Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Kana Jotoku

Hiroyuki Hirata

Katsuki Tanaka

Takahiro Osuki

Hirokazu Okada

Shinnosuke Kurihara

Tomohiko Omura

Jun Nakamura

Toshihide Ono

Yuhei Suzuki

Tomoaki Hamaguchi

Kenta Yamada

Yoshitaka Nishiyama

Hiroyuki Semba

Atsuro Iseda

Masaki Ueyama

Masaaki Terunuma

Shohgo Aota

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

A method of producing a ferritic heat-resistant steel welded joint, the method including: a multi-layer welding step in which a ferritic heat-resistant steel base material including B at 0.006% by mass to 0.023% by mass is multi-layer welded using a Ni-based welding material for heat-resistant alloy, wherein root pass welding is performed under a welding condition such that a ratio of an area [S] that has been melted of the ferritic heat-resistant steel base material to an area [S] of a weld metal, in a transverse cross-section of a weldment after the root pass welding but before second pass welding in the multi-layer welding step, satisfies the following formula (1): 0.1&#x2264;[S]/[S]&#x2264;&#x2212;50&#xd7;[% B]+1.3, with respect to a mass percent of B, [% B], which is included in the ferritic heat-resistant steel base material.

Method of producing ferritic heat-resistant steel welded joint

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

A austenitic stainless steel which has a chemical composition consisting of, by mass %, C: 0.04 to 0.12%, Si: 0.25 to 0.55%, Mn: 0.7 to 2.0%, P: 0.035% or less, S: 0.0015% or less, Cu: 0.02 to 0.80%, Co: 0.02 to 0.80%, Ni: 10.0 to 14.0%, Cr: 15.5 to 17.5%, Mo: 1.5 to 2.5%, N: 0.01 to 0.10%, Al: 0.030% or less, O: 0.020% or less, Sn: 0 to 0.01%, Sb: 0 to 0.01%, As: 0 to 0.01%, Bi: 0 to 0.01%, V: 0 to 0.10%, Nb: 0 to 0.10%, Ti: 0 to 0.10%, W: 0 to 0.50%, B: 0 to 0.005%, Ca: 0 to 0.010%, Mg: 0 to 0.010% and REM: 0 to 0.10%, with the balance being Fe and impurities, and satisfying [18.0&#x2264;Cr+Mo+1.5&#xd7;Si&#x2264;20.0] and [14.5&#x2264;Ni+30&#xd7;(C+N)+0.5&#xd7;(Mn+Cu+Co)&#x2264;19.5].

Austenitic stainless steel

A austenitic stainless steel weld metal which has a chemical composition consisting of, by mass %, C: 0.01 to 0.10%, Si: 0.20 to 0.70%, Mn: 0.8 to 2.5%, P: 0.035% or less, S: 0.0030% or less, Cu: 0.01 to 0.60%, Co: 0.01 to 1.00%, Ni: 8.0 to 12.0%, Cr: 14.5 to 17.5%, Mo: 1.0 to 2.2%, N: 0.02 to 0.10%, Al: 0.030% or less, O: 0.020% or less, Sn: 0 to 0.01%, Sb: 0 to 0.01%, As: 0 to 0.01%, Bi: 0 to 0.01%, V: 0 to 0.10%, Nb: 0 to 0.10%, Ti: 0 to 0.10%, W: 0 to 0.50%, B: 0 to 0.005%, Ca: 0 to 0.010%, Mg: 0 to 0.010% and REM: 0 to 0.10%, with the balance being Fe and impurities, and satisfying [17.5&#x2264;Cr+Mo+1.5&#xd7;Si&#x2264;19.5] and [11.0&#x2264;Ni+30&#xd7;(C+N)+0.5&#xd7;(Mn+Cu+Co)&#x2264;17.0].

Austenitic stainless steel weld metal and welded structure

The present invention provides a welding material for ferritic heat-resistant steel, a welded joint for ferritic heat-resistant steel, and a method for producing the welded joint for to form a weld metal having a high creep strength and a high toughness in welding a ferritic heat-resistant steel that contains B. The welding material for ferritic heat-resistant steel has a chemical composition containing, in mass %, C: 0.06 to 0.10%, Si: 0.1 to 0.4%, Mn: 0.3 to 0.7%, Co: 2.6 to 3.4%, Ni: 0.01 to 1.10%, Cr: 8.5 to 9.5%, W: 2.5 to 3.5%, Nb: 0.02 to 0.08%, V: 0.1 to 0.3%, Ta: 0.02 to 0.08%, B: 0.007 to 0.015%, N: 0.005 to 0.020%, with the balance being Fe and impurities, and satisfying Formula (1):0.5&#x2264;Cr+6Si+1.5W+11V+5Nb+10B&#x2212;40C&#x2212;30N&#x2212;4Ni&#x2212;2Co&#x2212;2Mn&#x2264;10.0&#x2003;&#x2003;(1).

Welding material for ferritic heat-resistant steel, welded joint for ferritic heat-resistant steel, and method for producing welded joint for ferritic heat-resistant steel

An austenitic stainless steel weld metal which has a chemical composition consisting of, by mass %, C: 0.05 to 0.11%, Si: 0.10 to 0.50%, Mn: 1.0 to 2.5%, P: 0.035% or less, S: 0.0030% or less, Co: 0.01 to 1.00%, Ni: 9.0 to 11.5%, Cr: 17.0 to 21.0%, Nb: 0.60 to 0.90%, Ta: 0.001 to 0.100%, N: 0.01 to 0.15%, Al: 0.030% or less, O: 0.020% or less, V: 0 to 0.10%, Ti: 0 to 0.10%, W: 0 to 0.50%, Mo: 0 to 0.50%, Cu: 0 to 0.50%, B: 0 to 0.005%, Ca: 0 to 0.010%, Mg: 0 to 0.010% and REM: 0 to 0.10%, with the balance being Fe and impurities, and satisfying [Nb&#x2212;7.8&#xd7;C&#x2264;0.25].

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

A high Cr austenitic stainless steel with a chemical composition consisting of in terms of % by mass, 0.03 to 0.12% of C, 0.10 to 1.00% of Si, 0.10 to 3.00% of Mn, 0.030% or less of P, 0.020% or less of S, 21.50 to 28.00% of Cr, more than 26.00 and not more than 35.00% of Ni, more than 2.00 and not more than 5.00% of W, 0.80% or less of Co, 0.01 to 0.70% of V, 0.15 to 1.00% of Nb, 0.001 to 0.040% of Al, 0.0001 to 0.0100% of B, 0.010 to 0.400% of N, 0.001 to 0.200% of Zr, 0.001 to 0.200% of Nd, 0.001 to 0.200% of Ta, 0.020 to 0.200% of Ta+0.8Nd+0.5Zr, 0.025% or less of Ti+Sn+Sb+Pb+As+Bi, 0.0090% or less of O, and a remainder consisting of Fe and impurities.

High Cr-based austenitic stainless steel

A welded joint is obtained by using a welding material having a composition: Cr: 15.0 to 30.0%; and Ni: 40.0 to 70.0%, including: a base material having a composition: C: 0.03 to 0.075%; Si: 0.6 to 2.0%; Mn: 0.05 to 2.5%; P: up to 0.04%; S: up to 0.015%; Cr: more than 16.0% and less than 23.0%; Ni: not less than 20.0% and less than 30.0%; Cu: 0.5 to 10.0%; Mo: less than 1%; Al: up to 0.15%; N: 0.005 to 0.20%; O: up to 0.02%; Ca: 0 to 0.1%; REM: 0 to 0.15%; V: not less than 0% and less than 0.5%; and Nb: 0 to 2%, a balance being Fe and impurities and a first-layer weld metal including Fe content from 10 to 40%, all % by mass.

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Tokyo, Japan

Kana Jotoku