operation temperature after welding with higher heat input. The steel material has a chemical composition which consists of, in mass %, C: 0.030% or less, Si: 1.50% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.0300% or less, Cr: 15.00 to 25.00%, Ni: 8.00 to 20.00%, N: 0.050 to 0.250%, Nb: 0.10 to 1.00%, Mo: 0.05 to 5.00%, and B: 0.0005 to 0.0100%, with the balance being Fe and impurities, and a ratio of the dissolved N amount (mass %) with respect to the content of N (mass %) in the steel material is 0.40 to 0.90.

Austenitic stainless steel material

An austenitic stainless steel material is provided that has excellent sensitization resistance properties even after use for a long time period at an average operation temperature of 400 to 700° C. after welding with higher heat input. The steel material of the present disclosure has a chemical composition which contains, in mass %, C: 0.020% or less, Si: 1.50% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.0300% or less, Cr: 15.00 to 25.00%, Ni: 9.00 to 20.00%, N: 0.05 to 0.15%, Nb: 0.1 to 0.8%, Mo: 0.10 to 4.50%, and W: 0.01 to 1.00%, and satisfies Formula (1). The content of Nb in a residue obtained by an extraction residue method is, in mass %, 0.050 to 0.267%, and the content of Cr in the residue is, in mass %, 0.125% or less.21.9Mo+5.9W−5.0≥0  (1).

Austenitic stainless steel material and welded joint

There is provided a duplex stainless steel tube including a chemical composition consisting of, in mass %, C: 0.008 to 0.030%, Si: 0.10 to 0.70%, Mn: 0.80 to 2.60%, P: 0.030% or less, S: 0.0001 to 0.0050%, O: 0.0004 to 0.0150%, Sn: 0.0001% or more to less than 0.0100%, Cu: 0.10 to 2.50%, Ni: more than 2.50 to 5.50% or less, Cr: 21.5 to 25.5%, Mo: 0.10 to 0.50%, N: 0.050 to 0.200%, Al: 0.200% or less, and optional elements, with the balance: Fe and impurities, wherein 4S+8O+Sn is 0.0040 to 0.0900, and 4S+Sn is 0.0180 or less.

Duplex stainless steel tube and welded joint

A high-Ni alloy having excellent weld-hot-cracking resistance includes, in mass %, Cr: 16-30%, Ni: 18-50%, Al: 0.01-1.0%, and Ti: 0.01-1.5%. In a first aspect of the invention, a relationship between number density of TiC precipitates having 1.0 μm or more of equivalent circle diameter and Mg content in steel satisfies formula (1) below. In a second aspect of the invention, S average concentration in oxide- and sulfide-inclusions is 0.70 mass % or more. In a third aspect of the invention, mass ratios of CaO, MgO, and AlOin inclusions, where O or S is detected, satisfy formula (2), the mass ratios being respectively calculated from average concentrations of Ca, Mg and Al in the inclusions, (1) number density of TiC (number of pieces/mm)≤463−9.5×Mg concentration in steel (mass ppm) and (2) [CaO−0.6×MgO] (mass %)/[CaO+MgO+AlO] (mass %)≥0.20.

High nickel alloy excellent in high welding temperature cracking resistance

An austenitic stainless steel, which consists of by mass percent, C: not more than 0.02%, Si: not more than 1.5%, Mn: not more than 2%, Cr: 17 to 25%, Ni: 9 to 13%, Cu: more than 0.26% not more than 4%, N: 0.06 to 0.35%, sol. Al: 0.008 to 0.03%. One or more elements selected from Nb, Ti, V, TA, Hf, and Zr in controlled amounts can be included with the balance being Fe and impurities. P, S, Sn, As, Zn, Pb and Sb among the impurities are controlled as P: 0.006 to 0.04%, S: 0.0004 to 0.03%, Sn: 0.001 to 0.1%, As: not more than 0.01%, Zn: not more than 0.01%, Pb: not more than 0.01% and Sb: not more than 0.01%. The amounts of S, P, Sn, As, Zn, Pb and Sb and the amounts of Nb, Ta, Zr, Hf, and Ti are further controlled using formulas.

Austenitic stainless steel

Provided is an austenitic stainless steel weld joint that is excellent in polythionic acid SCC resistance and naphthenic acid corrosion resistance, and is also excellent in creep ductility. An austenitic stainless steel weld joint includes a base material and a weld metal. The weld metal has a chemical composition at its width-center position and at its thickness-center position consisting of, in mass %, C: 0.050% or less, Si: 0.01 to 1.00%, Mn: 0.01 to 3.00%, P: 0.030% or less, S: 0.015% or less, Cr: 15.0 to 25.0%, Ni: 20.0 to 70.0%, Mo: 1.30 to 10.00%, Nb: 0.05 to 3.00%, N: 0.150% or less, and B: 0.0050% or less, with the balance: Fe and impurities.

Austenitic stainless steel weld joint

An austenitic stainless steel is provided which has a chemical composition that consists, by mass %, of: C: 0.015% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.05% or less, S: 0.030% or less, Cr: 16.0% or more and less than 22.0%, Ni: 11.0 to 16.0%, Mo: 2.5 to 5.0%, N: 0.07% or more and less than 0.15%, Nb: 0.20 to 0.50%, Al: 0.005 to 0.040%, Sn: 0 to 0.080%, Zn: 0 to 0.0060%, Pb: 0 to 0.030%, and the balance: Fe and impurities, and that satisfies the formula [Mo/Mo&#x2265;0.98] (Mo: Mo amount dissolved in the steel).

Austenitic stainless steel and production method therefor

A high-strength austenitic stainless steel, which has good hydrogen embrittlement resistance and hydrogen fatigue resistance, has a chemical composition including, in mass %, C: up to 0.10%; Si: up to 1.0%; Mn: not less than 3.0% and less than 7.0 %; Cr: 15 to 30%; Ni: not less than 12.0% and less than 17.0%; Al: up to 0.10%; N: 0.10 to 0.50%; P: up to 0.050%; S: up to 0.050%; at least one of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%; and other elements, the balance being Fe and impurities, wherein the ratio of the minor axis to the major axis of the austenite crystal grains is greater than 0.1, the crystal grain size number of austenite crystal grains is not lower than 8.0, and the tensile strength is not less than 1000 MPa.

Austenitic stainless steel and method of manufacturing the same

A welded joint having high strength and good hydrogen embrittlement resistance is provided. A welded joint is a welded joint obtained by welding a base material using a welding material. The base material has a chemical composition of, in mass %: C: 0.005 to 0.1%; Si: up to 1.2%; Mn: 2.5 to 6.5%; Ni: 8 to 15%; Cr: 19 to 25%; Mo: 0.01 to 4.5%; V: 0.01 to 0.5%; Nb: 0.01 to 0.5% Al: less than 0.05%; N: 0.15 to 0.45%; O: up to 0.02%; P: up to 0.05%; and S: up to 0.04%, and a balance being iron and impurities, and which satisfies Equation (1). The welding material has a chemical composition which satisfies Equations (1) and (2).Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6C&#x2265;29&#x2003;&#x2003;(1)0.31C+0.048Si&#x2212;0.02Mn&#x2212;0.056Cr+0.007Ni&#x2212;0.013Mo&#x2264;&#x2212;1.0&#x2003;&#x2003;(2)

Welded joint and method of manufacturing welded joint

There is provided an austenitic stainless steel having a high strength and an excellent hydrogen brittleness resistance and further having an excellent machinability. The austenitic stainless steel of the present embodiment has a chemical composition including: in mass %, C: 0.10% or less; Si: 1.0% or less; Mn: 2.1 to 6.0%; P: 0.045% or less; S: 0.1% or less; Ni: 8.0 to 16.0%; Cr: 15.0 to 30.0%; Mo: 1.0 to 5.0%; N: 0.05 to 0.45%; Nb: 0 to 0.50%; and V: 0 to 0.50%, with the balance being Fe and impurities, and satisfying Formula (1). The austenitic stainless steel of the present embodiment has a grain size number of less than 8.0 and a tensile strength of 690 MPa or more.15&#x2264;12.6C+1.05Mn+Ni+15N&#x2003;&#x2003;(1)

Austenitic stainless steel and method for producing the same

There is provided a carburization resistant metal material suitable as a raw material for cracking furnaces, reforming furnaces, heating furnaces, heat exchangers, etc. in petroleum and gas refining, chemical plants, and the like. This metal material consists of, by mass %, C: 0.03 to 0.075%, Si: 0.6 to 2.0%, Mn: 0.05 to 2.5%, P: 0.04% or less, S: 0.015% or less, Cr: higher than 16.0% and less than 20.0%, Ni: 20.0% or higher and less than 30.0%, Cu: 0.5 to 10.0%, Al: 0.15% or less, Ti: 0.15% or less, N: 0.005 to 0.20%, and O (oxygen): 0.02% or less, the balance being Fe and impurities. The metal material may further contain one kind or more kinds of Co, Mo, W, Ta, B, V, Zr, Nb, Hf, Mg, Ca, Y, La, Ce and Nd.

Carburization resistant metal material

There is provided a welding material used for welding of SUS310 stainless steel base metal that contains at least one of Nb and V and is excellent in intergranular corrosion resistance, the chemical composition of the welding material consisting, by mass percent, of C: 0.02% or less, Si: 2% or less, Mn: 2% or less, Cr: 26 to 50%, N: 0.15% or less, P: 0.02% or less, S: 0.002% or less, and Ni: a content percentage satisfying [5&#x2264;Ni&#x2264;Cr&#x2212;14], and the balance of Fe and impurities. Also, there is provided a welding joint of an austenitic stainless steel, which consists of the base metal and a weld metal formed by using the welding material.

Welding material and welding joint

A welding material, to be used for welding a base metal made of an austenitic alloy comprising C&#x2266;2.0%, Si&#x2266;4.0%, Mn: 0.01 to 3.0%, P: more than 0.03% to not more 0.3%, S&#x2266;0.03%, Cr: 12 to 35%, Ni: 6 to 80%, sol. Al: 0.001 to 1% and N&#x2266;0.3%, with the balance being Fe and impurities to a base metal made of another austenitic alloy, which comprises C: more than 0.3% to 3.0%, Si&#x2266;4.0%, Mn&#x2266;3.0%, P&#x2266;0.03%, S&#x2266;0.03%, Cr: more than 22% to 55%, Ni: more than 30% to not more than 70%, sol. Al: 0.001 to 1% and N&#x2266;0.3%, with the balance being Fe and impurities can suppress the weld solidification cracking which occurs in an austenitic alloy having a high P content and showing fully austenitic solidification. Therefore, the said welding material can be widely used in such fields where a welding fabrication is required. The said welding material may contain a specific amount or amounts of one or more elements selected from Cu, Mo, W, V, Nb, Ti, Ta, Zr, Hf, Co, B, Ca, Mg and REM.

Welding material and welded joint structure

An austenitic stainless steel welded joint, whose base metal and weld metal each comprises, by mass percent, C: not more than 0.3%, Si: not more than 2%, Mn: 0.01 to 3.0%, P: more than 0.04% to not more than 0.3%, S: not more than 0.03%, Cr: 12 to 30%, Ni: 6 to 55%, rare earth metal(s): more than 0.2% to not more than 0.6%, sol. Al: 0.001 to 3% and N: not more than 0.3%, with the balance being Fe and impurities, and satisfies the formula of (Cr+1.5&#xd7;Si+2&#xd7;P)/(Ni+0.31&#xd7;Mn+22&#xd7;C+14.2&#xd7;N+5&#xd7;P)&#x3c;1.388, in spite of having a high P content and showing the fully austenitic solidification, has excellent resistance to the weld solidification cracking. Therefore, the said austenitic stainless steel welded joint can be widely used in such fields where a welding fabrication is required. Each element symbol in the above formula represents the content by mass percent of the element concerned.

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Nishinomiya, Japan

Takahiro Osuki