CA1106652A - Low thermal expansion nickel-iron base alloy - Google Patents
Low thermal expansion nickel-iron base alloyInfo
- Publication number
- CA1106652A CA1106652A CA316,724A CA316724A CA1106652A CA 1106652 A CA1106652 A CA 1106652A CA 316724 A CA316724 A CA 316724A CA 1106652 A CA1106652 A CA 1106652A
- Authority
- CA
- Canada
- Prior art keywords
- alloy
- boron
- thermal expansion
- low thermal
- nickel
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
-
- 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
- C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
- C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Heat Treatment Of Steel (AREA)
- Powder Metallurgy (AREA)
- Ceramic Products (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A castable nickel-iron base alloy suitable for high temperature service and characterized by low thermal expansion and freedom from notch sensitivity and deleterious microshrinkage in castings. The alloy consists essentially of at least 16% nickel, at least 10% cobalt, up to 5% columbium, up to 3% tantalum, up to 2.5% titanium, up to 2% aluminum, 0.06% to 0.25% boron, up to 0.1% carbon, and the balance iron.
A castable nickel-iron base alloy suitable for high temperature service and characterized by low thermal expansion and freedom from notch sensitivity and deleterious microshrinkage in castings. The alloy consists essentially of at least 16% nickel, at least 10% cobalt, up to 5% columbium, up to 3% tantalum, up to 2.5% titanium, up to 2% aluminum, 0.06% to 0.25% boron, up to 0.1% carbon, and the balance iron.
Description
BACKGROUND OF THE INVENTIO~
In the past~ iron nickel alloys have been developed having extremely low thermal expansion coefficients which enable them to be used over wide temperature ranges without losing strength and without any substantial change in elasticity.
Examples of such alloys are given in UOS. Patent Nos. 3,157,495 and 4,006,011 and ~ypically contain controlled amounts of cobalt, columbium and titanium. They are used in such applica~ions as rocket engine parts and the like which must have superior resistance to thermal fatigue. A difficulty with alloys of this type, however~ is theîr notch sensitivity and severe micro shrinkage upon cooling from the molten state. As a resultg they have not been used in the cast orm.
The present invention resides in the disc-overy that critical amounts o boron can be added to nickel-iron b~se alloys o~ the type described above to eliminate notch sensitivi~y and dele~erious microshrinlcage in castingsO At the same time, the alloy retains its low thermal expansion charaeteristics.
Specifically, it has been found that the addi~ion of about .06%
, - . - . , :
' ~ .
to .25% boron to certain types of iron-nickel base alloys ~7ill promote the formation of a eutectic boride during solidification;
and it is the presence of this eutec~ic boride which improves castability of the alloy. Alloys of this type are characterized by a wide liquidus to solidus range and can be cast or hot-worked and used in wrought form, provided that a suitable heat treat-ment for the wrought form is provided.
The above and other objects and features of the invention ~ill become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification/ and in which:
Figures lA and lB are photomicrographs at magnifica-tions of 50X and 400X, respectively, showing the formation of a eutectic boride in the alloy of the invention; and Figs. 2A and 2B are differential thermal analysis plots showing the effect of variation in boron in the alloy of the invention upon the solidus temperature.
The alloy of the invention has ~he ollowing broad and preferred ranges of composi~ion:
T~BLE I
Broad Preferred Nickel at least 16% 30-50%
Gobal~ at least 10% 10-20%
Columbium 0-5% 2-4C/o 25 - Tantalum 0-3% 0-1%
Titanium 0-2~5% 1-2%
Aluminum 0-2% .25-1%
Boron at least .06% .06-.30%
Carbon 0-.1% .015-.045%
Iron Bal. Bal.
The carbon should be kept as low as possible in order that it will not produce carbide clusters in the boride eutectic about to be described. Additionally, the alloy can contain up to 0.1% zirconi~ which is desirable to impede the S formation of Ni3Cb at the grain boundaries of the alloy. Up to 0.1% oE rare earths can be added which act as scavengers to prevent delet~rious sulfide formations and the formation of acicular phases; while up to 1% hafni~m can be added which acts as a carbide former and widens the liquidus to solidus temperature range. As is knownj small amounts of tan~alum are often associated with columbium vbtained from commercial sources. Normally, these small amounts of tantalum occur in amounts up to about 3% of the total content of columbium plus tantalum. As used in the following claims, therefore, the term "columbium" means pure columbium (if it is available) vr columbium plus certain amounts of tantalum. A certain amount of the columbium content, however, can be replaced by pure tantalum in the ratio of two parts tantalum to one part columbium~
As will be see~ from the following deseription, alloys in the foregolng range of composition have low thermal expansion characteristics and are free o notch sensitivity, making them especially available for use as an alloy used in castings intended for use over a wide ramperature range.
Properties of the new and improved alloy of the invention are established by the following Table II which shows the analysis of five different heats having varying amounts of boron additions:
S~-lOg3 - T~BLE Il Analysis (Aim) Heat No. C B Ni Co Cb Ti Al Fe _ D]-939 0.03 0.005 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-940 0.03 0.050 38.2 15.3 3.0 1.7 0.8 ~al.
Dl-979 0.02 0.100 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-10320.02 0.160 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-12870.02 0.300 38.2 15.3 3.0 1.7 0~ Bal.
Heat No. Dl-939 is a standard prior art alloy similar to that described in the aforesaid U.S. Patent No.
3,157,495. An alloy of this type is characteri~ed by a ~icro-structure which shows no eutectic boride phase and contains large amounts of porosity which leads ~o poor stress rupture life. All of the heats in the ~oregoing Table II were cast in investment molds to yield test bars. These bars were ~hen heat-treated and machined to 0.250 inch diameter bars which were subsequently stress rupture tested. The results of the stress rupture tests are shown in the following Table III:
TABLE III
,Stress Rupture (1200F!9 Heat Boron*~Life Elong. R~A.
N _ (Wt, ~/O~ ) (%~_ Dl-939 0.0052 0.2 2~0 9.2 Dl~940 0.050 0.7 1.3 6.9 Dl-979 0.094 66.2 3.9 6.7 Dl-1032 0.156 138~5 8.0 9.7 Dl-1032* 0.156 172.2 8.2 11~2 *Combination smooth tensile bar and notched tensile bar.
*J~A~tual Wto % as contrasted with aim of Table Il~
As can be seen from the Eoregoing Table III, the - standard prior ~rt alloy Dl-939 containing only .0052% boron has a s~ress rupture lie of only 0.2 hour at 1200F/90 Ksi wilh a 2% elonga~ion and 9.2% reduction in areaO Furth~r additions of boron up to 0.05~% (Heat Dl-940) have very little ~ ~ 66 ~ 2 SIi-1093 effect on the s-ress rupture life which increases Lo only 0.7%
at 1,3% elongation and 6.9C,~ reduction in area. ~lowev2r in Heat Dl 979 with a boron addition of 0.094~/0, stress rupture liEe under the same conditions is dramatically ;ncreased to 66.2 hours at 3.9% elongation and 6.7% reduction in area. Boron additions of 0.156% (Heat Dl-1032) more than double the stress rupture life to 138.5 hours at 8% elongation and 9.7% reduction in area. Heat Dl-1032~' is the same as ~hat previously described except that the test specimen was a combination smooth tensile bar and notched tensile bar. Here the stress rupture life is further increased.
As shown in Figs. lA and lB, photomicrographs of the alloy of Heat Dl-1032 containing 0.16% boron shows large amounts of eutectic boride and exhib;ts freedom from deleterious micro-shrinkage. I~ ha~ an average thermal coefficient of expansion of about 4.7 x 10 in/in/ F at room temperature to 800Fo It is helieved that the alloy of the invention derives its improved castability through the formation of eutectic boride during solidification.
The stress rupture characteristics of Heat Dl-1287 (Table II) containing 0.3~/O boron were not determined; however photomicrographs of this alloy show the same large amounts of eutectic borideO It is believed that boron ~ddi~ions materially above 0.3% w;ll cause the volume of the inner dendritic eutfctic to become excessive, resulting in large crack paths which could impair ~he physical properties of the alloy.
The difference in solidification characterist'cs of this alloy as compared to prior ar~ alloys is shown in the t:hermal diagrams o~ Figs. 2A and 2B. The upper diagram (Fi~. 2A) is for a conventional prior ar~ nickel-iron alloy containin~
S~ g3 0.005% boron (Heat Dl-939); while the d.iagram of ~ is for Heat Dl-1032 containing 0.16% boron~ Note that the alloy of the invention contai.ning boron is characteri~ed by a wider liquidus to solidus ranre.
Although the invention has been shown in connection with certain speciic embodiments, it Will be readily ap?arent to those skilled in the art that various c'nanges in form and arrangement of parts may be made to suit requiremen~s without departing from the spirit and scope o:~ the invention.
, ,
In the past~ iron nickel alloys have been developed having extremely low thermal expansion coefficients which enable them to be used over wide temperature ranges without losing strength and without any substantial change in elasticity.
Examples of such alloys are given in UOS. Patent Nos. 3,157,495 and 4,006,011 and ~ypically contain controlled amounts of cobalt, columbium and titanium. They are used in such applica~ions as rocket engine parts and the like which must have superior resistance to thermal fatigue. A difficulty with alloys of this type, however~ is theîr notch sensitivity and severe micro shrinkage upon cooling from the molten state. As a resultg they have not been used in the cast orm.
The present invention resides in the disc-overy that critical amounts o boron can be added to nickel-iron b~se alloys o~ the type described above to eliminate notch sensitivi~y and dele~erious microshrinlcage in castingsO At the same time, the alloy retains its low thermal expansion charaeteristics.
Specifically, it has been found that the addi~ion of about .06%
, - . - . , :
' ~ .
to .25% boron to certain types of iron-nickel base alloys ~7ill promote the formation of a eutectic boride during solidification;
and it is the presence of this eutec~ic boride which improves castability of the alloy. Alloys of this type are characterized by a wide liquidus to solidus range and can be cast or hot-worked and used in wrought form, provided that a suitable heat treat-ment for the wrought form is provided.
The above and other objects and features of the invention ~ill become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification/ and in which:
Figures lA and lB are photomicrographs at magnifica-tions of 50X and 400X, respectively, showing the formation of a eutectic boride in the alloy of the invention; and Figs. 2A and 2B are differential thermal analysis plots showing the effect of variation in boron in the alloy of the invention upon the solidus temperature.
The alloy of the invention has ~he ollowing broad and preferred ranges of composi~ion:
T~BLE I
Broad Preferred Nickel at least 16% 30-50%
Gobal~ at least 10% 10-20%
Columbium 0-5% 2-4C/o 25 - Tantalum 0-3% 0-1%
Titanium 0-2~5% 1-2%
Aluminum 0-2% .25-1%
Boron at least .06% .06-.30%
Carbon 0-.1% .015-.045%
Iron Bal. Bal.
The carbon should be kept as low as possible in order that it will not produce carbide clusters in the boride eutectic about to be described. Additionally, the alloy can contain up to 0.1% zirconi~ which is desirable to impede the S formation of Ni3Cb at the grain boundaries of the alloy. Up to 0.1% oE rare earths can be added which act as scavengers to prevent delet~rious sulfide formations and the formation of acicular phases; while up to 1% hafni~m can be added which acts as a carbide former and widens the liquidus to solidus temperature range. As is knownj small amounts of tan~alum are often associated with columbium vbtained from commercial sources. Normally, these small amounts of tantalum occur in amounts up to about 3% of the total content of columbium plus tantalum. As used in the following claims, therefore, the term "columbium" means pure columbium (if it is available) vr columbium plus certain amounts of tantalum. A certain amount of the columbium content, however, can be replaced by pure tantalum in the ratio of two parts tantalum to one part columbium~
As will be see~ from the following deseription, alloys in the foregolng range of composition have low thermal expansion characteristics and are free o notch sensitivity, making them especially available for use as an alloy used in castings intended for use over a wide ramperature range.
Properties of the new and improved alloy of the invention are established by the following Table II which shows the analysis of five different heats having varying amounts of boron additions:
S~-lOg3 - T~BLE Il Analysis (Aim) Heat No. C B Ni Co Cb Ti Al Fe _ D]-939 0.03 0.005 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-940 0.03 0.050 38.2 15.3 3.0 1.7 0.8 ~al.
Dl-979 0.02 0.100 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-10320.02 0.160 38.2 15.3 3.0 1.7 0.8 Bal.
Dl-12870.02 0.300 38.2 15.3 3.0 1.7 0~ Bal.
Heat No. Dl-939 is a standard prior art alloy similar to that described in the aforesaid U.S. Patent No.
3,157,495. An alloy of this type is characteri~ed by a ~icro-structure which shows no eutectic boride phase and contains large amounts of porosity which leads ~o poor stress rupture life. All of the heats in the ~oregoing Table II were cast in investment molds to yield test bars. These bars were ~hen heat-treated and machined to 0.250 inch diameter bars which were subsequently stress rupture tested. The results of the stress rupture tests are shown in the following Table III:
TABLE III
,Stress Rupture (1200F!9 Heat Boron*~Life Elong. R~A.
N _ (Wt, ~/O~ ) (%~_ Dl-939 0.0052 0.2 2~0 9.2 Dl~940 0.050 0.7 1.3 6.9 Dl-979 0.094 66.2 3.9 6.7 Dl-1032 0.156 138~5 8.0 9.7 Dl-1032* 0.156 172.2 8.2 11~2 *Combination smooth tensile bar and notched tensile bar.
*J~A~tual Wto % as contrasted with aim of Table Il~
As can be seen from the Eoregoing Table III, the - standard prior ~rt alloy Dl-939 containing only .0052% boron has a s~ress rupture lie of only 0.2 hour at 1200F/90 Ksi wilh a 2% elonga~ion and 9.2% reduction in areaO Furth~r additions of boron up to 0.05~% (Heat Dl-940) have very little ~ ~ 66 ~ 2 SIi-1093 effect on the s-ress rupture life which increases Lo only 0.7%
at 1,3% elongation and 6.9C,~ reduction in area. ~lowev2r in Heat Dl 979 with a boron addition of 0.094~/0, stress rupture liEe under the same conditions is dramatically ;ncreased to 66.2 hours at 3.9% elongation and 6.7% reduction in area. Boron additions of 0.156% (Heat Dl-1032) more than double the stress rupture life to 138.5 hours at 8% elongation and 9.7% reduction in area. Heat Dl-1032~' is the same as ~hat previously described except that the test specimen was a combination smooth tensile bar and notched tensile bar. Here the stress rupture life is further increased.
As shown in Figs. lA and lB, photomicrographs of the alloy of Heat Dl-1032 containing 0.16% boron shows large amounts of eutectic boride and exhib;ts freedom from deleterious micro-shrinkage. I~ ha~ an average thermal coefficient of expansion of about 4.7 x 10 in/in/ F at room temperature to 800Fo It is helieved that the alloy of the invention derives its improved castability through the formation of eutectic boride during solidification.
The stress rupture characteristics of Heat Dl-1287 (Table II) containing 0.3~/O boron were not determined; however photomicrographs of this alloy show the same large amounts of eutectic borideO It is believed that boron ~ddi~ions materially above 0.3% w;ll cause the volume of the inner dendritic eutfctic to become excessive, resulting in large crack paths which could impair ~he physical properties of the alloy.
The difference in solidification characterist'cs of this alloy as compared to prior ar~ alloys is shown in the t:hermal diagrams o~ Figs. 2A and 2B. The upper diagram (Fi~. 2A) is for a conventional prior ar~ nickel-iron alloy containin~
S~ g3 0.005% boron (Heat Dl-939); while the d.iagram of ~ is for Heat Dl-1032 containing 0.16% boron~ Note that the alloy of the invention contai.ning boron is characteri~ed by a wider liquidus to solidus ranre.
Although the invention has been shown in connection with certain speciic embodiments, it Will be readily ap?arent to those skilled in the art that various c'nanges in form and arrangement of parts may be made to suit requiremen~s without departing from the spirit and scope o:~ the invention.
, ,
Claims (5)
1. An alloy suitable for high temperature service and characterized by low thermal expansion and freedom from notch sensitivity and deleterious microshrinkage, consisting essentially of 30% to 50% nickel, 10% to 20% cobalt, up to 5% columbium, up to 3% tantalum, up to 2.5% titanium, up to 0.1% carbon, up to 2% aluminum, 0.06% to 0.3% boron, and the balance iron.
2. The alloy of claim 1 wherein columbium is present in the range of 2% to 4%, titanium is present in the range of 1% to 2%, aluminum is present in the range of .25% to 1%, and carbon is present in the range of .015% to .045%, the balance being essentially all iron.
3. A castable alloy suitable for high temperature service and characterized by low thermal expansion and freedom from notch sensitivity and deleterious microshrinkage, consisting essentially of about 38% nickel, 15% cobalt, 3% columbium, 1.7% titanium, 0.8% aluminum, 0.02% carbon, 0.16% boron and the balance iron.
4. The castable alloy of claim 2 characterized in con-taining eutectic boride.
5. The castable alloy of claim 4 in which the alloy has an average thermal coefficient of expansion of about 4.7 x 10-6 in/in/°F at room temperature to 800°F.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US85859077A | 1977-12-08 | 1977-12-08 | |
| US858,590 | 1977-12-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106652A true CA1106652A (en) | 1981-08-11 |
Family
ID=25328660
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA316,724A Expired CA1106652A (en) | 1977-12-08 | 1978-11-23 | Low thermal expansion nickel-iron base alloy |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5490013A (en) |
| AU (1) | AU520982B2 (en) |
| CA (1) | CA1106652A (en) |
| CH (1) | CH644636A5 (en) |
| DE (1) | DE2852142C2 (en) |
| FR (1) | FR2411246B1 (en) |
| GB (1) | GB2009787B (en) |
| IL (1) | IL56095A (en) |
| IT (1) | IT1106368B (en) |
| SE (1) | SE447487B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4685978A (en) * | 1982-08-20 | 1987-08-11 | Huntington Alloys Inc. | Heat treatments of controlled expansion alloy |
| US4487743A (en) * | 1982-08-20 | 1984-12-11 | Huntington Alloys, Inc. | Controlled expansion alloy |
| US4713576A (en) * | 1985-04-24 | 1987-12-15 | Hitachi, Ltd. | Color picture tube with shadow mask |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1104932A (en) * | 1965-06-18 | 1968-03-06 | Wilkinson Sword Ltd | Improvements in or relating to safety razor blades |
| US4006011A (en) * | 1972-09-27 | 1977-02-01 | Carpenter Technology Corporation | Controlled expansion alloy |
-
1978
- 1978-11-13 AU AU41533/78A patent/AU520982B2/en not_active Expired
- 1978-11-23 CA CA316,724A patent/CA1106652A/en not_active Expired
- 1978-11-30 IL IL56095A patent/IL56095A/en unknown
- 1978-11-30 IT IT52154/78A patent/IT1106368B/en active
- 1978-12-01 JP JP14895578A patent/JPS5490013A/en active Pending
- 1978-12-01 DE DE2852142A patent/DE2852142C2/en not_active Expired
- 1978-12-05 CH CH1240778A patent/CH644636A5/en not_active IP Right Cessation
- 1978-12-05 GB GB7847174A patent/GB2009787B/en not_active Expired
- 1978-12-07 SE SE7812604A patent/SE447487B/en not_active IP Right Cessation
- 1978-12-08 FR FR7834684A patent/FR2411246B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IL56095A0 (en) | 1979-01-31 |
| AU520982B2 (en) | 1982-03-11 |
| DE2852142A1 (en) | 1979-06-13 |
| AU4153378A (en) | 1979-06-14 |
| CH644636A5 (en) | 1984-08-15 |
| FR2411246B1 (en) | 1985-09-27 |
| IT1106368B (en) | 1985-11-11 |
| FR2411246A1 (en) | 1979-07-06 |
| GB2009787B (en) | 1982-04-28 |
| IL56095A (en) | 1981-09-13 |
| JPS5490013A (en) | 1979-07-17 |
| DE2852142C2 (en) | 1985-04-18 |
| SE7812604L (en) | 1979-06-09 |
| SE447487B (en) | 1986-11-17 |
| GB2009787A (en) | 1979-06-20 |
| IT7852154A0 (en) | 1978-11-30 |
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