Low-cost titanium alloy, preparation method and application

Abstract

The invention belongs to the technical field of titanium alloy materials, and particularly relates to a low-cost titanium alloy, a preparation method and application, the nominal composition of the low-cost titanium alloy material is Ti-6Al-3Fe-2Cr-2Sn-0.2 Gd-0.2 O, and the low-cost titanium alloy material is composed of, by mass, 5.0%-7.0% of Al, 1.5%-4.0% of Fe, 1.0%-3.0% of Cr, 1.0%-3.0% of Sn, 0.1%-0.4% of Gd, 0.1%-0.3% of O, smaller than or equal to 0.05% of C, smaller than or equal to 0.03% of N, smaller than or equal to 0.015% of H and the balance Ti. And other elements are unavoidable impurities, wherein the single element is less than or equal to 0.1% and the total is less than or equal According to the preparation method disclosed by the invention, the low-cost and high-performance titanium alloy is finally obtained through the proportioning of the raw materials and the design of a hot working and heat treatment process, and the manufacturing cost of the alloy can be reduced by about 20%.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloy materials, and in particular relates to a low-cost titanium alloy, a preparation method and an application thereof. Background Art

[0002] Starting from 2021, the modernization of the Chinese military has officially entered an accelerated period. The use of titanium in high-end fields such as aerospace and military equipment has increased significantly. At the same time, titanium alloys have gradually begun to be widely used in civilian fields such as shipbuilding, chemical industry, medical treatment, nuclear power, and fire protection. However, due to the high chemical activity, low thermal conductivity, difficulty in deformation, and high requirements for heat treatment control of titanium and titanium alloys, the extraction, smelting and processing of titanium are very difficult. The cost of titanium and titanium alloy products mainly comes from raw materials, smelting and deformation processing. High cost has become the main factor restricting the mass production and application of titanium components. Therefore, the development of low-cost titanium alloys and the low-cost preparation of titanium alloys have become one of the important topics that many scientific research institutions and production units continue to tackle.

[0003] A lot of research and engineering applications have been done in low-cost titanium alloy materials at home and abroad. However, there are few low-cost titanium alloy grades in my country, and they are not widely used. In particular, for the demand for large-scale titanium alloy parts in the field of weapons and ships, such as armored vehicles and gun body structures, large ship structures, etc., which use a lot of titanium alloys, it is urgent to develop a specific grade of titanium alloy that meets the low-cost requirements and has good room temperature and high temperature mechanical properties.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to propose a low-cost titanium alloy, a preparation method and an application. The method adopts a component composition with a set mass ratio, selects cheap elements to replace high-cost elements, and obtains a titanium alloy ingot with a nominal composition of Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O through the preparation method, thereby providing a low-cost titanium alloy material that can be widely promoted and used in my country's weapons, ships, aerospace, petrochemical and other industries.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a low-cost titanium alloy, the nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, and the alloy is composed of the following components in mass percentage: Al: 5.0% to 7.0%, Fe: 1.5% to 4.0%, Cr: 1.0% to 3.0%, Sn: 1.0% to 3.0%, Gd: 0.1% to 0.4%, O: 0.1% to 0.3%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, and other elements are unavoidable impurities: ≤0.1% individually and ≤0.4% in total.

[0008] Furthermore, the nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, which is composed of the following components in mass percentage: Al: 5.0%~6.0%, Fe: 2.8%~4.0%, Cr: 1.0%~1.5%, Sn: 1.0%~2.0%, Gd: 0.1%~0.2%, O: 0.2%~0.3%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, and other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

[0009] Furthermore, the nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, which is composed of the following components in mass percentage: Al: 6.0%~7.0%, Fe: 1.5%~2.8%, Cr: 1.5%~2.0%, Sn: 2.0%~3.0%, Gd: 0.2%~0.3%, O: 0.1%~0.2%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, and other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

[0010] On the other hand, the present invention also provides a method for preparing a low-cost titanium alloy, comprising the following steps:

[0011] Step 1: prepare ingredients according to the mass percentage of each element in the low-cost titanium alloy as described above, mix the raw materials evenly, and press them into electrode blocks;

[0012] Step 2, welding a plurality of electrode blocks into a titanium alloy consumable electrode;

[0013] Step 3: The titanium alloy consumable electrode is smelted multiple times in a vacuum consumable arc furnace, and cooled to below 400° C. to obtain a titanium alloy ingot with a nominal composition of Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O.

[0014] Furthermore, in step 1, the raw materials include primary titanium sponge, aluminum beans, titanium-iron master alloy, aluminum-gadolinium master alloy, titanium-tin master alloy, titanium dioxide, etc.;

[0015] Among them, the titanium-iron master alloy is TiFe70, the aluminum-gadolinium master alloy is AlGd30, and the titanium-tin master alloy is Ti80Sn.

[0016] Furthermore, in step 2, a plurality of electrode blocks are welded into long strip-shaped titanium alloy consumable electrodes by using vacuum plasma or argon shielded plasma.

[0017] Furthermore, in step 3, when the smelting is performed twice, the smelting current of the titanium alloy consumable electrode is set to 6KA~12KA, and the smelting voltage is set to 28V~35V for one smelting to obtain an ingot, and then the first ingot is inverted for a second smelting, and the smelting current is set to 7KA~13KA, and the smelting voltage is set to 28V~37V.

[0018] On the other hand, the present invention provides a method for preparing a low-cost titanium alloy material, wherein the titanium alloy ingot prepared by the preparation method as described above is processed into titanium alloy bars, tubes, plates, wires, foils or special-shaped forgings through peeling, sawing, heat treatment, open forging, intermediate forging and annealing.

[0019] The titanium alloy ingot is peeled, flaw-detected, and the riser is sawn, and samples are taken for chemical composition and phase transition point testing;

[0020] The peeled and sawed titanium alloy ingot is charged into a furnace at 750℃~850℃, preheated at 850℃~900℃ for 1h~3h, heated to 1150℃ and kept for 2h~3h, forged, and water-cooled after forging;

[0021] The intermediate billet is forged 4 times, the temperature is selected to be 15℃~40℃ below the phase transformation point, two upsetting and two drawing are performed in each time, and the deformation amount is 40%~60%;

[0022] After forging, annealing heat treatment is performed, and the annealing system is 750℃~850℃ for 1h~2h and then air cooling to finally obtain a titanium alloy rod blank.

[0023] Furthermore, the room temperature mechanical properties of the prepared titanium alloy rod after annealing are: Rm≥1100MPa, R P0.2 ≥1000MPa, A≥15%, Z≥30%, aku≥30J / cm 2 ; 400℃ high temperature mechanical properties: Rm≥750MPa, R P0.2 ≥600MPa, A≥20%, Z≥40%; 500℃ high temperature mechanical properties: Rm≥650MPa, R P0.2≥550MPa, A≥30%, Z≥60%.

[0024] In addition, a low-cost titanium alloy as described above is used in materials for components of weapons, ships, etc.

[0025] The low-cost titanium alloy provided by the present invention improves the overall strength and high-temperature performance of the titanium alloy by improving the composition and adding elements such as Sn and Gd, based on the existing low-cost titanium alloy using cheap elements such as Fe and Cr to replace expensive elements such as Mo and V. Among them, the Sn element, as a neutral element, has a large solid solubility in both α-Ti and β-Ti. It can play a supplementary strengthening role when added together with elements such as Fe and Cr, and can also reduce the sensitivity of the alloy to hydrogen embrittlement. The Gd element, as a rare earth element, can reduce the interfacial energy of the melt because the rare earth element is a surfactant, thereby reducing the critical nucleation work and ultimately increasing the nucleation rate. In addition, the high-melting-point rare earth particles can become the non-uniform nucleation core of α precipitation. The Gd element can be pinned to the grain boundary, hindering the movement of the grain boundary and the growth of the grains during thermal deformation and heat treatment, thereby achieving the effect of refining the grains. At the same time, the formed Gd oxide particles as the dispersed particles of the alloy nucleation and the dislocation substructure formed around the oxide particles can strengthen the alloy, so that the alloy has the strongest thermal strength and thermal stability at the use temperature.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention provides a low-cost titanium alloy, which mainly uses cheap Fe and Cr elements instead of high-cost V and Mo elements as alloy strengtheners, and adds an appropriate amount of Sn element for supplementary strengthening, and combines an appropriate amount of Gd element to reduce the interfacial energy of the melt, thereby reducing the critical nucleation work, increasing the nucleation rate, and pinning at the grain boundary to hinder the grain boundary movement and the growth of grains during thermal deformation and heat treatment, thereby achieving the effect of grain refinement.

[0028] 2) The present invention provides a method for preparing a low-cost titanium alloy, which can reduce the alloy manufacturing cost by about 20% by finally obtaining a low-cost, high-performance titanium alloy through the ratio of various raw materials, heat processing and heat treatment process design. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 The present invention is a flow chart of the method for preparing low-cost titanium alloy. DETAILED DESCRIPTION

[0032] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0033] Example 1

[0034] On the one hand, the present embodiment provides a low-cost titanium alloy, which has a composition of Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O, and is composed of the following components in mass percentage: Al: 5.0%, Fe: 2.0%, Cr: 2.0%, Sn: 2.0%, Gd: 0.2%, O: 0.15%, and the balance is Ti. Other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

[0035] On the other hand, this embodiment provides a method for preparing a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy bar, comprising the following steps:

[0036] Step 1, weighing and mixing various raw materials according to the mass percentage required by the titanium alloy of this embodiment, and pressing them into an electrode block with a single weight of 80 kg on a press;

[0037] Step 2: All the electrode blocks obtained in step 1 are welded into long strip-shaped titanium alloy consumable electrodes by using a vacuum plasma welder;

[0038] Step 3: The titanium alloy consumable electrode obtained in step 2 is melted twice in a vacuum consumable arc furnace and cooled to 400°C to avoid oxidation and other defects of the uncooled ingot after it is taken out of the furnace, and finally a 800kg grade Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot is obtained (see the preparation process for details). Figure 1 );

[0039] Step 4, peeling, flaw detection, and sawing the riser of the titanium alloy ingot obtained in step 3, and taking samples for chemical composition and phase change point testing;

[0040] Step 5, the peeled and sawed titanium alloy ingot is charged into a furnace at 800°C, preheated at 880°C for 1.5 hours, heated to 1150°C and kept for 3 hours, forged, and water-cooled to obtain an intermediate billet after forging;

[0041] Step 6, the intermediate billet obtained in step 5 is forged for 4 times, the temperature is selected to be 25°C below the phase transformation point, two upsetting and two drawing are performed in each fire, and the deformation amount is 50%;

[0042] Step 7: The rod blank obtained in step 6 is kept at 750° C. for 1.5 hours and then air-cooled to obtain a titanium alloy rod.

[0043] Specifically, in step 1, the raw materials include primary titanium sponge, aluminum beans, titanium-iron master alloy, aluminum-gadolinium master alloy, titanium-tin master alloy and titanium dioxide, among which the titanium-iron master alloy is TiFe70, the aluminum-gadolinium master alloy is AlGd30, and the titanium-tin master alloy is Ti80Sn.

[0044] The specific process in step 3 is:

[0045] The titanium alloy consumable electrode is first smelted in a vacuum consumable arc furnace to obtain a primary ingot, with a smelting current of 10KA and a smelting voltage of 32V;

[0046] The primary ingot was inverted and used as a consumable electrode for secondary smelting in a vacuum consumable arc furnace to obtain a finished ingot, i.e., a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot, with a smelting current of 10KA and a smelting voltage of 33V.

[0047] The specific process of step 4 is: use a lathe to peel the titanium alloy ingot, then use ultrasonic testing to determine the position of the ingot riser and saw the riser, and at the same time, take block and chip samples from the top, middle and bottom of the ingot for component analysis. The chemical composition analysis results are shown in Table 1:

[0048] Table 1 Chemical composition of 800kg-level low-cost titanium alloy ingots prepared

[0049]

[0050] In step 5, the specific process of blank forging is:

[0051] φ440×380 drawing → φ295×660 upsetting → φ415×335 drawing → φ295×660 upsetting → φ415×335 → drawing φ295×660;

[0052] The 440×380mm ingot after being taken out of the furnace is drawn out to obtain a φ295×660mm billet, and then the φ295×660mm billet is upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm billet, which is further upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm intermediate billet.

[0053] In step 6, the specific process of forging the intermediate billet is as follows:

[0054] 2. Fire forging: upsetting and drawing at 20℃ below the phase transformation point, specifically φ295×660 upsetting→φ415×335 drawing→φ295×660 upsetting→φ415×335 drawing→φ295×660, chamfering, upsetting flat head and tail;

[0055] 3. After the 3rd fire forging is kept at 30℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ415×335 drawing→φ295×660 upsetting→φ415×335 drawing→φ295×660, chamfering, upsetting the head and tail;

[0056] 4. After the fire forging is kept at 40℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ415×335 drawing→φ295×660 upsetting→φ415×335 drawing→φ295×660, chamfering, upsetting the head and tail;

[0057] After 5 fire forgings at 40℃ below the phase transformation point for 3.5h, upsetting and drawing are carried out, specifically φ295×660 upsetting→φ415×335 drawing→φ295×660 upsetting→φ415×335 drawing→φ295×660 rounding→φ250×900.

[0058] In order to demonstrate the efficacy of the present invention, the performance of the titanium alloy rod prepared in this example was tested, see Table 2.

[0059] Table 2 Mechanical properties of titanium alloy bars with a diameter of 250 × 900 mm

[0060] Detection temperature Rm / MPa <![CDATA[R P0.2 / MPa]]> A / ％ Z / ％ <![CDATA[aku / J / cm 2 ]]> 25℃ 1150 1050 18 35 32 400℃ 780 650 25 46 / 500℃ 680 580 35 65 /

[0061] Example 2

[0062] On the one hand, the present embodiment provides a low-cost titanium alloy, which has a composition of Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O, and is composed of the following components in mass percentage: Al: 5.5%, Fe: 2.2%, Cr: 2.2%, Sn: 2.2%, Gd: 0.25%, O: 0.20%, and the balance is Ti. Other elements are unavoidable impurities: a single element ≤0.10%, a total of ≤0.40%.

[0063] On the other hand, this embodiment provides a method for preparing a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy bar, comprising the following steps:

[0064] Step 1, weighing and mixing various raw materials according to the mass percentage required by the titanium alloy of this embodiment, and pressing them into an electrode block with a single weight of 80 kg on a press;

[0065] Step 2: All the electrode blocks obtained in step 1 are welded into long strip-shaped titanium alloy consumable electrodes by using a vacuum plasma welder;

[0066] Step 3, the titanium alloy consumable electrode obtained in step 2 is melted twice in a vacuum consumable arc furnace, and cooled to 380° C. to avoid oxidation and other defects of the uncooled ingot after it is taken out of the furnace, and finally a 800 kg grade Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot is obtained;

[0067] Step 4, peeling, flaw detection, and sawing the riser of the titanium alloy ingot obtained in step 3, and taking samples for chemical composition and phase change point testing;

[0068] Step 5, the peeled and sawed titanium alloy ingot is charged into a furnace at 850°C, preheated at 900°C for 3h, heated to 1150°C and kept for 2h, forged, and water-cooled to obtain an intermediate billet after forging;

[0069] Step 6, the intermediate billet obtained in step 5 is forged for 4 times, the temperature is selected to be 15°C below the phase transformation point, two upsetting and two drawing are performed in each fire, and the deformation amount is 40%;

[0070] Step 7: The rod blank obtained in step 6 is kept at 850° C. for 1.5 h and then air-cooled to obtain a titanium alloy rod.

[0071] Specifically, in step 1, the raw materials include primary titanium sponge, aluminum beans, titanium-iron master alloy, aluminum-gadolinium master alloy, titanium-tin master alloy and titanium dioxide, among which the titanium-iron master alloy is TiFe70, the aluminum-gadolinium master alloy is AlGd30, and the titanium-tin master alloy is Ti80Sn.

[0072] The specific process in step 3 is:

[0073] The titanium alloy consumable electrode is first smelted in a vacuum consumable arc furnace to obtain an ingot, with a smelting current of 6KA and a smelting voltage of 28V;

[0074] The primary ingot was inverted and used as a consumable electrode for secondary smelting in a vacuum consumable arc furnace to obtain a finished ingot, i.e., a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot, with a smelting current of 7KA and a smelting voltage of 28V.

[0075] The specific process of step 4 is: use a lathe to peel the titanium alloy ingot, then use ultrasonic testing to determine the position of the ingot riser and saw the riser, and at the same time take block and chip samples from the top, middle and bottom of the ingot for composition analysis.

[0076] Table 3 Chemical composition of 800kg-level low-cost titanium alloy ingots prepared

[0077]

[0078] In step 5, the specific process of blank forging is:

[0079] φ440×380 drawing → φ295×660 upsetting → φ415×335 drawing → φ295×660 upsetting → φ415×335 → drawing φ295×660;

[0080] The 440×380mm ingot after being taken out of the furnace is drawn out to obtain a φ295×660mm billet, and then the φ295×660mm billet is upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm billet, which is further upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm intermediate billet.

[0081] In step 6, the specific process of forging the intermediate billet is as follows:

[0082] 2. After the second forging is kept at 20℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ400×360 drawing→φ295×660 upsetting→φ400×360 drawing→φ295×660, chamfering, upsetting the head and tail;

[0083] 3. After the heat forging is kept at 30℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ400×360 drawing→φ295×660 upsetting→φ400×360 drawing→φ295×660, chamfering, upsetting the head and tail;

[0084] 4. After the forging is kept at 40℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ400×360 drawing→φ295×660 upsetting→φ400×360 drawing→φ295×660, chamfering, upsetting the head and tail;

[0085] After 5 fire forgings at 40℃ below the phase transformation point for 3.5h, upsetting and drawing are carried out, specifically φ295×660 upsetting→φ400×360 drawing→φ295×660 upsetting→φ400×360 drawing→φ295×660 rounding→φ280×730.

[0086] In order to demonstrate the efficacy of the present invention, the performance of the titanium alloy rod prepared in this example was tested, see Table 4.

[0087] Table 4 Mechanical properties of titanium alloy bars with a specification of φ280×730mm

[0088] Detection temperature Rm / MPa <![CDATA[R P0.2 / MPa]]> A / ％ Z / ％ <![CDATA[aku / J / cm 2 ]]> 25℃ 1145 1030 17 34 32 400℃ 795 670 28 48 / 500℃ 680 576 36 64 /

[0089] Example 3

[0090] On the one hand, the present embodiment provides a low-cost titanium alloy, which has a composition of Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O, and is composed of the following components in mass percentage: Al: 6.5%, Fe: 2.5%, Cr: 2.0%, Sn: 2.5%, Gd: 0.25%, O: 0.18%, and the balance is Ti. Other elements are unavoidable impurities: a single element ≤0.1%, a total of ≤0.40%.

[0091] On the other hand, this embodiment provides a method for preparing a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy bar, comprising the following steps:

[0092] Step 1, weighing and mixing various raw materials according to the mass percentage required by the titanium alloy of this embodiment, and pressing them into an electrode block with a single weight of 80 kg on a press;

[0093] Step 2: All the electrode blocks obtained in step 1 are welded into long strip-shaped titanium alloy consumable electrodes by using a vacuum plasma welder;

[0094] Step 3, the titanium alloy consumable electrode obtained in step 2 is melted twice in a vacuum consumable arc furnace, and cooled to 350° C. to avoid oxidation and other defects of the uncooled ingot after it is taken out of the furnace, and finally a 800 kg grade Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot is obtained;

[0095] Step 4, peeling, flaw detection, and sawing the riser of the titanium alloy ingot obtained in step 3, and taking samples for chemical composition and phase change point testing;

[0096] Step 5, the peeled and sawed titanium alloy ingot is charged into a furnace at 750° C., preheated at 850° C. for 1 hour, heated to 1150° C. and kept warm for 2.5 hours, forged, and water-cooled to obtain an intermediate billet after forging;

[0097] Step 6, the intermediate billet obtained in step 5 is forged for 4 times, the temperature is selected to be 40°C below the phase transformation point, two upsetting and two drawing are performed in each fire, and the deformation amount is 60%;

[0098] Step 7: The rod blank obtained in step 6 is kept at 800° C. for 2 hours and then air-cooled to obtain a titanium alloy rod.

[0099] Specifically, in step 1, the raw materials include primary titanium sponge, aluminum beans, titanium-iron master alloy, aluminum-gadolinium master alloy, titanium-tin master alloy and titanium dioxide, among which the titanium-iron master alloy is TiFe70, the aluminum-gadolinium master alloy is AlGd30, and the titanium-tin master alloy is Ti80Sn.

[0100] The specific process in step 3 is:

[0101] The titanium alloy consumable electrode is first smelted in a vacuum consumable arc furnace to obtain a primary ingot, with a smelting current of 12KA and a smelting voltage of 35V;

[0102] The primary ingot was inverted and used as a consumable electrode for secondary smelting in a vacuum consumable arc furnace to obtain a finished ingot, i.e., a Ti-5.0Al-2Fe-2Cr-2Sn-0.2Gd-0.15O titanium alloy ingot, with a smelting current of 13KA and a smelting voltage of 37V.

[0103] The specific process of step 4 is: use a lathe to peel the titanium alloy ingot, then use ultrasonic testing to determine the position of the ingot riser and saw the riser, and at the same time take block and chip samples from the top, middle and bottom of the ingot for composition analysis.

[0104] Table 5 Chemical composition of 800kg low-cost titanium alloy ingots prepared

[0105]

[0106] In step 5, the specific process of blank forging is:

[0107] φ440×380 drawing → φ295×660 upsetting → φ415×335 drawing → φ295×660 upsetting → φ415×335 → drawing φ295×660;

[0108] The 440×380mm ingot after being taken out of the furnace is drawn out to obtain a φ295×660mm billet, and then the φ295×660mm billet is upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm billet, which is further upset to obtain a φ415×335mm billet, which is further drawn out to obtain a φ295×660mm intermediate billet.

[0109] In step 6, the specific process of forging the intermediate billet is as follows:

[0110] 2. After the second forging is kept at 20℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ430×310 drawing→φ295×660 upsetting→φ430×310 drawing→φ430×310, chamfering, upsetting the head and tail;

[0111] 3. After the 3rd fire forging is kept at 30℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ430×310 drawing→φ295×660 upsetting→φ430×310 drawing→φ295×660, chamfering, upsetting the head and tail;

[0112] 4. After the fire forging is kept at 40℃ below the phase transformation point for 3.5h, it is upsetting and drawing, specifically φ295×660 upsetting→φ430×310 drawing→φ295×660 upsetting→φ430×310 drawing→φ295×660, chamfering, upsetting the head and tail;

[0113] After 5 fire forgings at 40℃ below the phase transformation point for 3.5h, upsetting and drawing are carried out, specifically φ295×660 upsetting→φ430×310 drawing→φ295×660 upsetting→φ430×310 drawing→φ295×660 rounding→φ230×1080.

[0114] In order to demonstrate the efficacy of the present invention, the performance of the titanium alloy rod prepared in this example was tested, see Table 6.

[0115] Table 6 Mechanical properties of titanium alloy bars with a specification of φ230×1080mm

[0116] Detection temperature Rm / MPa <![CDATA[R P0.2 / MPa]]> A / ％ Z / ％ <![CDATA[aku / J / cm 2 ]]> 25℃ 1146 1020 19 37 32 400℃ 786 654 28 49 / 500℃ 678 595 34 63 /

[0117] It can be seen from Table 2, Table 4 and Table 6 that the titanium alloy rod prepared in the present invention has good room temperature and high temperature mechanical properties.

[0118] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0119] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A low-cost titanium alloy, characterized in that: The nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, which is composed of the following components in mass percentage: composition: Al: 5.0%~7.0%, Fe: 1.5%~4.0%, Cr: 1.0%~3.0%, Sn: 1.0%~3.0%, Gd: 0.1%~0.4%, O: 0.1%~0.3%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

2. The low-cost titanium alloy according to claim 1, characterized in that: The nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, which is composed of the following components in mass percentage: composition: Al: 5.0%~6.0%, Fe: 2.8%~4.0%, Cr: 1.0%~1.5%, Sn: 1.0%~2.0%, Gd: 0.1%~0.2%, O: 0.2%~0.3%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

3. The low-cost titanium alloy according to claim 1, characterized in that: The nominal composition of the low-cost titanium alloy is Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O, which is composed of the following components in mass percentage: composition: Al: 6.0%~7.0%, Fe: 1.5%~2.8%, Cr: 1.5%~2.0%, Sn: 2.0%~3.0%, Gd: 0.2%~0.3%, O: 0.1%~0.2%, C: ≤0.05%, N: ≤0.03%, H: ≤0.015%, the balance is Ti, other elements are unavoidable impurities: individual ≤0.1%, total ≤0.4%.

4. A method for preparing a low-cost titanium alloy, characterized in that: The following steps are involved: Step 1, proportioning the elements in the low-cost titanium alloy according to any one of claims 1 to 3 in terms of mass percentage, mixing the raw materials evenly, and pressing them into electrode blocks; Step 2, welding the electrode block obtained in step 1 into a titanium alloy consumable electrode; Step 3: The titanium alloy consumable electrode is smelted multiple times in a vacuum consumable arc furnace, and cooled to below 400° C. to obtain a titanium alloy ingot with a nominal composition of Ti-6Al-3Fe-2Cr-2Sn-0.2Gd-0.2O.

5. The method for preparing a low-cost titanium alloy according to claim 4, characterized in that: In step 1, the raw materials include primary titanium sponge, aluminum beans, titanium-iron master alloy, aluminum-gadolinium master alloy, titanium-tin master alloy, and titanium dioxide; Among them, the titanium-iron master alloy is TiFe70, the aluminum-gadolinium master alloy is AlGd30, and the titanium-tin master alloy is Ti80Sn.

6. The method for preparing a low-cost titanium alloy according to claim 4, characterized in that: In step 2, a plurality of electrode blocks are welded into long strip-shaped titanium alloy consumable electrodes by using vacuum plasma or argon gas shielded plasma.

7. The method for preparing low-cost titanium alloy according to claim 4, characterized in that: In step 3, when the smelting is performed twice, the smelting current of the titanium alloy consumable electrode is set to 6KA~12KA, and the smelting voltage is set to 28V~35V for one smelting to obtain an ingot, and then the first ingot is inverted for a second smelting, and the smelting current is set to 7KA~13KA, and the smelting voltage is set to 28V~37V.

8. A method for preparing a low-cost titanium alloy material, characterized in that: The titanium alloy ingot obtained by the preparation method according to any one of claims 4 to 7 is processed into titanium alloy bars, tubes, plates, wires, foils or special-shaped forgings by peeling, sawing, heat treatment, blank forging, intermediate blank forging and annealing.

9. The low-cost titanium alloy material according to claim 8, characterized in that: The room temperature mechanical properties of the prepared titanium alloy rod after annealing are: Rm≥1100MPa, R P0.2 ≥1000MPa, A≥15%, Z≥30%, aku≥30J / cm 2 ; 400℃ high temperature mechanical properties: Rm≥750MPa, R P0.2 ≥600MPa, A≥20%, Z≥40%; 500℃ high temperature mechanical properties: Rm≥650MPa, R P0.2 ≥550MPa, A≥30%, Z≥60%.

10. Use of the low-cost titanium alloy according to any one of claims 1 to 3 in weapons and ship parts materials.

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