阅读说明：本技术 一种高均匀钛金属铸锭熔炼方法 (High-uniformity titanium metal ingot smelting method ) 是由 杨胜 周慧 周科朝 张晓泳 张慧杰 张宏岭 向午渊 欧阳涛 肖芬 于 2021-02-01 设计创作，主要内容包括：本发明公开一种高均匀钛金属铸锭熔炼方法,包括制作扇形电极块、制作自耗电极、第一次真空自耗熔炼、第二次真空自耗熔炼和第三次真空自耗熔炼等,本发明在真空自耗电弧熔炼炉内进行,通过匹配熔炼过程的熔炼速度和熔池深度来实现控制熔池的过冷度方向,从而改变柱状晶的生长方向,使铸锭整体获得沿轴向定向生长的柱状晶组织,结合相邻两次真空自耗熔炼中调换铸锭头部和底部的熔炼方式,能有效抑制钛金属中偏析元素Fe、Cr等扩散导致的成分偏析,同时可消除铸锭中柱状晶区与等轴晶区的组织差异,利于提高锻造组织均匀性。(The invention discloses a method for smelting a high-uniformity titanium metal ingot, which comprises the steps of manufacturing a fan-shaped electrode block, manufacturing a consumable electrode, performing first vacuum consumable smelting, performing second vacuum consumable smelting, performing third vacuum consumable smelting and the like.)

1. A method for smelting a high-uniformity titanium metal ingot is characterized by comprising the following steps:

providing a titanium metal ingot, wherein the titanium metal ingot contains positive segregation elements;

the method comprises the following steps: selecting titanium sponge, a metal simple substance and an intermediate alloy according to the components required by the prepared titanium metal ingot to prepare a fan-shaped electrode block;

step two: manufacturing the sector electrode block obtained in the step one into a consumable electrode;

step three: carrying out first vacuum consumable melting on the consumable electrode obtained in the step two to obtain a primary ingot, wherein: the end of the primary cast ingot with the riser is a head, and the other end of the primary cast ingot with the riser is a bottom; the first vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 5.0 Pa; the smelting current is 12-18 kA; the smelting voltage is 20-30V; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 400-600L/min; the cooling time after smelting is more than or equal to 5 h;

step four: and D, carrying out second vacuum consumable melting on the primary ingot obtained in the step three to obtain a secondary ingot, wherein: the head part is downward, and the bottom part is upward; the parameters of the second vacuum consumable melting are as follows: the vacuum degree is less than or equal to 3.0 Pa; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 800-; controlling the smelting speed to be 3-7kg/min, and the depth of a molten pool to be 40-150mm, and ensuring that the supercooling degree direction is from bottom to top along the axial direction of the cast ingot; the cooling time after smelting is more than or equal to 7 h;

step five: and C, carrying out third vacuum consumable melting on the secondary ingot obtained in the step four to obtain the titanium metal ingot with high component uniformity of the columnar crystal structure and axially oriented growth, wherein: the head part is upward, and the bottom part is downward; the parameters of the third vacuum consumable melting are as follows: the vacuum degree is less than or equal to 1.0 Pa; the arc stabilizing current adopts direct current of 5-10A; the flow rate of the cooling water is 800-; controlling the smelting speed to be 2-5kg/min, and the depth of a molten pool to be 40-150mm, and ensuring that the supercooling degree direction is from bottom to top along the axial direction of the cast ingot; the cooling time after smelting is more than or equal to 9 h.

2. The method for smelting the high-uniformity titanium metal ingot according to claim 1, wherein N times of vacuum consumable melting are further included between the third time of vacuum consumable melting and the titanium metal ingot obtaining in the fifth step, N is an integer greater than or equal to 1, and the smelting process parameters are the same as those in the fifth step; and the upper and lower positions of the head part and the bottom part are changed in the adjacent two times of vacuum consumable melting.

3. The method of melting a high uniformity titanium metal ingot according to any one of claims 1 to 2, wherein the positive segregation element contained in the titanium metal ingot is at least one of Fe, Cr and Cu.

4. The method for smelting the high-uniformity titanium metal ingot according to claim 1, wherein the fan-shaped electrode block in the first step is made of aluminum beans, master alloy and titanium sponge.

5. The method for smelting the high-uniformity titanium metal ingot according to claim 1, wherein the ingot in the third step is a columnar crystal oriented radial or axial growth structure.

6. The method for smelting the high-uniformity titanium metal ingot according to claim 5, wherein in the fourth step, the secondary ingot is a columnar crystal oriented axially-growing structure.

7. The method for smelting the high-uniformity titanium metal ingot according to claim 6, wherein in the fifth step, the titanium metal ingot is a columnar crystal oriented axially-growing structure.

Technical Field

The invention relates to the technical field of metal smelting, in particular to a method for smelting a high-uniformity titanium metal ingot.

Background

At present, a vacuum consumable melting technology is generally adopted for melting titanium metal ingots, and although the melting technology is mature, the problems that the ingot components are not uniform, the phase change points of different parts are different greatly, the uniformity control difficulty of subsequent forging structures is large and the like exist in the conventional vacuum consumable melting technology.

This method cannot suppress the diffusion segregation of positive segregation elements such as Fe, Cr, and Cu in the case of Ti-1023, TC17, and other Fe-and Cr-rich titanium ingots. Generally, columnar crystal structures obtained by vacuum consumable melting are shown in the way that tail columnar crystals grow upwards along the longitudinal direction and side columnar crystals grow inwards along the transverse direction, the directions of the columnar crystals are different, the diffusion directions of elements such as Fe, Cr and Cu are disordered, and the uniformity of components is difficult to control. And three-layer structure states of an external equiaxed crystal layer, a columnar crystal layer and an internal equiaxed crystal layer are distributed from the surface to the core part in the cast ingot, and different structures have different deformation conditions in the forging process, so that adverse effects are caused on the uniformity of subsequent forged structures.

Therefore, the development of a titanium metal ingot smelting method with high uniformity of components and structure morphology is of great significance.

Disclosure of Invention

The invention provides a method for smelting a high-uniformity titanium metal ingot, which is based on the following principle: the crystallization temperature range of the titanium alloy is narrow, the width of a solidification zone in a molten pool is narrow, once crystal grains nucleate at the front edge of a solid-liquid interface in the solidification process, namely, the crystal grains are solidified in a sequential solidification mode, the solid-liquid interface gradually advances towards the opposite direction of a supercooling direction, crystal grains with the growth direction (beta titanium alloy is <100 >) parallel to the heat flow direction preferentially grow in the process, and the crystal grains which are not parallel to the heat dissipation direction are inhibited. The result of this competing growth is a reduction in the number of grains within the ingot and the direction of growth always tends to be parallel to and opposite to the direction of heat flow, ultimately forming columnar crystalline regions. According to the element diffusion rule, positive segregation elements such as Fe, Cr, Cu and the like are always enriched at the solidification front edge of a solid/liquid interface, and the enrichment degree of the positive segregation elements is higher as columnar crystals grow gradually and the more the positive segregation elements reach the tail end. In the process of the vacuum consumable arc melting furnace, the heat flow direction is always vertical to the solid-liquid interface of the molten pool and is conducted from the liquid phase to the solid phase. In the general method, because the molten pool is V-shaped and has larger depth, the growth direction of the columnar crystal points to the axis from the circumferential surface of the ingot and inclines towards the head of the ingot, so that positive segregation elements are enriched in the axis and the head of the ingot, and radial and axial segregation is generated. The invention controls the supercooling direction of the molten pool by matching the smelting speed and the molten pool depth in the smelting process, thereby changing the growth direction of the columnar crystal from the radial direction to the axial direction, leading the ingot to integrally obtain the columnar crystal structure which directionally grows along the axial direction, leading the positive segregation elements such as Fe, Cr, Cu and the like to be integrally directionally diffused, combining the smelting modes of exchanging the head part and the bottom part of the ingot in the adjacent two times of vacuum consumable smelting, leading the segregation elements which have undergone directional diffusion to generate reverse diffusion, effectively inhibiting the component segregation caused by the diffusion of the segregation elements such as Fe, Cr, Cu and the like in the titanium metal, simultaneously effectively inhibiting the occurrence of the isometric crystal of the core part of the ingot and being beneficial to improving the uniformity of the forging structure. The specific technical scheme is as follows:

a method for smelting a high-uniformity titanium metal ingot comprises the following steps: the method is characterized in that the supercooling degree direction of a molten pool is changed by adjusting the smelting process parameters, and columnar crystals growing in the radial direction are changed into columnar crystals growing in the axial direction, and the method specifically comprises the following steps:

providing a titanium metal ingot, wherein the titanium metal ingot contains positive segregation elements (Fe, Cr, Cu and the like);

the method comprises the following steps: selecting titanium sponge, a metal simple substance and an intermediate alloy according to the components required by the prepared titanium metal ingot to prepare a fan-shaped electrode block;

step two: manufacturing the sector electrode block obtained in the step one into a consumable electrode;

step three: carrying out first vacuum consumable melting on the consumable electrode obtained in the step two to obtain a primary ingot, wherein: the end of the primary cast ingot with the riser is a head, and the other end of the primary cast ingot with the riser is a bottom; the first vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 5.0 Pa; the smelting current is 12-18 kA; the smelting voltage is 20-30V; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 400-600L/min; the cooling time after smelting is more than or equal to 5 h;

step four: and D, carrying out second vacuum consumable melting on the primary ingot obtained in the step three to obtain a secondary ingot, wherein: the head part is downward, and the bottom part is upward; the parameters of the second vacuum consumable melting are as follows: the vacuum degree is less than or equal to 3.0 Pa; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 800-; controlling the smelting speed to be 3-7kg/min, and the depth of a molten pool to be 40-150mm, and ensuring that the supercooling degree direction is from bottom to top along the axial direction of the cast ingot; the cooling time after smelting is more than or equal to 7 h;

step five: and C, carrying out third vacuum consumable melting on the secondary ingot obtained in the step four to obtain the titanium metal ingot with high component uniformity of the columnar crystal structure and axially oriented growth, wherein: the head part is upward, and the bottom part is downward; the parameters of the third vacuum consumable melting are as follows: the vacuum degree is less than or equal to 1.0 Pa; the arc stabilizing current adopts direct current of 5-10A; the flow rate of the cooling water is 800-; controlling the smelting speed to be 2-5kg/min, and the depth of a molten pool to be 40-150mm, and ensuring that the supercooling degree direction is from bottom to top along the axial direction of the cast ingot; the cooling time after smelting is more than or equal to 9 h.

Preferably, in the above technical scheme, N times of vacuum consumable melting are further included between the third time of vacuum consumable melting and the obtaining of the titanium metal ingot in the fifth step, N is an integer greater than or equal to 1, and the melting process parameters are the same as those in the fifth step; and the upper and lower positions of the head part and the bottom part are changed in the adjacent two times of vacuum consumable melting.

In the above aspect, the positive segregation element contained in the titanium metal ingot is preferably at least one of Fe, Cr, and Cu.

Preferably, in the above technical scheme, in the first step, the sector electrode block is made of aluminum beans, intermediate alloy and titanium sponge.

Preferably, in the above technical scheme, in the third step, the ingot casting is a columnar crystal oriented radial or axial growth structure.

Preferably, in the fourth step, the secondary ingot is a columnar crystal oriented axially-grown structure.

Preferably, in the fifth step, the titanium metal ingot is a columnar crystal oriented axially-grown structure.

Drawings

FIG. 1 is a schematic diagram showing the growth of columnar crystals in comparative example 1 (conventional melting);

FIG. 2 is a schematic view of directional solidification melting of columnar crystals in example 1;

FIG. 3 is a longitudinal section of an ingot of TB6 grown in columnar crystal orientation prepared in example 1;

FIG. 4 is a longitudinal section structure of a TB6 ingot obtained by adopting a traditional vacuum consumable melting process in comparative example 1;

FIG. 5 is a schematic view showing nine-point sampling of a titanium metal ingot in example 1;

FIG. 6 is a distribution diagram of the Fe element composition of the titanium metal ingot prepared in example 1;

FIG. 7 is a distribution diagram of the Fe element composition of the titanium metal ingot prepared in comparative example 1;

FIG. 8 is a distribution diagram of Cr element composition of a titanium metal ingot prepared in example 6;

FIG. 9 is a distribution diagram of Cr element composition of a titanium metal ingot prepared in comparative example 6;

wherein: 1. consumable electrode, 2, molten pool, 3, columnar crystal growing radially, 4, equiaxial crystal, 5, columnar crystal growing axially.

Detailed Description

The embodiments of the present invention will be described in detail with reference to the accompanying drawings so that the advantages and features of the invention can be more easily understood by those skilled in the art, and the scope of the invention will be clearly and clearly defined.

Comparative example 1:

preparing a TB6 titanium metal ingot, wherein the preparation process comprises the following steps:

1. in the comparative example, firstly, alloy required by TB6 titanium metal is pressed and welded by an electrode to prepare a phi 480mm consumable electrode;

2. carrying out primary smelting on the consumable electrode to prepare a primary casting ingot of the TB6 titanium metal phi 580 mm; the primary smelting process parameters of the comparative example are as follows: the vacuum degree is less than or equal to 5.0Pa, the smelting current is 12-15kA, the smelting voltage is 20-30V, the arc stabilizing current adopts direct current of 3-8A, the flow rate of cooling water is 400-plus 600L/min, the cooling time after smelting is more than or equal to 5h, and the obtained ingot is defined as a primary ingot;

3. placing the primary ingot with the head downward and the bottom upward in a crucible of phi 680mm for secondary smelting; the secondary smelting process parameters are as follows: the vacuum degree is less than or equal to 3.0Pa, the smelting rate is 16-18kg/min, the depth of a molten pool is 600-800mm, the arc stabilizing current adopts direct current of 3-8A, the flow rate of cooling water is 800-1000L/min, the cooling time after smelting is more than or equal to 7h, and the obtained cast ingot is a secondary cast ingot;

4. turning the cast ingot again, enabling the head to be upward and the bottom to be downward, placing the cast ingot into a phi 780mm crucible, and carrying out smelting for three times, wherein the three-time smelting process parameters of the comparative example are as follows: the vacuum degree is less than or equal to 1.0Pa, the smelting rate is 12-14kg/min, the depth of a molten pool is 300-500mm, the arc stabilizing current adopts direct current of 5-10A, the flow rate of cooling water is 800-1000L/min, the cooling time after smelting is more than or equal to 9h, and finally the preparation of the TB6 titanium metal cast ingot with the specification of phi 780mm is completed.

The schematic diagram of the growth of columnar crystals in comparative example 1 is shown in fig. 1.

Example 1:

a smelting method for obtaining a high-uniformity TB6 titanium metal ingot, in particular to a TB6 titanium metal ingot with the specification of phi 780mm, which comprises the following steps:

the method comprises the following steps: according to the requirement of the GB/T3620.1-2016 on the TB6 titanium metal component, weighing aluminum beans, Al-V intermediate alloy, Fe blocks and titanium sponge (containing positive segregation element Fe) with approximate granularity, weighing by a mixing and batching system, mixing by a blanking machine, pressing into a phi 480mm fan-shaped electrode block by a 8000 ton oil press, and welding into a phi 480mm cylindrical consumable electrode in a vacuum plasma welding box;

step two: carrying out first vacuum consumable melting on the consumable electrode obtained in the step one in vacuum consumable melting by adopting a phi 580mm crucible to obtain a primary ingot, wherein: the end of the primary cast ingot with the riser is a head, and the other end of the primary cast ingot with the riser is a bottom; the first vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 5.0 Pa; the smelting current is 12-15 kA; the smelting voltage is 20-30V; the arc stabilizing current adopts direct current of 3-8A; the cooling time after smelting is more than or equal to 5h, and the flow rate of cooling water is 400-plus 600L/min;

step three: removing surface pollutants from the primary cast ingot obtained in the step two, enabling the head to be downward and the bottom to be upward, and carrying out secondary vacuum consumable melting by adopting a crucible with the diameter of 680mm to obtain a secondary cast ingot, wherein the secondary vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 3.0 Pa; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 800-; the smelting speed is controlled to be 4-5 Kg/min; the depth of a molten pool is 80-120 mm; the cooling time after smelting is more than or equal to 7 h;

step four: removing surface oxides from the secondary ingot obtained in the step three, enabling the head to be upward and the bottom to be downward, and carrying out third vacuum consumable melting by adopting a phi 780mm crucible to obtain a TB6 titanium metal ingot with a columnar crystal structure growing in an axial direction, wherein the process parameters of the third vacuum consumable melting are as follows: the vacuum degree is less than or equal to 1.0 Pa; the arc stabilizing current adopts direct current of 5-10A; the flow rate of the cooling water is 800-; the smelting speed is controlled to be 4-5 Kg/min; the depth of a molten pool is 80-120 mm; the cooling time after smelting is more than or equal to 9 h.

The principle of the titanium metal ingot obtained in this embodiment is shown in fig. 2, and the longitudinal section structures of the titanium metal ingot obtained in this embodiment and the titanium metal ingot obtained by the conventional melting method are shown in fig. 3 and 4, and it can be known from fig. 3 and 4 that the columnar crystal structure in the conventional melting scheme grows in the radial direction, while the columnar crystal structure in this embodiment grows in the axial direction (i.e., the columnar crystal solidification structure is mainly used as the axial direction).

Peeling the titanium metal ingot obtained in the embodiment and the titanium metal ingot obtained by the traditional smelting scheme, and sampling at the longitudinal head, middle and bottom of the side surface of the ingot at nine points, wherein the sampling method comprises the following steps: the head end face is 30mm, the head end face is 80mm, the middle part and the bottom end face are 20mm respectively cut at the position of the ingot casting which is 30mm away from the head part, the position of the ingot casting which is 80mm away from the head part, the middle part (the middle position between the head part and the bottom part) and the position of the ingot casting which is 20mm away from the bottom part along the outer radial direction, and performing 9-point sampling on each section by using a 9-point sampling method as shown in fig. 5 (wherein the e-th sampling point is a center part, the a-th, b-h, i-th sampling points are side parts, the c-th, d-th, f-th, and g-th sampling points are middle parts, and the distance from the middle sampling point to the center sampling point is half of the radius of the section, namely R/2), to obtain a content distribution map and content data of Fe elements at nine points a to i, and the component detection results are shown in fig. 6 and 7, as can be known by combining fig. 6 and 7, by using the scheme of the present embodiment, the component uniformity of the finally obtained titanium metal ingot is significantly better than that of the prior art.

Examples 2 to 5:

examples 2-5 differ from example 1 in table 1.

The properties of the highly homogeneous titanium ingots obtained according to the protocols of examples 2-5 are detailed in Table 1.

Comparative examples 2 to 5:

comparative examples 2 to 5 differ from example 1 in table 1.

The properties of the highly homogeneous titanium ingots obtained according to the protocols of comparative examples 1-5 are detailed in table 1.

TABLE 1 statistics of parameters of examples 1-5 and comparative examples 1-5 and properties of titanium metal ingots

As can be seen from Table 1 in combination with examples 1 to 5 and comparative examples 1 to 5:

under the condition that the parameters of the first vacuum consumable melting are the same, the parameters of the second vacuum consumable melting and the third vacuum consumable melting are within the parameter range of the invention, the obtained titanium metal ingot has good uniformity, and the principle is as follows: the selection of parameters of the second vacuum consumable melting and the third vacuum consumable melting can control the supercooling degree direction of a molten pool, so that the growth direction of columnar crystals is changed, the ingot is integrally made to obtain columnar crystal tissues which grow along the axial direction, and the composition segregation caused by the diffusion of segregation element Fe in titanium metal can be effectively inhibited by combining the melting modes of exchanging the head and the bottom of the ingot in the two adjacent vacuum consumable melting, meanwhile, the tissue difference between a columnar crystal area and an equiaxed crystal area in the ingot can be eliminated, and the uniformity of the forging tissues is improved.

The selection of the control ranges of the smelting speed and the molten pool depth for the second-time vacuum consumable smelting and the third-time vacuum consumable smelting is very important, and the unreasonable control of the smelting speed and the molten pool depth can influence the uniformity and the surface quality of the titanium metal cast ingot: if the depth of the molten pool is too large (comparative examples 1-3), the uniformity of the titanium metal ingot can be influenced; too small a depth of the melt pool (comparative examples 4-5) affects the surface quality of the ingot.

According to the embodiment 1 and the embodiments 4 to 5, under the condition that the parameters of the second vacuum consumable melting and the third vacuum consumable melting are not changed, the parameters of the first vacuum consumable melting are changed, and the high-uniformity titanium metal ingot can be obtained, so that the parameter matching control of the second vacuum consumable melting and the third vacuum consumable melting plays a decisive role in the composition and structure uniformity of the ingot.

Comparative example 6:

preparing a TC17 titanium metal ingot, wherein the preparation process comprises the following steps:

1. in the comparative example, firstly, the alloy required by TC17 titanium metal is pressed and welded into a phi 480mm consumable electrode;

2. carrying out primary smelting on the consumable electrode to prepare a TC17 titanium metal phi 580mm primary ingot; the primary smelting process parameters of the comparative example are as follows: the vacuum degree is less than or equal to 5.0Pa, the smelting current is 12-18kA, and the smelting voltage is 20-30V; the arc stabilizing current adopts direct current of 3-8A, the flow rate of cooling water is 400-600L/min, the cooling time after smelting is more than or equal to 5h, and the obtained ingot is defined as a primary ingot;

3. placing the primary ingot with the head downward and the bottom upward in a crucible of phi 680mm for secondary smelting; the secondary smelting process parameters are as follows: the vacuum degree is less than or equal to 3.0 Pa; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 800-; controlling the smelting speed at 16-18 Kg/min; the depth of the molten pool is 600 mm and 800 mm; the cooling time is more than or equal to 7 hours after smelting, and the obtained cast ingot is a secondary cast ingot;

4. turning the cast ingot again, wherein the head part is upward, the bottom part is downward, placing the cast ingot in a crucible with the diameter of 780mm, and carrying out three-time smelting, wherein the three-time smelting process parameter of the comparative example is that the vacuum degree is less than or equal to 1.0 Pa; the arc stabilizing current adopts direct current of 5-10A; the flow rate of the cooling water is 800-; controlling the smelting speed to be 12-14 Kg/min; the depth of the molten pool is 300-500 mm; the cooling time after smelting is more than or equal to 9h, and finally the preparation of the cast ingot with the TC17 titanium phi 780mm specification is completed.

Example 6:

a smelting method for obtaining a high-uniformity TC17 titanium metal ingot, in particular to a TC17 titanium metal ingot with the specification of phi 780mm, comprises the following steps:

the method comprises the following steps: according to the proportion of TC17 titanium metal components, 0-grade titanium sponge, Al beans, AlMo alloy, zirconium sponge, AlCr intermediate alloy, TiSn intermediate alloy and TiO are selected₂Pressing the electrode block and welding into a circular consumable electrode with phi 480 mm;

step two: carrying out first vacuum consumable melting on the consumable electrode obtained in the step one in vacuum consumable melting by adopting a phi 580mm crucible to obtain a primary ingot, wherein: the end of the primary cast ingot with the riser is a head, and the other end of the primary cast ingot with the riser is a bottom; the first vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 5.0 Pa; the smelting current is 12-18kA, and the smelting voltage is 20-30V; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 400-600L/min; the cooling time after smelting is more than or equal to 5 h;

step three: removing surface pollutants from the primary cast ingot obtained in the step two, enabling the head to be downward and the bottom to be upward, and carrying out secondary vacuum consumable melting by adopting a crucible with the diameter of 680mm to obtain a secondary cast ingot, wherein the secondary vacuum consumable melting parameters are as follows: the vacuum degree is less than or equal to 3.0 Pa; the arc stabilizing current adopts direct current of 3-8A; the flow rate of the cooling water is 800-; the smelting speed is controlled to be 4-5 Kg/min; the depth of a molten pool is 80-120 mm; the cooling time after smelting is more than or equal to 7 h;

step four: removing surface oxides from the secondary ingot obtained in the step three, enabling the head to be upward and the bottom to be downward, and carrying out third vacuum consumable melting by adopting a phi 780mm crucible to obtain a TB6 titanium metal ingot with a columnar crystal structure growing in an axial direction, wherein the process parameters of the third vacuum consumable melting are as follows: the vacuum degree is less than or equal to 1.0 Pa; the arc stabilizing current adopts direct current of 5-10A; the flow rate of the cooling water is 800-; the smelting speed is controlled to be 4-5 Kg/min; the depth of a molten pool is 80-120 mm; the cooling time after smelting is more than or equal to 9 h.

The finished titanium metal ingots obtained in example 6 and comparative example 6 were scalped and sampled at the head, middle and bottom of the longitudinal side surface of the ingot in the manner of example 1, and the results are shown in fig. 8 and 9:

1. as can be seen from fig. 8, the structure of the titanium metal ingot prepared in this example is mainly an axial columnar solidification structure.

2. Comparing fig. 8 and fig. 9, it can be seen that the scheme of the embodiment can effectively eliminate the diffusion segregation of the positive segregation element Cr, and the composition uniformity of the TC17 titanium metal ingot is good.

Examples 7 to 10:

examples 7-10 differ from example 6 in table 2.

The properties of highly homogeneous titanium ingots obtained according to the protocols of examples 7-10 are detailed in Table 2.

Comparative examples 7 to 10:

comparative examples 7 to 10 differ from example 6 in table 2.

The properties of the highly uniform titanium ingots obtained according to the protocols of comparative examples 7-10 are detailed in Table 2.

TABLE 2 statistics of parameters and properties of titanium metal ingots for examples 6 to 10 and comparative examples 6 to 10

As can be seen from Table 2 in combination with examples 6 to 10 and comparative examples 6 to 10:

under the condition that the parameters of the first vacuum consumable melting are the same, the parameters of the second vacuum consumable melting and the third vacuum consumable melting are within the parameter range of the invention, the obtained titanium metal ingot has good component uniformity, and the principle is as shown in an embodiment 6-8: the selection of parameters of the second vacuum consumable melting and the third vacuum consumable melting can control the supercooling degree direction of a molten pool, thereby changing the growth direction of columnar crystals, enabling the ingot to integrally obtain columnar crystal tissues growing along the axial direction, combining the melting modes of exchanging the head and the bottom of the ingot in the two adjacent vacuum consumable melting, effectively inhibiting the component segregation caused by the diffusion of the segregation element Cr in the titanium metal, simultaneously eliminating the tissue difference between a columnar crystal zone and an equiaxed crystal zone of the ingot, and being beneficial to improving the uniformity of the forging tissues. Unreasonable control of the smelting speed and the depth of a molten pool can influence the uniformity and the surface quality of the titanium metal cast ingot: if the depth of the molten pool is too large (comparative examples 6-8), the uniformity of the titanium metal ingot can be influenced; too small a depth of the melt pool (comparative examples 9-10) affects the surface quality of the ingot.

Under the condition that the parameters of the second vacuum consumable melting and the third vacuum consumable melting are not changed, the parameters of the first vacuum consumable melting are changed, and a high-component uniform titanium metal ingot can be obtained, and the details are shown in the comparison of examples 6-8 and examples 9-10.

In conclusion, the method realizes the control of the supercooling degree direction of the molten pool by matching the smelting speed and the molten pool depth in the smelting process, thereby changing the growth direction of the columnar crystal, leading the ingot to integrally obtain the columnar crystal structure which directionally grows along the axial direction, combining the smelting mode of exchanging the head part and the bottom part of the ingot in the adjacent two times of vacuum consumable smelting, effectively inhibiting the component segregation caused by the diffusion of segregation elements Fe, Cr and the like in the titanium metal, and being beneficial to improving the uniformity of the forging structure.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.