A high-aluminum titanium cast nickel-based superalloy purification smelting method

Abstract

The present application relates to high-temperature alloy smelting technical field, specifically relates to a kind of high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method.The pure smelting method, step one, low calcium nickel alloy preparation;Step two, pure smelting: batching and furnace charging, melting period, refining period, alloying period, calcium treatment purification period and casting period;Pure smelting process is carried out in vacuum induction melting furnace, 2 / 3 low calcium nickel alloy is directly loaded into magnesium oxide crucible when furnace charging, and the remaining 1 / 3 low calcium nickel alloy is added in calcium treatment purification period.The present application prepares a kind of component accurately controllable "low calcium nickel alloy" as master alloy by pre-preparation, is added in key smelting stage, solves the problem of calcium element direct addition, realizes the deep deoxidation denitrogenation desulfurization of alloy melt, significantly reduces the oxygen, nitrogen, sulfur impurity content in alloy, to improve the purity and comprehensive mechanical properties of alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature alloy smelting, and particularly relates to a high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method. BACKGROUND

[0002] Cast nickel-based high-temperature alloys are widely used in the hot end components of aero-engines and gas turbines, such as turbine blades and nozzles, due to their excellent high-temperature strength, creep resistance and corrosion resistance. Such alloys usually contain high contents of active elements such as aluminum (Al) and titanium (Ti) to form the strengthening phase γ'-Ni3(Al, Ti).

[0003] However, cast high-temperature alloys containing high contents of Al and Ti elements are prone to chemical reactions with furnace lining materials (such as MgO crucibles) and impurity oxygen (O) and sulfur (S) in the melt during vacuum induction melting, generating high-melting-point non-metallic inclusions such as oxides (such as Al2O3 and TiO2) and sulfides. These inclusions not only become crack sources, significantly reducing the fatigue life and stress-rupture properties of the alloy, but also deteriorate the casting fluidity and hot working properties of the alloy. In particular, even at very low contents (usually ppm level), sulfur elements will segregate at grain boundaries, severely deteriorating the grain boundary strength, and are one of the most harmful elements in high-temperature alloys.

[0004] For the removal of oxygen, nitrogen and sulfur elements, the existing technology mainly uses rare earth elements (such as Ce and La) or calcium (Ca) at the end of smelting to deoxidize and desulfurize. However, Ca is extremely active, has a small density (1.55 g / cm 3 ), and a low boiling point (1484℃). If it is directly added to a nickel-based alloy melt at high temperature (usually more than 1500℃), it is easy to cause violent boiling and spattering, leading to an increase in the burning loss rate of Ca and other alloy elements, and an extremely unstable recovery rate. At the same time, excessive Ca elements will form CaO or CaS inclusions, which are harmful to the performance. Therefore, how to achieve efficient, stable and controllable addition of Ca elements, and fully play its deep purification role while avoiding its negative effects, is a technical problem that needs to be solved in the field.

[0005] Chinese patent CN107686901A discloses a high-purity nickel or high-temperature alloy smelting method using pure calcium wire. The method uses vacuum smelting and self-made pure calcium wire to solve the problems of high cost of using high-purity raw materials and calcium oxide crucibles, and the pollution of traditional calcium wire to high-temperature alloy master alloys. The structure of the self-made pure calcium wire has a pure calcium wire as the inner core, and the outer skin uses pure nickel or a hollow rod with the same composition as the high-temperature alloy to avoid the introduction of other alloy element pollution. However, the patent uses pure nickel or high-temperature alloy to wrap the calcium wire, and the phenomenon of calcium gasification causing steel liquid boiling still exists in the smelting process.

[0006] Chinese patent CN110592409A discloses a preparation method of a nickel-calcium intermediate alloy to solve the problem that calcium cannot be quantitatively added for desulfurization and deoxidation operation in the process of vacuum melting of the alloy containing nickel. The nickel-calcium is changed into an intermediate alloy, which can be used in the vacuum metallurgical process and is convenient to measure, compared with CaFe cored wire. The density of the prepared alloy is large, and it is directly sunk into the bottom of the molten metal when added into the molten nickel alloy, thereby greatly improving the utilization rate of calcium. However, the melting point of calcium is 828℃, the boiling point is 1484℃, and the melting point and density of nickel are 1453℃ and 8.903g / cm 3 The melting temperature of the nickel-calcium alloy in the patent is 1440-1450℃, and the casting temperature is 1410-1420℃, both of which are lower than the melting point of nickel. In the melting process, the calcium and nickel liquid may not be fully mixed, and the flowability of the casting is poor, which is not easy to form. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method. A "low-calcium nickel alloy" with precise and controllable composition is prepared as a master alloy and added at a key stage of smelting to solve the problem of direct addition of calcium, achieve deep deoxidation and desulfurization of the alloy melt, significantly reduce the content of oxygen, nitrogen and sulfur impurities in the alloy, and thereby improve the purity and comprehensive mechanical properties of the alloy.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] The high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method comprises the following steps:

[0010] Step one, low-calcium nickel alloy preparation: taking pure nickel and metallic calcium as raw materials, a low-calcium nickel alloy with a calcium content of 0.5-0.8wt.% is prepared by vacuum melting, and the low-calcium nickel alloy is processed into blocks or sheets;

[0011] Step two, purification smelting: using a magnesia crucible, the following stages are included in the vacuum induction melting furnace in sequence:

[0012] S1, batching and charging: batching according to the target composition of the high-aluminum titanium cast high-temperature alloy, charging 2 / 3 low-calcium nickel alloy and 1 / 2 carbon, metallic chromium, metallic cobalt, metallic tungsten, metallic molybdenum, metallic niobium and metallic nickel into the magnesia crucible; 1 / 2 carbon, metallic aluminum, metallic tantalum, nickel boron alloy, nickel zirconium alloy, metallic titanium and 1 / 3 low-calcium nickel alloy are sequentially charged into the charging bucket;

[0013] S2, melting period: melting to obtain molten steel;

[0014] S3, refining period: refining the molten steel under vacuum; 1 / 2 carbon is added before refining, and after refining is completed, the alloying period is entered;

[0015] S4, alloying period: power off and cooling to the surface of the molten steel film, adding metal aluminum, heating; power off and cooling to the surface of the molten steel film, adding metal tantalum, heating; power off and cooling to the surface of the molten steel film, adding nickel boron alloy, heating; power off and cooling to the surface of the molten steel film, adding nickel-zirconium alloy, heating; power off and cooling to the surface of the molten steel film, adding metal titanium, heating;

[0016] S5, calcium treatment purification period: power off and cooling to the surface of the molten steel film, adding 1 / 3 low calcium nickel alloy, heating and holding;

[0017] S6, casting period: heating to 1550-1570℃ for casting to obtain the master alloy ingot.

[0018] Wherein:

[0019] In step one, the purity of pure nickel and metal calcium is 99.0% or more.

[0020] In step one, vacuum melting is carried out under the protection of 3900-4100Pa argon, the melting temperature is 1540-1560℃, and the holding time is 9-11min.

[0021] Preferably, in step one, the wire cutting is used to process into a sheet shape.

[0022] In step S1, the target composition of high-aluminum titanium cast high-temperature alloy is as follows: C: 0.09-0.13%, Al: 3.20-3.70%, Ti: 3.20-3.70%, Cr: 15.7-16.3%, Nb: 0.60-1.10%, Ta: 1.50-2.0%, Co: 8.0-9.0%, Mo: 1.50-2.0%, W: 2.40-2.80%, Zr: 0.02-0.05%, B: 0.007-0.012%, Ca: 0.10-0.50%, and the balance is Ni and inevitable impurities. Among them, the Ca content is the target feeding amount, and most of it is consumed during the melting process.

[0023] In step S2, the operation of the melting period is as follows: vacuumizing to a vacuum degree lower than 5Pa, then melting at a power of 90-110kW, after the furnace charge is completely melted, adjusting the power to 140-160kW, the steel liquid temperature is 1600-1620℃, entering the refining period, the vacuum degree is <0.01Pa.

[0024] In step S3, the refining temperature is 1600-1620℃, and the refining time is 10-20min.

[0025] In step S4, the surface of the molten steel is formed into a film when the surface temperature of the molten steel is 1380-1420℃; the temperature is raised to 1550-1570℃, and the power for the temperature raising is 140-160kW.

[0026] In step S5, the temperature for the heat preservation is 1530-1550℃, and the time is 25-35min.

[0027] In step S6, the oxygen and nitrogen content of the master alloy ingot is lower than 4ppm, and the sulfur content is lower than 3ppm.

[0028] Preferably, the high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method has the following specific steps:

[0029] Step one, preparation of low-calcium nickel alloy:

[0030] A 50kg vacuum induction melting furnace is used to smelt pure nickel and metal calcium with a purity of more than 99.0% as raw materials under an argon gas protection atmosphere of 4000Pa to obtain a low-calcium nickel alloy with a calcium content of 0.5-0.8wt.%; after smelting, the alloy ingot is cast and processed into blocks or sheets for standby;

[0031] Step two, purification smelting:

[0032] A magnesia crucible is used in a vacuum induction melting furnace, which includes the following stages in turn:

[0033] S1, batching and charging: batching according to the target composition of the high-aluminum titanium cast high-temperature alloy, then charging 2 / 3 low-calcium nickel alloy and 1 / 2 carbon, metal chromium, metal cobalt, metal tungsten, metal molybdenum, metal niobium and metal nickel into the magnesia crucible; 1 / 2 carbon, metal aluminum, metal tantalum, nickel boron alloy, nickel zirconium alloy, metal titanium, and 1 / 3 low-calcium nickel alloy are sequentially charged into the charging bucket;

[0034] S2, melting period: after vacuumizing to a vacuum degree lower than 5Pa, melting is carried out at a power of 100±10kW, after the furnace charge is completely melted, the power is adjusted to 150±10kW, the temperature of the molten steel is 1600-1620℃, and the refining period is entered, the vacuum degree is <0.01Pa;

[0035] S3, refining period: the vacuum degree is kept unchanged, 1 / 2 carbon is added, the power is adjusted to 75±5kW, the temperature of the molten steel is kept unchanged, and the temperature is kept for 10-20min, then the power is stopped to reduce the temperature and enter the alloying period;

[0036] S4, alloying period: cooling to the surface of the molten steel film, at this moment the surface temperature of the molten steel is 1380-1420℃, then add metal aluminum, and then adjust the power to 150±10kW, and heat to 1550-1570℃; then power off to cool to the surface of the molten steel film, then add metal tantalum, and then adjust the power to 150±10kW, and heat to 1550-1570℃; according to the operation, add nickel boron alloy, nickel zirconium alloy, and metal titanium in turn;

[0037] S5, calcium treatment purification period: after the surface of the molten steel film is formed, add 1 / 3 low calcium nickel alloy, adjust the power to 150±10kW, heat to 1530-1550℃, then adjust the power to 75±5kW, keep the temperature unchanged, and keep the temperature for 30±5min;

[0038] S6, casting period: adjust the power to 150±10kW, heat to 1550-1570℃, and cast into a master alloy ingot.

[0039] Compared with the prior art, the beneficial effects of the present application are as follows:

[0040] 1) The present application prepares "low calcium nickel alloy" by pre-smelting, and the high-activity calcium exists in the form of stable alloy, which overcomes the problems of large burning loss, unstable recovery rate, and easy spatter caused by direct addition of pure calcium. The calcium exists in the form of solid solution or intermetallic compound in the nickel matrix, and releases more gently and fully when added to the high-temperature melt.

[0041] 2) By adding 2 / 3 low calcium nickel alloy when charging, the calcium element in the low calcium nickel alloy slowly precipitates with the slow melting of the metal material, and can effectively reduce the oxygen and sulfur elements in the molten steel together with 1 / 2 carbon. At the same time, 1 / 2 carbon is added before refining, and metal aluminum, metal tantalum, nickel boron alloy, nickel zirconium alloy, and metal titanium are added in turn during the alloying period, which can effectively avoid the formation of nitrides that are difficult to remove. At the same time, 1 / 3 low calcium nickel alloy is added during the calcium treatment purification period, which can effectively reduce and remove the residual O and S in the melt, thereby significantly reducing the oxygen, sulfur content in the final alloy. Through detection, the oxygen content in the alloy can be reduced to below 4ppm, the nitrogen content can be reduced to below 4ppm, and the sulfur content can be reduced to below 3ppm.

[0042] 3) The number of inclusions is greatly reduced, especially the harmful effect of sulfur is greatly inhibited, and the room temperature tensile strength, high temperature endurance life and fatigue performance of the alloy are significantly improved. The composition of the low calcium nickel alloy is fixed, which is convenient for accurate calculation and control of the addition amount, avoids the problem of large fluctuation of calcium content in the traditional process, and ensures the consistency and stability of the quality of alloys of different furnace batches.

[0043] 4) The present application has good compatibility with the existing process. The method does not need to make large changes to the existing vacuum induction melting equipment, only needs to adjust the raw material preparation and feeding sequence, and is easy to realize industrialized popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a scanning photograph of the low calcium nickel alloy of Example 1;

[0045] Figure 2 is the oxygen atom distribution of the low calcium nickel alloy of Example 1;

[0046] Figure 3 is the calcium atom distribution of the low calcium nickel alloy of Example 1;

[0047] Figure 4 is the nitrogen atom distribution of the low calcium nickel alloy of Example 1;

[0048] Figure 5 is the XRD analysis result of the low calcium nickel alloy of Example 1. DETAILED DESCRIPTION

[0049] The present application will be further described below in conjunction with examples.

[0050] All raw materials used in the examples are commercially available, except for special instructions.

[0051] Example 1

[0052] The high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method is carried out according to the following steps:

[0053] Step one, preparation of low calcium nickel alloy:

[0054] A 50kg vacuum induction melting furnace is used, 49.5kg of pure nickel (purity ≥ 99.0%) and 0.5kg of metal calcium (purity ≥ 99.5%) are weighed. 49.5kg of pure nickel (purity ≥ 99.0%) is added to the magnesium oxide crucible, and 0.5kg of metal calcium (purity ≥ 99.5%) is placed into the feeding bin. After vacuumizing to 5Pa, the power is sent to 55kW, until the pure nickel raw material is melted, the power is kept unchanged, the temperature is raised to 1550±10℃, the power is adjusted to 20kW, the refining period is entered, the refining temperature is 1550±10℃, and the time is 10min. After refining, the temperature is lowered to the surface film of the molten steel and high-purity argon is filled to a pressure of 4000Pa for protection. Then 0.5kg of metal calcium is added through the feeding bin. Adjust the power to 55kW, raise the temperature to 1550±10℃, then adjust to power 25KW for pouring, and pour into a low calcium nickel alloy ingot with calcium content of 0.77wt.%. Processed into a sheet by wire cutting for standby.

[0055] Figure 1is a scanning photo of the low calcium nickel alloy of Example 1 ; Figure 2 is the oxygen atom distribution of the low calcium nickel alloy of Example 1 ; Figure 3 is the calcium atom distribution of the low calcium nickel alloy of Example 1 ; Figure 4 is the nitrogen atom distribution of the low calcium nickel alloy of Example 1 ; Figure 5 is the XRD analysis result of the low calcium nickel alloy of Example 1 ; from Figures 1-4 It can be seen that the calcium nickel alloy has precipitates along the grain boundaries, and is rich in calcium elements. Figure 5 It is further illustrated that the precipitates along the grain boundaries are CaNi5 compounds.

[0056] Step two, pure smelting (target alloy weight: ~ 50 kg):

[0057] S1, batching and charging: batching according to the target composition limit (C: 0.11%, Al: 3.45%, Ti: 3.45%, Cr: 16.0%, Nb: 0.85%, Ta: 1.75%, Co: 8.5%, Mo: 1.75%, W: 2.60%, Zr: 0.035%, B: 0.0095%, Ca: 0.50% (added in the form of calcium nickel alloy), the balance is Ni and unavoidable impurities). 2 / 3 of the total low calcium nickel alloy and 1 / 2 of the carbon, all of the metal chromium, metal cobalt, metal tungsten, metal molybdenum, metal niobium and metal nickel are loaded into a magnesium oxide crucible. The remaining 1 / 2 carbon, metal aluminum, metal tantalum, nickel boron alloy, nickel zirconium alloy, metal titanium and 1 / 3 low calcium nickel alloy are loaded into a charging bucket in turn.

[0058] S2, melting period: vacuum extraction to <5 Pa, melting at a power of 100 kW. After cleaning, the power is increased to 150 kW, the steel liquid temperature reaches 1610°C, the vacuum degree is increased to <0.01 Pa, and the refining period is entered.

[0059] S3, refining period: keep the vacuum degree unchanged, add the remaining 1 / 2 carbon, reduce the power to 75 kW, refine at 1610°C for 15 min, and then stop power to cool down.

[0060] S4, alloying period: cool down to the steel liquid surface film, at this moment the steel liquid surface temperature is 1400°C, add metal aluminum. Increase the power to 150 kW, and heat up to 1560°C. Stop power to cool down to the steel liquid surface film, add metal tantalum particles, and then heat up to 1560°C. Repeat this operation, and add nickel boron alloy, nickel zirconium alloy, and metal titanium particles in turn.

[0061] S5, calcium treatment purification period: after the steel liquid surface is filmed again, add the remaining 1 / 3 low calcium nickel alloy. Increase the power to 150 kW, and heat up to 1540°C. Then reduce the power to 75 kW, and keep the temperature for 30 min.

[0062] S6, Casting stage: after the end of insulation, the power is increased to 150 kW, and the temperature is increased to 1560℃ for casting, to obtain the master alloy ingot.

[0063] The detection result is that the oxygen content of the obtained master alloy ingot is 3.8 ppm, the nitrogen content is 2.0 ppm, the sulfur content is 2.3 ppm, and the calcium content is 0.0028%.

[0064] Example 2

[0065] The high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method is performed according to the following steps:

[0066] Step one, preparation of low calcium nickel alloy: same as example 1.

[0067] Step two, purification smelting (target alloy weight: ~ 50 kg, Al / Ti content is taken as the upper limit):

[0068] The process steps are the same as example 1, and the target composition is adjusted to: C: 0.10%, Al: 3.70%, Ti: 3.70%, Cr: 15.7%, Nb: 1.10%, Ta: 2.0%, Co: 9.0%, Mo: 2.0%, W: 2.80%, Zr: 0.05%, B: 0.012%, Ca: 0.50% (added in the form of calcium nickel alloy), and the balance is Ni and unavoidable impurities.

[0069] Key process parameter control: refining temperature 1600℃, refining time 20min; alloying temperature 1550℃; calcium treatment holding temperature 1530℃, holding time 35min; casting temperature 1550℃.

[0070] The detection result is that the oxygen content of the obtained master alloy ingot is 3.8 ppm, the nitrogen content is 2.5 ppm, the sulfur content is 2.7 ppm, and the calcium content is 0.0035%.

[0071] Example 3

[0072] The high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method is performed according to the following steps:

[0073] Step one, preparation of low calcium nickel alloy: same as example 1.

[0074] Step two, purification smelting (target alloy weight: ~ 50 kg, C content is taken as the upper limit):

[0075] Process steps are the same as Example 1, target composition is adjusted to: C: 0.13%, Al: 3.20%, Ti: 3.20%, Cr: 16.3%, Nb: 0.60%, Ta: 1.50%, Co: 8.0%, Mo: 1.50%, W: 2.40%, Zr: 0.02%, B: 0.007%, Ca: 0.50% (added in the form of low-Ca nickel alloy), balance Ni and inevitable impurities.

[0076] Key process parameters: refining temperature 1620°C, refining time 10 min; alloying temperature 1570°C; Ca treatment holding temperature 1550°C, holding time 25 min; pouring temperature 1570°C.

[0077] Test results: the obtained master alloy ingot has oxygen content of 3.5 ppm, nitrogen content of 2.5 ppm, sulfur content of 2.8 ppm, and calcium content of 0.0022%.

[0078] Comparative Example 1 (without adding low-Ca nickel alloy)

[0079] Process: except that no low-Ca nickel alloy is added, the rest of the ingredients, process steps and parameters (including adding 1 / 2 carbon during S3 refining period) are exactly the same as Example 1.

[0080] Test results: the obtained master alloy ingot has oxygen content of 15.6 ppm, nitrogen content of 11.2 ppm, and sulfur content of 25.4 ppm (all sulfur comes from raw materials and is not removed).

[0081] Compared with Example 1, the oxygen content, nitrogen content and sulfur content are greatly increased.

[0082] Comparative Example 2 (directly adding metallic calcium instead of low-Ca nickel alloy)

[0083] Process: the ingredients are the same as Example 1 (without calcium element), but in S5 stage, instead of adding low-Ca nickel alloy, a calculated amount of all metallic calcium blocks are directly added (so that the final calcium content is equivalent to that of Example 1).

[0084] When the metallic calcium blocks are added, the melt appears violent boiling and spattering. After pouring, obvious inclusions and cold shut can be seen on the surface of the master alloy ingot.

[0085] Test results: the obtained master alloy ingot has oxygen content of 9.8 ppm, nitrogen content of 6.5 ppm, sulfur content of 15.2 ppm, and calcium content of 0.0030%. The purification effect is much worse than Example 1, and the process is unstable, and the product has many defects.

[0086] Comparative Example 3 (changing the adding time of low-Ca nickel alloy: adding all at once before the refining period)

[0087] The ingredients are the same as in Example 1, but all the low calcium nickel alloy is charged into the crucible at S1 together with other furnace charges. Only Al, Ta, B, Zr, Ti, etc. are added in the subsequent S4 alloying period, and no more is added in the S5 stage.

[0088] The detection results show that the obtained master alloy ingot has an oxygen content of 11.2 ppm, a nitrogen content of 8.8 ppm, a sulfur content of 18.5 ppm, and a calcium content of 0.0018%.

[0089] Since all the low calcium nickel alloy is added at one time before the refining period, most of the calcium is evaporated and lost in the subsequent long-time high-temperature (1610℃) and high-vacuum (<0.01 Pa) refining process, so that the calcium is consumed when the oxygen introduced after the addition of active elements such as Al and Ti is really needed for purification, and therefore the purification effect is significantly reduced.

[0090] The obtained master alloy ingots prepared in the examples and comparative examples are sampled and analyzed, and the analysis results are shown in Table 1.

[0091] The analysis standards or equipment are as follows:

[0092] The test standards are HB5143 "Metal Tensile Test Method at Room Temperature" and HB5150 "Metal High Temperature Tensile Durability Test Method".

[0093] The oxygen and nitrogen are analyzed by using an ONH-P oxygen and nitrogen analyzer, and the sulfur element is analyzed by using a CS-3000 carbon and sulfur analyzer.

[0094] The CMT-5105 room temperature testing machine and the RJ-50 durability testing machine are used to perform tests at room temperature and 760℃ / 585MPa.

[0095] Table 1 Analysis results of alloy ingots

[0096]

[0097] Through the comparison of the three examples and the three comparative examples, the following conclusions can be clearly drawn:

[0098] The strong correlation between purity and mechanical properties is verified: the data clearly shows that lower oxygen, nitrogen and sulfur contents directly translate into more excellent high-temperature durability and better room temperature plasticity. The examples of the present application, with their ultra-low impurity levels, comprehensively crush all the comparative examples in key mechanical properties.

[0099] The improvement of high-temperature durability performance is particularly significant: the average durability life (~130h) of the three examples is almost twice that of Comparative Example 1 (68h). This proves that the realization of ultra-low sulfur through calcium treatment plays a decisive role in strengthening the grain boundary and inhibiting the initiation and expansion of cracks at the grain boundary.

[0100] The process of the present application has double advantages in performance and stability: the mechanical property data of Comparative Example 2 (direct addition of calcium) fluctuate greatly and have low absolute values, which contrasts the excellent performance of the process of the present application through the "low calcium nickel alloy" and "gradual addition".

[0101] In summary, the high-aluminum titanium cast nickel-based high-temperature alloy purification smelting method provided by the present application, through the precise controllable calcium treatment technology, realizes the ultra-high purity of the alloy, and significantly and stably improves the key mechanical properties of the alloy, especially the high-temperature durability performance which determines the service life of the component.

Claims

1. A method of purifying smelting of high-aluminum titanium cast nickel-based superalloy, characterized in that: The method comprises the following steps: Step one, low calcium nickel alloy preparation: taking pure nickel and metal calcium as raw materials, a low calcium nickel alloy with calcium content of 0.5-0.8wt.% is prepared by vacuum smelting, and is processed into block or sheet shape; Step two, pure refining: in a vacuum induction smelting furnace, a magnesia crucible is used, and the following stages are included in sequence: S1, batching and charging: according to the target composition of high-aluminum titanium cast high-temperature alloy, 2 / 3 low calcium nickel alloy and 1 / 2 carbon, metal chromium, metal cobalt, metal tungsten, metal molybdenum, metal niobium and metal nickel are charged into the magnesia crucible; S2, melting period: melting, obtaining the molten steel; S3, refining period: refining the molten steel under vacuum; before refining, 1 / 2 carbon is added, and after refining, the alloying period is entered; S4, alloying period: power-off cooling to the molten steel surface film, adding metal aluminum, heating; power-off cooling to the molten steel surface film, adding metal tantalum, heating; power-off cooling to the molten steel surface film, adding nickel boron alloy, heating; power-off cooling to the molten steel surface film, adding nickel zirconium alloy, heating; power-off cooling to the molten steel surface film, adding metal titanium, heating; S5, calcium treatment purification period: power-off cooling to the molten steel surface film, adding 1 / 3 low calcium nickel alloy, heating and holding; S6, casting period: heating to 1550-1570℃ for casting, obtaining the master alloy ingot; In step S1, the target composition of high-aluminum titanium cast high-temperature alloy is as follows in terms of mass percentage: C: 0.09-0.13%, Al: 3.20-3.70%, Ti: 3.20-3.70%, Cr: 15.7-16.3%, Nb: 0.60-1.10%, Ta: 1.50-2.0%, Co: 8.0-9.0%, Mo: 1.50-2.0%, W: 2.40-2.80%, Zr: 0.02-0.05%, B: 0.007-0.012%, Ca: 0.10-0.50%, and the balance is Ni and inevitable impurities.

2. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step one, the purity of pure nickel and metal calcium is above 99.0%.

3. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step one, the vacuum smelting is carried out under the protection of 3900-4100Pa argon, the smelting temperature is 1540-1560℃, and is maintained for 9-11min.

4. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step one, the wire cutting is used to process into sheet shape.

5. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step S2, the operation of the melting period is as follows: after vacuumizing to a vacuum degree below 5Pa, melting is carried out under a power of 90-110kW, after the furnace charge is completely melted, the power is adjusted to 140-160kW, the molten steel temperature is 1600-1620℃, the refining period is entered, and the vacuum degree is <0.01Pa.

6. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step S3, the refining temperature is 1600-1620℃, and the refining time is 10-20min.

7. The high Al-Ti cast nickel-base superalloy purification melting method according to claim 1, characterized in that: In step S4, when the molten steel surface film is formed, the molten steel surface temperature is 1380-1420℃; the temperature is raised to 1550-1570℃, and the power for heating is 140-160kW.

8. The purification smelting method for high-alumina titanium-cast nickel-based high-temperature alloys according to claim 1, characterized in that: In step S5, the holding temperature is 1530-1550℃, and the time is 25-35min.

9. The purification smelting method for high-alumina titanium-cast nickel-based high-temperature alloys according to claim 1, characterized in that: In step S6, the oxygen and nitrogen content of the master alloy ingot is less than 4 ppm, and the sulfur content is less than 3 ppm.

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