US3403022A - Chromium base alloy - Google Patents

Chromium base alloy Download PDF

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Publication number
US3403022A
US3403022A US495998A US49599865A US3403022A US 3403022 A US3403022 A US 3403022A US 495998 A US495998 A US 495998A US 49599865 A US49599865 A US 49599865A US 3403022 A US3403022 A US 3403022A
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United States
Prior art keywords
chromium
alloy
columbium
carbide
chromium base
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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.)
Expired - Lifetime
Application number
US495998A
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English (en)
Inventor
Winston H Chang
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General Electric Co
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General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US495998A priority Critical patent/US3403022A/en
Priority to GB42160/66A priority patent/GB1111036A/en
Priority to BE687729D priority patent/BE687729A/xx
Priority to FR78614A priority patent/FR1495789A/fr
Priority to DE19661533263 priority patent/DE1533263A1/de
Application granted granted Critical
Publication of US3403022A publication Critical patent/US3403022A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/06—Alloys based on chromium

Definitions

  • This invention relates to a chromium base alloy and, more particularly, to a chromium base alloy of improved strength particularly in sheet form.
  • Another object is to provide an improved chromium base alloy having improved high temperature strength as well as a recrystallization temperature sufficiently high to further take advantage of work hardening and inhibit embrittlement of the alloy.
  • a chromium base alloy of improved strength can be provided by the addition of a particular a-mount of columbium, in the presence of carbon in certain proportions to control a iine dispersion of columbium carbide.
  • This dispersion within the range of 4this invention strengthens chromium both in the cast as well as in the wrought condition yet the amount of carbon is controlled-to avoid formation of the embrittling chromium carbide phase.
  • the alloy of the present invention consists essentially of, by weight, (S-0.15% C.; 0.5-1.5% Cb; ODS-0.2% Y; 0.05.0.2% 'Ih; up to 0.2% Zr; with the balance essentialy chromium and incidental impurities.
  • the relationship of alloying additions such as the Group IV-A and Group V-A metals along with carbon in chromium base alloys is particularly significant.
  • the fiow and fracture behavior of chromium is profoundly affected by interstitials.
  • the arrangements, size and type of carbide has been found to affect strength, ductility and air oxidation in-difi'erent ways.
  • the influence of processing and heat treatment in controlling these kinds of mechanisms and hence the properties is significantly important in chromium base alloys. For example, in the presence of about 0.1 weight percent carbon in a chromium base, the element zirconium will form a carbide precipitate significantly different from that formed through the addiice tion of columbium.
  • the zirconium carbide because of its relatively low solubility in chromium, forms in the ascast condition a carbide network in the grain boundaries.
  • Columbium has agreater solubility in chromium than does zirconium.
  • columbium will precipitate as a fine rather than coarse dispersion of columbium carbide throughout the matrix as well as in the grain boundary of the chromium base structure.
  • the columbium addition will provide greater strengthening to the Valloy because of the formation of a fine precipitate different in kind than that of zirconium.
  • the recrystallization temperature can be maintained sufiiciently high, at least at about 2300 F.
  • the alloy -of the present invention can be further improved to resistance to oxidation ⁇ and nitrification through the retention of yttrium and thorium such as in the range of about (M15-0.2% Y and (LOS-0.2% Th. Below these amounts there is insufficient yttrium and thorium retained in the alloy either to getter the interstitials or to afford a significant amount of improvement in air oxidation resistance. Above those stated amounts, the alloy of the present invention tends to become embrittled.
  • One of the most useful forms of the alloy of the present invention is as a sheet material because of its high strength combined with good ductility and ⁇ good air oxidation resistance particularly up to 1800 F. Because its processability is good, it is readily reduced into sheet fro-m ⁇ a cast form.
  • the range of columbium included within the alloy of the present invention is 0.5-1.5 weight percent.
  • the addition of amounts in excess of about 1.5% Cb allows the formation of too much CbCr2 which is a coarse intermetallic phase. CbCr2 tends to lower the melting point of the alloy and is detrimental to oxidation resistance.
  • the inclusion of less than about 0.5 weight percent columbium in the presence of an excess of carbon allows the formation of the embrittling chromium carbide-such as Cr23C6 rather than the fine columbium carbide.
  • the carbon range is controlled to be within the range of about 0.05-015 weight percent.
  • the inclusion of too much of either columbium or carbon outside the range of the present invention leads to the formation of massive carbides. Unlike the fine carbide dispersion found in the present invention, the massive carbides lead to lower strength.
  • the excess of columbium or carbon increases aging kinetics which has a significantly adverse effect on mechanical properties.
  • Typical of the alloys within the scope of the present invention are those listed in the following Table I in which compositions of the Cb/C atomic ratio is in the particularly beneficial range of 1-3 to l.
  • the alloy of the present invention can include up to ⁇ about ⁇ 0.2 weight percent zirconium without signiicantly adverse elect on the mechanical properties of the alloy through the formation of the more massive zirconium carbide.
  • the alloy compositions shown in Table I were induction melted under argon to insure homogeneity and to minimize ingot cracking.
  • the alloy was cast into a 3" diameter Y2O3-stabilized zirconia Crucible.
  • the yttrium and thorium additions in the charges were about 6 and 2 times, respectively, larger than the nominal contents to compensate for their losses through scavenging effects. Therefore the percentages for those elements listed in the specification refer to the retained amount rather than the amount added.
  • the casting was extruded into bar before rolling into sheet.
  • higher extrusion temperatures were required.
  • the extrusion temperature should not exceed 2800 F. to avoid incipient fusion. Therefore, a temperature of 2700 F. was selected for initial extrusion.
  • the extruded bar was first reduced 50% in thickness at about 2000 F. followed by rolling in the range of about 1500-1800 F. to produce the sheets of 0.05 thick material.
  • the rolled sheets were stress relieved at 2000 F. for 1 hour after which physical properties were determined.
  • a comparison between the alloy of the present invention and a known sheet alloy reported to be one of the best available based on chromium is shown in the drawing.
  • the known alloy has a composition, by weight, of 93.5% chromium, 0.5% titanium and 6% magnesium oxide. Both sheet alloys were at the same thickness of about 50 mils. The signicantly better strength of th alloy of the present invention is shown by the drawing.
  • the alloy of the present invention is particularly suitable for use in an air oxidizing atmosphere.
  • the good oxidation and nitrication resistance is shown by the data of Table III.
  • OXIDATION DATA Weight gain (mgJcm) Unlike alloys dispersion strengthened with more massive carbide such as zirconium carbide, the effect on ox-v idation resistance of reduction from cast to wrought condition is not great.
  • the hour oxidation tests conducted to obtain the data of Table III were performed on bar specimens of 0.22 x 0.35 x 0.5 specimens in the rolled condition. The specimens were prepared by grinding and polishing through 400 grit paper followed by water and alcohol rinsing. Specimens were placed in zirconia crucibles and oxidized continuously in a tubular furnace with natural air convection.
  • a chromium base alloy of improved strength consisting essentially of, by weight, 0.5-1.5% Cb; 0.05- 0.l5% C; 0.05-0.2% Y; 0.05-0.2% Th; up to about 0.2% Zr; with the balance chromium and incidental impurities.
  • a chromium base alloy of improved strength consisting essentially of, by weight, about 1% Cb; about 0.1% C; 0.050.2% Y; 0.05-0.2% Th; up to about 0.2% Zr; with the balance chromium and incidental impurities.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Powder Metallurgy (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
US495998A 1965-10-14 1965-10-14 Chromium base alloy Expired - Lifetime US3403022A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US495998A US3403022A (en) 1965-10-14 1965-10-14 Chromium base alloy
GB42160/66A GB1111036A (en) 1965-10-14 1966-09-21 Improvements in chromium base alloy
BE687729D BE687729A (en)) 1965-10-14 1966-10-03
FR78614A FR1495789A (fr) 1965-10-14 1966-10-03 Alliage à base de chrome
DE19661533263 DE1533263A1 (de) 1965-10-14 1966-10-04 Chromlegierung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US495998A US3403022A (en) 1965-10-14 1965-10-14 Chromium base alloy

Publications (1)

Publication Number Publication Date
US3403022A true US3403022A (en) 1968-09-24

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US495998A Expired - Lifetime US3403022A (en) 1965-10-14 1965-10-14 Chromium base alloy

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US (1) US3403022A (en))
BE (1) BE687729A (en))
DE (1) DE1533263A1 (en))
FR (1) FR1495789A (en))
GB (1) GB1111036A (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6446891B1 (en) 1999-10-29 2002-09-10 Re{Acute Over (V)}El Inc. Wet and dry food grinder

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955937A (en) * 1958-01-21 1960-10-11 James A Mcgurty Oxidation resistant chromium alloy
US3011889A (en) * 1959-09-25 1961-12-05 Gen Electric Oxidation resistant alloy
GB923039A (en) * 1960-04-25 1963-04-10 United Aircraft Corp Improvements relating to chromium-base alloys
US3137572A (en) * 1960-06-30 1964-06-16 Lewis R Aronin Chromium base alloy possessing high strength at elevated temperatures
US3174853A (en) * 1962-03-15 1965-03-23 Gen Electric Chromium base alloys
US3208847A (en) * 1962-03-26 1965-09-28 Gen Electric Chromium base alloy
US3227548A (en) * 1963-02-18 1966-01-04 Gen Electric Chromium base alloy

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955937A (en) * 1958-01-21 1960-10-11 James A Mcgurty Oxidation resistant chromium alloy
US3011889A (en) * 1959-09-25 1961-12-05 Gen Electric Oxidation resistant alloy
GB923039A (en) * 1960-04-25 1963-04-10 United Aircraft Corp Improvements relating to chromium-base alloys
US3137572A (en) * 1960-06-30 1964-06-16 Lewis R Aronin Chromium base alloy possessing high strength at elevated temperatures
US3174853A (en) * 1962-03-15 1965-03-23 Gen Electric Chromium base alloys
US3208847A (en) * 1962-03-26 1965-09-28 Gen Electric Chromium base alloy
US3227548A (en) * 1963-02-18 1966-01-04 Gen Electric Chromium base alloy

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6446891B1 (en) 1999-10-29 2002-09-10 Re{Acute Over (V)}El Inc. Wet and dry food grinder

Also Published As

Publication number Publication date
FR1495789A (fr) 1967-09-22
GB1111036A (en) 1968-04-24
BE687729A (en)) 1967-03-16
DE1533263A1 (de) 1969-12-11

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