Sumitomo Metal Industries, Inc.

Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Hiroyuki Semba

Masaaki Igarashi

Hirokazu Okada

Hiroyuki Hirata

Atsuro Iseda

Tomohiko Omura

Kazuhiro Ogawa

Mitsuo Miyahara

Jun Nakamura

Kaori Kawano

Yusaku Tomio

Osamu Miyahara

Masaaki Terunuma

Mitsuru Yoshizawa

Kazuhiro Shimoda

Tomio Yamakawa

Takahiro Osuki

Tomoaki Hamaguchi

Kazuhiko Ogawa

Kana Jotoku

Toshihide Ono

Katsuki Tanaka

Hirofumi Hori

Tsuneo Kondo

K Shimoda

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

There is provided an austenitic stainless steel for high-pressure hydrogen gas consisting, by mass percent, of C: 0.10% or less, Si: 1.0% or less, Mn: 3% or more to less than 7%, Cr: 15 to 30%, Ni: 10% or more to less than 17%, Al: 0.10% or less, N: 0.10 to 0.50%, and at least one kind of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%, the balance being Fe and impurities, wherein in the impurities, the P content is 0.050% or less and the S content is 0.050% or less, the tensile strength is 800 MPa or higher, the grain size number (ASTM E112) is No. 8 or higher, and alloy carbo-nitrides having a maximum diameter of 50 to 1000 nm are contained in the number of 0.4/&#x3bc;mor larger in cross section observation.

High-strength austenitic stainless steel for high-pressure hydrogen gas

A Ni-based alloy includes, as a chemical composition, C, Si, Mn, Cr, Mo, Co, Al, Ti, B, P, S, and a balance consisting of Ni and impurities. The average grain size d is 10 &#x3bc;m to 300 &#x3bc;m, when the average grain size d is an average grain size in unit of &#x3bc;m of a &#x3b3; phase included in a metallographic structure of the Ni-based alloy. Precipitates with a major axis of 100 nm or more are absent in the metallographic structure. An area fraction &#x3c1; is f2 or more, when the area fraction &#x3c1; and the f2 are expressed by using the average grain size d and amounts in mass % of each element in the chemical composition.

Ni-based alloy

A Ni-based heat resistant alloy as pipe, plate, rod, forgings and the like consists of C&#x2266;0.15%, Si&#x2266;2%, Mn&#x2266;3%, P&#x2266;0.03%, S&#x2266;0.01%, Cr: 15% or more and less than 28%, Mo: 3 to 15%, Co: more than 5% and not more than 25%, Al: 0.2 to 2%, Ti: 0.2% to 3%, Nd: fn to 0.08%, and O&#x2266;0.4Nd, further containing, as necessary, at least one kind of Nb, W, B, Zr, Hf, Mg, Ca, Y, La, Ce, Ta, Re and Fe of specific amounts, the balance being Ni and impurities, wherein, fn=1.7&#xd7;10d+0.05{(Al/26.98)+(Ti/47.88)+(Nb/92.91)}. In the formula, d denotes an average grain size (&#x3bc;m), and each element symbol denotes the content (mass %) of that element. If the alloy contains W, Mo+(W/2)&#x2266;15% holds. The alloy has improved ductility after long-term use at high temperatures, and cracking due to welding can be avoided.

Ni-based heat resistant alloy

An austenitic heat resistant alloy includes, by mass percent, C: 0.15% or less, Si: 2% or less, Mn: 3% or less, Ni: 40 to 60%, Co: 10.14 to 25%, Cr: 15% or more and less than 28%, either one or both of Mo: 12% or less and W: less than 0.05%, the total content thereof being 0.1 to 12%, Nd: 0.001 to 0.1%, B: 0.0005 to 0.006%, N: 0.03% or less, O: 0.03% or less, at least one selected from Al: 1.36% or less, Ti: 3% or less, and Nb: 3% or less, and the balance being Fe and impurities. The contents of P and S in the impurities are P: 0.03% or less and S: 0.01% or less. The alloy satisfies 1&#x2266;4&#xd7;Al+2&#xd7;Ti+Nb&#x2266;12 and P+0.2&#xd7;Cr&#xd7;B&#x2266;0.035, where an element in the Formulas represents the content by mass percent.

Austenitic heat resistant alloy

An austenitic heat resistant alloy, which comprises by mass percent, C: over 0.02 to 0.15%, Si&#x2266;2%, Mn&#x2266;3%, P&#x2266;0.03%, S&#x2266;0.01%, Cr: 28 to 38%, Ni: over 40 to 60%, Co&#x2266;20% (including 0%), W over 3 to 15%, Ti: 0.05 to 1.0%, Zr: 0.005 to 0.2%, Al: 0.01 to 0.3%, N&#x2266;0.02%, and Mo&#x3c;0.5%, with the balance being Fe and impurities, in which the following formulas (1) to (3) are satisfied has high creep rupture strength and high toughness after a long period of use at a high temperature, and further it is excellent in hot workability. This austenitic heat resistant alloy may contain a specific amount of one or more elements selected from Nb, V, Hf, B, Mg, Ca, Y, La, Ce, Nd, Sc, Ta, Re, Ir, Pd, Pt and Ag. P&#x2266;3/{200(Ti+8.5&#xd7;Zr)} . . . (1), 1.35&#xd7;Cr&#x2266;Ni+Co&#x2266;1.85&#xd7;Cr . . . (2), Al&#x2267;1.5&#xd7;Zr . . . (3).

Austenitic heat resistant alloy, heat resistant pressure member comprising the alloy, and method for manufacturing the same member

[Problem to be Solved] A Ni-based alloy product consisting of, by mass percent, C: 0.03 to 0.10%, Si: 0.05 to 1.0%, Mn: 0.1 to 1.5%, Sol.Al: 0.0005 to 0.04%, Fe: 20 to 30%, Cr: not less than 21.0% and less than 25.0%, W: exceeding 6.0% and not more than 9.0%, Ti: 0.05 to 0.2%, Nb: 0.05 to 0.35%, and B: 0.0005 to 0.006%, the balance being Ni and impurities, the impurities being P: 0.03% or less, S: 0.01% or less, N: less than 0.010%, Mo: less than 0.5%, and Co: 0.8% or less, wherein a value of effective B (Beff) defined by the formula, Beff (%)=B&#x2212;(11/14)&#xd7;N+(11/48)&#xd7;Ti, is 0.0050 to 0.0300%, and the rupture elongation in a tensile test at 700&#xb0; C. and at a strain rate of 10/sec is 20% or more. This alloy may contain one or more kinds of Cu, Ta, Zr, Mg, Ca, REM, and Pd.

Ni-based alloy product and producing method thereof

An austenitic stainless steel for use in a hydrogen gas atmosphere comprises, in mass %, C: 0.10% or less, Si: 1.0% or less, Mn: 0.01 to 30%, P: 0.040% or less, S: 0.01% or less, Cr: 15 to 30%, Ni: 5.0 to 30%, Al: 0.10% or less, N: 0.001 to 0.30% with the balance Fe and inevitable impurities. An X-ray (111) integration intensity of a cross section along the direction rectangular to the working direction is five times that in a random direction or less, and the X-ray integration intensity ratio of a cross section along the working direction satisfies I(220)/I(111)&#x2266;10. The high strength steel can also contain one or more of the groups of Mo and W; V, Nb, Ta, Ti, Zr and Hf; B; Cu and Co; Mg, Ca, La, Ce, Y, Sm, Pr and Nd.

Austenitic stainless steel for hydrogen gas and a method for its manufacture

Provided is a low alloy steel for high-pressure hydrogen gas environments, which contains, by mass percent, C: 0.15 to 0.60%, Si: 0.05 to 0.5%, Mn: 0.05 to 3.0%, P: not more than 0.025%, S: not more than 0.010%, Al: 0.005 to 0.10%, Mo: 0.5 to 3.0%, V: 0.05 to 0.30%, O (oxygen): not more than 0.01%, N: not more than 0.03%, and the balance Fe and impurities, and has tensile strength of not less than 900 MPa. This low alloy steel desirably contains B of 0.0003 to 0.003%, but in this case, N is limited to not more than 0.010%. It is desirable to contain at least one among Cr, Nb, Ti, Zr, and Ca. The contents of Mo and V desirably satisfy the following formula (1):[Mo(%)]&#xb7;[V(%)]&#x2267;0.32&#x2003;&#x2003;(1).

Low alloy steel for high-pressure hydrogen gas environment and container for high-pressure hydrogen

An austenitic heat resistant alloy, which contains, by mass percent, C&#x2266;0.15%, Si&#x2266;2%, Mn&#x2266;3%, Ni: 40 to 80%, Cr: 15 to 40%, W and Mo: 1 to 15% in total content, Ti&#x2266;3%, Al&#x2266;3%, N&#x2266;0.03%, O&#x2266;0.03%, with the balance being Fe and impurities, and among the impurities P&#x2266;0.04%, S&#x2266;0.03%, Sn&#x2266;0.1%, As&#x2266;0.01%, Zn&#x2266;0.01%, Pb&#x2266;0.01% and Sb&#x2266;0.01%, and satisfies the conditions [P1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5}&#x2266;0.050], [0.2&#x2266;P2=Ti+2Al&#x2266;7.5&#x2212;10&#xd7;P1], [P2&#x2266;9.0&#x2212;100&#xd7;O] and [N&#x2266;0.002&#xd7;P2+0.019] can prevent both the liquation crack in the HAZ and the brittle crack in the HAZ and also can prevent defects due to welding fabricability, which occur during welding fabrication, and moreover has excellent creep strength at high temperatures. Therefore, the alloy can be used suitably as a material for constructing high temperature machines and equipment, such as power generating boilers, plants for the chemical industry and so on. The ally may contain a specific amount or amounts of one or more elements selected from Co, B, Ta, Hf, Nb, Zr, Ca, Mg, Y, La, Ce and Nd.

A high strength, ductile, and tough Ni-base heat resistant alloy comprises by mass percent, C: 0.1% or less, Si: 1% or less, Mn: 1% or less, Cr: not less than 15% to less than 28%, Fe: 15% or less, W: more than 5% to not more than 20%, Al: more than 0.5% to not more than 2%, Ti: more than 0.5% to not more than 2%, Nd: 0.001 to 0.1% and B: 0.0005 to 0.01%, with the balance being Ni and impurities. Impurity contents of P, S, Sn, Pb, Sb, Zn and As are P: 0.03% or less, S: 0.01% or less, Sn: 0.020% or less, Pb: 0.010% or less, Sb: 0.005% or less, Zn: 0.005% or less and As: 0.005% or less, and formulas of [0.015&#x2266;Nd+13.4&#xd7;B&#x2266;0.13], [Sn+Pb&#x2266;0.025] and [Sb+Zn +As&#x2266;0.010] are met.

Ni-base heat resistant alloy

A high-strength stainless steel, having good mechanical properties and corrosion resistance in a high-pressure hydrogen gas environment, is used as a container or other device for high-pressure hydrogen gas, and consists of, by mass %, C: not more than 0.04%, Si: not more than 1.0%, Mn: 7 to 30%, Cr: 15 to 22%, Ni: 5 to 20%, V: 0.001 to 1.0%, N: 0.20 to 0.50% and Al: not more than 0.10%, and the balance Fe and impurities. Among the impurities, P is not more than 0.030%, S is not more than 0.005%, and Ti, Zr and Hf are not more than 0.01% respectively, and the contents of Cr, Mn and N satisfy the relationship, 2.5Cr+3.4Mn&#x2266;300N. The weld metal of the welded joint of the container or other device made of the said stainless steel satisfies the relationship, &#x2212;11&#x2266;Nieq&#x2212;1.1&#xd7;Creq&#x2266;&#x2212;8.

Stainless steel for high-pressure hydrogen gas

A high-strength stainless steel, having good mechanical properties and corrosion resistance in a high-pressure hydrogen gas environment, and excellent in stress corrosion cracking resistance, and a container or other device for high-pressure hydrogen gas, which is made of the said stainless steel, are provided. The stainless steel is characterized in that it consists of, by mass %, C: not more than 0.02%, Si: not more than 1.0%, Mn: 3 to 30%, Cr: more than 22% but not more than 30%, Ni: 17 to 30%, V: 0.001 to 1.0%, N: 0.10 to 0.50% and Al: not more than 0.10%, and the balance Fe and impurities. Among the impurities, P is not more than 0.030%, S is not more than 0.005%, and Ti, Zr and Hf are not more than 0.01% respectively, and the contents of Cr, Mn and N satisfy the following relationship [1]:5Cr+3.4 Mn&#x2266;500 N&#x2003;&#x2003;[1].

A weld joint having a base material and a weld metal both of an austenitic steel, wherein the weld metal has a chemical composition, in mass %, that C: 0.04% or less, Si: 1.0% or less, Mn: 3% or less, P: 0.02% or less, S: 0.005% or less, Cr: 15 to 25%, Ni: 30% or more, Mo: 10% or less, Nb: 2.5 to 5%, Al: 3.0% or less, Ti: 0.5% or less, and the balance: Fe and inevitable impurities, the contents of Al and Ti satisfying the following: (Ti+Al)&#x3e;Nb/8. The weld joint is a high strength austenitic steel weld joint which exhibits excellent toughness at a low temperature and excellent resistance to hydrogen embrittlement, which are required for a piping and a vessel for high pressure hydrogen, particularly also in a welded zone.

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Sanda, Japan

Hiroyuki Semba