CA1133363A - Method for heat treating iron-nickel-chromium alloy - Google Patents
Method for heat treating iron-nickel-chromium alloyInfo
- Publication number
- CA1133363A CA1133363A CA352,685A CA352685A CA1133363A CA 1133363 A CA1133363 A CA 1133363A CA 352685 A CA352685 A CA 352685A CA 1133363 A CA1133363 A CA 1133363A
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- Prior art keywords
- alloy
- temperature
- cool
- cold
- nickel
- Prior art date
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- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 18
- BIJOYKCOMBZXAE-UHFFFAOYSA-N chromium iron nickel Chemical compound [Cr].[Fe].[Ni] BIJOYKCOMBZXAE-UHFFFAOYSA-N 0.000 title claims abstract description 5
- 229910000623 nickel–chromium alloy Inorganic materials 0.000 title claims abstract description 4
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 36
- 239000000956 alloy Substances 0.000 claims abstract description 36
- 230000002902 bimodal effect Effects 0.000 claims abstract description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000009826 distribution Methods 0.000 claims abstract description 8
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000011651 chromium Substances 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 6
- 239000011733 molybdenum Substances 0.000 claims abstract description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 5
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 5
- 229910052742 iron Inorganic materials 0.000 claims abstract description 5
- 239000010936 titanium Substances 0.000 claims abstract description 5
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 5
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 239000010955 niobium Substances 0.000 claims abstract description 4
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 3
- 238000010438 heat treatment Methods 0.000 claims description 12
- 238000005482 strain hardening Methods 0.000 claims description 6
- 239000002244 precipitate Substances 0.000 claims description 3
- 229910001203 Alloy 20 Inorganic materials 0.000 claims 1
- 238000005097 cold rolling Methods 0.000 claims 1
- 206010023204 Joint dislocation Diseases 0.000 abstract 1
- 238000011282 treatment Methods 0.000 description 29
- 210000004027 cell Anatomy 0.000 description 12
- 230000000930 thermomechanical effect Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 230000008961 swelling Effects 0.000 description 9
- 239000000203 mixture Substances 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910000601 superalloy Inorganic materials 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- PXHVJJICTQNCMI-OUBTZVSYSA-N nickel-60 atom Chemical compound [60Ni] PXHVJJICTQNCMI-OUBTZVSYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
Classifications
-
- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- 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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Nonferrous Metals Or Alloys (AREA)
Abstract
13 47,107I
ABSTRACT OF THE DISCLOSURE
A method for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a bimodal distri-bution of gamma prime phase within a network of dis-locations, the alloy consisting essentially of about 25% to 45% nickel, 10% to 16% chromium, 1.5% to 3% of an element selected from the group consisting of molybdenum and niobium, about 2% titanium, about 3% aluminum and the remainder substantially all iron. To obtain optimum re-sults, the alloy is heated to a temperature of 1025°C to 1075°C for 2-5 minutes, cold-worked about 20% to 60%, aged at a temperature of about 775°C for 8 hours followed by an air-cool, and then heated to a temperature in the range of 650°C to 700°C for 2 hours followed by an air-cool.
ABSTRACT OF THE DISCLOSURE
A method for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a bimodal distri-bution of gamma prime phase within a network of dis-locations, the alloy consisting essentially of about 25% to 45% nickel, 10% to 16% chromium, 1.5% to 3% of an element selected from the group consisting of molybdenum and niobium, about 2% titanium, about 3% aluminum and the remainder substantially all iron. To obtain optimum re-sults, the alloy is heated to a temperature of 1025°C to 1075°C for 2-5 minutes, cold-worked about 20% to 60%, aged at a temperature of about 775°C for 8 hours followed by an air-cool, and then heated to a temperature in the range of 650°C to 700°C for 2 hours followed by an air-cool.
Description
1~L33363 1 47,1071 METHOD FOR HEAT TREATING IRON-NICKEL-CHROMIUM ALLOY
BACKGROUND OF THE INVENTION
The present invention is particularly adapted ~or use with a nickel-chromium-iron alloy such as that described in U.S. Patent No. 4,236,943 issued on Decem-5 ber 2, 1980, which has strong mechanical properties and,at the same time, has swelling resistance under the in-fluence of irradiation and low neutron absorbence~ As such, it is particularly adapted ~or use as a duct~ng and cladding alloy ~or fast breeder reactors~
A material of this type is a gamma-prime strengthened superalloy; and its properties can be altered drastically by varying the thermomechanical treatment to which it is sub~ected. For nuclear reactor applications it is, of course, desirable to subject the alloy to a thermomechanical treatment which will produce the greatest irradiation-induced swelling resistance and/or the highest strength and most importantly the highest post irradiation ductility.
3~
X
33 3 ~ 3
BACKGROUND OF THE INVENTION
The present invention is particularly adapted ~or use with a nickel-chromium-iron alloy such as that described in U.S. Patent No. 4,236,943 issued on Decem-5 ber 2, 1980, which has strong mechanical properties and,at the same time, has swelling resistance under the in-fluence of irradiation and low neutron absorbence~ As such, it is particularly adapted ~or use as a duct~ng and cladding alloy ~or fast breeder reactors~
A material of this type is a gamma-prime strengthened superalloy; and its properties can be altered drastically by varying the thermomechanical treatment to which it is sub~ected. For nuclear reactor applications it is, of course, desirable to subject the alloy to a thermomechanical treatment which will produce the greatest irradiation-induced swelling resistance and/or the highest strength and most importantly the highest post irradiation ductility.
3~
X
33 3 ~ 3
2 47,107I
SUMMARY OF THE INVENTION
In accordance with the present invention, an alloy having a composition of about 25% to 45% nickel, 10% to 16~ chromium, 1.5% to 3% of an element selected from the group cons$sting of molybdenum and niobium, about 1% to 3% titanium, about 0~5% to 3.0% aluminum and the remainder substantially all iron, initially heated to a temperature in the range of about 1000C to 1100C for a period o~ 30 seconds to one hour; although the preferred heat treatment is to h~at in the range of 1025C to 1075C
for 2-5 minutes to minimize the time in the furnace. mis initial heat treatment is followed by a furnace-cool and cold-working in the range o~ about 20Yo to 60% although cold working within the range between 10% ~nd 80% is useful.
Thereafter, the alloy i~ heated to a temperature in the range of 750C to 825C for 4-15 hours and preferably 775C
for 8 hours, followed by an air-cool. mereafter, the alloy is again heated to a temperature in the range of about 6500C
to 700C for 2-20 hours ~ollowed by an air-cool.
The abo~e and oth~r objects and features of the invention will become apparent ~rom the following detailed description taken in connection with the accompanying drawing which is a plot of percent swelling versus an-nealing temperature for an alloy within the scope of the in~ention.
In order to establish the desirable re~ult~ of the invention, an alloy having the following composition was subject to uarious thermomechanical treatment~ herein-after described:
TABLE I
Nickel - 45%
Chromium - 12%
Molybdenum _ 30/O
Silicon - 0.5%
Zirconium - 0.05%
Titanium - 2.5~
Aluminum - 2.5%
Carbon - 0.~3%
~33363 2a 47 ,1 07I
Boron - 0 . 005%
Iron - BalO
SUMMARY OF THE INVENTION
In accordance with the present invention, an alloy having a composition of about 25% to 45% nickel, 10% to 16~ chromium, 1.5% to 3% of an element selected from the group cons$sting of molybdenum and niobium, about 1% to 3% titanium, about 0~5% to 3.0% aluminum and the remainder substantially all iron, initially heated to a temperature in the range of about 1000C to 1100C for a period o~ 30 seconds to one hour; although the preferred heat treatment is to h~at in the range of 1025C to 1075C
for 2-5 minutes to minimize the time in the furnace. mis initial heat treatment is followed by a furnace-cool and cold-working in the range o~ about 20Yo to 60% although cold working within the range between 10% ~nd 80% is useful.
Thereafter, the alloy i~ heated to a temperature in the range of 750C to 825C for 4-15 hours and preferably 775C
for 8 hours, followed by an air-cool. mereafter, the alloy is again heated to a temperature in the range of about 6500C
to 700C for 2-20 hours ~ollowed by an air-cool.
The abo~e and oth~r objects and features of the invention will become apparent ~rom the following detailed description taken in connection with the accompanying drawing which is a plot of percent swelling versus an-nealing temperature for an alloy within the scope of the in~ention.
In order to establish the desirable re~ult~ of the invention, an alloy having the following composition was subject to uarious thermomechanical treatment~ herein-after described:
TABLE I
Nickel - 45%
Chromium - 12%
Molybdenum _ 30/O
Silicon - 0.5%
Zirconium - 0.05%
Titanium - 2.5~
Aluminum - 2.5%
Carbon - 0.~3%
~33363 2a 47 ,1 07I
Boron - 0 . 005%
Iron - BalO
3 47,107I
'Ihe foregoing alloy is a gamma-prime strength-ene(l superalloy. Its properties can be altered drasti-c~lly b~ varying its thermomechanical treatment prior to testing. The following Table II sets forth the various 'j thermomechanical treatments to which the alloy set forth in Table I was subjected; while Table III lists the re-sultin~ microstructural and mechanical properties of the alloy after heat treatment:
T~ LE II
Vesi.gna-tion_ Thermomechanical Treatment AR 103~C~l hr/FC + 60% CW
IN-I ~982C/1 hr/AC ~ 788C/1 hr/AC + 720C/24 hr/AC
IN-2 ~890C/1 hr/AC + 800C/11 hr/AC + 700C/2 hr/AC
1'j EC -~927C/1 hr/AC + 800C/ll hr/AC + 700C/2 hr/AC
EE *800C/ll hr/AC + 700C/2 hr/AC
ter l~g~C/I hr/FC + 60% CW.
TABLE_LII
Designa- 650C
20 tion Comments UTS (ksi) 80 ksi SR (hr) AR No gamma-prime, high - 67.9 dislocation density IN-l Bimodal gamma-prime, 151.5 0.,3 recrystallized above gamma-prime solvus lN-2 Trimodal gamma-prime 141.3 81.9 (~islocated) EC Trimodal gamma-prime - 64.7 recrystallized below gamma-prime solvus EE Bimodal gamma-prime, - 235 equiaxed cells As can be seen from Table III above, the EC
treatment produces higher stress rupture properties than treatment IN-l. The EC treatment results in a trimodal distribution of gamma-prime since the recrystallization 1.~33363 ~ 4 47,107I
anneal is below the gamma-prime solvus and results in the prccipitation of a small volume of large (approximately 600 nm) gamma-prime precipitates.
Of the treatments set forth in Tables II and III, three treatments produced dislocated structures.
These are treatments AR, IN-2 and EE. The stress rupture data of Table II reveals that heat treatment EE produces a significantly stronger material. This structure consists of an interwoven dislocated cell structure which is pinned by a bimodal gamma-prime distribution. This condition has the highest strength of any tested and is very stable because of the pinned nature of the dislocation cells.
The graph shown in the attached figure illus-trates the swelling behavior of the alloy set forth in Table I in three thermomechanical conditions, ST, EC and EE. The swelling versus temperature curves are for radia-tion doses of 30 dpae, which is equivalent to 203x103 ~-(i.e., greater than the goal fluence of 120x103 ~-). The data reveals that the ST and EE treatments produce the lowest swelling in the alloy set forth in Table II above.
The EC treatment produces an acceptable level of swelling at goal fluences but the treatment is far from optimum for in-reactor applications.
In similar tests, an alloy having the following composition was tested:
TABLE IV
Nickel 60 Chromium 15 Molybdenum 5.0 Niobium 1.5 Silicon 0.5 Zirconium ~ .03 Titanium 1.5 Aluminum 1.5 Carbon 0,03 Boron 0.01 Iron Bal.
47,~071 Ihe thermomechanica:l treatalents given to t:he aforesaid alloy o~` T~ble IV and the microstructures and mechanical properties of the resulting alloy are given in the follow-ing Tables V and VI:
TABLE V
Designa-tion Thermomechanical Treatment*
BP 1038C/1 hr/AC + 800 C/ll hr/AC + 700C/2 hr/AC
BR 927C/1 hr/AC + 800C/ll hr/AC ~ 700C/2 hr/AC
BT 1038C/0.25 hr/AC + 899C/l hr/AC +
749C/8 hr/AC
CT 30%CW at 1038C + 800C/ll hr/AC +
700C/2 hr/AC
CU 890C/1 hr/AC + 800C/ll hr/AC +
700C/2 hr/AC + 30 BU 800C/ll hr/AC + 700C/2 hr/AC
*A~ter TO38~7r-hr/Fc ~ 60% CW.
TABLE VI
Designa- 650C
20 tion Com,ents ~ r) BP Small gamma-prime, no 136.7 dislocations BP Bimodal gamma-prime, 152.5 73 gamma cells 25 BT Bimodal gamma-prime 135.3 no dislocations CT Bimodal gamma-prime, 154.6 non-uniform structure (long banded cells, some subgrains) CU Bimodal gamma-prime, 147.0 elongated cells BIJ Bimodal gamma-prime, 156.4 74 equiaxed cells ~5 The gamma-prime solvus and the one hour recrystalliza~ion temperature for the alloy set forth in Table IV are 915C
3~3 6 47,1071 I()"(` al-l(l lO()()QC + 20(`, respectively. Therefore, unlike thc alloy given in 'I'ab]e I, there is no temperature range in which recrystallization can be accomplished while aging. Consistent with this fact, treatments BP and BT
which involve annealing at 1038C and subsequent double-aging, both produce a dislocation-free austenite matrix and a bimodal gamma-prime distribution. Structures pro-duced by treatments CU and BU, which do not induce recrys-tallization, all contain a highly dislocated cell struc-l~ ture containing various distributions of gamma-prime.
Table VI is a summary of the observed structures and corresponding physical properties. Note that the mechanical property values are grouped into two classes.
These are non-dislocation density, gamma-prime containing structures having 650C, ultimate ten~ile strengths be-tween 135 and 137 ksi, and the dislocated gamma-prime structures, which are much stronger, with ultimate tensile strengths between 147 and 157 ksi. Because of their superior strength and because of the benefit of an in-creased incubation time for swelling, dislocated struc-tures are preferred.
Treatment CU set forth in Tables V and VI above, starts with a dislocated cell structure with a trimodal gamma-prime distribution which is subsequently cold-worked 2~j 30%. The final cold-working operation actually decreases the strength as indicated by the 650C ultimate tensile strength data set form in Table VI, apparently by des-troying the integrity of the dislocation cell walls.
Treatments BR and BU of the alloy set forth in Table IV both produce a highly dislocated, partially recrystallized or recovered cell structure with bimodal gamma-prime size distribution. The BU treatment is pre-ferre~ since it yields slightly higher stress rupture ~ than the BR treatment. The dislocation and 3~, gamma-prime structures for the BU treatment produce a cell structure which is much more dispersed and interwoven than that produced by the EE treatment of the alloy set forth in Table I. The minimum cell thickness of the BU treat-:1~ 3~363 7 47,107I
mellt is appro.~imately the satne as the gamma-prime particle C i ~l g .
Ln order to further demonstrate the improvement that is obtained by means of the thermomechanical treat-ment of the present invention, reference may be had to thefollowing Tables VII and VIII which shows that this treat-ment is very effective in promoting high post radiation ductility. In this regard it should be pointed out that there exists a trough in which the ductility of these materials is materially decreased when tested at a temper-ature which is 110C above the temperature at which the material has been irradiated. Thus, the poorest ductility would be found at a temperature of 805C where the mater-ial has been irradiated at 695C. This 110 should ac-1'> count for all transient conditions of operation of forexample a fast breeder reactor. Thus the selection of the material and the heat treatment or the thermomechanical heat treatment of the material which when irradiated at 695centigrade should be tested at 805C where the lowest post irradiation ductility has occurred. Reference to the following Tables VII and VIII make it abundantly clear for example that the solution treated condition of alloy D66 when irradiated at 695C and tested at 805C exhibits zero ductility. In contrast thereto, material which has been subjected to the treatment set forth in the claims append-ed hereto of the same alloy irradiated at 695C and tested at 805C shows that a 1.1% uniform elongation is avail-able. It is critically important to maintain a greater than 0.3% ductility under these conditions since this is necessary to maintain fuel pin integrity during reactor transient conditions and the tables demonstrate the at-tainment of those goals. Tables VII and VIII also illus-trate that the higher ductility of this treatment is also accompanied by higher strength which is a highly unex-pected as respects these irradiated materials. Thesehigher strengths also attest to the fact of the excellent swelling resistance demonstrated by the alloys ~hich are subjected to the method of this treatment.
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` 1~333~;3 47,107I
Although the invention has been shown in connec-tion with certain specific embodiments, it will be readily apparent to ~hose skilled in the art that various changes in method steps and compositional limits can be made to suit requirements without departing from the spirit and scope of the invention.
'Ihe foregoing alloy is a gamma-prime strength-ene(l superalloy. Its properties can be altered drasti-c~lly b~ varying its thermomechanical treatment prior to testing. The following Table II sets forth the various 'j thermomechanical treatments to which the alloy set forth in Table I was subjected; while Table III lists the re-sultin~ microstructural and mechanical properties of the alloy after heat treatment:
T~ LE II
Vesi.gna-tion_ Thermomechanical Treatment AR 103~C~l hr/FC + 60% CW
IN-I ~982C/1 hr/AC ~ 788C/1 hr/AC + 720C/24 hr/AC
IN-2 ~890C/1 hr/AC + 800C/11 hr/AC + 700C/2 hr/AC
1'j EC -~927C/1 hr/AC + 800C/ll hr/AC + 700C/2 hr/AC
EE *800C/ll hr/AC + 700C/2 hr/AC
ter l~g~C/I hr/FC + 60% CW.
TABLE_LII
Designa- 650C
20 tion Comments UTS (ksi) 80 ksi SR (hr) AR No gamma-prime, high - 67.9 dislocation density IN-l Bimodal gamma-prime, 151.5 0.,3 recrystallized above gamma-prime solvus lN-2 Trimodal gamma-prime 141.3 81.9 (~islocated) EC Trimodal gamma-prime - 64.7 recrystallized below gamma-prime solvus EE Bimodal gamma-prime, - 235 equiaxed cells As can be seen from Table III above, the EC
treatment produces higher stress rupture properties than treatment IN-l. The EC treatment results in a trimodal distribution of gamma-prime since the recrystallization 1.~33363 ~ 4 47,107I
anneal is below the gamma-prime solvus and results in the prccipitation of a small volume of large (approximately 600 nm) gamma-prime precipitates.
Of the treatments set forth in Tables II and III, three treatments produced dislocated structures.
These are treatments AR, IN-2 and EE. The stress rupture data of Table II reveals that heat treatment EE produces a significantly stronger material. This structure consists of an interwoven dislocated cell structure which is pinned by a bimodal gamma-prime distribution. This condition has the highest strength of any tested and is very stable because of the pinned nature of the dislocation cells.
The graph shown in the attached figure illus-trates the swelling behavior of the alloy set forth in Table I in three thermomechanical conditions, ST, EC and EE. The swelling versus temperature curves are for radia-tion doses of 30 dpae, which is equivalent to 203x103 ~-(i.e., greater than the goal fluence of 120x103 ~-). The data reveals that the ST and EE treatments produce the lowest swelling in the alloy set forth in Table II above.
The EC treatment produces an acceptable level of swelling at goal fluences but the treatment is far from optimum for in-reactor applications.
In similar tests, an alloy having the following composition was tested:
TABLE IV
Nickel 60 Chromium 15 Molybdenum 5.0 Niobium 1.5 Silicon 0.5 Zirconium ~ .03 Titanium 1.5 Aluminum 1.5 Carbon 0,03 Boron 0.01 Iron Bal.
47,~071 Ihe thermomechanica:l treatalents given to t:he aforesaid alloy o~` T~ble IV and the microstructures and mechanical properties of the resulting alloy are given in the follow-ing Tables V and VI:
TABLE V
Designa-tion Thermomechanical Treatment*
BP 1038C/1 hr/AC + 800 C/ll hr/AC + 700C/2 hr/AC
BR 927C/1 hr/AC + 800C/ll hr/AC ~ 700C/2 hr/AC
BT 1038C/0.25 hr/AC + 899C/l hr/AC +
749C/8 hr/AC
CT 30%CW at 1038C + 800C/ll hr/AC +
700C/2 hr/AC
CU 890C/1 hr/AC + 800C/ll hr/AC +
700C/2 hr/AC + 30 BU 800C/ll hr/AC + 700C/2 hr/AC
*A~ter TO38~7r-hr/Fc ~ 60% CW.
TABLE VI
Designa- 650C
20 tion Com,ents ~ r) BP Small gamma-prime, no 136.7 dislocations BP Bimodal gamma-prime, 152.5 73 gamma cells 25 BT Bimodal gamma-prime 135.3 no dislocations CT Bimodal gamma-prime, 154.6 non-uniform structure (long banded cells, some subgrains) CU Bimodal gamma-prime, 147.0 elongated cells BIJ Bimodal gamma-prime, 156.4 74 equiaxed cells ~5 The gamma-prime solvus and the one hour recrystalliza~ion temperature for the alloy set forth in Table IV are 915C
3~3 6 47,1071 I()"(` al-l(l lO()()QC + 20(`, respectively. Therefore, unlike thc alloy given in 'I'ab]e I, there is no temperature range in which recrystallization can be accomplished while aging. Consistent with this fact, treatments BP and BT
which involve annealing at 1038C and subsequent double-aging, both produce a dislocation-free austenite matrix and a bimodal gamma-prime distribution. Structures pro-duced by treatments CU and BU, which do not induce recrys-tallization, all contain a highly dislocated cell struc-l~ ture containing various distributions of gamma-prime.
Table VI is a summary of the observed structures and corresponding physical properties. Note that the mechanical property values are grouped into two classes.
These are non-dislocation density, gamma-prime containing structures having 650C, ultimate ten~ile strengths be-tween 135 and 137 ksi, and the dislocated gamma-prime structures, which are much stronger, with ultimate tensile strengths between 147 and 157 ksi. Because of their superior strength and because of the benefit of an in-creased incubation time for swelling, dislocated struc-tures are preferred.
Treatment CU set forth in Tables V and VI above, starts with a dislocated cell structure with a trimodal gamma-prime distribution which is subsequently cold-worked 2~j 30%. The final cold-working operation actually decreases the strength as indicated by the 650C ultimate tensile strength data set form in Table VI, apparently by des-troying the integrity of the dislocation cell walls.
Treatments BR and BU of the alloy set forth in Table IV both produce a highly dislocated, partially recrystallized or recovered cell structure with bimodal gamma-prime size distribution. The BU treatment is pre-ferre~ since it yields slightly higher stress rupture ~ than the BR treatment. The dislocation and 3~, gamma-prime structures for the BU treatment produce a cell structure which is much more dispersed and interwoven than that produced by the EE treatment of the alloy set forth in Table I. The minimum cell thickness of the BU treat-:1~ 3~363 7 47,107I
mellt is appro.~imately the satne as the gamma-prime particle C i ~l g .
Ln order to further demonstrate the improvement that is obtained by means of the thermomechanical treat-ment of the present invention, reference may be had to thefollowing Tables VII and VIII which shows that this treat-ment is very effective in promoting high post radiation ductility. In this regard it should be pointed out that there exists a trough in which the ductility of these materials is materially decreased when tested at a temper-ature which is 110C above the temperature at which the material has been irradiated. Thus, the poorest ductility would be found at a temperature of 805C where the mater-ial has been irradiated at 695C. This 110 should ac-1'> count for all transient conditions of operation of forexample a fast breeder reactor. Thus the selection of the material and the heat treatment or the thermomechanical heat treatment of the material which when irradiated at 695centigrade should be tested at 805C where the lowest post irradiation ductility has occurred. Reference to the following Tables VII and VIII make it abundantly clear for example that the solution treated condition of alloy D66 when irradiated at 695C and tested at 805C exhibits zero ductility. In contrast thereto, material which has been subjected to the treatment set forth in the claims append-ed hereto of the same alloy irradiated at 695C and tested at 805C shows that a 1.1% uniform elongation is avail-able. It is critically important to maintain a greater than 0.3% ductility under these conditions since this is necessary to maintain fuel pin integrity during reactor transient conditions and the tables demonstrate the at-tainment of those goals. Tables VII and VIII also illus-trate that the higher ductility of this treatment is also accompanied by higher strength which is a highly unex-pected as respects these irradiated materials. Thesehigher strengths also attest to the fact of the excellent swelling resistance demonstrated by the alloys ~hich are subjected to the method of this treatment.
8 4 7 , 1 0 1 1 lu 11 ~ ~ r~
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~0 ~V~ _ _ . _1 _ _~ _, _, ~ _ _ _ _ ~ _, _, el ~ ~ Cr~ ~ O~ U~ _~ O U) O ~ O
~ E~ ~_ c~l ~ _~ _ o~ ~ ~o ~ ~ _ o~
--_ _ _ _ _ _ _ _ O _ _ _ _ _ H ~1 _ C _~ _~ _ oo ~ O~ ~ c~
~ :) CC _~ _ ~7 ~ ~ O _~ _ ~S: _ _ _ ~ ~O _ i~ ~ ~ . O C~ ~ Ul O _ CC _ _ _ 1~ ~0 _ ~:~ ~ ol:~ O O ~ U~ I~ O O ~ ~t I~
Z O 1-~ _ _ _ ~ _ N ~ _ _~ C _ O _ _ _ ~ _ 0 ~ ~ ~ ~ ~O ~ Il~ `~0 _ 1~ 0~0 ~ ~0 O
O P~ ~ _ __ 0 ao 0 x o~ ~ r~ u~ 1~ ~ ~ o~ _ H V Z ~ _ _ O O O X ' ~,s c~ ~ ~ ~ o oo u~ u~ t" O O uO~ ~ _ ~1 E~ ~0 ~`J c~l u~ `D ~O I~ I~ ~ 0~ O~ ~ ~
æ ~ ~ _ _ _ _ _ _ _ _ _ _ E~ ~ ~ C~ ~ 8 8 o~ ~ ~ o o~ ~ g ~5~ ~ ~O ~ u~ ~D ~O ~ I~ U~ `D ~ u~
~c _ ~. _ _ _ _ _ _ _ _ _ _ _ o Z C O ~ Z ~ Z ~ e 1 _ _ _ 1 _ ~' ' ' ' , 9 47 ,107I
~ ~ ~- : ~ ~
C C w _ _ _ o c r ____ ~ o ~ o _ o c ~ _ _ _ r u_ o ~ ~ o t~ E u _ _ _ _ o _ _ _ _ _ _ _ __ _ _ 1~ o _ _ E ~ ~ o: ~ ~ ~
O _ _ r _ ec _ _ _ r~ o _ o~ o o ~- o u~ ~ _ _~ ~ o c .t __ _ _ _ _ _ _ __ o~ _ _ _ ~ u~ _ __ _ o _ _ _ _ ~ ~ o ~
Z g .~ r~ t~l_ _ OO~ _~ ~ C~ r~ ~ O~ ~ ~ _~ O O ~ O
U S O _ _ O_ _ __ _ _ _ O _ b _ _ ~ ~ ~ _ ~
F L~ ~ N ~r ~ O~ ~ _ r _ .7 N : _ O~ (`I _ _ r~ _ c c ~¦~ 3 ~ 1` -- ~ r,~ r r o ,. ,~ r ~ V _ _ r O. _ r O
c ~ I _ _ _ o __ o _~ ~ ~ _ _ _ . _ _ _ _ ~ _ ~ o ~ _ L C 111 _ E X KX X XX X X XX X X X X _ F L~ X X X O D
L-. o)E~J e ~ .. .. o o o o ~ ~ o o o o ~ el o ~ ~ ~ o o ~-: ~ /__ _ O r~ r r ~ O U~ O _ r ~ _ Ir r r,~ r I _l l r r r r L~ O X _ __ _ _ _ ---- -- ~ r Z -- E ~J U o o~ r o o o o ~7 r o o o o a U¦ u~ o o o o ¦ o E C --L O ~ r~ _ r _ _ _ ,~ _ " o _ lo __ L ~ _ r _ ul E Q E~ ~ Q ~ Q Q ~ Q , G Q ~ Q _ ~L~ u~ Q Q ~ ¦ Q
` 1~333~;3 47,107I
Although the invention has been shown in connec-tion with certain specific embodiments, it will be readily apparent to ~hose skilled in the art that various changes in method steps and compositional limits can be made to suit requirements without departing from the spirit and scope of the invention.
Claims (11)
What is claimed is:
1. A method for heat treating an iron-nickel-chromium alloy consisting essentially of about 25% to 45%
nickel, 10% to 16% chromium, 1.5% to 3% of an element selected from the group consisting of molybdenum and niobium, about 1% to 3% titanium, about 0.5% to 3.0%
aluminum and the remainder substantially all iron; which method comprises the steps of heating the alloy to a temperature in the range of 1000°C to 1100°C for 30 se-conds to 1 hour followed by a furnace-cool, cold-working the alloy 10% to 80%, heating the alloy to a temperature of about 750°C to 800°C for 4-15 hours followed by an air-cool, and then heating the alloy to a temperature in the range of 650°C to 700°C for 2-20 hours followed by an air-cool.
nickel, 10% to 16% chromium, 1.5% to 3% of an element selected from the group consisting of molybdenum and niobium, about 1% to 3% titanium, about 0.5% to 3.0%
aluminum and the remainder substantially all iron; which method comprises the steps of heating the alloy to a temperature in the range of 1000°C to 1100°C for 30 se-conds to 1 hour followed by a furnace-cool, cold-working the alloy 10% to 80%, heating the alloy to a temperature of about 750°C to 800°C for 4-15 hours followed by an air-cool, and then heating the alloy to a temperature in the range of 650°C to 700°C for 2-20 hours followed by an air-cool.
2. The method of claim 1 wherein the alloy is initially heated to a temperature in the range of 1025°C
to 1075°C for 2-5 minutes.
to 1075°C for 2-5 minutes.
3. The method of claim l wherein said alloy is qo~/o f o ~o~c cold-worked by cold rolling 20% to 60%.
4. The method of claim 3 wherein said alloy is cold-rolled 30% to 50%.
5. The method of claim 1 wherein said alloy is in the form of a tube and is cold-worked by drawing the tube to produce a reduction of 15% to 35%.
6. The method of claim 5 wherein said reduction is within the range of 20% to 30%.
7. The method of claim l wherein, after cold-working, said alloy is heated to a temperature of about 12 47,107I
775°C for 8 hours followed by an air-cool.
775°C for 8 hours followed by an air-cool.
8. The method of claim 1 wherein the method steps comprise heating to a temperature of 1025°C to 1075°C for 2-5 minutes followed by a furnace-cool, cold-working the alloy 20% to 60% ? heating the alloy to a temperature of about 775°C for 8 hours followed by an air-cool, and then heating the alloy to a temperature of 700°C for 2 hours followed by an air-cool.
9. The method according to claim 1 wherein said element is molybdenum.
10. me method according to claim 1 or 9 further comprising the forming of a microstructure in said alloy having dislocations and a bimodal distribution of gamma prime precipitates.
11. me method according to claim 10 wherein said dislocations comprise interwoven dislocated cell structures which are pined by said bimodal gamma prime precipitates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6122979A | 1979-07-27 | 1979-07-27 | |
| US061,229 | 1979-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1133363A true CA1133363A (en) | 1982-10-12 |
Family
ID=22034466
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA352,685A Expired CA1133363A (en) | 1979-07-27 | 1980-05-26 | Method for heat treating iron-nickel-chromium alloy |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5620123A (en) |
| BE (1) | BE883413A (en) |
| CA (1) | CA1133363A (en) |
| DE (1) | DE3019931A1 (en) |
| ES (1) | ES491749A0 (en) |
| FR (1) | FR2462478A1 (en) |
| GB (1) | GB2058834B (en) |
| IT (1) | IT1136403B (en) |
| NL (1) | NL8002490A (en) |
| SE (1) | SE452992B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4359350A (en) * | 1981-03-27 | 1982-11-16 | The United States Of America As Represented By The Department Of Energy | High post-irradiation ductility thermomechanical treatment for precipitation strengthened austenitic alloys |
| US5137684A (en) * | 1991-03-06 | 1992-08-11 | Rockwell International Corporation | Hydrogen embrittlement resistant structural alloy |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1250642B (en) * | 1958-11-13 | 1967-09-21 | ||
| FR1439636A (en) * | 1964-07-08 | 1966-05-20 | Atomic Energy Authority Uk | Improvements in heat treatment of metals |
| US3592632A (en) * | 1966-07-14 | 1971-07-13 | Int Nickel Co | High temperature nickel-chromium-iron alloys particularly suitable for steam power applications |
| GB1132724A (en) * | 1966-10-03 | 1968-11-06 | Wiggin & Co Ltd Henry | Nickel-chromium-iron alloys |
| DE2415881A1 (en) * | 1974-04-02 | 1975-10-23 | Kernforschung Gmbh Ges Fuer | PROCESS FOR PRODUCING METALLIC SHELLING MATERIALS FOR FAST REACTORS |
| US4236943A (en) * | 1978-06-22 | 1980-12-02 | The United States Of America As Represented By The United States Department Of Energy | Precipitation hardenable iron-nickel-chromium alloy having good swelling resistance and low neutron absorbence |
-
1980
- 1980-04-28 GB GB8013969A patent/GB2058834B/en not_active Expired
- 1980-04-29 NL NL8002490A patent/NL8002490A/en not_active Application Discontinuation
- 1980-05-21 BE BE0/200704A patent/BE883413A/en not_active IP Right Cessation
- 1980-05-22 ES ES491749A patent/ES491749A0/en active Granted
- 1980-05-23 SE SE8003879A patent/SE452992B/en not_active IP Right Cessation
- 1980-05-24 DE DE19803019931 patent/DE3019931A1/en active Granted
- 1980-05-26 CA CA352,685A patent/CA1133363A/en not_active Expired
- 1980-05-27 IT IT41570/80A patent/IT1136403B/en active
- 1980-05-27 JP JP6970280A patent/JPS5620123A/en active Granted
- 1980-05-29 FR FR8011958A patent/FR2462478A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ES8105787A1 (en) | 1981-05-16 |
| BE883413A (en) | 1980-11-21 |
| SE8003879L (en) | 1981-01-28 |
| ES491749A0 (en) | 1981-05-16 |
| JPH0130891B2 (en) | 1989-06-22 |
| FR2462478B1 (en) | 1984-11-23 |
| IT8041570A0 (en) | 1980-05-27 |
| DE3019931A1 (en) | 1981-12-03 |
| DE3019931C2 (en) | 1989-04-13 |
| NL8002490A (en) | 1981-01-29 |
| FR2462478A1 (en) | 1981-02-13 |
| GB2058834B (en) | 1984-07-25 |
| IT1136403B (en) | 1986-08-27 |
| GB2058834A (en) | 1981-04-15 |
| JPS5620123A (en) | 1981-02-25 |
| SE452992B (en) | 1988-01-04 |
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