CN114182140A - Tantalum-containing cast nickel-based high-temperature alloy for 700 ℃ unit and preparation method thereof - Google Patents
Tantalum-containing cast nickel-based high-temperature alloy for 700 ℃ unit and preparation method thereof Download PDFInfo
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 71
- 239000000956 alloy Substances 0.000 title claims abstract description 71
- 229910052715 tantalum Inorganic materials 0.000 title claims abstract description 43
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 229910052759 nickel Inorganic materials 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title claims description 6
- 238000000034 method Methods 0.000 claims abstract description 17
- 239000006104 solid solution Substances 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 238000003723 Smelting Methods 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 238000007670 refining Methods 0.000 claims abstract description 5
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 4
- 238000007599 discharging Methods 0.000 claims abstract description 4
- 239000010959 steel Substances 0.000 claims abstract description 4
- 229910000601 superalloy Inorganic materials 0.000 claims description 35
- 239000010955 niobium Substances 0.000 claims description 18
- 230000009467 reduction Effects 0.000 claims description 16
- 238000005266 casting Methods 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 230000006698 induction Effects 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 abstract description 12
- 239000013078 crystal Substances 0.000 abstract description 8
- 230000008569 process Effects 0.000 abstract description 7
- 239000000243 solution Substances 0.000 abstract description 6
- 239000000203 mixture Substances 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 2
- 239000010936 titanium Substances 0.000 description 36
- 238000005728 strengthening Methods 0.000 description 21
- 229910052782 aluminium Inorganic materials 0.000 description 20
- 229910052719 titanium Inorganic materials 0.000 description 20
- 239000011651 chromium Substances 0.000 description 13
- 230000003647 oxidation Effects 0.000 description 10
- 238000007254 oxidation reaction Methods 0.000 description 10
- 229910052804 chromium Inorganic materials 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 230000007774 longterm Effects 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 5
- 238000005204 segregation Methods 0.000 description 5
- 239000011573 trace mineral Substances 0.000 description 5
- 235000013619 trace mineral Nutrition 0.000 description 5
- 101000912561 Bos taurus Fibrinogen gamma-B chain Proteins 0.000 description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 230000032683 aging Effects 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- 229910017052 cobalt Inorganic materials 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- 229910052758 niobium Inorganic materials 0.000 description 4
- 210000001787 dendrite Anatomy 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- 206010014970 Ephelides Diseases 0.000 description 2
- 208000003351 Melanosis Diseases 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000521 B alloy Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 229910001005 Ni3Al Inorganic materials 0.000 description 1
- 229910001362 Ta alloys Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- QDWJUBJKEHXSMT-UHFFFAOYSA-N boranylidynenickel Chemical compound [Ni]#B QDWJUBJKEHXSMT-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910001063 inconels 617 Inorganic materials 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910001068 laves phase Inorganic materials 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- VMJRMGHWUWFWOB-UHFFFAOYSA-N nickel tantalum Chemical compound [Ni].[Ta] VMJRMGHWUWFWOB-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
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- 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
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/02—Making non-ferrous alloys by melting
- C22C1/023—Alloys based on nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
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- Mechanical Engineering (AREA)
- Metallurgy (AREA)
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- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
The tantalum-containing cast nickel-based high-temperature alloy for the 700 ℃ unit comprises, by mass, 0.2-2.0% of Ta, 20-23% of Cr, 11-13% of Co, 8-9% of Mo, 1.2-2.4% of Al + Ti, less than or equal to 1% of Nb, less than or equal to 0.06% of C, less than or equal to 0.004% of B and the balance of Ni; the method comprises (1) preparing raw materials according to set components; (2) smelting under a vacuum condition; (3) refining and removing impurities, and then pouring in vacuum; (4) keeping the vacuum condition until the molten steel is filmed, and then discharging to prepare an ingot; (5) keeping the temperature of 1150-1200 ℃ for 1-2 h for solution treatment and cooling with water. The invention utilizes the proportioning of several elements including Ta element to ensure the strength of solid solution, simultaneously form more stable precipitation phase, inhibit the coarsening of crystal boundary, and simultaneously determine the optimal chemical composition range, the element addition proportion and the optimal heat treatment process system.
Description
Technical Field
The invention belongs to the technical field of heat-resistant alloys, and particularly relates to a tantalum-containing cast nickel-based high-temperature alloy for a 700 ℃ unit and a preparation method thereof.
Background
The high-temperature alloy has excellent high-temperature mechanical property, thermal corrosion resistance and good long-term structure stability, so that the high-temperature alloy becomes an indispensable material for core hot end parts in the industrial fields of nuclear power, thermal power, aviation, aerospace and the like, and can bear the interaction of severe conditions such as high temperature, corrosion, oxidation, load and the like in the service process. Among them, the nickel-based superalloy is the most widely used superalloy, and has excellent oxidation resistance and corrosion resistance. Nickel-base superalloys are generally divided into solid solution strengthened and precipitation strengthened superalloys, where the types of elements in the two alloys are approximately the same, and the main difference is the difference in the content of the elements forming the strengthening phase. The nickel-based superalloy generally contains a plurality of alloy elements, such as W, Cr, Co, Mo, Nb, and the like, which are expensive, so that the manufacturing cost of the nickel-based superalloy is increased, and in this case, how to improve the durability of the nickel-based superalloy is very important, which is an effective method for realizing the improvement of the use safety of parts and the reduction of the use cost of the alloys, and is a research hotspot of the current alloys.
At present, the structure performance of the alloy is improved by adjusting the content of alloy elements, adding the alloy elements or adding trace elements, for example, the Inconel740 alloy is based on the composition of Nimonic263 alloy, the content of Cr and Mo is increased to enhance the oxidation resistance and the hot corrosion resistance, and Nb is added to enhance the precipitation of a gamma' strengthening phase, so that the high-temperature strength of the alloy is improved; the improved Inconel740H alloy of the Inconel740 alloy is characterized in that the content of Si element is reduced by adjusting the content of Al and Ti elements, so that the precipitation of harmful phases during the long-term service period of the alloy is inhibited, and the stability of the structure is improved; some trace elements are added into the nickel-based high-temperature alloy, so that the stability of the structure can be effectively improved, for example, 20-50 ppm of B element is added into the Inconel617 alloy, so that an improved Inconel617B alloy strengthened by B metallurgy is developed, the B element has an obvious grain boundary strengthening effect, the creep resistance of the alloy is obviously improved, and the service life is prolonged; according to the current research result, the alloy is suitable for preparing castings such as large valve bodies, cylinder bodies and the like on a generator set, but the structure stability and the durability of the alloy still need to be improved because precipitated phases are aggregated and coarsened at grain boundaries during service, the grain boundaries are weakened, strain aging cracks are generated, and the mechanical property is reduced.
If the elements added in the alloy can not only improve the strength of the high-temperature alloy, but also give consideration to the corrosion resistance, the alloy is a good choice for the design of the alloy. Ta is an effective solid solution strengthening element and can improve the strength of an alloy matrix; the element is also a forming element of a gamma 'strengthening phase, and the precipitation strengthening effect of the gamma' phase is effectively enhanced; meanwhile, the MC type carbide is a strong forming element, and has good stability, so that the stability of the structure is improved; in addition, the generation tendency of freckles in the casting process can be reduced, and the casting performance of the high-temperature alloy is obviously improved; however, because the melting point of Ta is high, the atomic radius is large, the solid solubility in the nickel-based superalloy is limited, the diffusion speed is slow, serious element segregation is easy to generate in the solidification process, and massive MC type carbide is formed, so that the uniformity of alloy structure is reduced by excessive Ta elements, and the mechanical property of the alloy is influenced; therefore, the structural stability of the nickel-based superalloy in long-term high-temperature service can be effectively improved through the reasonable element proportion and component range of the main gamma' phase forming elements Al and Ti and the Ta element.
Disclosure of Invention
The invention aims to provide a tantalum-containing cast nickel-based high-temperature alloy for a 700 ℃ unit and a preparation method thereof, which improve the alloy strength and improve the alloy structure stability by adding a proper amount of tantalum into the nickel-based high-temperature alloy and adjusting the contents of aluminum and titanium elements, thereby prolonging the service life of the alloy and reducing the use cost of parts.
The tantalum-containing cast nickel-based high-temperature alloy comprises, by mass, 0.2-2.0% of Ta, 20-23% of Cr, 11-13% of Co, 8-9% of Mo, 1.2-2.4% of Al and Ti, no more than 1% of Nb, no more than 0.06% of C, no more than 0.004% of B, and the balance of Ni and inevitable impurities, wherein (Al + Ti)/Ta is no less than 0.8; and Ti/Al is less than or equal to 0.8.
Tensile strength sigma of the tantalum-containing cast nickel-base superalloyb580 to 600MPa, yield strength sigma0.2260 to 275MPa, 47 to 51 percent of elongation at break and 52 to 55 percent of reduction of area.
The tensile strength sigma of the tantalum-containing cast nickel-based superalloy at 700 +/-1 DEG Cb370-390 MPa, yield strength sigma0.2138 to 143MPa, 55 to 61% elongation at break and 46 to 50% reduction of area.
The preparation method of the tantalum-containing cast nickel-based superalloy is carried out according to the following steps;
(1) preparing raw materials according to set components;
(2) putting the raw materials into a vacuum induction furnace, and smelting under a vacuum condition;
(3) refining and removing impurities from the smelted material under a vacuum condition, and then pouring under the vacuum condition;
(4) after the pouring is finished, keeping the vacuum condition until the molten steel is filmed, discharging, and cooling to normal temperature to prepare an ingot;
(5) and heating the cast ingot to 1150-1200 ℃, preserving heat for 1-2 h, carrying out solid solution treatment, and then cooling with water to room temperature to prepare the tantalum-containing cast nickel-based superalloy.
In the above steps (2), (3) and (4), the vacuum condition is a degree of vacuum <1.0 Pa.
In the step (2), the melting temperature is 1530. + -. 25 ℃.
In the step (3), the casting is wax pattern casting.
In the step (3), the casting temperature is 1460. + -. 25 ℃.
In the step (5), the water cooling means immersion in water cooling.
The element design principle of the invention is as follows:
tantalum is an effective solid solution strengthening element and can improve the strength of an alloy matrix; the element is also a forming element of a gamma 'strengthening phase, and the precipitation strengthening effect of the gamma' phase is effectively enhanced; meanwhile, the MC type carbide is a strong forming element, and has good stability, so that the stability of the structure is improved; in addition, the tantalum can also reduce the generation tendency of freckles in the casting process and obviously improve the casting performance of the high-temperature alloy; however, because the melting point of tantalum is high, the atomic radius is large, the solid solubility of the tantalum in the nickel-based superalloy is limited, the diffusion speed is slow, serious element segregation is easy to generate in the solidification process, and massive MC type carbide is formed, so that the uniformity of alloy structures can be reduced by excessive tantalum elements, and the mechanical property of the alloy is influenced; therefore, the optimal control range of the tantalum content in the alloy is 0.5-2.0%;
chromium is an indispensable alloy element in the high-temperature alloy, is a key element for ensuring that the high-temperature alloy has excellent corrosion resistance and oxidation resistance, is generally added by more than 15%, but is excessively added, so that chromium-rich carbide coarsening or harmful phase precipitation can be caused, and the stability of the structure is influenced, therefore, the content of the element is strictly controlled, and the optimal control range of the chromium content in the alloy is 20-23%;
the cobalt is added into the nickel-based alloy, so that a good solid solution strengthening effect can be achieved, and the stacking fault energy can be reduced, so that the dislocation movement resistance is improved, and the high-temperature strength is improved, but the manufacturing cost is obviously increased due to excessive cobalt with a high price, so that the content of the cobalt is controlled to be 11-13%;
molybdenum is an important solid solution strengthening element, can obviously increase the lattice constant of a matrix and increase a long-range elastic stress field, thereby hindering the movement of dislocation; but in the solidification process, the molybdenum has poor diffusion performance, and can be strongly and partially polymerized to dendrite dryness to influence the uniformity of the structure, so that the content of molybdenum is generally controlled to be 8-9%;
aluminum and titanium are main forming elements of a gamma 'strengthening phase and are important elements for ensuring the high-temperature strength of the alloy, but the content of the aluminum and the titanium is too high, so that the gamma' strengthening phase can be seriously coarsened during service, and the plasticity and the toughness of the alloy are reduced; therefore, the content of aluminum and titanium is respectively controlled to be 1.0-2.0% and 0.2-0.4%;
carbon is a grain boundary strengthening element and is also a forming element of carbide, but usually, the carbon element is added into the nickel-based alloy as a trace element, and excessive carbon can be segregated to the grain boundary, so that the carbide on the grain boundary is coarsened, the grain boundary is prevented from becoming brittle, cracks are easy to nucleate and expand, and the endurance performance of the alloy is influenced; therefore, the carbon content is controlled below 0.06 percent;
boron is also a crystal boundary strengthening element, and the segregation of the crystal boundary reduces the crystal boundary to strengthen the crystal boundary and can fill the vacancy around the carbide, thereby effectively preventing the diffusion of the carbon element to the carbide and inhibiting the coarsening of the carbide. But as a trace element, the content of the trace element is strictly controlled to be less than 0.004;
niobium is one of the common solid solution strengthening elements, with Nb being mainly dissolved in the γ' phase. Meanwhile, Nb also increases the lattice constant and plays a significant role in solid solution strengthening of the gamma matrix. However, too much Nb causes precipitation of Laves phase, which adversely affects alloy properties. Therefore, the Nb content is controlled to < 1%;
nickel is an important matrix component and a forming element of a gamma' strengthening phase, and the nickel-based alloy has good high-temperature strength and excellent structure stability, and is the most widely applied alloy in the high-temperature alloy.
The invention has the advantages and beneficial effects that:
compared with the Inconel617B alloy, the alloy provided by the invention has the advantages that the high-temperature tensile property is high, the room-temperature microhardness is large, the room-temperature tensile property plasticity is basically kept flat, and the oxidation resistance of the alloy is excellent; the comprehensive action of Ta, Al and Ti elements reduces the element segregation degree of Al and Ti and promotes the formation of primary MC carbide; in the long-term aged structure, Ta promotes the precipitation of more stable carbide in the crystal, inhibits the coarsening of the carbide in the crystal boundary, improves the long-term aged structure stability and ensures the durability of the alloy;
the coarsening of the carbide is obvious due to the influence of B on the carbide at the grain boundary, when the content of C is less than or equal to 0.06 percent, the (Al + Ti)/Ta is controlled to be more than or equal to 0.8, the reduction of film-shaped carbide on the grain boundary can be promoted, the increase of primary blocky carbide in the grain can be promoted, and the structural stability is improved;
because Al element has stronger oxidation resistance than Ti element, and Ni is ensured3The stability of the Al (Ti) phase ensures that the precipitated phase has the best strengthening effect, the contents of Al and Ti are ensured to be 1.2-2.4%, and meanwhile, the ratio of Ti to Al is required to be controlled to be less than or equal to 0.8;
carrying out solid solution treatment on the cast ingot at 1150-1200 ℃ for 1-2 hours and water cooling to finally obtain an alloy with an austenite structure and intragranular Ni3The Al (Ti) phase strengthening phase is uniformly dispersed and distributed, the volume fraction is about 5-15%, and the grain boundary carbide is discontinuously distributed.
According to the invention, under the guidance of a phase change theory and an alloy strengthening theory, an alloy with higher durability, good oxidation corrosion resistance and good long-term structure stability is obtained through alloy component design according to the performance requirement of a heat-resistant alloy for a 700 ℃ ultra-supercritical thermal power generating unit under the service condition; the invention utilizes the proportioning of several elements including Ta element to ensure the strength of solid solution, simultaneously form more stable precipitation phase, inhibit the coarsening of crystal boundary, and simultaneously determine the optimal chemical composition range, the element addition proportion and the optimal heat treatment process system.
Drawings
FIG. 1 is a micrograph of an as-cast structure of an ingot according to example 1 of the present invention;
FIG. 2 is a scanning electron micrograph of an ingot treated with a solution treatment in example 1 of the present invention;
FIG. 3 is a microstructure of tantalum-containing cast nickel-base superalloy of example 1 after aging at 700 ℃ for 7000 hours according to the present invention;
FIG. 4 is a gamma prime texture map of tantalum-containing cast nickel-base superalloys of example 1 of the present invention after aging at 700 deg.C for 7000 hours.
Detailed Description
The alloy of the present invention will be further described with reference to the following examples, but the present invention is not limited to these examples.
The structure of the tantalum-containing cast nickel-based superalloy in the embodiment of the invention is austenite and Ni35-15% of Al (Ti) phase and Ni3Al (Ti) phase is uniformly distributed, and grain boundary carbide is discontinuously distributed.
The normal-temperature Vickers hardness of the tantalum-containing cast nickel-based superalloy in the embodiment of the invention is 180-186 HV.
The raw materials adopted in the embodiment of the invention are metal nickel ingot, nickel-tantalum alloy, metal chromium, metal cobalt, metal molybdenum, aluminum-titanium alloy and metal niobium, as well as pyrolytic graphite and nickel-boron alloy.
The temperature of the refining process in the embodiment of the invention is 1580 ℃ at 1500-. Injecting a proper amount of vulcanizing agent and oxidant into the crucible to perform precipitation deoxidation and precipitation desulfurization.
Example 1
Preparing raw materials according to set components; the raw materials comprise, by mass, 0.49% of Ta, 22.21% of Cr, 12.00% of Co, 8.55% of Mo, 1.2% of Al, 0.34% of Ti, 1.54% of Al and Ti, 0.044% of C, 0.004% of B, and the balance of Ni, wherein the ratio of (Al and Ti)/Ta is 1.54/0.49, 3.14 is more than or equal to 0.8; and 0.28 is equal to or less than 0.8 is equal to 0.34/1.2;
putting the raw materials into a vacuum induction furnace, and smelting under a vacuum condition; the smelting temperature is 1530 +/-25 ℃;
refining and removing impurities from the smelted material under a vacuum condition, and then carrying out wax mold casting under the vacuum condition; the casting temperature is 1460 +/-25 ℃;
after the pouring is finished, keeping the vacuum condition until the molten steel is filmed, discharging, and cooling to normal temperature to prepare an ingot;
as shown in FIG. 1, the cast structure of the ingot is mainly composed of typical dendrites, wherein the secondary dendrite spacing is about 96 μm, and the average grain size is about 850 μm; the grain boundary is a saw-toothed grain boundary and is distributed with semi-continuous lath-shaped chromium-rich M23C6Carbide;
heating the ingot at normal temperature to 1180 ℃, carrying out solution treatment for 1h, and then cooling to room temperature by water to prepare the tantalum-containing cast nickel-based high-temperature alloy;
the vacuum condition of each step is that the vacuum degree is less than 1.0 Pa;
the appearance of the scanning electron microscope after the solution treatment is shown in figure 2, and as can be seen from the figure, the cast coarse carbides are almost completely dissolved, the structure becomes more uniform, the element segregation degree is greatly improved, and the grain boundaries are distributed with granular carbides;
tensile strength sigma of tantalum-containing cast nickel-base superalloyb588.5MPa, yield strength sigma0.2263.0MPa, elongation at break of 48.5 percent and reduction of area of 53.0 percent;
tensile strength sigma of tantalum-containing cast nickel-base superalloy at 700 +/-1 DEG Cb380.0MPa, yield strength sigma0.2139.5MPa, elongation at break of 58.8 percent and reduction of area of 47.5 percent;
the tantalum-containing cast nickel-base superalloy is subjected to oxidation resistance test, and the result shows that the oxidation parabola rate constant (k) at 900 ℃ is 6.06 multiplied by 10-7g2 cm-4s-1An oxidation parabola rate constant (k) of 3.91X 10 at 1000 DEG C-6g2 cm-4s-1；
The Vickers hardness at room temperature of the tantalum-containing cast nickel-based superalloy is 181 HV;
aging tantalum-containing cast nickel-base superalloy at 700 + -1 deg.C for 7000 hr to obtain a structure morphology shown in FIG. 3, and distributing rod-like M around grain boundary23C6Carbide and continuous film-shaped chromium-rich carbide is not formed in the grain boundary, so that the structural stability of the alloy is ensured; the gamma 'morphology is shown in FIG. 4, and it can be seen from the figure that the gamma' particles are relatively uniform in size, the average size is 59.4 + -8.8 nm, and the volume fraction is 4.4%.
Example 2
The method is the same as example 1, except that:
(1) the raw materials comprise, by mass, 0.5% of Ta, 20.5% of Cr, 11.4% of Co, 8.5% of Mo, 1.15% of Al, 0.36% of Ti, 1.51% of Al and Ti, 0.057% of C, 0.003% of B, and the balance of Ni, wherein the ratio of (Al and Ti)/Ta is 1.51/0.5, 3.02 is more than or equal to 0.8; and 0.31 is equal to 0.8 or less for Ti/Al 0.36/1.15;
(2) carrying out solution treatment when the temperature is reduced to 1200 ℃, wherein the time is 1.5 h;
(3) tantalum-containing cast nickel-based superalloy normal-temperature tensile strength sigmab581MPa, yield strength sigma0.2269MPa, elongation at break of 49% and reduction of area of 52%; tensile Strength σ at 700. + -. 1 ℃b385MPa, yieldIntensity sigma0.2138MPa, elongation at break of 56% and reduction of area of 49%.
Example 3
The method is the same as example 1, except that:
(1) the raw materials comprise, by mass, 1.89% of Ta, 22.5% of Cr, 12% of Co, 8.4% of Mo, 1.25% of Al, 0.34% of Ti, 1.59% of Al and Ti, 0.05% of C, 0.004% of B and the balance of Ni, wherein the ratio of (Al and Ti)/Ta is 1.59/1.89, and is more than or equal to 0.84; and 0.272 is equal to 0.8 is equal to 0.34/1.25 is equal to 0.272;
(2) carrying out solid solution treatment when the temperature is reduced to 1150 ℃ for 2 h;
(3) tantalum-containing cast nickel-based superalloy normal-temperature tensile strength sigmab590MPa, yield strength sigma0.2272MPa, elongation at break of 47-51% and reduction of area of 55%; tensile Strength σ at 700. + -. 1 ℃b390MPa, yield strength sigma0.2139MPa, elongation at break of 60% and reduction of area of 49%.
Example 4
The method is the same as example 1, except that:
(1) the raw materials comprise, by mass, 0.2% of Ta, 22.3% of Cr, 13% of Co, 8.7% of Mo, 1.25% of Al, 0.34% of Ti, 1.59% of Al and Ti, 0.5% of Nb, 0.05% of C, 0.004% of B, and the balance of Ni, (Al and Ti)/Ta is 1.59/0.2, 7.95 is more than or equal to 0.8; and 0.272 is equal to 0.8 is equal to 0.34/1.25 is equal to 0.272;
(2) carrying out solution treatment when the temperature is reduced to 1200 ℃, and the time is 1 h;
(3) tantalum-containing cast nickel-based superalloy normal-temperature tensile strength sigmab586MPa, yield strength sigma0.2268MPa, elongation at break of 48 percent and reduction of area of 52 percent; tensile Strength σ at 700. + -. 1 ℃b379MPa, yield strength sigma0.2143MPa, elongation at break of 59% and reduction of area of 47%.
Example 5
The method is the same as example 1, except that:
(1) the raw materials comprise, by mass, 0.49% of Ta, 22.2% of Cr, 11.3% of Co, 8.3% of Mo, 1.2% of Al, 0.45% of Ti, 1.65% of Al and Ti, 0.055% of C, 0.004% of B, and the balance of Ni, wherein (1.65/0.49% of Al and Ti)/Ta is more than or equal to 3.37 and more than or equal to 0.8; and Ti/Al is 0.45/1.2 is 0.375 is less than or equal to 0.8;
(2) carrying out solid solution treatment when the temperature is reduced to 1150 ℃ for 1.5 h;
(3) tantalum-containing cast nickel-based superalloy normal-temperature tensile strength sigmab593MPa, yield strength sigma0.2264MPa, elongation at break of 47.4 percent and reduction of area of 54 percent; tensile Strength σ at 700. + -. 1 ℃b383MPa, yield strength sigma0.2141MPa, elongation at break of 56% and reduction of area of 48%.
Claims (8)
1. The tantalum-containing cast nickel-based high-temperature alloy for the 700 ℃ unit is characterized by comprising 0.2-2.0% of Ta, 20-23% of Cr, 11-13% of Co, 8-9% of Mo, 1.2-2.4% of Al + Ti, less than or equal to 1% of Nb, less than or equal to 0.06% of C, less than or equal to 0.004% of B and the balance of Ni and inevitable impurities by mass, wherein (Al + Ti)/Ta is more than or equal to 0.8; and Ti/Al is less than or equal to 0.8.
2. The tantalum-containing cast nickel-base superalloy for 700 ℃ units as claimed in claim 1, wherein the tantalum-containing cast nickel-base superalloy has a tensile strength σb580 to 600MPa, yield strength sigma0.2260 to 275MPa, 47 to 51 percent of elongation at break and 52 to 55 percent of reduction of area.
3. The tantalum-containing cast nickel-base superalloy for 700 ℃ unit as claimed in claim 1, wherein the tantalum-containing cast nickel-base superalloy has a tensile strength σ at 700 ± 1 ℃b370-390 MPa, yield strength sigma0.2138 to 143MPa, 55 to 61% elongation at break and 46 to 50% reduction of area.
4. The preparation method of the tantalum-containing cast nickel-based superalloy for the 700 ℃ unit according to claim 1 is characterized by comprising the following steps;
(1) preparing raw materials according to set components;
(2) putting the raw materials into a vacuum induction furnace, and smelting under a vacuum condition;
(3) refining and removing impurities from the smelted material under a vacuum condition, and then pouring under the vacuum condition;
(4) after the pouring is finished, keeping the vacuum condition until the molten steel is filmed, discharging, and cooling to normal temperature to prepare an ingot;
(5) and heating the cast ingot to 1150-1200 ℃, preserving heat for 1-2 h, carrying out solid solution treatment, and then cooling with water to room temperature to prepare the tantalum-containing cast nickel-based superalloy.
5. The method for preparing the tantalum-containing cast nickel-base superalloy for the 700 ℃ unit according to claim 4, wherein in the steps (2), (3) and (4), the vacuum condition is a vacuum degree <1.0 Pa.
6. The method for preparing the tantalum-containing cast nickel-base superalloy for the 700 ℃ unit according to claim 4, wherein the melting temperature in the step (2) is 1530 ± 25 ℃.
7. The method for preparing the tantalum-containing cast nickel-base superalloy for 700 ℃ units according to claim 4, wherein the step (3) is a wax pattern casting.
8. The method for preparing the tantalum-containing cast nickel-base superalloy for the 700 ℃ unit according to claim 4, wherein the casting temperature in the step (3) is 1460 ± 25 ℃.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115323220A (en) * | 2022-09-13 | 2022-11-11 | 中国联合重型燃气轮机技术有限公司 | Crack-free nickel-based high-temperature alloy and preparation method and application thereof |
| CN115572850A (en) * | 2022-10-27 | 2023-01-06 | 惠州市惠阳协力精密铸造有限公司 | High-temperature alloy casting and preparation method thereof |
-
2021
- 2021-12-16 CN CN202111542300.9A patent/CN114182140A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| SHUANG GAO等: "Effect of Ta on microstructural evolution and mechanical properties ofa solid-solution strengthening cast Ni-based alloy during long-term thermal exposure at 700℃", 《JOURNAL OF ALLOYS AND COMPOUNDS》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115323220A (en) * | 2022-09-13 | 2022-11-11 | 中国联合重型燃气轮机技术有限公司 | Crack-free nickel-based high-temperature alloy and preparation method and application thereof |
| CN115323220B (en) * | 2022-09-13 | 2023-09-12 | 中国联合重型燃气轮机技术有限公司 | Crack-free nickel-based superalloy, and preparation method and application thereof |
| CN115572850A (en) * | 2022-10-27 | 2023-01-06 | 惠州市惠阳协力精密铸造有限公司 | High-temperature alloy casting and preparation method thereof |
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