CN111286637A - Electron beam cold bed smelting method of TA15 titanium alloy - Google Patents

Abstract

The application discloses an electron beam cold bed smelting method of a TA15 titanium alloy ingot. The method comprises the following steps: s1, preparing a raw material containing metal elements of Ti, Al, Mo, V and Zr; s2, feeding the raw materials into an electron beam cold hearth furnace for smelting to obtain a TA15 titanium alloy; the raw materials comprise sponge titanium, aluminum beans, aluminum molybdenum intermediate alloy, aluminum vanadium intermediate alloy and aluminum zirconium intermediate alloy; the aluminum zirconium master alloy comprises an aluminum zirconium 50 master alloy. Through experimental research, the inventor of the application finds that the zirconium element has a volatilization rate of up to 10% in the smelting process of the TA15 titanium alloy. Therefore, the volatilization of the zirconium element is not negligible, and the invention controls the combined volatilization rate of the aluminum-zirconium element in a reasonable range through a plurality of tests and research analysis, wherein the volatilization rate of Al is less than or equal to 15.5 percent, and the volatilization rate of Zr is less than or equal to 3.5 percent.

Description

A kind of electron beam cooling bed melting method of TA15 titanium alloy

technical field

The invention relates to the field of titanium alloy preparation, in particular to an electron beam cooling bed smelting method of TA15 titanium alloy.

Background technique

Titanium alloy is one of the important selection materials for contemporary aircraft structure design, and its application level has even become one of the important symbols to measure the advanced degree of aircraft structure design material selection. Titanium alloys can play an incomparable role in reducing the overall structural weight of aircraft, improving structural design efficiency, improving structural reliability, improving airframe life, and meeting high temperature and high load and corrosive environment requirements.

TA15 (Ti-6.5Al-1Mo-1V-2Zr) is a kind of high aluminum equivalent damage tolerance type near α titanium alloy, which has good thermal strength and weldability, and has process plasticity close to α-β type titanium alloy. , is an important structural material in my country's aviation field. The alloy has good thermal stability, the room temperature strength is 30-50MPa higher than that of Ti-6Al-4V, and the processing and welding performance is good. It can be used to produce thin plates, bars, forgings, plates and profiles and other products. It has a wide range of applications, such as: TA15 titanium alloy whole frame die forging is a typical representative of large-scale titanium alloy aerospace structural parts.

At present, the main methods of producing TA15 alloy are multiple smelting in vacuum consumable arc (VAR) furnace and preparation by powder metallurgy. The main disadvantage of the former is that the impurities and inclusions contained in the raw materials (consumable electrodes) will directly enter the ingot and cannot be effectively peeled off. The obtained TA15 titanium alloy has defects such as high and low density inclusions and macrosegregation. Practical application It will seriously damage the fatigue and durability of engine components; the main disadvantage of the latter is the difficulty of large-scale preparation, high cost, and limited large-scale production and application.

Electron beam cooling bed smelting (EB) furnace smelting material melting and ingot solidification are completely isolated, and there is a refining and purification area, in which melting and refining are carried out in a cooling bed, and solidification is carried out in a crystallizer; therefore, it is possible to remove high and low Density inclusions can achieve purification; EB furnace melting chamber vacuum degree (0.01 ~ 1.0Pa) is relatively high, and the melting temperature is about 100 °C higher than VAR melting, so the gas impurity removal effect is obvious; EB furnace can be based on the electron beam gun. Arrangement of positions, diversify the design of ingot specifications (such as: cylindrical, square, annular, etc.). However, there is no report on the production of TA15 alloy using EB furnace smelting.

SUMMARY OF THE INVENTION

In view of the defects existing in the prior art, the purpose of the present invention is to provide an electron beam cooling bed furnace smelting method for TA15 titanium alloy, which can simultaneously reduce the volatilization rate of Al and Zr in the TA15 titanium alloy product, and simultaneously improve the Al and Zr uniformity.

In order to achieve the above purpose, the technical scheme adopted in the present invention is:

The invention provides an electron beam cooling bed furnace smelting method for TA15 titanium alloy, which comprises the following steps:

S1. Prepare raw materials containing Ti, Al, Mo, V and Zr metal elements;

S2, the raw material is sent into the electron beam cooling bed furnace for smelting;

The raw materials include titanium sponge, aluminum beans, aluminum molybdenum master alloy, aluminum vanadium master alloy and aluminum zirconium master alloy;

The aluminum zirconium master alloy includes aluminum zirconium 50 master alloy.

In the aluminum-zirconium 50 master alloy, the content of Zr is 50.0% to 55.0%, the content of Al is 44.659% to 49.659%, and the balance is impurities;

The content of the aluminum zirconium 50 master alloy in the raw material is 3.72-4.12 wt %.

In the above method, the raw materials are mixed and pressed into blocks, the blocks are divided into head discharge, normal material and tail discharge, and the feeding into the electron beam cooling bed furnace is carried out according to the head discharge, normal material and tail discharge. Discharging is carried out in sequence;

The described head discharge is in the smelting/solidification process that has not yet formed a stable and uniform speed in the electron beam cooling bed furnace after starting the gun, and various process parameters (specifically, the power of the electron gun, the vacuum degree in the furnace, the current of the electron gun, the voltage of the electron gun, the smelting When the power and smelting speed) are not running smoothly, the raw materials are sent to the electron beam cooling bed furnace for smelting ingots;

The head discharge is placed at the front end of the feeder. During the smelting process, it is first melted, and then flows into the mold through the cooling bed and solidifies into the tail of the ingot. Because the tail of the ingot and the ingot pulling mechanism need to form a solid connection, it is bombarded by electron beams. It takes a long time, usually 30-70min. This stage is called the "bottom making" stage of electron beam smelting; during this period, excessive volatilization and burning of volatile alloy elements will be caused; Excessive volatile alloying elements;

The normal material is the raw material that is fed into the electron beam cooling bed furnace for smelting and ingot casting when a stable and uniform smelting/solidification process has been formed in the electron beam cooling bed furnace, and when various process parameters run smoothly;

After the normal material is placed in the middle of the feeder, the placement method and quantity depend on the size of the final ingot, which can be placed in single or double layers, and the maximum quantity can reach 1.5 tons; due to the operation of various process parameters Stable, the volatilization rate of alloying elements is less than the "bottom making" stage, so this stage is called "normal smelting stage" or "stable smelting stage"; therefore, the supplementary amount of volatile alloying elements in normal material is smaller than that of head discharge;

The tail discharge is at the end of smelting. Since the unilateral material has been melted, or the current needs to be actively reduced at the end of smelting, the smelting speed is slow, and the smelting power and smelting speed begin to drop before the end of the smelting in the electron beam cooling bed furnace until the end of smelting ingots. During the period, the raw materials for smelting ingots are sent into the electron beam cooling bed furnace;

After the tail discharge material is placed in the feeder as normal material, it is finally melted in the smelting process; due to the low melting speed of the tail discharge material, the molten metal flows from the melting zone to the refining zone and flows into the crystallization zone for a long time. The volatilization time of the corresponding volatile element Al increases, resulting in excessive volatilization of Al element, so the amount of alloying elements added in the tail discharge material is larger than that of the normal material.

The Zr element content in the head discharge material is 0.01-0.1wt% lower than the Zr element content in the normal material; preferably, 0.03-0.08wt%, more preferably, 0.04-0.06wt%, more preferably 0.05wt%;

The Zr element content in the tail discharge material is 0.01-0.1wt% lower than the Zr element content in the normal material; preferably, 0.02-0.08wt%, more preferably, 0.04-0.06wt%, more preferably 0.05wt%;

Preferably, the content of Zr element in the normal material is 2.0-2.2wt%, preferably 2.05-2.15wt%, more preferably 2.10%.

In the above method, the Al element content in the head discharge material is higher than that in the normal material by 0.3-0.8wt%; preferably 0.4-0.6wt%, more preferably 0.5%;

The Al element content in the tail discharge material is higher than that in the normal material by 0.3-0.8wt%; preferably 0.4-0.6wt%, more preferably 0.5%;

Preferably, the content of Al element in the normal material is 7.2-7.6wt%, preferably 7.5%.

In the above method, the content of V element in the normal material is 1.5-1.7wt%, preferably 1.5wt%, the content of Mo element is 0.9-1.3wt%, preferably 1.0wt%; the content of Ti element is 87.7-89wt% %, preferably 87.7wt%;

And/or, the content of V element in the head discharge material is 1.3-1.6wt%, preferably 1.45%, the content of Mo element is 0.8-1.2wt%, preferably 0.9wt%; the content of Ti element is 87-88wt% , preferably 87wt%;

And/or, the content of V element in the head discharge material is 1.3-1.6wt%, preferably 1.45%, the content of Mo element is 0.8-1.2wt%, preferably 0.9wt%; the content of Ti element is 87-88wt% , preferably 87wt%.

In the above method, the content of Zr in the raw material is 2.0-2.2wt%, preferably 2.1wt%;

And/or, the content of Al in the raw material is 7.2-8.0wt%, preferably 7.6wt%;

And/or, the content of Ti in the raw material is 86.9-89wt%, preferably 87.6wt%;

And/or, the content of Mo in the raw material is 0.9-1.1wt%, preferably 1.0wt%;

And/or, the content of V in the raw material is 1.3-1.7 wt %, preferably 1.5 wt %.

In the above method, the smelting includes three stages:

1) Start the electron gun stage: the liquid formed from starting the electron gun to the melting of the raw material flows into the crystallizer for the first time; wherein, the vacuum degree in the furnace is 1.87×10 ^-2 -9.03×10 ^-3 Torr; the time is 30-70min;

2) Bottom-making stage of ingot: from the first time the liquid formed by melting the raw material flows into the mold to the first time the ingot is pulled down; the vacuum degree in the furnace is 9.03×10 ^-3 -5.57×10 ^-3 Torr; the time is 15 -30min;

3) Normal smelting stage: the smelting speed and smelting power of the electron beam cooling bed furnace are basically constant, and the ingot is pulled down for the first time to the stage where the smelting speed and smelting power of the electron beam cooling bed furnace begin to decrease; The degree is 5.57×10 ^-3 -1.85×10 ^-3 Torr, preferably 2×10 ^-3 -3×10 ^-3 Torr.

In the above method, the average smelting speed in the normal smelting stage is 140-220 kg/h, preferably 150-200 kg/h.

In the above method, the power ratios of the melting zone, refining zone and solidification zone in the electron beam cooling bed furnace in the normal smelting stage are: 58-68%, 8-15%, 23-32%, preferably, 64% -65%, 9.5-11%, 25-26%.

In the above method, the powers of the melting zone, the refining zone and the solidification zone in the electron beam cooling bed furnace in the normal smelting stage are respectively 240-300kw, 35-45kw, and 100-110kw, preferably 270kw, 40kw and 105kw;

Preferably, the average smelting speed in the normal smelting stage is 200-140Kg/h, preferably 190-150Kg/h.

In the above method, compared with the raw material before smelting, the TA15 titanium alloy has a volatilization rate of Al ≤ 15.5%, and a volatilization rate of Zr ≤ 3.5%; Rate≤3.33%.

In addition, the present invention also provides a TA15 titanium alloy prepared by any of the above methods.

Beneficial effects:

Zirconium is a low saturated vapor pressure element. According to literature records and practical experience, its volatilization can be ignored during the smelting process of titanium alloys. However, the inventors of the present application have found through experimental research that the zirconium element has a volatilization rate of up to 10% during the smelting process of the TA15 titanium alloy. Therefore, the volatilization of zirconium element is a non-negligible problem. The present invention controls the combined volatilization rate of aluminum and zirconium elements within a reasonable range through multiple tests and researches. ≤3.5%.

Description of drawings

The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the attached image:

Fig. 1 is a curve diagram of electron gun current fitting.

Figure 2 is a curve fitting the sum of the vacuum degree in the electron beam cooling-bed furnace and the current of each gun.

FIG. 3 is a graph showing the ratio of the current of each electron gun to the sum of the current.

Fig. 4 is a fitting curve diagram of feeding speed and ingot pulling speed.

5 is a comparison of the Al content in the TA15 alloy obtained from different raw materials in Example 1.

FIG. 6 is a comparison of the Zr content in the TA15 alloy obtained from different raw materials in Example 1.

Detailed ways

The electron beam cooling bed furnace used in the following examples is a 1350KWB BMO-25 electron beam cooling bed furnace prepared locally.

Except for the "%" used for the volatilization rate in the following examples, the rest of the "%" are "wt%" unless otherwise specified.

The titanium sponge used in the following examples is produced by Chaoyang Parkson Titanium Co., Ltd., and the production batch number is 1903-L426; the Al beans are produced by Chengde Tianda Vanadium Co., Ltd., and the production batch number is DA20171101; AlMo70 master alloy is Chengde Tianda It is produced by Vanadium Industry Co., Ltd. with the production batch number M20181110; the AlV55 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd. with the production batch number V20180134; the AlZr50 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd. with the production batch number JAZ20170401; The AlZr40 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd. with the batch number of JAZ20180813; the AlZr60 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd. with the production batch number of JAZ20180324; the AlZr70 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd. Production, the production batch number is JAZ20180621; the AlZr80 master alloy is produced by Chengde Tianda Vanadium Industry Co., Ltd., and the production batch number is JAZ20190115.

In the following examples, the volatilization rate is the percentage of the loss of alloying elements in the ingot to the weight of the corresponding elements in the raw material.

Example 1. Influence of different raw materials on smelting of TA15 titanium alloy

1. Preparation of raw materials

The different raw materials shown in Table 1 were mixed and pressed into three kinds of blocks with different element contents on the hydraulic press: head discharge, normal material and tail discharge (as shown in Table 2). (Thickness is 170mm) sent to drying box for drying, drying time is 2~4h, temperature is 115~125℃.

Table 1. Composition of different raw materials (unit, wt%)

In Table 1, the composition content of the titanium sponge is: the content of O is 0.054%, the content of N is 0.007%, the content of Fe is 0.055%, the content of C is 0.015%, and the content of H is 0.001%;

The purity of the Al beans is greater than 99.6%;

The composition content of the AlMo70 master alloy is: the content of Mo is 72.5%, the content of Al is 27.2%, and the content of impurities is 0.30%;

The composition content of the AlV55 master alloy is: the content of V is 58.0%, the content of Al is 41.47%, and the content of impurities is 0.53%;

The composition content of the AlZr50 master alloy is: the content of Zr is 52.5%, the content of Al is 47.159%, and the content of impurities is 0.341%;

The composition content of the AlZr80 master alloy is: the content of Zr is 78.11%, the content of Al is 21.44%, and the content of impurities is 0.45%;

The composition content of the AlZr70 master alloy is: the content of Zr is 67.25%, the content of Al is 32.23%, and the content of impurities is 0.52%;

The composition content of the AlZr60 master alloy is: the content of Zr is 59.25%, the content of Al is 40.33%, and the content of impurities is 0.42%;

The composition content of the AlZr40 master alloy is: the content of Zr is 40.5%, the content of Al is 59.13%, and the content of impurities is 0.37%.

Table 2. Contents of final ingredients

The balance in each block in Table 1 is impurities.

2. Electron beam cooling bed furnace melting process

The dried blocks are placed in the horizontal feeder by 2 blocks in each row, and sent to the electron beam cooling bed furnace in the order of head discharge, normal material and tail discharge in sequence to obtain TA15 titanium alloy ingots for one-time smelting.

Among them, the weight of the head discharge placed in the horizontal feeder is 40kg; the weight of the normal material is 440kg; the weight of the tail discharge is 40kg;

The vacuum degree in the electron beam cooling-bed furnace is higher than 1.0×10 ^-2 Torr, and the furnace leakage rate should be lower than 3.3 Torr·l/s using a helium mass spectrometer leak detector.

The smelting process control steps are as follows:

1) Start the electron gun stage: the liquid formed from starting the electron gun to the melting of the raw material flows into the crystallizer for the first time; wherein, the average vacuum degree in the furnace is 9.03×10 ^-3 Torr; the time is 60min;

2) Bottom-making stage of ingot: the liquid formed by melting the raw material flows into the crystallizer for the first time until the ingot is pulled down for the first time; wherein, the average vacuum degree in the furnace is 6.0×10 ^-3 Torr; the time is 30min;

3) Normal smelting stage: The smelting speed and smelting power are basically constant, and the smelting speed and smelting power begin to decrease from the first time the ingot is pulled down. The average vacuum degree in the furnace is 2.0×10 ^-3 Torr.

In the normal smelting stage, the current function and power of each electron gun and its proportion to the total power are controlled as follows:

The 1# electron gun is used in the raw material melting area to ensure the normal melting of the raw material, the current is controlled at around 9.2A, and the power of the melting area is 270kw, accounting for 65.06% of the total power;

The 3# electron gun is used in the refining area to ensure that the material flows into the mold from the cooling bed through the gate, the current is controlled at around 1.3A, and the melting area power is 40kw, accounting for 9.64% of the total power;

The 2# electron gun is used in the crystallization area, the surface of the molten pool in the mold is completely melted, the current is controlled at around 3.5A, and the power of the melting area is 105kw, accounting for 25.3% of the total power.

Other process parameters are: the evacuation time is 1.5-2.5h, the average melting speed is 180kg/h, the average feeding speed is 9.0mm/min, and the average ingot pulling speed is 6.0mm/min, wherein, the melting speed = ingot pulling speed × Ingot cross-sectional area × TA15 alloy density.

4) Smelting end stage: from the beginning of smelting power and smelting speed to the end of smelting ingot; the time is 10 minutes, and the average vacuum degree in the furnace is 1.85×10 ^-3 Torr.

Figures 1 to 4 show the process parameter records in the EB smelting process of TA15 titanium alloy.

3. Analysis of ingot composition

1. Ingot sampling point and identification

(1) Identification of ingot sampling point

Use a horizontal lathe to sequentially sample the axial surface of the ingot (turning chips), take a point 50mm from the head of the ingot and mark it as sample point 1, and at an interval of 100mm, take point 2; take a point 50mm from the tail of the ingot and mark it as sample point 1 Sample point 7, at an interval of 100mm, take point 6; then the middle section of the ingot is divided into 4 equal points to take points 3, 4, and 5 in turn, and there are 7 sampling points in the axial direction of the ingot. [Here, the number of samples can be determined according to the specific situation. Generally, the sample points 1 and 2 at the head of the ingot are determined, and the sample points n-1 and n at the tail of the ingot are determined, and then the middle section of the ingot is processed (n-3), etc. Determine the number of samples by points, where n represents the total number of samples]

(2) Detection: Take 0.1g of chips from each sampling point, dissolve them in 1:2 sulfuric acid, and analyze the chemical composition of aluminum, zirconium, molybdenum, and vanadium with ICP-7300V inductively coupled plasma emission spectrometer of American PE company. Use 178C, 203A, TC4, 175D, 173C and TA15 six standard samples to draw the working curve of ICP-7300; the RF power is selected as 1150W; the analytical lines of aluminum and zirconium are 396.153, 243.823, 202.031, 210.356nm respectively.

2. Ingot composition analysis results

成分检测结果如表3-7所示，其中Al和Zr的含量对比如图5-6所示。The spindle weight is 488kg and the size is

The composition test results are shown in Table 3-7, and the content comparison of Al and Zr is shown in Figure 5-6.

Table 3, Axial chemical composition of ingot obtained from 1# raw material

Table 4. Axial chemical composition of ingot obtained from 2# raw material

Table 5. The axial chemical composition of the ingot obtained from the 3# raw material

Table 6, Axial chemical composition of ingot obtained from 4# raw material

Axial chemical composition of ingot obtained from table 7, 5# raw material

The results in Table 3-7 and Figure 5-6 show that the TA15 alloy ingot obtained from the 1# raw material has the best uniformity, and the volatilization rate of Al is the lowest, which is 15.33%, and the volatilization rate of Zr is the lowest, which is 3.33%. It is indicated that the volatilization rate of zirconium is the lowest when using AlZr50 as the addition method of zirconium element in TA15 alloy ingots when other raw materials and processes are determined.

Among them: 1# ingot is made of AlZr50 alloy, and the volatilization rates of Al and Zr elements are 15.3% and 3.33% respectively; 2# ingot is made of AlZr80 alloy, and the volatilization rates of Al and Zr elements of the obtained ingot are 16.11% and 6.33%; 3# ingot was batched with AlZr70 alloy, and the volatilization rates of Al and Zr elements were 16.93% and 8.14% respectively; 4# ingot was batched with AlZr60 alloy, and the obtained ingot Al and Zr elements The volatilization rates were 17.43% and 5.5%, respectively; the 5# ingot was prepared with AlZr40 alloy, and the volatilization rates of Al and Zr elements were 15.7% and 5%, respectively.

In the raw materials of 1-5# of Example 1, Al and Zr have the same value. Compared with 1#, when Zr element in 2#-4# is added in the form of AlZr80, AlZr70 and AlZr60 alloys, the required Al beans ( The addition of Al element in the form of element) increases, and never leads to the increase of Al volatilization in the ingot, which is greater than 15.3% in 1#. In 5#, the Zr element is added in the form of AlZr40, and the amount of Al beans required is small, and the volatilization of Al is not much different from that of 1#, but the volatilization of Zr is also higher than that of 1#. Comprehensive comparison and consideration found that when the AlZr50 alloy was added in the form of Al and Zr, the volatilization amount of Al and Zr elements was small, and the distribution uniformity in the ingot was the best. In addition, this result was confirmed by repeated experiments.

Example 2. Influence of smelting process on smelting of TA15 titanium alloy

The raw material is carried out according to the 1# raw material in the embodiment 1, and the process method and the ingot composition analysis method are carried out according to the method of the embodiment 1, the difference is: the melting power is set to different gradients, and in the electron beam melting process, the electron gun melting The voltage is kept constant, and the power is reflected by the change of the current: the current in the melting zone is 7A, 8A, 9A, and 9.5A, the current in the refining zone is 1A, 1.5A, and 2A, and the current in the crystallization zone is 3A, 3.5A, and 4A. The results are shown in Table 8-9. shown.

Table 8. Different smelting power settings

Table 9. Axial chemical composition of ingots obtained by different melting power (wt%)

The results in Tables 8-9 show that the different smelting power will cause Al and Zr elements to produce different volatilization rates during the smelting process, so the content and uniformity in the ingot will also be different. In Example 2-1, the power ratio is 56%: 16%: 28%, the total melting power is 375KW, and the volatilization rates of Al and Zr elements in the obtained ingot are both high, which reflects the difference in the distribution and size of the melting power. Rationality (210KW power in the melting zone is too small, while 60KW in the refining zone is too large); in Example 2-2, the power ratio is 59.26%: 11.11%: 29.63%, and the total melting power is 405KW. In this example, the crystallization zone The power is 60KW, and the volatilization rates of Al and Zr elements in the ingot are both high and the uniformity is poor; in Example 2-4, the power ratio is 65.51%: 10.34%: 24.14%, and the total melting power is 435KW. In this example The melting zone and crystallization zone have higher power, and Al and Zr volatilization rates are relatively high, and the uniformity is also poor. In Example 2-3, the power ratio is 64.3%: 10.7%: 25%, and the total smelting power is 420KW, among which, the power of the melting zone is 270KW, the power of the refining zone is 45KW, and the power of the crystallization zone is 105KW, which is basically the same as that of Example 1. The obtained ingot has good compositional uniformity, and the volatilization rates of Al and Zr are well controlled.

By analyzing the above results, it can be seen that the adjustment of the melting power directly affects the volatilization rate of Al and Zr elements, and the size and distribution of them need to be reasonably designed. Among them, the power ratio is 64.3%: 10.7%: 25%, and the total melting power is The volatilization rate of Al and Zr is the lowest when the power of the melting zone is 420KW, the power of the melting zone is 270KW, the power of the refining zone is 45KW, and the power of the crystallization zone is 105KW.

Example 3. Influence of smelting process on smelting of TA15 titanium alloy

The raw material is carried out according to the 1# raw material in the embodiment 1, and the process method and the ingot composition analysis method are carried out according to the method of the embodiment 1, the difference is: the average melting speed of the normal melting stage is set to different gradients, and the melting speed is The feeding speed and ingot pulling speed are closely related, and the vacuum degree also has a certain influence on the smelting speed. The results are shown in Tables 10 to 14.

Different process parameters adopted in table 10, embodiment 3

deal with Vacuum/Torr Feeding speed mm/min Ingot drawing speed mm/min Melting speed Kg/h Example 1 2.0×10^-3 9 6 180 Example 3-1 1.5×10^-3 15 10 306 Example 3-2 1.5×10^-3 12 8.5 260 Example 3-3 4×10^-3 10 7 214 Example 3-4 3×10^-3 8 5 153

Table 11. Axial chemical composition of the ingot obtained in Example 3-1

Table 12. The axial chemical composition of the ingot obtained in Example 3-2

Table 13. The axial chemical composition of the ingot obtained in Example 3-3

Table 14. The axial chemical composition of the ingot obtained in Example 3-4

The results in Tables 10-14 show that under the condition of the same batching scheme, the effect of vacuum degree and smelting speed on the chemical composition of TA15 titanium alloy ingot is very obvious. In Example 3-1, the smelting speed reached 306Kg/h. Because the smelting speed was too fast and the metal liquid state retention time was short, the volatilization rate of Al and Zr was small, and the content in the ingot was relatively high, and the average content reached 6.66% and 6.66% respectively. 2.05%; in addition, the excessively fast smelting speed also leads to problems such as poor chemical composition uniformity, high impurity content and poor surface quality of the ingot. In Example 3-2, the smelting speed was 260Kg/h, the smelting speed decreased, the Al and Zr contents in the corresponding ingots were reduced and the distribution uniformity was improved, but the problems of high impurity content and poor surface quality of the ingots Still exist. In Example 3-3, the smelting rate was further reduced to 214Kg/h, the volatilization rates of Al and Zr elements were within the expected range, and the uniformity in the ingot was further improved, but due to the poor vacuum (4×10 ^-3 Torr), the impurity content is also high, especially N% exceeds the scope of the national standard. In Example 3-4, the smelting speed was controlled at about 153Kg/h, and the vacuum degree in the furnace was controlled at 3×10 ^-3 Torr. The content of Al and Zr elements is reduced, but the uniformity is good. At the same time, the improvement of vacuum degree makes the impurity content well controlled. According to Table 14, the content of O and N elements has been reduced and meets the requirements of the national standard.

Contents not described in detail in this specification belong to the prior art known to those skilled in the art. The above descriptions are merely examples of the present application, and are not intended to limit the present application. Various modifications and variations of this application are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

Claims (10)

1. An electron beam cold hearth melting method of TA15 titanium alloy, characterized by comprising the steps of:

s1, preparing a raw material containing metal elements of Ti, Al, Mo, V and Zr;

s2, feeding the raw materials into an electron beam cold hearth furnace for smelting to obtain a TA15 titanium alloy;

the raw materials comprise sponge titanium, aluminum beans, aluminum molybdenum intermediate alloy, aluminum vanadium intermediate alloy and aluminum zirconium intermediate alloy;

the aluminum zirconium master alloy comprises an aluminum zirconium 50 master alloy.

2. The method of claim 1, wherein the raw materials are mixed and pressed into briquettes, the briquettes comprise a head discharge, a normal material and a tail discharge, and the feeding into the electron beam cold bed furnace is performed in sequence according to the head discharge, the normal material and the tail discharge;

the Zr element content in the head discharge is 0.01-0.1 wt% lower than that in the normal material; preferably, 0.03 to 0.08 wt%, more preferably, 0.04 to 0.06 wt%, more preferably 0.05 wt%;

the Zr element content in the tail discharge material is 0.01-0.1 wt% lower than that in the normal material; preferably, 0.02 to 0.08 wt%, more preferably, 0.04 to 0.06 wt%, more preferably 0.05 wt%;

preferably, the content of Zr element in the normal material is 2.0-2.2 wt%, preferably 2.05-2.15 wt%, more preferably 2.10 wt%.

3. The method according to claim 1 or 2, wherein the elemental Al content in the head discharge is 0.3 to 0.8 wt% higher than the elemental Al content in the normal charge; preferably 0.4-0.6 wt%, more preferably 0.5%;

the Al element content in the tail discharge material is 0.3-0.8 wt% higher than that in the normal material; preferably 0.4-0.6 wt%, more preferably 0.5%;

preferably, the content of Al element in the normal material is 7.2-7.6 wt%, preferably 7.5 wt%.

4. A method according to claim 2 or 3, characterized in that: the content of the V element in the normal material is 1.5-1.7 wt%, preferably 1.5 wt%, and the content of the Mo element is 0.9-1.3 wt%, preferably 1.0 wt%; the content of Ti element is 87.7-89 wt%, preferably 87.7 wt%;

and/or the head discharge has a content of the element V of 1.3 to 1.6 wt%, preferably 1.45 wt%, and a content of the element Mo of 0.8 to 1.2 wt%, preferably 0.9 wt%; the content of Ti element is 87-88 wt%, preferably 87 wt%;

and/or the content of the V element in the tail discharge material is 1.3-1.6 wt%, preferably 1.45 wt%, and the content of the Mo element is 0.8-1.2 wt%, preferably 0.9 wt%; the content of Ti element is 87-88 wt%, preferably 87 wt%.

5. The method according to any one of claims 1 to 4, characterized in that the Zr content in the feedstock is 2.0-2.2 wt.%, preferably 2.1 wt.%;

and/or the content of Al in the raw material is 7.2-8.0 wt%, preferably 7.6 wt%;

and/or the content of Ti in the raw material is 86.9-89 wt%, preferably 87.6 wt%;

and/or the content of Mo in the raw material is 0.9-1.1 wt%, preferably 1.0 wt%;

and/or the content of V in the raw material is 1.3-1.7 wt%, preferably 1.5 wt%.

6. The method according to any one of claims 1-5, wherein: the smelting comprises three stages:

1) starting an electron gun: from starting the electron gun to melting the material to form a liquidFlows into the crystallizer for the first time; wherein the vacuum degree in the furnace is 1.87 multiplied by 10^-2-9.03×10^-3Torr; the time is 30-70 min;

2) ingot casting and bottom making: liquid formed by melting raw materials flows into the crystallizer for the first time and is pulled down for the first time by the ingot casting; wherein the vacuum degree in the furnace is 9.03 multiplied by 10^-3-5.57×10^-3Torr; the time is 15-30 min;

3) and (3) a normal smelting stage: the smelting speed and the smelting power of the electron beam cold bed furnace are basically constant, and the ingot is pulled down for the first time to the stage that the smelting speed and the smelting power of the electron beam cold bed furnace begin to decline; wherein the vacuum degree in the furnace is 5.57 multiplied by 10^-3-1.85×10^-3Torr, preferably 2X 10^-3-3×10^-3Torr。

7. The method of claim 6, wherein: the average smelting speed in the normal smelting stage is 140-220kg/h, preferably 150-200 kg/h.

8. The method according to any one of claims 6 or 7, wherein: the power of the melting zone, the refining zone and the solidification zone in the electron beam cold hearth furnace in the normal melting stage respectively accounts for the following ratio: 58-68%, 8-15%, 23-32%, preferably, 64-65%, 9.5-11%, 25-26%;

preferably, the power of the melting zone, the refining zone and the solidification zone in the normal smelting stage electron beam cold bed furnace is 240-300kw, 35-45kw and 100-110kw, preferably 270kw, 40kw and 105kw respectively;

preferably, the average smelting speed in the normal smelting stage is 200-140Kg/h, preferably 190-150 Kg/h.

9. The method according to any one of claims 1-8, wherein: compared with the raw materials before smelting, the TA15 titanium alloy has the volatilization rate of Al less than or equal to 15.5 percent and the volatilization rate of Zr less than or equal to 3.5 percent.

10. A TA15 titanium alloy produced by the method of any one of claims 1-9.

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