CN111534713B - Purification treatment method of cast high-temperature alloy return material and high-temperature alloy - Google Patents
Purification treatment method of cast high-temperature alloy return material and high-temperature alloy Download PDFInfo
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- CN111534713B CN111534713B CN202010643195.7A CN202010643195A CN111534713B CN 111534713 B CN111534713 B CN 111534713B CN 202010643195 A CN202010643195 A CN 202010643195A CN 111534713 B CN111534713 B CN 111534713B
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/00—Making non-ferrous alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/045—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds for horizontal casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/02—Making non-ferrous alloys by melting
Abstract
The embodiment of the application provides a purification treatment method of a cast high-temperature alloy return material and a high-temperature alloy, and relates to the field of purification and remelting of the return material. The purification treatment method of the cast high-temperature alloy return material mainly comprises the steps of mixing the treated return material with a new material for high-temperature refining, adding covering slag on the surface of molten steel for deslagging treatment in the high-temperature refining process, wherein the covering slag comprises the following components: CaO-Al2O3‑CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4-6: 2-3: 1-3: 0 to 1; and carrying out vacuum horizontal continuous casting and billet ejection on the molten steel after the deslagging treatment to obtain the purified master alloy casting rod. The purification treatment method for the cast high-temperature alloy return material provided by the embodiment of the application has the advantages of simple process, low cost and good purification effect.
Description
Technical Field
The application relates to the field of purification and remelting of returns, in particular to a purification treatment method for cast high-temperature alloy returns and a high-temperature alloy.
Background
At present, in the casting process of the high-temperature alloy, the crucible and shell surface layer aggregate are corroded, the core and shell materials and molten steel react to cause online pollution, the high-temperature oxidation and sand burning on the surface of a casting are caused, and the shrinkage cavity of a riser adsorbs the gas and dust on the surface, so that the content of inclusions and harmful gas in the cast high-temperature alloy return material is increased, the toughness and the fatigue life of the alloy are seriously influenced, and great risk is brought to the reliable service of the alloy. Taking widely used trunk casting high temperature alloy K417 as an example, the inclusion content of more than 50 mu m in each 10kg of new material mother alloy is about 7.35mg, the inclusion content of more than 50 mu m in each 10kg of return material remelting mother alloy reaches more than 20mg, the cleanliness is reduced by nearly 3 times, and correspondingly, the low-cycle fatigue life of 650 ℃/400MPa is reduced by about 50%.
Because the high-temperature alloy is cast by high alloying degree and contains a large amount of noble metal elements such as cobalt, tungsten, molybdenum, tantalum, hafnium and the like, the return material is treated as a waste product, generally only the nickel element in the return material can be recovered, other noble metal elements are wasted, and the quality of downstream products (such as stainless steel) is also greatly influenced. For example, the oriented superalloy DZ4125 contains high amounts of precious metal elements such as cobalt, tungsten, tantalum, and hafnium, so that the price of a new master alloy is high, reaching 75 ten thousand yuan/ton, and if the alloy is recovered with a nickel content of 60%, the price of a return material is only about 5 ten thousand yuan/ton.
In order to realize the purification and remelting treatment of the return material, at present, a ceramic filtering technology is generally introduced in the casting process at home and abroad, inclusions larger than the size of a filter mesh in molten steel are removed by a physical isolation method, and a part of fine inclusions are removed by a physical adsorption method. However, the technology has significant problems in practical application: along with the increase of molten steel, the filter meshes are easily blocked, and in the continuous filtering process, the subsequent molten steel can impact the adsorbed inclusions and brings the adsorbed inclusions into the molten steel again, so that the ceramic filtering technology cannot well meet the purification treatment requirement of the cast high-temperature alloy return. In addition, new technologies developed in recent years in the field of pure smelting include: duplex/triplet smelting process, EBCHR electron beam cold bed furnace technology, CaO/Y2O3The novel crucible smelting technology and the like have the problems of complex operation process and high preparation cost, and cannot be applied to industrial production of purification treatment of cast high-temperature alloy return.
Disclosure of Invention
The embodiment of the application aims to provide a purification treatment method for a cast high-temperature alloy return material and a high-temperature alloy, and the purification treatment method is simple in process, low in cost and good in purification effect.
In a first aspect, an embodiment of the present application provides a method for purifying a cast superalloy return material, which includes the following steps:
mixing the treated return material with the new material for high-temperature refining, and in the high-temperature refining process, adding covering slag on the surface of the molten steel for deslagging, wherein the covering slag comprises the following components: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4-6: 2-3: 1-3: 0 to 1;
and carrying out vacuum horizontal continuous casting and billet ejection on the molten steel after the deslagging treatment to obtain the purified master alloy casting rod.
In the technical scheme, the purification is carried out by relying on high-temperature refining and vacuum horizontal continuous casting technologies and by adding covering slag on the surface of molten steel in the refining process. The covering slag selected by AS in the embodiment of the application is CaO-Al2O3The reducing slag system is a foundation, the melting point of the slag system is higher, the volatility is lower, the slag system is suitable for being added in the vacuum smelting process of high-temperature alloy, and the viscosity of covering slag can be ensured to be within a certain range according to a certain proportion, and impurities in molten steel can be more easily adsorbed; meanwhile, the pure CaO-Al2O3Has a higher melting point, so CaF is added2So as to reduce the melting point of the slag system, ensure the melting point of the slag system to be in a certain range and more easily adsorb impurities in the molten steel; in addition, MgO can be added according to the type of the high-temperature alloy to increase the adsorption capacity of the covering slag on the impurities. The composition of the covering slag is dynamically adjusted according to the types of the inclusions in the cast high-temperature alloy return, and the purpose is to enable the inclusions in the molten steel to fully float upwards and to be captured by the covering slag in time after floating upwards, so that the inclusions in the molten steel are greatly reduced, and the cleanliness and the mechanical property of the remelting mother alloy of the return after purification treatment can reach the level of a new mother alloy. Therefore, the purification treatment method has the advantages of simple process, low cost and good purification effect.
In one possible implementation, the return includes at least one of a runner, a feeder, and a used casting;
the pouring gate processing method comprises the following steps: carrying out treatment by adopting a sand blasting or shot blasting mode; the method for treating the casting head comprises the following steps: firstly, removing impurities at the open type defect position, and then carrying out integral surface treatment by adopting a shot blasting mode; the treatment method of the waste casting comprises the following steps: firstly, performing depoling treatment and then performing surface treatment.
In the above technical solution, the purpose of the pretreatment of the returning charge is to remove inclusions on the surface of the returning charge.
In a possible implementation mode, 50-100% of treated return materials and 0-50% of new materials are mixed according to weight percentage for high-temperature refining.
In the above technical solution, although the principle of the returning charge treatment is to increase the adding proportion of the returning charge as much as possible, so as to greatly reduce the cost, the higher the adding proportion of the returning charge is, the better the adding proportion of the returning charge is, the upper limit depends on the level of ensuring that the treated alloy reaches the new alloy in terms of cleanliness, and therefore, the adding proportion of the returning charge is determined according to the cleanliness of the returning charge and the number of times of returning charge. The types of return materials for casting the high-temperature alloy comprise pouring channels, dead heads, waste castings and the like, relatively clean pouring channels are adopted, the utilization rate of the return materials can reach 100%, and for the dead heads and the waste castings with particularly high inclusion content, the addition proportion of the return materials needs to be lower. In addition, some harmful impurity elements (such as Si element) in the return material are difficult to remove in the remelting purification process, and the Si element has an accumulation trend along with the increase of the addition proportion and the use times of the return material, and needs to be diluted by adding a certain proportion of new material. Comprehensively considering, the adding proportion of the return material in the embodiment of the application is 50% -100%.
In one possible implementation mode, the addition amount of covering slag is 0.5-2% of the weight of the molten steel.
In the technical scheme, the addition amount of the covering slag is 0.5-2% of the weight of the molten steel, and the covering slag is used for fully capturing inclusions in the molten steel.
In one possible implementation mode, the melting point of the covering slag is 50-80 ℃ higher than that of the molten steel; and/or the viscosity of the covering slag is 9-11 times of that of the molten steel.
In the technical scheme, the melting point and the viscosity of the covering slag are regulated and controlled within a proper range by regulating the composition of the covering slag, so that the covering slag can capture impurities in a mode of adhesion diffusion, interfacial tension transfer and chemical adsorption.
In one possible implementation, for the purification treatment of JG4246A alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 5.5-6: 2-3: 1 to 2.5;
for the clean-up K418 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4.5-5: 2.5-3: 2-3;
for the purification treatment of the DZ4125 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4-5: 2.5-3: 2 to 3.5;
for the cleaned K4169 alloy, the corresponding covering slag composition was: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4.5-5: 1.5-2: 2-3: 1.
in the technical scheme, the composition of the covering slag is dynamically adjusted according to the types of inclusions in the cast high-temperature alloy return: for high-temperature alloys with high Al and Ti contents such as JG4246A alloy and K418 alloy, the CaO proportion in the slag system needs to be increased by the aid of CaO to Al2O3Adsorbing to generate aluminum silicate to eliminate Al2O3And (4) inclusion. For the DZ4125 alloy, the high temperature alloy containing Hf rare earth element, Al is increased2O3: CaO ratio, in the same time as a portion of CaF2Instead of CaO, the melting point and viscosity of the slag system are reduced to promote HfO2With Al2O3Thereby increasing the reaction rate to HfO2And (4) capturing the inclusions. For the high-temperature alloy with high Cr content, such as K4169 alloy, the generated inclusions mainly take TiN and CrN asMainly, CaO-Al is used because it is necessary to increase the surface tension of the slag system without increasing the melting point of the slag system2O3-CaF2A small amount of MgO is added on the basis of the slag to increase the adsorption capacity of covering slag on the impurities.
In one possible implementation mode, covering slag is added when the temperature of molten steel is 1440-1550 ℃;
and/or the covering slag is added in the following mode: adding covering slag for multiple times; optionally, after the covering slag added each time is aged, the aged covering slag moves to the position near the crucible wall through electromagnetic stirring to be gathered and adhered to the crucible wall, and then new covering slag is added;
and/or in the deslagging treatment process, the molten steel is electromagnetically stirred to promote the floating of the inclusion in the molten steel.
In the technical scheme, when the temperature of the molten steel reaches 1440-1550 ℃ in the refining process, most of inclusions in the molten steel can quickly float up to the surface of the molten steel under the action of buoyancy, and at the moment, covering slag is added to quickly adsorb the inclusions on the surface; the covering slag is added for multiple times, so that impurities in the molten steel can be gradually adsorbed, and the adsorption efficiency is ensured; by electromagnetically stirring the molten steel, small-size and high-specific-gravity inclusions which are difficult to float upwards in the molten steel can reach the surface of the molten steel under the driving action of molten steel circulation.
In one possible implementation mode, the method for the vacuum horizontal continuous casting and the knockout comprises the following steps: under the conditions that the casting starting temperature is 1400-1480 ℃ and the circulating cooling water is 5-10 t/h, the molten steel is continuously discharged at the withdrawal speed of 0.6-1.4 m/min.
In the technical scheme, the casting process can ensure the metallurgical quality of the cast billet according to a certain casting speed and the cast billet is discharged at a certain casting starting temperature and a certain circulating cooling water condition: on one hand, if the billet discharging is slow or the billet is stopped, the gap between the casting blank and the vacuum lock is increased due to the solidification shrinkage of the casting blank, the vacuum degree is influenced, and the purity of the molten steel is further reduced; on the other hand, if the blank discharging speed is too high, the pulling-off or steel leakage is easily caused, and the complete forming of the casting blank is influenced.
In one possible implementation, the position of the ejection is the bottom of the molten steel.
In the technical scheme, the steel is discharged from the bottom of the molten steel, so that inclusions on the surface of the molten steel can be kept away in the molten steel solidification forming process, and secondary pollution of the inclusions in the solidification forming stage is avoided.
In a second aspect, embodiments of the present application provide a superalloy, which is obtained by the purification method provided in the first aspect.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a device corresponding to a method for cleaning a cast superalloy return material according to an embodiment of the present disclosure;
FIG. 2 is a schematic view showing the covering slag adsorbing inclusions in molten steel.
Icon: 110-a crucible; 120-an induction coil; 130-water cooling crystallizer; 140-a throwing system; 151-molten steel; 152-inclusions; 153-covering slag; 154-continuous casting bar.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
First, the inventors analyzed the origin and type of inclusions in the cast superalloy return:
1) MgO and SiO during alloy smelting due to crucible spalling and corrosion2When crucible materials are likely to fall into molten steel to form inclusions; smelting of high Al alloy and Hf-containing alloyIn the process, if the temperature of the molten pool is not properly controlled, crucible reaction is easy to occur to generate Al2O3And HfO2And the like.
2) During alloy casting, the shell surface layer material such as SiO is eroded by high-temperature melt2And Al2O3There is a possibility that the molten steel may enter, thereby forming inclusions in the casting return.
3) After the casting is formed, the surface is not easy to remove by high-temperature oxidation and sand adhesion, and inclusions are easy to form during remelting; open defects such as shrinkage cavities, looseness and the like at the casting head can adsorb dust to bring foreign inclusions, the cutting material inclusions can be brought in when the casting head is cut, nitrogen and oxygen in the air can be adsorbed due to the large specific surface area of the defect, and the gases and active elements in the alloy can form inclusions such as oxides, nitrides and the like during remelting and smelting, so that the alloy is polluted.
Aiming at the source and the type of the inclusions, the inventor discovers a purification treatment method of the cast high-temperature alloy return, which mainly purifies the inclusions generated in the casting before the casting is formed and the inclusions introduced due to surface defects after the casting is formed, and has the difficulty in treating the inclusions generated in the casting.
The method of cleaning the cast superalloy return material according to the embodiment of the present application will be specifically described below.
The embodiment of the application provides a purification treatment method of a cast high-temperature alloy return material, which comprises the following steps:
(1) pretreatment of the returning material:
the return material for purifying treatment in the embodiment of the application mainly comprises at least one of a riser, a pouring gate and a waste casting. Correspondingly, the method for pretreating the return materials comprises the step of treating at least one of a pouring gate, a casting head, a riser and a waste casting.
In general, most of oxides on the surface of a runner or a casting head can be removed by performing an overall surface treatment by a mechanical treatment such as sand blasting or shot blasting. As an embodiment, the runner may be processed by: the treatment is carried out by adopting a sand blasting or shot blasting mode (mechanical treatment); the method for treating the casting head can be as follows: firstly removing impurities at open defects (such as shrinkage cavity and shrinkage porosity), and then carrying out overall surface treatment by adopting a shot blasting mode.
The processing method of the waste casting (such as a waste hollow blade and an adjusting sheet) and the riser with the ceramic filter and the like comprises the following steps: the method comprises the steps of performing core removal treatment by adopting an alkali boiling and acid washing mode, and performing targeted surface treatment.
(2) High-temperature refining and deslagging treatment:
mixing the pretreated returned material and the new material for high-temperature refining, wherein 50-100% (optionally 50-85%) of the pretreated returned material and 0-50% (optionally 15-50%) of the new material are mixed as smelting materials in percentage by weight for high-temperature refining (namely smelting). The returned material and the fresh material used in the purification treatment are the returned material and the fresh material of the same high-temperature alloy.
As an example of the present application, the method of high temperature refining is: in a vacuum environment, after smelting materials are completely melted to form molten steel (melt), heating to 80-100 ℃ above the melting point of the molten steel, starting refining, wherein the refining time is 30-60 min, the refining vacuum degree is controlled to be not more than 3Pa, argon is filled in the last stage of refining, a deoxidizing agent is added, the adding amount is about 500ppm, and the molten steel stands for 5min after the adding is finished, so that the solid-solution oxygen and nitrogen elements in the molten steel are removed.
After the high-temperature refining is finished, covering slag is added on the surface of the molten steel according to the temperature of the molten steel for deslagging treatment, and the covering slag comprises the following components: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4-6: 2-3: 1-3: 0 to 1. In the embodiment of the application, the specific composition of the covering slag is dynamically adjusted according to the types of the inclusions in the cast high-temperature alloy return, and generally needs to meet the following requirements: the melting point of the covering slag is 50-80 ℃ higher than that of the molten steel; the viscosity of the covering slag is 9-11 times of that of the molten steel. In practical operation, the slag is added when the temperature of the molten steel is reduced to 50-80 ℃ above the melting point of covering slag, and the temperature is usually reduced to 1440-1550 ℃ when the temperature of the molten steel is reducedEntering; the addition amount of covering slag is 0.5-2% of the weight of the molten steel, such as 0.5%, 1%, 1.5% or 2%; adding covering slag for multiple times, such as adding covering slag in 3 batches; in the process of slag removal treatment, most of inclusions can quickly float to the surface of molten steel in a stokes movement mode under the action of buoyancy, the floating speed is slow and even the inclusions cannot float aiming at small-size and high-specific-gravity inclusions which are difficult to float in a melt, and the molten steel is electromagnetically stirred to reach the surface of the molten steel under the driving action of molten steel circulation so as to promote the floating of the inclusions.
In the examples of the present application, the covering slag is CaO-Al2O3The reducing slag system is a base, and a small amount of other components are added: CaF2MgO, CaO: al (Al)2O3In a weight ratio of 1: 1-1: 2, the viscosity of the covering slag can be ensured to be between 0.2 and 0.6 m.pa at 1400 ℃. For the high temperature alloy with the total content of Al and Ti of JG4246A alloy and K418 alloy being about 10 percent, in order to eliminate the Al with a large amount in the melt2O3The inclusion, in the range satisfying the covering slag melting point, increases the CaO proportion as much as possible. For the DZ4125 alloy containing Hf element, Al is increased2O3: CaO ratio, in the same time as a portion of CaF2Instead of CaO, the melting point and viscosity of the slag system are reduced to promote HfO2With Al2O3Thereby increasing the reaction rate to HfO2And (4) capturing the inclusions. For the K4169 alloy with high Cr content, because the melt is easy to fix nitrogen, the TiN inclusion in the alloy is more and the size is larger, and the TiN has no chemical adsorption with the component in the slag system, so the CaO-Al alloy has no chemical adsorption effect2O3-CaF2On the basis, MgO is used for replacing partial Al2O3Forming a quaternary slag system, increasing the surface tension and viscosity of the slag system under the condition of ensuring that the melting point of the slag system meets the requirement, and removing the inclusion TiN in the molten steel by means of the action of larger interfacial tension of covering slag. Based on the above analysis, the examples of the present application provide the following covering slag corresponding to the high temperature alloy return as an example:
for the purification treatment of the JG4246A alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And is andCaO、Al2O3、CaF2the weight ratio of (A) to (B) is 5.5-6: 2-3: 1-2.5, such as 6: 3: 1.
for the clean-up K418 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4.5-5: 2.5-3: 2-3, such as 5: 3: 2, no MgO.
For the purification treatment of the DZ4125 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4-5: 2.5-3: 2-3.5, such as 4: 3: 3.
for the cleaned K4169 alloy, the corresponding covering slag composition was: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4.5-5: 1.5-2: 2-3: 1, such as 5: 2: 2: 1.
it is particularly emphasized that the covering slag used in the embodiments of the present application is at most 4 yuan, compared to more yuan slag systems, such as slag system: CaO: 40 to 50wt% of Al2O3：16~25wt%，CaF2:13~20wt%，MgO：3~5wt%，SiO2：1~4wt%，Li2O: 2-7 wt%, BaO: 3-6 wt%, has obvious advantages for the following reasons:
the high temperature alloy has high Al and Ti content, and SiO is added into the slag system2The alloy is easy to generate replacement reaction with Al and Ti, the generated Si enters into an alloy melt, and the Si is a harmful element for high-temperature alloy and can seriously affect the durability and casting technological property of the alloy. Russian research shows that in ZhS32-VI alloy, the content of Si is increased from 0.144% to 0.185%, the endurance performance of the alloy at 975 ℃/300MPa is reduced from 82h to 58h, and therefore the slag system of the high-temperature alloy cannot select SiO2。
Li2O instead of CaF2Can play a role in S removal, but Li2The price of the O mineral is higher, and the cost for treating the return material is higher.
Although BaO can play a good role in desulfurization, BaO is not adopted in the application, and the following two main factors are considered: (1) for the treatment of the returning material, the covering slag is added for the main purpose of removing impurities, so that the covering slag with the required viscosity can be obtained for purification; (2) the addition of BaO easily causes the residual of Ba in molten steel, and Ba element in the high-temperature alloy is also an impurity element, which may affect the mechanical property of the alloy and has a certain risk.
In summary, in the case where the slag system satisfies the requirements, the simpler the composition, the better the composition, and the impurity element residue caused by the slag system can be avoided.
(3) Vacuum horizontal continuous casting and billet ejection:
carrying out vacuum horizontal continuous casting and billet discharging on the molten steel after the deslagging treatment, wherein the method for the vacuum horizontal continuous casting and billet discharging comprises the following steps: and continuously ejecting the molten steel at a throwing speed of 0.6-1.4 m/min under the conditions that the casting starting temperature is 1400-1480 ℃ and the circulating cooling water is 5-10 t/h, wherein the ejection position is the bottom of the molten steel, so that the purified master alloy cast rod is obtained.
In addition, the embodiment of the application provides a device corresponding to the purification treatment method of the cast superalloy return material, and the device is used for realizing the purification treatment method of the embodiment of the application.
Referring to fig. 1, the device comprises a vacuum furnace, the vacuum furnace comprises a tiltable crucible 110, a vacuum environment can be formed inside the crucible 110, an induction coil 120 for heating is arranged on the outer surface of the crucible 110, an electromagnetic stirring assembly is arranged in the crucible 110, the device further comprises a water-cooled crystallizer 130 communicated with the bottom of the crucible 110, and a blank drawing system 140 is arranged behind the water-cooled crystallizer 130.
The purification treatment of the cast high-temperature alloy return material is carried out by adopting the device shown in FIG. 1, and the specific process is as follows:
s1, mixing the pretreated return material and the new material, putting the mixture into a crucible 110, heating the smelting material by an induction coil 120 in a vacuum environment in the crucible 110, and starting high-temperature refining after the smelting material is completely melted to form molten steel 151.
After the high-temperature refining is completed, the covering slag 153 is added to the surface of the molten steel 151 to perform a slag-removing treatment, so that the inclusions 152 in the molten steel 151 float upward and are captured and adsorbed by the covering slag 153.
In the deslagging process, through low-power stirring of the electromagnetic stirring assembly, on one hand, the temperature of the molten steel 151 is increased, the viscosity of the molten steel 151 is reduced to be below 1/10 corresponding to the viscosity of the covering slag 153, on the other hand, the molten steel 151 forms a circular flow, and the inclusions 152 (particularly the inclusions 152 with small size and high specific gravity) reach the surface of the molten steel 151 under the driving action of the moving molten steel 151, but attention needs to be paid to the fact that stirring cannot cause slag entrapment behavior of the liquid surface to pollute the molten steel 151.
In the deslagging process, the covering slag 153 is added for multiple times, after the covering slag 153 added each time is aged, the crucible 110 is tilted at a small angle through high-power stirring of the electromagnetic stirring assembly, so that the aged covering slag 153 moves to the position close to the inner wall of the crucible 110 and is gathered and adhered to the inner wall of the crucible 110, and new covering slag 153 is added.
S2, on the basis of obtaining the high-cleanness molten steel 151, a bottom casting tapping technology is adopted, under the conditions of certain casting starting temperature and circulating cooling water, the molten steel 151 is rapidly solidified through the water-cooled crystallizer 130 at the bottom of the crucible 110 to form a bar blank with a solidified blank shell with a certain thickness, and then the bar blank is discharged out of the vacuum furnace at a continuous blank drawing speed under the traction action of the blank drawing system 140 to form a return material continuous casting blank with a surface free of oxide skin and a compact internal structure, namely a continuous casting bar 154. The solidification forming process is far away from the inclusions 152 on the surface of the molten steel 151, and secondary pollution of the inclusions 152 in the solidification forming stage in the vacuum die casting process similar to the traditional process is avoided.
Referring to fig. 2, in the embodiment of the present invention, the covering slag adsorbs inclusions in molten steel in three forms, where the horizontal line indicates a boundary between molten steel and covering slag, the lower side of the horizontal line indicates a liquid phase formed by molten steel, and the upper side of the horizontal line indicates a slag phase formed by covering slag. Wherein (a) indicates that inclusions in the molten steel stay at the interface between the molten steel and the covering slag and then gradually dissolve into the covering slag; (b) indicating that the inclusions in the molten steel are spontaneously transferred into the covering slag under the action of interfacial tension between the molten steel and the covering slag; (c) indicating that inclusions in the molten steel enter the covering slag by chemically reacting with the covering slag.
It can be seen that the embodiments of the present applicationThe purification treatment method is to capture impurities by utilizing covering slag through buoyancy adhesion diffusion, interface tension transfer and chemical adsorption, is different from the physical isolation method of the traditional filtration process, and is connected with CaO/Y2O3Compared with the novel crucible smelting technology, the novel crucible smelting technology can completely avoid the residual risk of trace elements Ca and Y, and meanwhile, the purification treatment method adopts a single-connection smelting process, is a low-cost return material remelting technology and meets the requirement of purification remelting treatment on batch industrial production of cast high-temperature alloy return materials.
In addition, the embodiment of the application also provides a high-temperature alloy which is prepared by adopting the purification treatment method. As an example, the superalloy is embodied as a continuous casting rod, the purity and mechanical properties of which reach the level of virgin master alloy.
The features and properties of the present application are described in further detail below with reference to examples.
Examples 1 to 4
Example 1 selecting a DZ4125 alloy containing Hf as a superalloy; example 2 a high Al content JG4246A alloy was selected as the superalloy; example 3 a high Al content K418 alloy was selected as the superalloy; example 4 a cleaning remelting test was performed by selecting high Cr and low Al K4169 as a superalloy and using the cleaning method of the examples of the present application. The purification remelting test is carried out on 800Kg vacuum horizontal continuous casting equipment, and the specific steps are as follows:
(1) the return material mainly comprises a riser, a pouring gate and waste castings (waste hollow blades and adjusting pieces), and is pretreated firstly: the pouring gate and the casting head are subjected to integral surface treatment by adopting a mechanical method of sand blasting or shot blasting; the waste hollow blades, the adjusting sheet and the dead head with the ceramic filter are subjected to depoling treatment in a mode of alkali boiling and acid washing, and then surface treatment with pertinence is carried out.
(2) Charging according to the charging amount of 600Kg, wherein the proportion of the return materials is 80%, the proportion of the rest new materials is 20%, after the furnace burden is completely melted, heating to 1550 ℃ to start refining, wherein the refining time is 30min, and the refining vacuum degree is controlled to be less than 3 Pa.
(3) Covering slag is added after high-temperature refining is finished, corresponding covering slag (comprising slag system composition and physical parameters) is selected according to the table 1 in each embodiment, the adding amount of the covering slag is about 1% of the weight of molten steel, the covering slag is added in three batches, after the covering slag added each time is aged, the aged covering slag moves to the position close to the crucible wall through electromagnetic stirring and is gathered and adhered to the crucible wall, and new covering slag is added.
TABLE 1 corresponding covering slag system compositions and parameters for different types of alloys
(4) Vacuum horizontal continuous casting and billet ejection: and (3) cooling to the casting starting temperature of 1400-1480 ℃, starting a continuous casting control device, controlling the withdrawal speed of 0.6-1.4 m/min and the cooling water flow of 5-10 t/h, realizing the rapid solidification of the molten steel in a crystallizer, and discharging the molten steel out of a furnace door under the traction action of a continuous casting machine to form a continuous purified master alloy bar, namely a continuous casting bar.
The detection shows that the alloy composition of the return material continuous casting rod of the JG4246A alloy meets the standard requirement of Q/S15.2104-2011; the alloy composition of the continuous casting rod of the return material of the DZ4125 alloy meets the requirements of Q/10S-0209-.
The contents of harmful gas elements (O, N, S) and the contents of macro-electrolytic inclusions (inclusions measured by macro-electrolysis) of the high-temperature alloy returns of examples 1 to 4 after the purification treatment are shown in tables 2 to 3:
table 2 comparison of the element contents of harmful gases before and after the purification treatment of different high-temperature alloy returns.
TABLE 3 analysis of the contents of inclusions in different high-temperature alloy returns after the purification treatment
As can be seen from the results in tables 2 and 3, after the cast superalloy returns are subjected to the purifying and remelting process of the examples of the present application, the contents of harmful gas elements and inclusions are significantly reduced compared with those before purification treatment, and the contents of electrolytic inclusions in the large samples are all less than 6mg/10 Kg.
Taking the DZ4125 alloy as an example, the contents of large-scale electrolytic inclusions and the mechanical properties of the continuous casting rod after the return material purification treatment were compared with those of the new mother alloy, and the results are shown in tables 4 to 5:
TABLE 4 comparison of inclusion content of DZ4125 alloy returned material and new mother alloy in continuous casting rod after purification treatment
TABLE 5 comparison of mechanical properties of continuous casting bar after purification treatment of DZ4125 alloy returning charge and new mother alloy
As is clear from the results in tables 4 and 5, the total amount of inclusions in the returned material was reduced and the sizes of inclusions were significantly reduced as compared with those of the virgin mother alloy, and the types of inclusions in the returned material were mainly Al based on the analysis of the binding energy spectrum2O3、SiO2Inclusions, and small amounts of TiN inclusions; and the 760 ℃ tensile property, 760 ℃/725MPa durability and 900 ℃/580MPa fatigue property of the continuous casting rod after the return material purification treatment all reach the level of the new material master alloy.
In summary, the purification treatment method for the cast high-temperature alloy return material in the embodiment of the application has the advantages of simple process, low cost and good purification effect.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (9)
1. A purification treatment method of a cast high-temperature alloy return material is characterized by comprising the following steps:
mixing the treated return material with the new material for high-temperature refining, and in the high-temperature refining process, adding covering slag on the surface of the molten steel for deslagging, wherein the covering slag comprises the following components: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4-6: 2-3: 1-3: 0 to 1;
carrying out vacuum horizontal continuous casting and blank ejection on the molten steel after the deslagging treatment to obtain a purified master alloy casting rod;
the melting point of the covering slag is 50-80 ℃ higher than that of the molten steel; and/or the viscosity of the covering slag is 9-11 times of that of the molten steel.
2. The method of claim 1, wherein the return material comprises at least one of a runner, a feeder, and a used casting;
wherein the runner processing method comprises the following steps: carrying out treatment by adopting a sand blasting or shot blasting mode; the method for treating the casting head comprises the following steps: firstly, removing impurities at the open type defect position, and then carrying out integral surface treatment by adopting a shot blasting mode; the treatment method of the waste casting comprises the following steps: firstly, performing depoling treatment and then performing surface treatment.
3. The method for purifying the cast high-temperature alloy return material according to claim 1, wherein 50-100% by weight of the treated return material and 0-50% by weight of the fresh material are mixed for high-temperature refining.
4. The method of claim 1, wherein the covering slag is added in an amount of 0.5 to 2% by weight based on the weight of the molten steel.
5. The casting high temperature of claim 1The purification treatment method of the alloy return material is characterized in that for the purification treatment of JG4246A alloy, the corresponding covering slag comprises the following components: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 5.5-6: 2-3: 1 to 2.5;
for the clean-up K418 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4.5-5: 2.5-3: 2-3;
for the purification treatment of the DZ4125 alloy, the corresponding covering slag composition is: CaO-Al2O3-CaF2And CaO, Al2O3、CaF2The weight ratio of (A) to (B) is 4-5: 2.5-3: 2 to 3.5;
for the cleaned K4169 alloy, the corresponding covering slag composition was: CaO-Al2O3-CaF2MgO, CaO, Al2O3、CaF2And the weight ratio of MgO is 4.5-5: 1.5-2: 2-3: 1.
6. the method for purifying the cast superalloy return material according to claim 1, wherein the covering slag is added when the molten steel temperature is 1440 ℃ to 1550 ℃;
and/or the covering slag is added in the following mode: adding covering slag for multiple times;
and/or in the deslagging treatment process, the molten steel is electromagnetically stirred to promote the floating of the inclusion in the molten steel.
7. The method for cleaning a cast superalloy return according to claim 1, wherein the step of removing the molten superalloy,
the covering slag is added for multiple times, and the method comprises the following steps: after each addition of covering slag is aged, the aged covering slag is moved to the vicinity of the crucible wall by electromagnetic stirring to be accumulated and adhered to the crucible wall, and new covering slag is added.
8. The method for purifying cast superalloy returns according to claim 1, wherein the vacuum horizontal continuous casting and ejection method comprises: under the conditions that the casting starting temperature is 1400-1480 ℃ and the circulating cooling water is 5-10 t/h, the molten steel is continuously discharged at the withdrawal speed of 0.6-1.4 m/min.
9. A method of cleaning a cast superalloy return according to claim 1, wherein the ejection position is the bottom of the molten steel.
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| CN113020552B (en) * | 2021-05-28 | 2021-09-17 | 北京科技大学 | Launder for metal casting and method for smelting GH4169 alloy by using return materials |
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| CN113652564B (en) * | 2021-10-19 | 2021-12-14 | 北京科技大学 | Method for smelting high-temperature alloy by using return material |
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| CN115852186B (en) * | 2022-12-21 | 2023-10-27 | 四川钢研高纳锻造有限责任公司 | Method for refining carbonitride in GH4169 alloy by controlling addition amount of return material |
| CN116904793B (en) * | 2023-09-13 | 2023-12-19 | 广州先艺电子科技有限公司 | Purifying remelting method for gold-tin alloy return material |
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