EP0708184A1 - Acier thermoresitant austenitique a resistance elevee presentant une excellente soudabilite et une bonne resistance a la corrosion a haute temperature - Google Patents

Acier thermoresitant austenitique a resistance elevee presentant une excellente soudabilite et une bonne resistance a la corrosion a haute temperature Download PDF

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Publication number
EP0708184A1
EP0708184A1 EP94914608A EP94914608A EP0708184A1 EP 0708184 A1 EP0708184 A1 EP 0708184A1 EP 94914608 A EP94914608 A EP 94914608A EP 94914608 A EP94914608 A EP 94914608A EP 0708184 A1 EP0708184 A1 EP 0708184A1
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EP
European Patent Office
Prior art keywords
corrosion resistance
temperature corrosion
content
strength
austenitic heat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP94914608A
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German (de)
English (en)
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EP0708184A4 (fr
Inventor
Hiroyuki Nippon Steel Corp. MIMURA
Masao Nippon Steel Corp. KIKUCHI
Satoshi Nippon Steel Corp. Hikari Works ARAKI
Hisashi Nippon Steel Corp. NAOI
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Nippon Steel Corp
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Nippon Steel Corp
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Publication date
Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
Publication of EP0708184A1 publication Critical patent/EP0708184A1/fr
Publication of EP0708184A4 publication Critical patent/EP0708184A4/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent

Definitions

  • thermal power plants are planning extra super critical temperature boilers with high-temperature, high-pressure steam conditions.
  • high-strength steels developed for withstanding use in such harsh environments include austenitic heat-resistant steels utilizing precipitation strengthening by carbo-nitrides of Nb, Ti and the like and solution strengthening by Mo.
  • the object of this invention is to provide an austenitic heat-resistant steel that exhibits good weldability and is excellent in high-temperature strength and high-temperature corrosion resistance property.
  • the inventors conducted various experiments regarding steel added with Mo and W in order to offset by solution strengthening the loss of high-temperature strength caused by reduction of C content and, as a result, succeeded in developing a heat-resistant steel which maintains high-temperature strength at a low C content while also securing high-temperature corrosion resistance property.
  • the gist of this invention is as follows:
  • Figure 1 is a graph showing the effect of Mo and W on the high-temperature corrosion resistance property of 20 Cr - 25 Ni steel.
  • Si not only is effective as a deoxidizing agent but is also an element which improves oxidation resistance and high-temperature corrosion resistance property, but an excessive Si content reduces creep rupture strength, toughness and weldability.
  • the upper limit is therefore set at 1.5%.
  • Mn is an element which has deoxidizing activity and improves weldability and hot workability.
  • the lower limit of Mn is set at 0.3%. Since an excessive Mn content degrades oxidation resistance, however, the upper limit is set to 1.5%.
  • Cr is an indispensable element for oxidation resistance, water vapor oxidation resistance and high-temperature corrosion resistance property.
  • the lower limit of Cr content is set at 18%, which is the same as the Cr content of austenitic stainless steels.
  • the upper limit is set at 26%.
  • Ni is an element required for increasing the stability of the austenite and suppressing formation of an intermetallic compound ⁇ phase.
  • An Ni content of not less than 20% is necessary for ensuring stability of the austenite against the content of Cr and other ferrite forming elements.
  • the Ni content is set at 20 - 40%.
  • Mo and W are both elements which markedly increase high-temperature strength as by entering solid solution. Neither has much effect when added at less than 0.5%, while addition of W at more than 10% leads to precipitation of intermetallic compounds such as Laves phase and reduces creep rupture ductility.
  • Mo is added alone, the high-temperature corrosion resistance property worsens as the Mo content increases.
  • tests show that adding W alone does not degrade the high-temperature corrosion resistance property and that adding it in combination with Mo improves the high-temperature corrosion resistance property over that of a steel added with Mo alone. Therefore, W is always added, and the range thereof is set at 0.5 - 10%. As Mo in particular degrades the high-temperature corrosion resistance property when added in excess of 2.0%, even when added in combination with W, it is added, when required, at 0.5 - 2.0%.
  • Nb and Ti markedly improve long-term creep rupture strength by forming minute carbo-nitrides. Since this effect is not obtained when the Nb content is less than 0.05% or the Ti content is less than 0.01%, the lower limits of Nb and Ti content are set at 0.05% and 0.01%. Although the aforesaid effect becomes more pronounced as the content of Nb and Ti soluble at the solid solution treatment temperature increases, adding Nb and Ti in excess of the solution limit degrades the creep rupture strength owing to the undissolved carbo-nitrides that remain. Therefore, the upper limits of Nb and Ti content are set at 0.4% and 0.2%, and for increasing the solid solution (Nb + Ti) content within these ranges, Nb and Ti are added in combination.
  • B is an element which has the effect of enhancing intergranular strength and increasing creep rupture strength. However, since this effect is small at less than 0.003% and a content exceeding 0.008% degrades weldability and hot workability, the B content range is set at 0.003 - 0.008%.
  • N is an element which markedly improves creep rupture strength by solution strengthening and formation of nitrides.
  • N cannot offset the loss of strength resulting from the reduction of C content for improving weldability, while addition at more than 0.3% produces little increase in long-term creep rupture strength but degrades toughness. Therefore, the N content range is set at 0.05 - 0.3%.
  • Table 1 and Table 2 (continued from Table 1) show the chemical compositions and material properties of tested steel specimens. After solution treatment at 1250°C , these steels were subjected to creep rupture test at 700 and 750°C and to high-temperature corrosion test at 700°C . The creep rupture strength data was organized using the Larson-Miller method for estimating the 700°C x 100,000 h rupture strength.
  • a - J are invention steels and K - U are comparison steels.
  • K corresponds to the widely used SUS347H.
  • the invention steels have high-temperature strengths and high-temperature corrosion resistance properties that are very superior in comparison with the SUS347H steel.
  • L - O are examples having low high-temperature strength because they contain neither Mo or W and their Nb or B content is outside the range of the invention.
  • P - U are examples with relatively high high-temperature strength but having poor high-temperature corrosion resistance property notwithstanding addition of Mo alone or in combination with W, owing to large Mo content.
  • Figure 1 shows the effect of Mo and W on the high-temperature corrosion resistance property of 20 Cr - 25 Ni steel. While corrosion weight loss is large when Mo is added alone ( ⁇ in the drawing), it will be noted that the high-temperature corrosion resistance property is improved when W is added in combination at 1.5% ( ⁇ in the figure). It can further be seen that the corrosion weight loss does not change when W is added alone ( ⁇ in the figure).
  • This invention enables realization of an austenitic heat-resistant steel that is excellent in weldability and secures high-temperature strength and high-temperature corrosion resistance property. It facilitates application of high-strength steel to high-temperature, high-pressure boilers and enables a reduction of implementation cost.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
EP94914608A 1993-05-13 1994-05-12 Acier thermoresitant austenitique a resistance elevee presentant une excellente soudabilite et une bonne resistance a la corrosion a haute temperature Withdrawn EP0708184A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP5111957A JPH06322488A (ja) 1993-05-13 1993-05-13 溶接性に優れ、耐高温腐食特性が良好な高強度オーステナイト系耐熱鋼
JP111957/93 1993-05-13
PCT/JP1994/000767 WO1994026947A1 (fr) 1993-05-13 1994-05-12 Acier thermoresitant austenitique a resistance elevee presentant une excellente soudabilite et une bonne resistance a la corrosion a haute temperature

Publications (2)

Publication Number Publication Date
EP0708184A1 true EP0708184A1 (fr) 1996-04-24
EP0708184A4 EP0708184A4 (fr) 1996-07-03

Family

ID=14574397

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94914608A Withdrawn EP0708184A4 (fr) 1993-05-13 1994-05-12 Acier thermoresitant austenitique a resistance elevee presentant une excellente soudabilite et une bonne resistance a la corrosion a haute temperature

Country Status (4)

Country Link
EP (1) EP0708184A4 (fr)
JP (1) JPH06322488A (fr)
CA (1) CA2162704A1 (fr)
WO (1) WO1994026947A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1445342A1 (fr) * 2003-01-29 2004-08-11 Sumitomo Metal Industries, Ltd. Acier inoxydable austénitique et son procédé de fabrication
US7815848B2 (en) * 2006-05-08 2010-10-19 Huntington Alloys Corporation Corrosion resistant alloy and components made therefrom
EP3100818A4 (fr) * 2014-01-27 2017-10-11 Nippon Steel & Sumitomo Metal Corporation Matériau de soudage pour alliage résistant à la chaleur à base de ni, métal soudé à l'aide de ce matériau, et raccord soudé

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2185624A1 (fr) * 1995-10-17 1997-04-18 John H. Culling Alliage tenace soudable refractaire
CN100406608C (zh) * 2005-04-18 2008-07-30 张光华 超强型耐热钢
JP5670103B2 (ja) * 2010-06-15 2015-02-18 山陽特殊製鋼株式会社 高強度オーステナイト系耐熱鋼
JP5661001B2 (ja) * 2011-08-23 2015-01-28 山陽特殊製鋼株式会社 時効後靭性に優れた高強度オーステナイト系耐熱鋼
JP5930635B2 (ja) * 2011-09-26 2016-06-08 山陽特殊製鋼株式会社 優れた高温強度を有するオーステナイト系耐熱鋼とその製造方法
JP5273266B2 (ja) * 2012-02-08 2013-08-28 新日鐵住金株式会社 二重管およびそれを用いた溶接構造体
JP6955322B2 (ja) * 2016-03-15 2021-10-27 山陽特殊製鋼株式会社 加工性、高温強度および時効後の靱性に優れたオーステナイト系耐熱鋼
CN114032434B (zh) * 2021-10-27 2023-09-26 江苏金合特种合金材料有限公司 高耐蚀n08120材料冶炼及大口径无缝管生产工艺
CN115505820B (zh) * 2022-09-15 2024-01-05 山西太钢不锈钢股份有限公司 一种含铌高氮镍基合金的连铸方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5681661A (en) * 1979-12-06 1981-07-03 Daido Steel Co Ltd Heat resistant cast alloy
JPS56105458A (en) * 1980-01-25 1981-08-21 Daido Steel Co Ltd Heat-resistant cast alloy
JPS6333549A (ja) * 1986-07-29 1988-02-13 Nippon Kokan Kk <Nkk> 耐石炭灰腐食ボイラ用オ−ステナイト鋼管およびその製造法
JPH0753898B2 (ja) * 1987-01-24 1995-06-07 新日本製鐵株式会社 高強度オ−ステナイト系耐熱合金
JP2510206B2 (ja) * 1987-07-03 1996-06-26 新日本製鐵株式会社 Ｓｉ含有量の少ない高強度オ−ステナイト系耐熱鋼

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1445342A1 (fr) * 2003-01-29 2004-08-11 Sumitomo Metal Industries, Ltd. Acier inoxydable austénitique et son procédé de fabrication
US6939415B2 (en) 2003-01-29 2005-09-06 Sumitomo Metal Industries, Ltd. Austenitic stainless steel and manufacturing method thereof
US7815848B2 (en) * 2006-05-08 2010-10-19 Huntington Alloys Corporation Corrosion resistant alloy and components made therefrom
EP3100818A4 (fr) * 2014-01-27 2017-10-11 Nippon Steel & Sumitomo Metal Corporation Matériau de soudage pour alliage résistant à la chaleur à base de ni, métal soudé à l'aide de ce matériau, et raccord soudé

Also Published As

Publication number Publication date
CA2162704A1 (fr) 1994-11-24
WO1994026947A1 (fr) 1994-11-24
JPH06322488A (ja) 1994-11-22
EP0708184A4 (fr) 1996-07-03

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