CN114959526A - Electromagnetic cold crucible circulating heat treatment system and method for refining titanium-aluminum alloy structure through circulating heat treatment - Google Patents
Electromagnetic cold crucible circulating heat treatment system and method for refining titanium-aluminum alloy structure through circulating heat treatment Download PDFInfo
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- CN114959526A CN114959526A CN202210518054.1A CN202210518054A CN114959526A CN 114959526 A CN114959526 A CN 114959526A CN 202210518054 A CN202210518054 A CN 202210518054A CN 114959526 A CN114959526 A CN 114959526A
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- 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
- C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
- C22F1/18—High-melting or refractory metals or alloys based thereon
- C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/42—Induction heating
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/78—Combined heat-treatments not provided for above
- C21D1/785—Thermocycling
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention relates to an electromagnetic cold crucible circulating heat treatment system and a method for refining a titanium-aluminum alloy structure through circulating heat treatment, and belongs to the technical field of electromagnetic cold crucibles. In order to solve the problems that the heating or heat preservation temperature is difficult to accurately control in common heat treatment and the continuous adjustment of the cooling rate cannot be realized, the invention provides an electromagnetic cold crucible circulating heat treatment system which comprises a heat treatment furnace, an electromagnetic cold crucible, an induction coil, a cooling system, an upper drawing rod, a directional treatment sample, a material rod for stabilizing power and a lower drawing rod. The invention also utilizes the electromagnetic cold crucible circulation heat treatment system to carry out electromagnetic cold crucible circulation heat treatment on the titanium-aluminum alloy, realizes the homogenization and refinement of the lamellar structure of the titanium-aluminum alloy through stable temperature field control and continuous control of the cooling rate in the heat treatment process, improves the alloy strength and the creep resistance, and has very important significance for promoting the engineering application of the electromagnetic cold crucible heat treatment process.
Description
Technical Field
The invention belongs to the technical field of electromagnetic cold crucibles, and particularly relates to a circulating heat treatment system of an electromagnetic cold crucible and a method for refining a titanium-aluminum alloy structure by circulating heat treatment.
Background
In recent years, the method for improving the alloy performance through titanium-aluminum alloy structure regulation has received general attention of researchers at home and abroad. The strength of the material and the grain size of the alloy are generally considered to accord with a Hall-batch relation, but the titanium-aluminum alloy is generally used in a high-temperature environment, and the fine grains can reduce the high-temperature creep resistance of the material. Researches find that a Hall-batch formula also exists in the lamella spacing and the material strength, and the material strength and the creep resistance are obviously improved along with the thinning of lamella tissues.
The inter-lamellar spacing of the titanium aluminium alloy is mainly influenced by the cooling rate during the heat treatment. Generally, the faster the cooling rate, the smaller the lamella spacing. In order to realize the refinement of lamellar structure, TiAl alloy is firstly heated to an alpha single-phase region, is cooled at different rates after being kept warm for a period of time, when the cooling rate is low, a full lamellar structure cannot be obtained, a gamma phase exists in the alloy, when the cooling rate is too high, a Widmannstatten structure appears, and the mechanical property of the material is obviously reduced.
Therefore, the control of the cooling rate is a key factor for refining the sheet layer by heat treatment to achieve the improvement of the mechanical properties of the material.
On one hand, the heating speed of a common heat treatment furnace is slow, and the heat treatment furnace stays in a phase zone of a preset temperature for a long time before heating to the preset temperature, so that the heating or heat preservation time in a certain phase zone is difficult to accurately control in fact, on the other hand, the continuous adjustment of the cooling rate cannot be realized, and the cooling mode generally comprises furnace cooling, nitrogen gas cooling, air cooling, oil quenching and water quenching, wherein the furnace cooling speed is slow, the cooling rate of the nitrogen gas cooling is difficult to accurately control, the material cooling needs to be taken out of the furnace in the latter three modes, the TiAl material needing high-temperature oxidation prevention needs to be taken out of the furnace, anti-oxidation measures such as quartz sealed tubes, metal foils and the like on the surface need to be removed, and the cooling in the process is also uncontrollable.
Disclosure of Invention
The invention provides an electromagnetic cold crucible circulating heat treatment system and a method for refining titanium-aluminum alloy tissues through circulating heat treatment, and aims to solve the problems that the heating or heat preservation temperature is difficult to accurately control, the continuous adjustment of the cooling rate cannot be realized, and the titanium-aluminum alloy sheets cannot be refined through the heat treatment in the common heat treatment.
The technical scheme of the invention is as follows:
an electromagnetic cold crucible circulation heat treatment system comprises a heat treatment furnace, an electromagnetic cold crucible, an induction coil, a cooling system, an upper drawing rod, a material rod for stabilizing power, a directional treatment sample and a lower drawing rod,
the electromagnetic cold crucible is fixedly arranged in the heat treatment furnace, the periphery of the electromagnetic cold crucible is provided with an induction coil, the cooling system is arranged below the electromagnetic cold crucible,
the upper drawing rod is arranged at the top of the outer side of the heat treatment furnace, the lower drawing rod is arranged at the bottom of the outer side of the heat treatment furnace,
go up pull pole, stabilize power and lie in same vertical line from top to bottom with charge bar, directional processing sample and lower pull pole in proper order, go up pull pole and pull pole pulling down and stabilize power and carry out reciprocating motion from top to bottom with charge bar and directional processing sample in the inside in step of electromagnetism cold crucible and cooling system.
Furthermore, the inside electromagnetism cold crucible first support, the electromagnetism cold crucible second support that still is provided with of heat treatment furnace, electromagnetism cold crucible first support and the electromagnetism cold crucible second support one end all with electromagnetism cold crucible fixed connection, the other end all with heat treatment furnace bottom fixed connection for fixed electromagnetism cold crucible.
Further, a first motor and a second motor are arranged outside the heat treatment furnace, a first screw rod is mounted at the output end of the first motor, the upper pulling rod is in threaded fit with the first screw rod through a first support arm, and the first motor drives the first screw rod to rotate so that the upper pulling rod reciprocates up and down and adjusts and controls the pulling speed of the upper pulling rod; the output end of the second motor is provided with a second screw rod; the lower pulling rod is in threaded fit with the second screw rod through the second support arm, and the second motor drives the second screw rod to rotate, so that the lower pulling rod can reciprocate up and down and the pulling speed of the lower pulling rod is controlled.
Furthermore, the height of the electromagnetic cold crucible is 20-50 mm.
Furthermore, the device also comprises a temperature polling instrument which is used for detecting the temperature inside the electromagnetic cold crucible.
Furthermore, the cooling liquid used at the low-temperature end of the cooling system is Ga-In liquid cooled by circulating water.
A method for refining titanium-aluminum alloy structure by using an electromagnetic cold crucible circulation heat treatment system provided by the invention comprises the steps of sequentially placing a titanium-aluminum alloy directional treatment sample and a power stabilizing material bar in an electromagnetic cold crucible, wherein the power stabilizing material bar is positioned above the titanium-aluminum alloy directional treatment sample, one end of the titanium-aluminum alloy directional treatment sample is placed at the middle height position of the electromagnetic cold crucible, increasing power in a gradient manner until the titanium-aluminum alloy directional treatment sample reaches the heat treatment temperature and is kept warm for a certain time, then drawing downwards at a certain speed to enable the power stabilizing material bar and the titanium-aluminum alloy directional treatment sample to synchronously move downwards, separating the heat treated titanium-aluminum alloy directional treatment sample from a hot area and cooling the titanium-aluminum alloy directional treatment sample in a cooling system, cooling the low-temperature end of the cooling system, and synchronously returning the power stabilizing material bar and the titanium-aluminum alloy directional treatment sample to the initial positions to start next circulation heating, the number of the circulating heat treatment is 2-6.
Further, the titanium-aluminum alloy directional processing sample comprises a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot.
Further, the heat treatment is performed in an argon atmosphere of 300 Pa.
Further, the gradient increasing power is that the induction heating power supply is increased to 140V at a speed of 20V/min, then to 160V at a speed of 10V/min, and then to 180V at a speed of 5V/min in the initial heating stage.
Further, the heat treatment temperature of the titanium-aluminum alloy directional treatment sample is 1350 +/-10 ℃, and the heat preservation time is 2-10 min.
Furthermore, the downward drawing speed is 0.1-5 mm/min.
Further, the cooling time of the titanium-aluminum alloy directional treatment sample in a cooling system is 2-10 min.
The invention has the beneficial effects that:
according to the electromagnetic cold crucible circulation heat treatment system provided by the invention, the material is subjected to heat treatment in a cold crucible induction heating mode, a more uniform magnetic field and temperature field distribution can be obtained in the heat treatment process, and the continuous control of the cooling speed in the heat treatment process can be realized.
The electromagnetic cold crucible circulation heat treatment system provided by the invention is used for carrying out circulation heat treatment on the titanium-aluminum alloy, and the homogenization and refinement of the lamellar structure of the titanium-aluminum alloy are realized through stable temperature field control and cooling rate adjustment in the heat treatment process. The invention refines the lamella of the titanium-aluminum alloy, improves the alloy strength and creep resistance, and has very important significance for promoting the engineering application of the heat treatment process of the electromagnetic cold crucible.
Drawings
FIG. 1 is a schematic structural diagram of an electromagnetic cold crucible circulation heat treatment system provided by the present invention;
FIG. 2 is a partially enlarged schematic view of an electromagnetic cold crucible cyclic heat treatment system provided by the present invention;
FIG. 3 is a cloud of magnetic field distributions during a heating induction heat treatment process with a single induction coil;
FIG. 4 is a cloud of magnetic field distributions during induction heating induction heat treatment of a cold-containing crucible;
FIG. 5 is a graph comparing the distribution of longitudinal magnetic fields on the surface of a workpiece during induction heating with and without a cold crucible;
FIG. 6 is a graph showing the comparison of the distribution of the longitudinal magnetic field on the surface of the workpiece when the cold crucibles of different heights are used for the heat treatment in examples 3 to 5;
FIG. 7 is a photograph of a microstructure of a titanium-aluminum alloy obtained without electromagnetic cold crucible heat treatment, i.e., after 0 cycles;
FIG. 8 is a photograph of the microstructure of a titanium-aluminum alloy obtained after 2 heat treatments in an electromagnetic cold crucible cycle in example 7;
FIG. 9 is a photograph of the microstructure of a titanium-aluminum alloy obtained after 4 heat treatments in an electromagnetic cold crucible cycle in example 8;
FIG. 10 is a photograph of the microstructure of the titanium-aluminum alloy obtained in example 9 after 6 cycles of the heat treatment in the electromagnetic cold crucible;
FIG. 11 is a TEM photograph of a titanium-aluminum alloy obtained without electromagnetic cold crucible heat treatment, i.e., after 0 cycles;
FIG. 12 is a TEM photograph of a titanium-aluminum alloy obtained after 2 cycles of heat treatment in an electromagnetic cold crucible in example 7;
FIG. 13 is a TEM photograph of a titanium-aluminum alloy obtained after 4 times heat treatment in an electromagnetic cold crucible cycle in example 8;
FIG. 14 is a TEM photograph of a titanium-aluminum alloy obtained after 6 times heat treatment in an electromagnetic cold crucible cycle in example 9;
in the figure, 1, a heat treatment furnace; 2. an electromagnetic cold crucible; 201. a first support of an electromagnetic cold crucible; 202. a second bracket of the electromagnetic cold crucible; 3. an induction coil; 4. a cooling system; 5. an upper pull rod; 501, a first support arm 6 and a power stabilizing material rod; 7. directionally treating the sample; 8. a lower pull rod; 801. a second support arm; 901. a first motor; 902. a second motor; 1001. a first lead screw; 1002. a second screw rod, 11 and a sliding sleeve of a sliding rail; 12. temperature polling instrument.
Detailed Description
The technical solutions of the present invention are further described below with reference to the following examples, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention. The process equipment or apparatus not specifically mentioned in the following examples are conventional in the art, and if not specifically mentioned, the raw materials and the like used in the examples of the present invention are commercially available; unless otherwise specified, the technical means used in the examples of the present invention are conventional means well known to those skilled in the art.
Example 1
The embodiment provides an electromagnetic cold crucible circulation heat treatment system.
The electromagnetic cold crucible circulation heat treatment system comprises a heat treatment furnace 1, an electromagnetic cold crucible 2, an induction coil 3, a cooling system 4, an upper drawing rod 5, a material rod 6 for stabilizing power, a directional treatment sample 7 and a lower drawing rod 8.
In the embodiment, the electromagnetic cold crucible 2 is fixedly arranged in the heat treatment furnace 1, the induction coil 3 is arranged on the periphery of the electromagnetic cold crucible 2, the cooling system 4 is arranged below the electromagnetic cold crucible 2, and the directional treatment sample 7 moves downwards in the heat treatment process and directly enters the cooling system after being separated from the hot area of the electromagnetic cold crucible.
The upper drawing rod 5 is arranged at the top of the outer side of the heat treatment furnace 1, and the lower drawing rod 8 is arranged at the bottom of the outer side of the heat treatment furnace 1;
go up pull pole 5, for stabilizing power charge bar 6, directional processing sample 7 and pull pole 8 down and be located same vertical line from top to bottom in proper order, go up pull pole 5 and pull pole 8 down and pull charge bar 6 for stabilizing power and directional processing sample 7 and carry out up-and-down reciprocating motion in the inside synchronization of electromagnetism cold crucible 2 and cooling system 4.
The system of the embodiment also comprises a vacuum system which mainly comprises a diffusion pump, a vacuum pump and a vacuum chamber; the device also comprises a control system which is mainly responsible for accurately controlling parameters such as heating power, vacuum degree, movement speed of the upper drawing rod and the lower drawing rod in the heat treatment process.
The material rod 6 for stabilizing power is arranged in the embodiment, in the circulating heat treatment process, the material rod 6 for stabilizing power can stabilize the power supply power of electromagnetic induction within the range of 13.8-14 kW, the heating temperature in the electromagnetic cold crucible can be stabilized within the range of 1350 +/-10 ℃, and the heat treatment temperature can be accurately controlled. The specific power value is subject to the condition that the workpiece temperature can be heated to the preset temperature range.
Because the workpiece is long, the end part of the workpiece is gradually separated from the heating area when the downward drawing is finished, so that the induction heating load is changed, and the material rod 6 with stable power is used for connection, so that the temperature change of the heat-treated workpiece caused by the load change is restrained. The problem that the heating temperature of the end part of the heat treatment workpiece is obviously increased and exceeds the range of 1350 +/-10 ℃ is solved, and the equipment is prevented from being damaged by power supply tripping easily when the workpiece is separated from the induction heating area.
Example 2
The embodiment provides an electromagnetic cold crucible circulation heat treatment system.
The electromagnetic cold crucible circulation heat treatment system comprises a heat treatment furnace 1, an electromagnetic cold crucible 2, an induction coil 3, a cooling system 4, an upper drawing rod 5, a material rod 6 for stabilizing power, a directional treatment sample 7, a lower drawing rod 8, a motor 9 and a screw rod 10.
In this embodiment, the electromagnetic cold crucible 2 is fixedly arranged in the heat treatment furnace 1, the electromagnetic cold crucible first support 201 and the electromagnetic cold crucible second support 202 are further arranged inside the heat treatment furnace 1, the electromagnetic cold crucible 2 is fixedly arranged in the heat treatment furnace 1 through the electromagnetic cold crucible first support 201 and the electromagnetic cold crucible second support 202, one end of each of the electromagnetic cold crucible first support 201 and the electromagnetic cold crucible second support 202 is fixedly connected with the electromagnetic cold crucible 2, and the other end of each of the electromagnetic cold crucible first support 201 and the electromagnetic cold crucible second support 202 is fixedly connected with the bottom of the heat treatment furnace 1.
The height of the electromagnetic cold crucible 2 in the embodiment is 20-50 mm, and the cold crucible with the height range of 20-50 mm in the embodiment has the function of a uniform magnetic field and can provide a uniform magnetic field and a temperature field in the heat treatment process. An induction coil 3 is arranged on the periphery of the electromagnetic cold crucible 2, the bottom of the electromagnetic cold crucible 2 is communicated with a cooling system 4 which is arranged at the bottom of the heat treatment furnace 1 and leads to the outside of the heat treatment furnace, and cooling liquid used at the low-temperature end of the cooling system is Ga-In liquid cooled by circulating water. The present embodiment is also provided with a temperature patrol instrument 12 for detecting the temperature in the electrically-measured cold crucible 2.
In this embodiment, the upper drawing rod 5 is disposed at the top of the outer side of the heat treatment furnace 1, the lower drawing rod 8 is disposed at the bottom of the outer side of the heat treatment furnace 1, the first motor 901 is further disposed outside the heat treatment furnace 1, and the first lead screw 1001 is mounted at the output end of the first motor 901. Go up pull pole 5 through first support arm 501 and first lead screw 1001 screw-thread fit, specifically for first support arm is the level setting, the one end and last pull pole 5 fixed connection of first support arm, and the other end is equipped with screw-nut, through screw-nut and first lead screw 1001 screw-thread fit. The first motor 901 drives the first lead screw 1001 to rotate, so that the upper drawing rod 5 reciprocates up and down and the drawing speed of the upper drawing rod 5 is regulated and controlled;
the exterior of the heat treatment furnace 1 is also provided with a second motor 902, and the output end of the second motor 902 is provided with a second screw rod 1002. Lower pull pole 8 passes through second support arm 801 and second lead screw 1002 screw-thread fit, specifically is that the second support arm is the level setting, the one end and the lower pull pole 8 fixed connection of second support arm, and the other end is equipped with screw-nut, through screw-nut and second lead screw 1002 screw-thread fit. The second motor 902 drives the second lead screw 1002 to rotate, so that the lower drawing rod 8 reciprocates up and down and the drawing speed of the lower drawing rod 8 is regulated.
In this embodiment, the upper pulling rod 5, the material rod 6 for stabilizing power, the directional processing sample 7 and the lower pulling rod 8 are sequentially located on the same vertical line from top to bottom, the upper pulling rod 5 is connected with the material rod 6 for stabilizing power, the material rod 6 for stabilizing power is connected with the directional processing sample 7, the directional processing sample 7 is connected with the lower pulling rod 8, the upper pulling rod 5 and the lower pulling rod 8 pull the material rod 6 for stabilizing power and the directional processing sample 7 to synchronously reciprocate up and down in the electromagnetic cold crucible 2 and the cooling system 4, the upper pulling rod 5 is controlled by the first motor 901, and the pulling speed of the lower pulling rod 8 is controlled by the second motor 902, so that the continuous control of the cooling rate of the directional processing sample 7 is realized, and the phase change and the tissue change of the alloy are more uniform and controllable. The embodiment is also provided with a sliding rail sliding sleeve 11 for keeping the stability of the screw rod and preventing the screw rod from shaking.
The present invention separately examines the magnetic field distribution during the induction heating process with or without the cold crucible, and the results are shown in fig. 3-5.
FIG. 3 is a cloud of magnetic field distributions during a heating induction heat treatment process with a single induction coil; FIG. 4 is a cloud of magnetic field distributions during induction heating induction heat treatment of a cold-containing crucible; it can be seen from the figure that, under the same condition of heating by adopting a single-turn coil, when the single induction coil is used for heating, the magnetic field distribution on the surface of the workpiece is concentrated, the magnetic induction intensity of the coil in the height range mapped on the surface of the workpiece is highest, the coil is quickly weakened towards the upper end and the lower end, the constant magnetic induction intensity line is a circular arc with a certain curvature, but when the cold crucible is added for induction heating, the concentration degree of the magnetic field in the longitudinal direction is inhibited, the constant magnetic induction intensity line tends to be flat, and the uniformity of the magnetic field distribution is obviously improved. It was found that by performing the heat treatment using the cold crucible, a more uniform magnetic field and thus a more uniform temperature distribution can be obtained on the surface of the sample.
FIG. 5 is a graph comparing the distribution of longitudinal magnetic fields on the surface of a workpiece during induction heating with and without a cold crucible; it can be seen that the magnetic field distribution trend in the induction heating process with or without the cold crucible is the same, but the magnetic induction intensity after the crucible is added is obviously reduced from the center to the two ends, the longitudinal distribution uniformity of the magnetic field is obviously improved, and the result is consistent with the result of the magnetic field distribution cloud chart.
Example 3
The present embodiment provides an electromagnetic cold crucible circulation heat treatment system, which is different from embodiment 2 only in that the height of the electromagnetic cold crucible in the present embodiment is 50 mm.
Example 4
The present embodiment provides an electromagnetic cold crucible circulation heat treatment system, which is different from embodiment 2 only in that the height of the electromagnetic cold crucible in the present embodiment is 30 mm.
Example 5
The present embodiment provides an electromagnetic cold crucible circulation heat treatment system, which is different from embodiment 2 only in that the height of the electromagnetic cold crucible in the present embodiment is 20 mm.
The invention respectively examines the distribution situation of the longitudinal magnetic field on the surface of the workpiece when the cold crucibles with different heights are subjected to heat treatment, and the result is shown in figure 6.
FIG. 6 is a graph showing the comparison of the distribution of the longitudinal magnetic field on the surface of the workpiece when the cold crucibles of different heights are used for the heat treatment in examples 3 to 5; it can be seen that the magnetic field homogenization effect is obviously improved along with the reduction of the height of the crucible, and when the height of the crucible is 20mm, the magnetic induction intensity change amplitude of the surface of the workpiece can be basically ignored in the area covered by the height of the crucible, and the magnetic induction intensity suddenly reduces to the edge of the crucible. Therefore, the magnetic field homogenization effect of the crucible can be optimized by adjusting the structure and the size of the crucible.
Example 6
The embodiment provides a method for refining a titanium-aluminum alloy structure by using the electromagnetic cold crucible circulating heat treatment system with the height of 50mm of the electromagnetic cold crucible provided in the embodiment 3.
In the embodiment, the titanium-aluminum alloy directional sample to be subjected to heat treatment is a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot, and is prepared by a method of primary arc melting and secondary vacuum induction melting. The primary arc melting is to prepare raw materials into primary melting ingots by adopting vacuum consumable arc melting equipment commonly adopted in the prior art. And putting the primary smelting ingot into a cold crucible vacuum induction smelting furnace for secondary smelting, gradually increasing the smelting power to 320kW, preserving the heat for 5min, and casting to obtain the secondary smelting ingot.
And (3) processing the Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot obtained by secondary smelting into a round rod with the diameter of 20mm for directional solidification experiments by adopting a wire electrical discharge machining method, and obtaining the titanium-aluminum alloy directional sample to be subjected to heat treatment after the directional solidification experiments.
The specific method for refining the titanium-aluminum alloy structure by the electromagnetic cold crucible circulation heat treatment comprises the following steps:
and sequentially placing the directional titanium-aluminum alloy sample to be heat-treated and the material rod for stabilizing the power supply power in an electromagnetic cold crucible, wherein the material rod for stabilizing the power is positioned above the directional titanium-aluminum alloy sample to be heat-treated, and one end of the directional titanium-aluminum alloy sample to be heat-treated is placed at the middle height position of the electromagnetic cold crucible.
The power is increased in a gradient manner in an argon environment with 300Pa, an induction heating power supply is increased from 60V to 140V at the speed of 20V/min, then is increased to 160V at the speed of 10V/min, and is increased to 180V at the speed of 5V/min until the titanium-aluminum alloy directional sample to be heat-treated reaches the heat treatment temperature of 1350 +/-10 ℃, the titanium-aluminum alloy directional sample is drawn downwards at the speed of 4mm/min after heat preservation for 5min, so that a material rod for stabilizing the power supply power and the titanium-aluminum alloy directional sample synchronously move downwards, the titanium-aluminum alloy directional sample after heat treatment is separated from a hot zone, and after cooling at the low-temperature end of a cooling system for 4min, the circulation heat treatment is not carried out, namely the number of circulation heat treatment is 1.
Example 7
In the embodiment, the electromagnetic cold crucible circulation heat treatment system with the height of 50mm provided in the embodiment 3 is utilized, and the method for refining the titanium-aluminum alloy structure through the electromagnetic cold crucible circulation heat treatment is provided.
The titanium-aluminum alloy directional sample to be heat treated in the embodiment is a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot, and is prepared by the same batch with the Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot used in the embodiment 6. Processing the Ti-47Al-2Cr-2Nb-0.2C alloy master ingot into a round rod with the diameter of 20mm for an oriented solidification experiment by adopting a wire cut electrical discharge machining method, and obtaining a titanium-aluminum alloy oriented sample to be subjected to heat treatment after the oriented solidification experiment.
The specific method for refining the titanium-aluminum alloy structure by the electromagnetic cold crucible circulation heat treatment comprises the following steps:
and sequentially placing the directional titanium-aluminum alloy sample to be heat treated and the material rod for stabilizing power supply power in an electromagnetic cold crucible, wherein the material rod for stabilizing power is positioned above the directional titanium-aluminum alloy sample to be heat treated, and one end of the directional titanium-aluminum alloy sample to be heat treated is placed at the middle height position of the electromagnetic cold crucible.
Increasing power in a gradient manner in an argon environment of 300Pa, starting an induction heating power supply from 60V, increasing the power supply to 140V at the speed of 20V/min, then increasing the power supply to 160V at the speed of 10V/min, increasing the power supply to 180V at the speed of 5V/min until the titanium-aluminum alloy directional sample to be heat-treated reaches the heat treatment temperature of 1350 +/-10 ℃, keeping the temperature for 5min, downwards drawing the titanium-aluminum alloy directional sample at the speed of 4mm/min, synchronously downwards moving a material rod for stabilizing the power supply power and the titanium-aluminum alloy directional sample, separating the heat-treated titanium-aluminum alloy directional sample from a hot zone, returning to the initial position after cooling the low-temperature end of a cooling system for 4min, and starting the next cycle heating, wherein the cycle heat treatment times are 2 times.
Example 8
In the embodiment, the electromagnetic cold crucible circulation heat treatment system with the height of 50mm provided in the embodiment 3 is utilized, and the method for refining the titanium-aluminum alloy structure through the electromagnetic cold crucible circulation heat treatment is provided.
The titanium-aluminum alloy directional sample to be heat treated in the embodiment is a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot, and is prepared by the same batch with the Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot used in the embodiment 6. Processing the Ti-47Al-2Cr-2Nb-0.2C alloy master ingot into a round rod with the diameter of 20mm for an oriented solidification experiment by adopting a wire cut electrical discharge machining method, and obtaining a titanium-aluminum alloy oriented sample to be subjected to heat treatment after the oriented solidification experiment.
The specific method for refining the titanium-aluminum alloy structure by the electromagnetic cold crucible circulation heat treatment comprises the following steps:
and sequentially placing the directional titanium-aluminum alloy sample to be heat-treated and the material rod for stabilizing the power supply power in an electromagnetic cold crucible, wherein the material rod for stabilizing the power is positioned above the directional titanium-aluminum alloy sample to be heat-treated, and one end of the directional titanium-aluminum alloy sample to be heat-treated is placed at the middle height position of the electromagnetic cold crucible.
Increasing power in a gradient manner in an argon environment of 300Pa, starting an induction heating power supply from 60V, increasing the speed of 20V/min to 140V, increasing the speed of 10V/min to 160V, increasing the speed of 5V/min to 180V until the temperature of the titanium-aluminum alloy directional sample to be heat-treated reaches 1350 +/-10 ℃, keeping the temperature for 5min, downwards drawing the titanium-aluminum alloy directional sample at the speed of 4mm/min, synchronously downwards moving a material rod for stabilizing the power supply power and the titanium-aluminum alloy directional sample, separating the heat-treated titanium-aluminum alloy directional sample from a hot area, cooling the low-temperature end of a cooling system for 4min, returning to the initial position to start next circulation heating, and carrying out circulation heat treatment for 4 times.
Example 9
In the embodiment, the electromagnetic cold crucible circulation heat treatment system with the height of 50mm provided in the embodiment 3 is utilized, and the method for refining the titanium-aluminum alloy structure through the electromagnetic cold crucible circulation heat treatment is provided.
The titanium-aluminum alloy directional sample to be heat treated in the embodiment is a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot, and is prepared by the same batch with the Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot used in the embodiment 6. Machining a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot into a round rod with the diameter of 20mm for directional solidification experiments by adopting a wire electrical discharge machining method, and obtaining a titanium-aluminum alloy directional sample to be subjected to heat treatment after the directional solidification experiments.
The specific method for refining the titanium-aluminum alloy structure by the electromagnetic cold crucible circulation heat treatment comprises the following steps:
and sequentially placing the directional titanium-aluminum alloy sample to be heat-treated and the material rod for stabilizing the power supply power in an electromagnetic cold crucible, wherein the material rod for stabilizing the power is positioned above the directional titanium-aluminum alloy sample to be heat-treated, and one end of the directional titanium-aluminum alloy sample to be heat-treated is placed at the middle height position of the electromagnetic cold crucible.
Increasing power in a gradient manner in an argon environment of 300Pa, starting an induction heating power supply from 60V, increasing the speed of 20V/min to 140V, increasing the speed of 10V/min to 160V, increasing the speed of 5V/min to 180V until the temperature of the titanium-aluminum alloy directional sample to be heat-treated reaches 1350 +/-10 ℃, keeping the temperature for 5min, downwards drawing the titanium-aluminum alloy directional sample at the speed of 4mm/min, synchronously downwards moving a material rod for stabilizing the power supply power and the titanium-aluminum alloy directional sample, separating the heat-treated titanium-aluminum alloy directional sample from a hot area, cooling the low-temperature end of a cooling system for 4min, returning to the initial position to start next circulation heating, and performing 6 circulation heat treatments.
FIGS. 7-10 are photographs of the microstructures of the samples that were not heat treated after 0 cycles, and the titanium aluminum alloys obtained after 2, 4, and 6 heat treatments of examples 7-9 with electromagnetic cold crucible cycles, in that order; as can be seen from the comparison of the figures, when the number of the circulation times is increased, the alloy matrixes are all alpha which are arranged alternately 2 And gamma lamellae. When the heat treatment is not carried out or the heat treatment frequency is low, the B2 phase and the gamma phase exist in the grain boundary and the sheet layer group, and the content of the B2 phase and the gamma phase increases along with the increase of the heat treatment cycle frequencyGradually decreased, the lamellar tissue is obviously homogenized, and basically no B2 phase remains after 6 times of circulation.
FIGS. 11-14 are TEM photographs of the titanium-aluminum alloy obtained after 0 cycles, i.e., the samples without heat treatment, and 2, 4, and 6 cycles of heat treatment of the electromagnetic cold crucible in examples 7-9, in this order; as can be seen from the comparison of the figures, the lamellar structure of the titanium-aluminum alloy is gradually thinned along with the increase of the heat treatment cycle number, the lamellar spacing of the TiAl alloy which does not pass through the cycle number is measured by adopting a line cutting method, and alpha is not distinguished during calculation 2 And gamma lamellae, the statistical results of which are shown in table 1, the lamella spacing decreases from 517nm to 225nm when the number of cycles increases from 0 to 6.
The thinning effect of the titanium-aluminum alloy sheet layers with different heat treatment cycle numbers is shown in table 1.
TABLE 1
As can be seen from Table 1, with the increase of the number of heat treatment cycles, the structure of the titanium-aluminum alloy sheet is gradually refined, thereby improving the alloy strength and the creep resistance.
Claims (10)
1. An electromagnetic cold crucible circulation heat treatment system is characterized by comprising a heat treatment furnace (1), an electromagnetic cold crucible (2), an induction coil (3), a cooling system (4), an upper drawing rod (5), a material rod (6) for stabilizing power, a directional treatment sample (7) and a lower drawing rod (8),
the electromagnetic cold crucible (2) is fixedly arranged in the heat treatment furnace (1), the periphery of the electromagnetic cold crucible (2) is provided with an induction coil (3), the cooling system (4) is arranged below the electromagnetic cold crucible (2),
the upper drawing rod (5) is arranged at the top of the outer side of the heat treatment furnace (1), the lower drawing rod (8) is arranged at the bottom of the outer side of the heat treatment furnace (1),
go up pull pole (5), stabilize for power charge bar (6), directional processing sample (7) and pull pole (8) down and be located same vertical line from top to bottom in proper order, go up pull pole (5) and pull pole (8) down and pull charge bar (6) and directional processing sample (7) and carry out reciprocating motion from top to bottom in electromagnetism cold crucible (2) and cooling system (4) inside in step.
2. The electromagnetic cold crucible circulation heat treatment system is characterized in that a first electromagnetic cold crucible support (201) and a second electromagnetic cold crucible support (202) are further arranged inside the heat treatment furnace (1), one end of each of the first electromagnetic cold crucible support (201) and the second electromagnetic cold crucible support (202) is fixedly connected with the electromagnetic cold crucible (2), and the other end of each of the first electromagnetic cold crucible support (201) and the second electromagnetic cold crucible support (202) is fixedly connected with the bottom of the heat treatment furnace (1) and used for fixing the electromagnetic cold crucible (2).
3. The electromagnetic cold crucible circulating heat treatment system according to claim 1 or 2, wherein a first motor (901) and a second motor (902) are further arranged outside the heat treatment furnace (1), a first screw rod (1001) is mounted at an output end of the first motor (901), the upper pull rod (5) is in threaded fit with the first screw rod (1001) through a first support arm (501), and the first motor (901) drives the first screw rod (1001) to rotate so that the upper pull rod (5) reciprocates up and down and regulates and controls the pull speed of the upper pull rod (5); the output end of the second motor (902) is provided with a second screw rod (1002); the lower drawing rod (8) is in threaded fit with a second screw rod (1002) through a second support arm (801), and a second motor (902) drives the second screw rod (1002) to rotate so that the lower drawing rod (8) can reciprocate up and down and the drawing speed of the lower drawing rod (8) can be regulated and controlled.
4. The electromagnetic cold crucible circulation heat treatment system of claim 3, wherein the height of the electromagnetic cold crucible (2) is 20-50 mm.
5. A method for refining a titanium-aluminum alloy structure by using the electromagnetic cold crucible circulating heat treatment system of any one of claims 1 to 4, which is characterized in that a titanium-aluminum alloy directional treatment sample and a power-stabilizing material rod are sequentially placed in the electromagnetic cold crucible, the power-stabilizing material rod is positioned above the titanium-aluminum alloy directional treatment sample, one end of the titanium-aluminum alloy directional treatment sample is placed at the middle height position of the electromagnetic cold crucible, power is increased in a gradient manner until the titanium-aluminum alloy directional treatment sample reaches the heat treatment temperature and is kept warm for a certain time, then the titanium-aluminum alloy directional treatment sample and the power-stabilizing material rod are pulled downwards at a certain speed to synchronously move downwards, the heat-treated titanium-aluminum alloy directional treatment sample is separated from a hot zone and enters a cooling system for cooling, after the low-temperature end of the cooling system is cooled, the power-stabilizing material rod and the titanium-aluminum alloy directional treatment sample synchronously return to the initial positions to start the next circulating heating, the number of the circulating heat treatment is 2-6.
6. The method for refining the titanium-aluminum alloy structure according to claim 5, wherein the titanium-aluminum alloy directionally-treated sample comprises a Ti-47Al-2Cr-2Nb-0.2C alloy mother ingot.
7. A method for refining Ti-Al alloy structure as claimed in claim 5 or 6, characterized in that the gradient increasing power is to increase the induction heating power from 60V to 140V at 20V/min, then to 160V at 10V/min and then to 180V at 5V/min in the initial heating stage.
8. The method for refining the titanium-aluminum alloy structure according to claim 7, wherein the heat treatment temperature of the titanium-aluminum alloy directional treatment sample is 1350 +/-10 ℃, and the heat preservation time is 2-10 min.
9. The method for refining a Ti-Al alloy structure according to claim 8, wherein the drawing speed is 0.1-5 mm/min.
10. The method for refining the titanium-aluminum alloy structure according to claim 9, wherein the cooling time of the titanium-aluminum alloy directional treatment sample in a cooling system is 2-10 min.
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