US3795509A - Austenitic steel of the cr-ni-mn group - Google Patents

Austenitic steel of the cr-ni-mn group Download PDF

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Publication number
US3795509A
US3795509A US00105096A US3795509DA US3795509A US 3795509 A US3795509 A US 3795509A US 00105096 A US00105096 A US 00105096A US 3795509D A US3795509D A US 3795509DA US 3795509 A US3795509 A US 3795509A
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steel
sus
strength
niobium
tantalum
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US00105096A
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T Mimino
K Kinoshita
T Shinoda
I Minegishi
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JFE Engineering Corp
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Nippon Kokan Ltd
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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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

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  • the steels being used in Japan where high strength at high temperatures is required are SUS 29 (similar to AISI 321), SUS 32 (similar to AISI 316) and SUS 28 (similar to AISI304L) and Japanese Industrial Standard SUS 27 (similar to USA. AISI304).
  • SUS 32 steel contains 2 to 3% molybdenum, high temperature strength can be obtained with these metals; however, they are expensive as materials.
  • SUS 27 steel and SUS 28 steel are cheaper than said SUS 29 steel and SUS 32 steel, they are inferior in high temperature strength and therefore they cannot be used Where high temperature strength is especially required. Consequently, the expensive SUS 29 steel or SUS 32 steel are used.
  • boilers tend to be used at higher temperatures and in greater sizes, it is necessary that the materials to be used should be much cheaper as well as stronger than SUS 29 steel and SUS 32 steel. Such requirements are encountered not only in the field of boilers but also in other fields which need high temperature strength.
  • the Cr-Ni-Mn group is used with a great quantity of nitrogen in order to stabilize austenitic phase as well as a substantial quantity of costly additional elements such as molybdenum, titanium, vanadium, niobium, Wolfram and so forth, to heighten high temperature strength. Consequently, material costs will be higher and also the long-time creep rupture strength tends to be lower, on account of the great content of nitrogen.
  • FIG. 1 is a diagram which compares in creep rupture strength the austenitic steels of the Cr-Ni-Mn Group in accordance with the present invention with the austenitic steel of the Cr-Ni-Mn Group containing none of the additional elements and SUS 27 steel, SUS 29 steel and SUS 32 steel which are used as high temperature and high pressure steels;
  • FIG. 2 is a diagram which compares in creep rupture strength the austenitic steels of the Cr-Ni-Mn Group with the austenitic steel of the Cr-Ni-Mn Group without boron in the additional elements and SUS 27 steel, SUS 29 steel and SUS 32 steel; and
  • FIG. 3 is a diagram which compares in creep rupture strength the austenitic steels of the Cr-Ni-Mn Group with the austenitic steel of Cr-Ni-Mn Group without vanadium in the additional elements and SUS 27 steel, SUS 29 steel and SUS 32 steel.
  • this invention relates to modified austenitic steels, the basic composition of which is' Cr-Ni-Mn; the chemical composition is essentially as follows:
  • Chromium 15.0 to 21.0% (preferably 17.0 to 19.0%)
  • Nickel 4.0 to 15.0% (preferably 5.0 to 8.0%)
  • Titanium 0.001 to 0.51% (preferably 0.01 to 0.2%)
  • Niobium and/or tantalum 0.001 to 0.50% (preferably The balance is composed of iron with some impurity. In other modifications, boron or vanadium are added, with the niobium and/or tantalum.
  • titanium, niobium and/ or tantalum are included, if titanium only or niobium and/or tantalum only. are added, it is impossible to avoid the coalescence of carbide precipitating by the mutual action of carbide, thereby lowering the long time strength.
  • titanium and niobium and/ or tantalum act on one another to avoid the coalescence so that a uniform and fine carbide distribution can be efficiently effected.
  • the reason for the adoption of the above mentioned composition range is that if chromium is less than 15.0%, the oxidation resistance will be poor and if it is more than 21.0%, the delta will appear as a consequence of balance with other elements so that a single austenitic phase is difiicult to obtain, so around 17.0 to 19.0% is optimal. If nickel is below 4.0%, it is impossible to obtain the single austenitic phase and if more than 15.0%, it will be economically disadvantageous; around 5.0 to 8.0% is preferable. Further, as to manganese if it is less than 4.0%, the delta phase appears in case nickel is low, so that it is diflicult to obtain the single austenitic phase; besides the strength at high temperature'is reduced.
  • the manganese content is too high, the delta phase is easy to appear; the most suitable range is around 6.0 to 10.0%.
  • the titanium content is more than 0.5%, the titanium carbide becomes too high, they cause coalescence and if used for a long time at high temperature the strength is reduced by the coarsening of carbide particles, and if it is below 0.001%, the titanium carbide quantity is too low so that it does not contribute to improvement of the strength. So, the most desirable range is around 0.01 to 0.20%.
  • niobium and tantalum are below 0.001%, since niobium and/or tantalum carbide quantities are lower, no elfect thereof will appear. On the other hand, if they are more than 0.50%, there is too much precipitated carbide of niobium and tantalum, and they cause coalescence so that it lowers the high temperature strength; the optimal range is around 0.05 to. 0.30%. Concerning carbon, if it is below 0.03%, there is a little quantity of precipitated carbide and if more than 0.3%, there is too much, conversely, causing to lower the long time creep rupture strength.
  • Table I shows chemical compositions embodying this invention.
  • Table II shows the result of creep rupture strength tests performed on the above mentioned 4 kinds of steels after they are melted and subjected to the appropriate conditions at each of the temperatures of 600 C., 650 C. and 700 C., respectively, during 10 hr. and 10 hr.
  • Table HI shows a chemical composition of austenitic steel of the Cr-Ni-Mn Group which contains no added titanium, niobium or tantalum;
  • Table IV shows creep rupture strength at each of the temperatures, 600 0., 650 C. and 700 C. during hr. and 10 hr.
  • Table V shows the result of creep rupture strength tests performed on the conventional SUS 27. steel, SUS 29 steel, and SUS 32 steel at each of the temperatures, 600 C., 650 C. and 700 C., during 10 hr. and 10 hr.
  • FIG. 1 diagrams the results in Tables II, IV and V; it is evident that the creep rupture strength of No. 5 (Cr-Ni-Mn steel containing no titanium, niobium or tantalum) is equal or inferior to the presently used SUS steel 27, SUS steel 29 and SUS steel 32, while those of No. 1, No. 2, No. 3 and No. 4 of this invention have more than twice as great a creep rupture strength as SUS 27 steel, and about 1.5 times as much as that of SUS steel 32.
  • No. 5 Cr-Ni-Mn steel containing no titanium, niobium or tantalum
  • this invention improves the unsatisfactory high temperature strength of the conventional steel. More over, the high temperature strength can be even further improved by adding a small quantity of boron and/or vanadium to the above-mentioned addition elements namely titanium, niobium and/ or tantalum.
  • the quantity of boron should be 0.0001 to 0.050%, preferably 0.001 to 0.02%, and, of vanadium, 0.001 to 1.0%, preferably 0.01 to 0.1%.
  • this boron addition can provide distribution of a uniform and fine carbide owing to multiplying action of titanium and tantalum.
  • chromium carbide is precipitated and distributed around these titanium, niobium and tantalum carbides
  • the presence of boron avoids chromium carbide from coalescing, thereby distributing it uniformly, also boron itself combines with carbon to contribute to improvement of high temperature strength.
  • boron is used within the above composition range, because if it 7 is below 0.0001%, its effect cannot be perceived and if more than 0.050%, difiiculties arise with respect to plasticity and processing.
  • vanadium is the same as that of boron.
  • the reason why it should be present within the above composition range is that if it is below 0.001%, the effect cannot be perceived, and if more than 1.0%, too much vanadium carbide will form and it will coalesce itself, lowering the strength for long-time use; moreover, it is not economically advantageous to add too much.
  • Table VI shows the chemical composition with addition of boron.
  • present invention ubstantially improves the tem- 3L6 2m 22 2M 1&6 15 perature strength which was unsatisfactory with the con- 7 7 ventional steel. Moreover, it is oxidation resistant and 33:3 32:3 23;? lg: ⁇ :12 free of difficulty, with respect to plasticity and weldability. As to its price, part of the costly nickel is replaced with cheaper manganese, and only small quantities of 20 titanium, niobium and/or tantalum and further small quantities of boron or vanadium are added, so that lowering of price results. Consequently, it can be utilized in all The results of the comparative tests run on these steels the fields Where high Strength and Oxidation resistance are listed in Table VII and No.
  • tantalum and niobium are difiicult to distinguish in the usual types of analyses 'of these elements, and to simplify matters only half of the tantalum content is taken instead of one quarter.
  • Austenitic heat-proof steel of the Cr-Ni-Mn group comprising essentially 15.0-21.0% Cr; 4.0-15% Ni; 4.0- 12.0% Mn; (Ll-1.0% Si; 0.03-0.30% C; 0.00l0.50%'Ti; and 0.00010.50% of a metal chosen from the group consisting of Nb and Ta, the remainder being Fe, wherein a first key ratio,
  • Austenitic steel as defined in claim 1, wherein the content of said metal chosen from the group consisting of Nb and Ta lies between 0.001 and 0.50%.
  • Austenitic steel as defined in claim 1 further comprising .001 to .1% of V.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
US00105096A 1967-11-10 1971-01-08 Austenitic steel of the cr-ni-mn group Expired - Lifetime US3795509A (en)

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US (1) US3795509A (enrdf_load_stackoverflow)
DE (1) DE1808249A1 (enrdf_load_stackoverflow)
FR (1) FR1592212A (enrdf_load_stackoverflow)
GB (1) GB1242871A (enrdf_load_stackoverflow)
SE (1) SE344477B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901690A (en) * 1971-05-11 1975-08-26 Carpenter Technology Corp Wear resistant alloy steels containing cb and one of ti, hf or zr
US3917493A (en) * 1973-08-13 1975-11-04 Nippon Kokan Kk Austenitic heat resisting steel
US3925064A (en) * 1973-05-31 1975-12-09 Kobe Steel Ltd High corrosion fatigue strength stainless steel
US3940267A (en) * 1973-08-13 1976-02-24 Nippon Kokan Kabushiki Kaisha Austenitic heat resisting steel
US4162930A (en) * 1976-03-30 1979-07-31 Nippon Steel Corporation Austenitic stainless steel having excellent resistance to intergranular and transgranular stress corrosion cracking
US4246046A (en) * 1979-03-09 1981-01-20 Michael Lameyer Stainless steel container for fluid and method
WO1992013179A1 (en) * 1991-01-23 1992-08-06 Man B&W Diesel A/S Valve with hard-facing
US20040062674A1 (en) * 2001-06-13 2004-04-01 Anders Bergkvist High density stainless steel products and method for the preparation thereof
EP2460904A3 (de) * 2010-12-03 2012-11-28 Bayerische Motoren Werke AG Austenitischer Stahl für die Wasserstofftechnik

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49113716A (enrdf_load_stackoverflow) * 1973-03-02 1974-10-30

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901690A (en) * 1971-05-11 1975-08-26 Carpenter Technology Corp Wear resistant alloy steels containing cb and one of ti, hf or zr
US3925064A (en) * 1973-05-31 1975-12-09 Kobe Steel Ltd High corrosion fatigue strength stainless steel
US3917493A (en) * 1973-08-13 1975-11-04 Nippon Kokan Kk Austenitic heat resisting steel
US3940267A (en) * 1973-08-13 1976-02-24 Nippon Kokan Kabushiki Kaisha Austenitic heat resisting steel
US4162930A (en) * 1976-03-30 1979-07-31 Nippon Steel Corporation Austenitic stainless steel having excellent resistance to intergranular and transgranular stress corrosion cracking
US4246046A (en) * 1979-03-09 1981-01-20 Michael Lameyer Stainless steel container for fluid and method
WO1992013179A1 (en) * 1991-01-23 1992-08-06 Man B&W Diesel A/S Valve with hard-facing
US20040062674A1 (en) * 2001-06-13 2004-04-01 Anders Bergkvist High density stainless steel products and method for the preparation thereof
US7311875B2 (en) * 2001-06-13 2007-12-25 Höganäs Ab High density stainless steel products and method for the preparation thereof
EP2460904A3 (de) * 2010-12-03 2012-11-28 Bayerische Motoren Werke AG Austenitischer Stahl für die Wasserstofftechnik

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GB1242871A (en) 1971-08-18
FR1592212A (enrdf_load_stackoverflow) 1970-05-11
DE1808249A1 (de) 1971-02-11
SE344477B (enrdf_load_stackoverflow) 1972-04-17

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