CN111321306B

CN111321306B - Method for manufacturing titanium alloy casting

Info

Publication number: CN111321306B
Application number: CN202010214073.6A
Authority: CN
Inventors: 刘海涛; 贺焱; 胡博; 李智; 邓斌; 焦晓慧; 张卫国; 姚进军; 马永健; 陈喜锋
Original assignee: Csic No12 Research Institute
Current assignee: Csic No12 Research Institute
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2021-12-21
Anticipated expiration: 2040-03-24
Also published as: CN111321306A

Abstract

The invention discloses a method for manufacturing a titanium alloy casting, which comprises the steps of pre-embedding an alloy bag in a titanium ingot, smelting the titanium ingot pre-embedded with the alloy bag in vacuum, stirring a melt by adopting a unidirectional rotating magnetic field generator after the titanium ingot and the alloy bag are melted and a molten pool is formed in a crucible, casting and molding molten metal in vacuum while stirring, and then carrying out shelling treatment to obtain the titanium alloy casting. The manufacturing method of the titanium alloy casting has simple process, shortens the production flow of the titanium alloy casting, reduces the smelting times, avoids the volatilization of alloy elements in the multiple smelting process, improves the uniformity of titanium alloy components, and saves the production cost of the titanium alloy casting.

Description

Method for manufacturing titanium alloy casting

Technical Field

The invention belongs to the technical field of metal material preparation, and relates to a method for manufacturing a titanium alloy casting.

Background

Titanium alloy is an alloy formed by adding other elements based on titanium element, is an important structural metal, has the characteristics of high strength, good corrosion resistance, high heat resistance and the like, and is widely used in various fields.

The conventional manufacturing method of the titanium alloy casting comprises the steps of firstly smelting a titanium alloy ingot which meets the design components through a vacuum consumable electro-arc furnace, then smelting for many times to enable the components in the alloy ingot to be uniform, finally processing the titanium alloy ingot to be suitable for casting in a vacuum skull furnace, remelting in the vacuum consumable skull furnace, and then casting. The manufacturing method has complex process and complicated process, and the excessive burning loss of alloy elements can be caused when the alloy ingot is smelted for multiple times, so that the chemical components of the titanium alloy casting are difficult to control.

Disclosure of Invention

The invention aims to provide a method for manufacturing a titanium alloy casting, which solves the problem that an alloy ingot needs to be smelted for multiple times in the existing method for manufacturing the titanium alloy casting, so that the alloy elements are excessively burnt.

The invention adopts the technical scheme that the method for manufacturing the titanium alloy casting comprises the following steps:

step 1: pre-burying an alloy bag in the titanium cast ingot;

step 2: vacuum smelting the titanium cast ingot pre-embedded with the alloy bag;

and step 3: after the titanium cast ingot and the alloy bag are melted and a molten pool is formed in the crucible, stirring the melt by adopting a unidirectional rotating magnetic field generator;

and 4, step 4: and (3) carrying out vacuum casting molding on the molten metal while stirring, and then carrying out shelling treatment to obtain the titanium alloy casting.

The present invention is also technically characterized in that,

step 1, pre-embedding an alloy package in the titanium ingot, including drilling a blind hole in the titanium ingot, putting the alloy package into the blind hole, covering the hole opening of the blind hole with a sheet material which is made of the same material as the titanium ingot, and finally sealing and welding the hole opening of the blind hole.

In the step 1, sealing welding is completed by argon arc welding.

The specific process of step 2 is as follows:

step 2.1: welding a titanium cast ingot pre-embedded with an alloy bag on a false electrode in a vacuum consumable skull furnace to ensure that the distance between the bottom surface of the titanium cast ingot and the bottom of a crucible is 30-45 mm, and then closing the vacuum consumable skull furnace;

step 2.2: vacuumizing the vacuum consumable skull furnace to ensure that the vacuum degree in the furnace is less than or equal to 2 Pa; adjusting the pneumatic pressure of an electrode of the vacuum consumable skull furnace to be 0.5-0.7 MPa, the total water pressure of cooling water to be 0.4-0.6 MPa, the water pressure of a crucible to be 0.2-0.4 MPa, and the no-load voltage to be 70-80V;

step 2.3: carrying out arc striking and preheating on the titanium cast ingot, wherein the arc striking voltage is 30-35V, the arc striking current is 3000-4000A, the preheating current is 5000-6000A, the preheating time is 1-1.5 min, and a molten pool is formed in the crucible;

step 2.4: and (3) arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 18000-20000A, the water temperature of the crucible inlet is controlled to be 17-20 ℃, and the water temperature of the crucible outlet is lower than 50 ℃.

The unidirectional rotation magnetic field generator is arranged between the crucible and the water jacket.

In the step 3, in the process of stirring the melt by the unidirectional rotating magnetic field generator, the power supply voltage of the unidirectional rotating magnetic field generator is 12V, and the current is 2-4A.

The step 4 specifically comprises the following steps:

step 4.1: preheating a casting mold;

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, pouring molten metal into the casting mold, then closing the unidirectional rotating magnetic field generator, cooling the molten metal to room temperature along with the furnace, and taking out the casting mold from the vacuum consumable skull furnace;

step 4.3: and (4) removing the casting in the casting mould, and removing impurities on the surface of the casting to obtain the titanium alloy casting.

In the step 4.1, the temperature of the preheated casting mold is 400-500 ℃.

And 4.2, in the process of pouring the molten metal into the casting mold, wherein the temperature of the casting mold is 300-400 ℃.

The invention has the beneficial effects that the alloy is pre-embedded on the titanium ingot, the vacuum consumable skull furnace is adopted for smelting, the unidirectional rotating magnetic field is added to stir the alloy melt, so that the alloy elements in the melt are uniformly distributed and then are directly poured into the titanium alloy casting, the process is simple, the operation is easy, and the casting efficiency of the titanium alloy casting is greatly improved; compared with the existing process method for producing the titanium alloy casting, the process method shortens the production flow of the titanium alloy casting, reduces the smelting times, avoids the volatilization of alloy elements in the multiple smelting processes, improves the uniformity of titanium alloy components, and saves the production cost of the titanium alloy casting; compared with an arc melting and recasting casting, the titanium alloy prepared by the titanium alloy casting manufacturing method has the structural characteristics of more uniform components and finer crystal grains, and the casting has higher tensile strength and yield strength, excellent mechanical property and wider application range.

Drawings

FIG. 1 is a schematic circuit diagram of a unidirectional rotating magnetic field generator of the present invention;

FIG. 2 is a schematic structural view of a mold in example 1 of the present invention;

FIG. 3 is a metallographic picture of a ZTC4 titanium alloy casting prepared in example 1 of the present invention;

FIG. 4 is a metallographic picture of a ZTA5 titanium alloy casting prepared in example 2;

FIG. 5 is a metallographic picture of a ZTA10 titanium alloy casting prepared in example 3;

FIG. 6 is a metallographic picture of a ZTC4 titanium alloy casting prepared in example 4.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a method for manufacturing a titanium alloy casting, which comprises the following steps:

step 1: the method comprises the steps of drilling a plurality of blind holes in a titanium ingot, enabling the distance between every two adjacent blind holes to be 45-55 mm, evenly dividing the alloy package into the number of parts which is the same as that of the blind holes, sequentially putting the alloy package into the blind holes, covering the orifices of the blind holes with sheets which are made of the same materials as the titanium ingot, and finally sealing and welding the orifices of the blind holes by adopting argon arc welding.

Step 2: vacuum melting titanium ingot embedded with alloy bag

Step 2.1: welding the titanium cast ingot pre-embedded with the alloy bag on a false electrode in a vacuum consumable skull furnace to ensure that the distance between the bottom surface of the titanium cast ingot and the bottom of a crucible is more than 30mm, and then closing the vacuum consumable skull furnace;

step 2.3: the method comprises the following steps of carrying out arc striking and preheating on titanium ingots, wherein the arc striking voltage is 30-35V, the arc striking current is 3000-4000A, the preheating current is 5000-6000A, the preheating time is 1-1.5 min, and in the process of arc striking and preheating on the titanium ingots, part of the titanium ingots are melted to form a molten pool in a crucible;

step 2.4: arc melting the titanium cast ingot, wherein in the melting process, the melting current is gradually increased to 18000-20000A, so that the water temperature at the inlet of the crucible is 17-20 ℃, and the water temperature at the outlet of the crucible is lower than 50 ℃;

and step 3: after the titanium ingot and the alloy package are melted and a molten pool is formed in the crucible, stirring the melt by adopting a unidirectional rotating magnetic field generator, wherein the unidirectional rotating magnetic field generator is arranged between the crucible and the water jacket, and in the process of stirring the melt, the power supply voltage of the unidirectional rotating magnetic field generator is 12V and the current is 2-4A;

and 4, step 4: vacuum casting and molding molten metal while stirring

Step 4.1: preheating a casting mold, wherein the temperature of the preheating casting mold is 400-500 ℃;

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, turning over a crucible, pouring molten metal into the casting mold, and finishing pouring within 3-5 s, wherein the temperature of the casting mold is 300-400 ℃ in the pouring process; closing the unidirectional rotating magnetic field generator after the pouring is finished, cooling the molten metal in the casting mold to room temperature along with the furnace, and finally taking out the casting mold from the vacuum consumable skull furnace;

step 4.3: and (4) removing impurities on the surface of the casting after the casting in the casting mould is subjected to shelling treatment, so that the titanium alloy casting is prepared.

Example 1

Preparing a ZTC4 titanium alloy casting, comprising the steps of:

step 1: preparing a TA2 titanium cast ingot and an alloy bag, wherein the TA2 titanium cast ingot is a cylindrical cast ingot with the diameter of 200mm and the height of 700 mm; the alloy bag is formed by mixing AlV55 powder and aluminum powder, wherein the mass of the AlV55 powder accounts for 5-9% of the melting amount of the titanium cast ingot, the granularity of the AlV55 powder is 60-100 meshes, and the mass of the aluminum powder accounts for 1-3% of the melting amount of the titanium cast ingot;

the chemical compositions of the TA2 titanium ingot and the AlV55 powder are shown in table 1:

TABLE 1 Mass fraction (%)% of chemical components in TA2, TA5 and AlV55

Number plate

Ti

V

Si

Fe

C

N

H

O

Al

TA2

Balance of

–

0.23

0.016

0.028

0.004

0.16

–

TA5

Balance of

–

0.16

0.017

0.030

0.005

0.18

4.1

AlV55

–

50.0～59.0

≤0.30

≤0.35

≤0.15

–

≤0.20

Balance of

Upwards drilling 8 blind holes uniformly in a row on the side wall of the TA2 titanium ingot at a position 50mm away from the bottom surface of the TA2 titanium ingot, wherein the interval between every two adjacent blind holes is 50mm, the diameter of each blind hole is 25mm, and the depth of each blind hole is 50 mm;

alloy packages are pre-embedded in the TA2 titanium cast ingot, the alloy packages are evenly divided into 8 parts, then one alloy package is placed in each blind hole, a TA2 thin wafer with the thickness of 1mm is used for covering the hole opening of each blind hole, and finally argon arc welding is adopted for sealing and welding the hole opening of each blind hole.

Step 2: vacuum melting titanium ingot embedded with alloy bag

Step 2.1: welding the titanium cast ingot pre-embedded with the alloy bag on a false electrode in a vacuum consumable skull furnace to ensure that the distance between the bottom surface of the titanium cast ingot and the bottom of a crucible is 40mm, and then closing the vacuum consumable skull furnace;

step 2.2: vacuumizing the vacuum consumable skull furnace to ensure that the vacuum degree in the furnace is less than or equal to 2 Pa; adjusting the electrode pneumatic pressure of the vacuum consumable skull furnace to be 0.6MPa, the total cooling water pressure to be 0.5MPa, the crucible water pressure to be 0.3MPa and the no-load voltage to be 70V;

step 2.3: carrying out arc striking and preheating on the titanium ingot, wherein the arc striking voltage is 35V, the arc striking current is 3000A, the titanium ingot and the solidified shell are preheated after arc striking, the preheating current is 5500A, the preheating time is 1min, and a molten pool is formed in a crucible;

step 2.4: and (3) arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 18000A, so that the water temperature at the inlet of the crucible is 19 ℃, and the water temperature at the outlet of the crucible is lower than 40 ℃.

And step 3: after the titanium cast ingot and the alloy package are melted and a molten pool is formed in the crucible, the melt is stirred by adopting the unidirectional rotating magnetic field generator, the schematic diagram of the unidirectional rotating magnetic field generator is shown in figure 1, direct current is supplied to the unidirectional rotating magnetic field generator, a longitudinal magnetic field is generated, and the longitudinal magnetic field enables molten metal in the molten pool to rotate to generate a stirring effect. The unidirectional rotating magnetic field generator is arranged between the crucible and the water jacket, and in the process of stirring the melt, the power supply voltage of the unidirectional rotating magnetic field generator is 12V, and the current is 3A;

the unidirectional rotating magnetic field generator is adopted to push the molten metal to rotate, an external unidirectional rotating magnetic field acts on the molten metal in the crystallizer, the molten metal is a conductor and generates induced current, the current interacts with the magnetic field generated by the inductor to generate electromagnetic force, the molten metal is pushed to rotate and forms relative motion with the molten metal, and the melt is stirred.

A large amount of texture structures exist in the molten liquid, the texture structures are derived from alpha-Al dendrites in the melting process, and the alpha-Al dendrites which are stirred and crushed by a magnetic field can be used as crystallization crystal nucleuses for later casting and solidification of titanium liquid to refine crystal grain structures and form a high-strength texture (alpha + beta) phase. The magnetic field can break flake alpha in a titanium alloy structure, and experiments prove that the average diameter of titanium alloy crystal grains without the action of the unidirectional rotating magnetic field is 4.8mm, the average diameter of titanium alloy crystal grains with the action of the unidirectional rotating magnetic field is 2.3mm, a compound is only precipitated in the crystal grains and is needle-shaped and granular, the maximum size of the needle-shaped compound is 224 mu m, the minimum size of the needle-shaped compound is 50 mu m, the maximum size of the granular compound is 63 mu m, and the minimum size of the granular compound is 10 mu m. Therefore, the grain is refined by the additional unidirectional rotating magnetic field, the problem of uniformity of alloy components can be effectively solved, the burning loss rate of alloy elements is reduced, and the product quality of the titanium alloy casting is improved.

And 4, step 4: vacuum casting molding

Step 4.1: referring to fig. 2, assembling a casting mold, and preheating the casting mold, wherein the temperature of the preheated casting mold is 500 ℃;

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, pouring molten metal into a cavity of the casting mold, wherein the pouring is completed within 3s, the temperature of the casting mold is 350 ℃ in the pouring process, closing the unidirectional rotating magnetic field generator after the pouring is completed, cooling the molten metal to room temperature along with the casting mold, and taking out the casting mold from the vacuum consumable skull furnace;

step 4.3: and (3) removing the casting in the casting mould, and removing impurities on the surface of the casting to obtain the ZTC4 titanium alloy casting.

Comparative example 1

The same raw materials as in example 1 were prepared, and a ZTC4 titanium alloy casting was produced by arc melting and recasting. The titanium alloy castings obtained in example 1 and comparative example 1 were subjected to the measurement of mechanical properties, and the results are shown in table 2:

TABLE 2 mechanical Properties of titanium alloy castings of example 1 and comparative example 1 were compared (GB/T6614-2014)

As can be seen from the data in Table 2, the titanium alloy castings prepared by the method for manufacturing titanium alloy castings of the present application have higher tensile strength and yield strength than arc melting recast castings.

Example 2

Preparing a ZTA5 titanium alloy casting, comprising the steps of:

step 1: preparing a TA2 titanium ingot and an alloy bag, wherein the chemical components of the TA2 titanium ingot are shown in Table 1, and the TA2 titanium ingot is a cylindrical ingot with the diameter of 200mm and the height of 500 mm; the alloy bag consists of high-purity aluminum beans, the mass of the high-purity aluminum beans accounts for 3.3-4.7% of the melting amount of the titanium cast ingot, and the granularity of the high-purity aluminum beans is 2-5 mm;

upwards drilling 5 blind holes uniformly in a row on the side wall of the TA2 titanium ingot at a position 50mm away from the bottom surface of the TA2 titanium ingot, wherein the interval between adjacent blind holes is 50mm, the diameter of each blind hole is 25mm, and the depth of each blind hole is 50 mm;

the alloy package is pre-embedded in the TA2 titanium cast ingot, the alloy package is divided into 5 parts, then one alloy package is placed in each blind hole, a TA2 thin wafer with the thickness of 1mm is used for covering the hole opening of the blind hole, and finally argon arc welding is adopted for sealing and welding the hole opening of the blind hole.

Step 2: vacuum melting titanium ingot embedded with alloy bag

Step 2.1: welding the titanium cast ingot pre-embedded with the alloy bag on a false electrode in a vacuum consumable skull furnace to ensure that the distance between the bottom surface of the titanium cast ingot and the bottom of a crucible is 45mm, and then closing the vacuum consumable skull furnace;

step 2.2: vacuumizing the vacuum consumable skull furnace to ensure that the vacuum degree in the furnace is less than or equal to 2 Pa; adjusting the electrode pneumatic pressure of the vacuum consumable skull furnace to be 0.65MPa, the total cooling water pressure to be 0.5MPa, the crucible water pressure to be 0.3MPa and the no-load voltage to be 70V;

step 2.3: the method comprises the following steps of (1) carrying out arc striking and preheating on a titanium ingot, wherein the arc striking voltage is 35V, the arc striking current is 3500A, the titanium ingot and a solidified shell are preheated after arc striking, the preheating current is 5500A, the preheating time is 1min, and a molten pool is formed in a crucible;

step 2.4: and (3) arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 18000A, the melting voltage is 38.5V, the water temperature at the inlet of the crucible is 19 ℃, and the water temperature at the outlet of the crucible is lower than 50 ℃.

And step 3: after the titanium cast ingot and the alloy package are melted and a molten pool is formed in the crucible, the unidirectional rotating magnetic field generator is adopted to stir the melt, direct current is supplied to the unidirectional rotating magnetic field generator to generate a longitudinal magnetic field, and the longitudinal magnetic field enables molten metal in the molten pool to rotate to generate a stirring effect. The unidirectional rotating magnetic field generator is arranged between the crucible and the water jacket, and in the process of stirring the melt, the power supply voltage of the unidirectional rotating magnetic field generator is 12V, and the current is 3A;

and 4, step 4: vacuum casting molding

Step 4.1: assembling a casting mold, preheating the casting mold, wherein the temperature of the casting mold after preheating is 500 ℃;

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, pouring molten metal into a cavity of the casting mold, wherein the pouring is completed within 4s, the temperature of the casting mold is 360 ℃ in the pouring process, closing the unidirectional rotating magnetic field generator after the pouring is completed, cooling the molten metal to room temperature along with the casting mold, and taking out the casting mold from the vacuum consumable skull furnace;

step 4.3: and (3) removing the casting in the casting mould, and removing impurities on the surface of the casting to obtain the ZTA5 titanium alloy casting.

Example 3

Preparing a ZTA10 titanium alloy casting, comprising the steps of:

step 1: preparing a TA2 titanium ingot and an alloy bag, wherein the chemical components of the TA2 titanium ingot are shown in Table 1, and the TA2 titanium ingot is a cylindrical ingot with the diameter of 200mm and the height of 500 mm; the alloy bag consists of TiMo15 powder and nickel sheets, wherein the mass of the TiMo15 powder accounts for 1.4-2.0% of the melting amount of the titanium ingot, the granularity of the TiMo15 powder is 800-1000 meshes, the mass of the nickel sheets accounts for 0.6-0.9% of the melting amount of the titanium ingot, and the nickel sheets have the length of 10mm, the width of 10mm and the thickness of 1 mm;

upwards drilling 4 blind holes uniformly in a row on the side wall of the TA2 titanium ingot at a position 50mm away from the bottom surface of the TA2 titanium ingot, wherein the axial interval between adjacent blind holes is 50mm, the diameter of each blind hole is 25mm, and the depth of each blind hole is 50 mm;

an alloy bag is pre-embedded in a TA2 titanium cast ingot, the alloy bag is divided into 4 parts, then one alloy bag is placed in each blind hole, a TA2 thin wafer with the thickness of 1mm is used for covering the hole opening of the blind hole, and finally argon arc welding is adopted for sealing and welding the hole opening of the blind hole.

Step 2: vacuum melting titanium ingot embedded with alloy bag

step 2.3: carrying out arc striking and preheating on the titanium ingot, wherein the arc striking voltage is 35V, the arc striking current is 4000A, the titanium ingot and the solidified shell are preheated after arc striking, the preheating current is 6000A, the preheating time is 1min, and a molten pool is formed in the crucible;

step 2.4: and (3) arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 18500A, the melting voltage is 38.5V, the water temperature at the inlet of the crucible is 19 ℃, and the water temperature at the outlet of the crucible is lower than 50 ℃.

And step 3: after the titanium cast ingot and the alloy package are melted and a molten pool is formed in the crucible, the unidirectional rotating magnetic field generator is adopted to stir the melt, direct current is supplied to the unidirectional rotating magnetic field generator to generate a longitudinal magnetic field, and the longitudinal magnetic field enables molten metal in the molten pool to rotate to generate a stirring effect. The unidirectional rotating magnetic field generator is arranged between the crucible and the water jacket, and in the process of stirring the melt, the power supply voltage of the unidirectional rotating magnetic field generator is 12V, and the current is 4A;

and 4, step 4: vacuum casting molding

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, pouring molten metal into a cavity of the casting mold, wherein the pouring is completed within 4s, the temperature of the casting mold is 370 ℃ in the pouring process, closing the unidirectional rotating magnetic field generator after the pouring is completed, cooling the molten metal to room temperature along with the casting mold, and taking out the casting mold from the vacuum consumable skull furnace;

step 4.3: and (3) removing the casting in the casting mould, and removing impurities on the surface of the casting to obtain the ZTA10 titanium alloy casting.

Example 4

The manufacturing method for preparing the ZTC4 titanium alloy casting comprises the following steps:

step 1: preparing a TA5 titanium ingot and an alloy package, wherein the chemical components of the TA5 titanium ingot are shown in Table 1, and the TA5 titanium ingot is a cylindrical ingot with the diameter of 250mm and the height of 800 mm; the alloy bag is composed of alloy AlV55 powder, the mass of the alloy AlV55 powder accounts for 6.6-7.0% of the melting amount of the titanium cast ingot, and the granularity of the alloy AlV55 powder is 60-100 meshes;

upwards drilling 8 blind holes uniformly in a row on the side wall of the TA5 titanium ingot at a position 50mm away from the bottom surface of the TA5 titanium ingot, wherein the axial interval between adjacent blind holes is 50mm, the diameter of each blind hole is 30mm, and the depth of each blind hole is 50 mm;

alloy packages are pre-embedded in the TA5 titanium cast ingot, the alloy packages are evenly divided into 8 parts, then one alloy package is placed in each blind hole, a TA5 thin wafer with the thickness of 1mm is used for covering the hole opening of each blind hole, and finally argon arc welding is adopted for sealing and welding the hole opening of each blind hole.

Step 2: vacuum melting titanium ingot embedded with alloy bag

step 2.2: vacuumizing the vacuum consumable skull furnace to ensure that the vacuum degree in the furnace is less than or equal to 2 Pa; adjusting the electrode pneumatic pressure of the vacuum consumable skull furnace to be 0.5MPa, the total cooling water pressure to be 0.4MPa, the crucible water pressure to be 0.4MPa and the no-load voltage to be 75V;

step 2.3: carrying out arc striking and preheating on the titanium ingot, wherein the arc striking voltage is 30V, the arc striking current is 4000A, the titanium ingot and the solidified shell are preheated after arc striking, the preheating current is 6000A, the preheating time is 1.5min, and a molten pool is formed in the crucible;

step 2.4: and (3) arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 20000A, the melting voltage is 38.5V, the water temperature at the inlet of the crucible is 19 ℃, and the water temperature at the outlet of the crucible is lower than 50 ℃.

And step 3: after the titanium cast ingot and the alloy package are melted and a molten pool is formed in the crucible, the unidirectional rotating magnetic field generator is adopted to stir the melt, direct current is supplied to the unidirectional rotating magnetic field generator to generate a longitudinal magnetic field, and the longitudinal magnetic field enables molten metal in the molten pool to rotate to generate a stirring effect. The unidirectional rotating magnetic field generator is arranged between the crucible and the water jacket, and the power supply voltage of the unidirectional rotating magnetic field generator is 12V and the current is 4A in the process of stirring the melt.

And 4, step 4: vacuum casting molding

step 4.2: moving the preheated casting mold into a vacuum consumable skull furnace, closing the vacuum consumable skull furnace, pouring molten metal into a cavity of the casting mold for 3-5 s, wherein the temperature of the casting mold is 380 ℃ in the pouring process, closing a unidirectional rotating magnetic field generator after pouring is finished, cooling the molten metal to room temperature along with the casting mold, and taking out the casting mold from the vacuum consumable skull furnace;

Chemical composition tests were performed on the titanium alloy castings prepared in examples 1 to 4, where table 3 is a table of chemical compositions of the upper, middle and lower parts of the ZTC4 titanium alloy casting prepared in example 1, table 4 is a table of chemical compositions of the upper, middle and lower parts of the ZTA5 titanium alloy casting prepared in example 2, table 5 is a table of chemical compositions of the upper, middle and lower parts of the ZTA10 titanium alloy casting prepared in example 3, and table 6 is a table of chemical compositions of the upper, middle and lower parts of the ZTC4 titanium alloy casting prepared in example 4. As is apparent from tables 3 to 6, the titanium alloy castings produced by the method for producing titanium alloy castings according to the present invention have uniform chemical compositions.

Mechanical property tests were performed on the titanium alloy castings prepared in examples 1 to 4, where table 7 is a mechanical property table of the ZTC4 titanium alloy casting prepared in example 1, table 8 is a mechanical property table of the ZTA5 titanium alloy casting prepared in example 2, table 9 is a mechanical property table of the ZTA10 titanium alloy casting prepared in example 3, and table 10 is a mechanical property table of the ZTC4 titanium alloy casting prepared in example 4. As can be seen from the contents in tables 3 to 6, the titanium alloy castings manufactured by the method for manufacturing the titanium alloy castings have high strength and good plasticity and meet the standard requirements.

Microstructure observation is carried out on the titanium alloy castings prepared in the embodiments 1-4, fig. 3 is a metallographic picture of the ZTC4 titanium alloy casting prepared in the embodiment 1, fig. 4 is a metallographic picture of the ZTA5 titanium alloy casting prepared in the embodiment 2, fig. 5 is a metallographic picture of the ZTA10 titanium alloy casting prepared in the embodiment 3, fig. 6 is a metallographic picture of the ZTC4 titanium alloy casting prepared in the embodiment 4, and as can be seen from fig. 3-6, the titanium alloy casting cast by the technology of the present invention has a uniform structure and fine grains.

Compared with the conventional manufacturing method, the method for manufacturing the titanium alloy casting reduces the burning loss rate of alloy elements, ensures that the internal chemical components of the manufactured titanium alloy casting are uniform, meets the standard requirement on mechanical property, shortens the production flow, reduces the casting cost of the titanium alloy, and improves the casting efficiency of the titanium alloy.

TABLE 3 upper, middle and lower compositions of ZTC4 titanium alloy casting in example 1 (GB/T15073-2014)

TABLE 4 upper, middle and lower compositions of ZTA5 titanium alloy casting in example 2 (GB/T15073-2014)

TABLE 5 upper, middle and lower compositions of ZTA10 titanium alloy casting in example 3 (GB/T15073-2014)

TABLE 6 upper, middle and lower compositions of ZTC4 titanium alloy casting in example 4 (GB/T15073-2014)

TABLE 7 mechanical Properties of ZTC4 titanium alloy casting in example 1 (GB/T6614-2014)

TABLE 8 mechanical properties of ZTA5 titanium alloy casting in example 2 (GB/T6614-2014)

Performance of	Rm(MPa)	Rp0.2(MPa)	A(％)	HBW
					Standard requirements	≥590	≥490	≥10	≤270
Measured value	656	538	12	218

TABLE 9 mechanical Properties of ZTA10 titanium alloy casting in example 3 (GB/T6614-2014)

Performance of	Rm(MPa)	Rp0.2(MPa)	A(％)	HBW
					Standard requirements	≥483	≥345	≥8	≤235
Measured value	538	382	13	185

TABLE 10 mechanical Properties of ZTC4 titanium alloy casting in example 4 (GB/T6614-2014)

Performance of	Rm(MPa)	Rp0.2(MPa)	A(％)	HBW
					Standard requirements	≥835	≥765	≥5	≤365
Measured value	932	857	9	337

In the above table, Rm represents tensile strength, rp0.2 represents yield strength, a represents elongation, and HBW represents brinell hardness.

Claims

1. A method for manufacturing a titanium alloy casting, characterized by comprising the steps of:

step 1: pre-embedding an alloy bag in a titanium ingot, wherein the method comprises the steps of drilling a blind hole in the titanium ingot, putting the alloy bag into the blind hole, covering an orifice of the blind hole with a sheet material which is made of the same material as the titanium ingot, and finally sealing and welding the orifice of the blind hole by adopting argon arc welding;

the specific process of the step 2 is as follows:

step 2.4: arc melting the titanium ingot, wherein in the melting process, the melting current is gradually increased to 18000-20000A, the water temperature at the inlet of the crucible is controlled to be 17-20 ℃, and the water temperature at the outlet of the crucible is lower than 50 ℃;

and 4, step 4: vacuum casting and molding the molten metal while stirring, and then carrying out shelling treatment to obtain a titanium alloy casting;

the step 4 specifically comprises the following steps:

step 4.1: preheating a casting mold;

step 4.3: the casting in the casting mould is shelled, and impurities on the surface of the casting are removed, so that the alloyed directly-melted titanium alloy casting is prepared.

2. The method of manufacturing a titanium alloy casting according to claim 1, wherein the unidirectional rotating magnetic field generator is installed between the crucible and the water jacket.

3. The method for manufacturing the titanium alloy casting according to claim 1, wherein in the step 3, in the process of stirring the melt by the unidirectional rotating magnetic field generator, the power supply voltage of the unidirectional rotating magnetic field generator is 12V, and the current is 2-4A.

4. The method for producing a titanium alloy cast product according to claim 1, wherein the temperature of the mold after preheating in step 4.1 is 400 to 500 ℃.

5. A method for manufacturing a titanium alloy cast product according to claim 4, wherein in the step 4.2, the temperature of the mold is 300 to 400 ℃ during the process of pouring the molten metal into the mold.