CN101392338A - Composite strengthened titanium alloy with high strength and high elastic modulus and preparation method thereof - Google Patents

Abstract

The invention discloses a compositely reinforced titanium alloy of high strength and high modulus of elasticity in the material preparation technical field and a preparation method thereof, which contains the following components by mass percent content: 5.1 percent to 6.5 percent of Al, 3.3 percent to 4.3 percent of V, 0.06 percent to 0.91 percent of B, 0.17 percent to 1.27 percent of C, and titanium as the rest. Titanium sponge, boron carbide, graphite, aluminum vanadium hardener and pure aluminum raw material are weighed and mixed evenly to be suppressed into an electrode which is installed in an arc furnace; titanium alloy cast ingot containing TiB and TiC of wild phase is obtained through smelting; billet forging is carried out to the titanium alloy cast ingot in beta phase area, then regular forging is carried out in alpha phase and beta phase, and after the completion of forging, the oxide skin on the surface of the titanium alloy, shrinkage holes, segregation and occluded defects are removed so that the titanium alloy is gotten. The invention is simple and rapid, and has low cost, more even distribution of wild phases, better combination of interfaces, high coefficient of thermal conductivity, low coefficient of linear expansion and outstanding comprehensive mechanical property.

Description

Composite strengthened titanium alloy with high strength and high elastic modulus and preparation method thereof

technical field

The invention relates to a titanium alloy in the technical field of metal materials and a preparation method thereof, in particular to a composite strengthened high-strength high-elastic modulus titanium alloy and a preparation method thereof.

Background technique

With the rapid development of the aerospace industry, improving aviation efficiency and reducing flight costs have put forward higher requirements for aircraft structural materials. In order to adapt to this development trend, titanium alloys with high strength (tensile strength at room temperature greater than 1000MPa), high elastic modulus (elastic modulus higher than 120GPa) and high toughness are becoming a new type of high-tech new material that has attracted much attention. Structural materials.

Reducing the specific gravity of materials can improve the thrust-to-weight ratio of the aircraft, increase the flight distance and reduce fuel costs. One of the main weight reduction methods for aircraft structural parts is to use α+β titanium alloys with high specific strength and good comprehensive performance. Compared with other high-strength engineering materials, titanium alloys have a lower modulus of elasticity, making structural parts designed for stiffness thicker and bulkier than those designed for strength.

The probe of the ultrasonic cell breaker adopts the traditional medium-strength titanium alloy Ti-6Al-4V, which has a low elastic modulus, making it difficult to make a smaller probe, and the scope of use is limited. At the same time, due to its insufficient wear resistance, the probe is worn Seriously, it will affect the crushing effect. At the same time, increasing the thermal conductivity will facilitate heat dissipation and prolong the life of the probe.

The antenna support components of space satellites need to withstand the complex environment of alternating high and low temperature in space, and have high requirements for dimensional stability. Therefore, only by maintaining a low coefficient of linear expansion in a large temperature range can a stable and reliable support be provided for the antenna.

Therefore, how to further improve the comprehensive properties of α+β-type titanium alloys and prepare titanium alloys with high strength and high elastic modulus at low cost has always been a concern of researchers.

Through the retrieval of prior art documents, it is found that the Chinese patent (disclosure) number is CN1978681, and the patent name is a titanium alloy with high strength and high modulus of elasticity. Although the titanium alloy with high strength and high modulus of elasticity has been obtained, the cost of the alloying elements of the titanium alloy used is high; the process of adding a reinforcing phase is complicated, the interface is poorly bonded, and segregation is prone to occur; at the same time, the patent A single TiB reinforcement phase is used, so the performance of the obtained titanium alloy is single, which limits its application range.

Contents of the invention

The present invention aims at the deficiencies of the above-mentioned prior art, and provides a composite strengthened high-strength high-elastic modulus titanium alloy and its preparation method, which adopts the low-cost traditional titanium alloy Ti-6Al-4V with the highest output and the widest application range , using the reaction between sponge titanium (Ti), boron carbide (B ₄ C) and graphite (C) to generate TiB and TiC for composite strengthening, and quickly and at low cost to prepare a more uniform reinforcement phase distribution, better interface bonding, High strength and high elastic modulus titanium alloy with high thermal conductivity, low linear expansion coefficient and excellent comprehensive mechanical properties. This method is suitable for large-scale industrial production and can meet the urgent demand for low-cost, high-performance titanium alloys.

The present invention is achieved through the following technical solutions:

The composite strengthened high-strength high-elastic modulus titanium alloy involved in the present invention contains the following mass percentages of each component element: Al 5.1%-6.5%, V 3.3%-4.3%, B 0.06%-0.91%, C 0.17% ~ 1.27%, the balance is titanium.

The V is added in the form of an aluminum-vanadium master alloy (AlV), and the V mass percentage content of the aluminum-vanadium master alloy is 50%-60%.

The B is added in the form of boron carbide (B ₄ C).

The preparation method of the high-strength and high-elastic modulus titanium alloy of composite strengthening involved in the present invention comprises the following specific steps:

Step 1, weighing sponge titanium, boron carbide, graphite, aluminum vanadium master alloy and pure aluminum according to the mass percentage content of each component element;

Step 2, mixing the raw materials weighed in step 1 evenly, pressing them into electrodes, and putting them into a vacuum consumable electric arc furnace or a vacuum non-consumable electric arc furnace;

Step 3, smelting two to three times to obtain a titanium alloy ingot containing reinforcement phases TiB and TiC;

The reinforcing phase is generated by the following reaction formula:

5Ti+B ₄ C→4TiB+TiC

Ti+C→TiC

The molar ratio of the reinforcing phases TiB and TiC is 1:20-4:1, and the sum of their volume fractions is controlled between 4%-6%.

Step 4: Carry out billet forging on the titanium alloy ingot in the β-phase region, and then carry out conventional forging in the α+β two-phase region. After the forging is completed, use machining equipment to remove the oxide skin, shrinkage cavity and segregation on the surface of the titanium alloy And inclusion defects, that is, a composite strengthened titanium alloy with high strength and high elastic modulus.

The blank forging has a deformation of more than 50%, and its working temperature ranges from 1080°C to 1200°C.

The conventional forging has a deformation of more than 75%, and its working temperature ranges from 980°C to 1050°C.

Compared with the prior art, the present invention can prepare titanium alloy with more uniform distribution of reinforcement phase, better interfacial bonding and excellent comprehensive mechanical properties simply, quickly and at low cost without changing the traditional titanium alloy preparation equipment and process flow. Titanium alloy with high strength and high modulus of elasticity. The TiB reinforcement phase significantly improves the room temperature strength and room temperature elastic modulus of the titanium alloy, the room temperature yield strength is greater than 950MPa, the room temperature tensile strength is greater than 1050MPa, and the room temperature elastic modulus is greater than 125GPa, which are respectively increased by 5% compared with Ti-6Al-4V , 10% and 12% or more, while the plasticity is greater than 8%; the TiC reinforcement phase significantly improves the wear resistance of the titanium alloy, which is more than 50% higher than that of Ti-6Al-4V; the thermal conductivity at room temperature is 8.2～9.0W/ (m·K), which is 26% to 38% higher than that of Ti-6Al-4V; the coefficient of linear expansion is between 7.1×10 ^-6 and 10.9×10 ^-6 (-100°C to 400°C). The composite strengthened high-strength and high-elastic-modulus titanium alloy prepared by the invention is the preferred choice for aviation structural materials, ultrasonic pulverizer probe materials and satellite antenna support components.

Detailed ways

This embodiment is carried out on the premise of the technical solution of the present invention, and the detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

A composite strengthened high-strength high-elastic modulus titanium alloy (TiB:TiC=1:1) with a volume fraction of the reinforcing phase of 5% was prepared.

Weighing 89.51% of primary sponge titanium, 0.62% of boron carbide, 0.40% of graphite, 6.89% of aluminum vanadium master alloy (V content is 55%) and 2.58% of pure aluminum according to the mass percentage, the preparation composition is Ti-5.7Al-3.8V- 0.48B-0.54C titanium alloy.

Mix the raw materials evenly, press them into electrodes, and put them into a vacuum consumable electric arc furnace or a vacuum non-consumable electric arc furnace; smelt two to three times to obtain titanium alloy ingots containing reinforced phases TiB and TiC; carry out in the β phase region Open billet forging (1170°C) with a deformation of 50%, then conventional forging in the α+β two-phase region (1020°C) with a deformation of 75%, using machining equipment to remove oxide scales and shrinkage cavities on the surface of the material, Defects such as segregation and inclusions are eliminated to obtain composite strengthened high-strength and high-elastic-modulus titanium alloys.

The reinforced phase of the alloy obtained in this example is evenly distributed, the interface is well bonded, and the comprehensive performance is excellent. The yield strength at room temperature is 1090MPa, the tensile strength at room temperature is 1178MPa, and the elastic modulus at room temperature is 127GPa, which are 21%, 24% and 15% higher than Ti-6Al-4V respectively, and the plasticity is 8%. -6Al-4V has increased by 85%; the thermal conductivity at room temperature is 8.5W/(m K), which is 31% higher than that of Ti-6Al-4V; the linear expansion coefficient is 8.0×10 ^-6 ~ 10.2×10 ^-6 (-100℃～400℃).

Example 2

Preparation of a composite strengthened high-strength high-elastic modulus titanium alloy (TiB:TiC=4:1) with a reinforcement phase volume fraction of 4%

Weighing 88.39% of primary sponge titanium, 0.77% of boron carbide, 0% of graphite, 7.19% of aluminum vanadium master alloy (V content is 60%) and 3.64% of pure aluminum according to the mass percentage, the preparation composition is Ti-6.5Al-4.3V- 0.61B-0.17C titanium alloy.

Mix the raw materials evenly, press them into electrodes, and put them into a vacuum consumable electric arc furnace or a vacuum non-consumable electric arc furnace; smelt two to three times to obtain titanium alloy ingots containing reinforced phases TiB and TiC; carry out in the β phase region Open billet forging (1080°C), with a deformation of 60%, and then perform conventional forging in the α+β two-phase region (980°C), with a deformation of 85%, and use machining equipment to remove oxide scales and shrinkage cavities on the surface of the material. Defects such as segregation and inclusions are eliminated to obtain composite strengthened high-strength and high-elastic-modulus titanium alloys.

The overall performance of the titanium alloy obtained in this example is similar to that of Example 1. The yield strength at room temperature, the tensile strength at room temperature and the modulus of elasticity at room temperature are slightly worse, the plasticity is slightly better, the wear resistance is slightly worse, the thermal conductivity at room temperature is slightly worse, and the linear expansion The coefficient (-100℃～400℃) is slightly worse.

Example 3

Preparation of Composite Strengthened High Strength and High Elastic Modulus Titanium Alloy (TiB:TiC=4:1) with Reinforcing Phase Volume Fraction of 6%

Weighing 88.24% of primary sponge titanium, 1.16% of boron carbide, 0% of graphite, 8.44% of aluminum vanadium master alloy (V content is 50%) and 2.16% of pure aluminum according to the mass percentage, the preparation composition is Ti-6.4Al-4.2V- 0.91B-0.25C titanium alloy.

Mix the raw materials evenly, press them into electrodes, and put them into a vacuum consumable electric arc furnace or a vacuum non-consumable electric arc furnace; smelt two to three times to obtain titanium alloy ingots containing reinforced phases TiB and TiC; carry out in the β phase region Open billet forging (1160°C) with a deformation of 50%, then conventional forging in the α+β two-phase region (1010°C) with a deformation of 80%, using machining equipment to remove oxide scales and shrinkage cavities on the surface of the material, Defects such as segregation and inclusions are eliminated to obtain composite strengthened high-strength and high-elastic-modulus titanium alloys.

The overall performance of the titanium alloy obtained in this embodiment is similar to that of Example 1. The yield strength at room temperature, the tensile strength at room temperature and the modulus of elasticity at room temperature are slightly better, the plasticity is slightly worse, and the wear resistance is slightly worse; the thermal conductivity is slightly better at room temperature, and the linear expansion The coefficient (-100°C to 400°C) is slightly better.

Example 4

Preparation of a composite strengthened high-strength high-elastic modulus titanium alloy (TiB:TiC=1:20) with a reinforcement phase volume fraction of 6%

Weigh 90.27% of primary sponge titanium, 0.07% of boron carbide, 1.26% of graphite, 5.94% of aluminum vanadium master alloy (V content is 55%) and 2.46% of pure aluminum according to the mass percentage, and the preparation composition is Ti-5.1Al-3.3V- 0.06B-1.27C titanium alloy.

Mix the raw materials evenly, press them into electrodes, and put them into a vacuum consumable electric arc furnace or a vacuum non-consumable electric arc furnace; smelt two to three times to obtain titanium alloy ingots containing reinforced phases TiB and TiC; carry out in the β phase region Open billet forging (1200°C), with a deformation of 60%, and then perform conventional forging in the α+β two-phase region (1050°C), with a deformation of 75%, and use machining equipment to remove oxide scales and shrinkage cavities on the surface of the material. Defects such as segregation and inclusions are eliminated to obtain composite strengthened high-strength and high-elastic-modulus titanium alloys.

The overall performance of the titanium alloy obtained in this embodiment is similar to that of Example 1, the yield strength at room temperature, the tensile strength at room temperature and the modulus of elasticity at room temperature are slightly worse, the plasticity is slightly worse, but the wear resistance is much better, and the thermal conductivity is slightly better at room temperature; The expansion coefficient (-100℃～400℃) is slightly better.

Claims (7)

1, a kind of high strength and high elastic modulus titanium alloy of complex intensifying is characterized in that, each component element and the mass percentage content thereof that comprise are: Al 5.1%～6.5%, V 3.3%～4.3%, B 0.06%～0.91%, and C 0.17%～1.27%, and surplus is a titanium.

2, the high strength and high elastic modulus titanium alloy of complex intensifying according to claim 1 is characterized in that, described V adds with the form of aluminium vanadium master alloy, and the V mass percentage content of aluminium vanadium master alloy is 50%～60%.

3, the high strength and high elastic modulus titanium alloy of complex intensifying according to claim 1 is characterized in that, described B adds with the form of norbide.

4, a kind of preparation method of high strength and high elastic modulus titanium alloy of complex intensifying as claimed in claim 1 is characterized in that, comprises the steps:

Step 1 takes by weighing titanium sponge, norbide, graphite, aluminium vanadium master alloy and fine aluminium by the mass percentage content of each component element;

Step 2, the raw material that step 1 is taken by weighing mixes, and is pressed into electrode, in pack into vacuum consumable electrode arc furnace or the vacuum non-consumable arc furnace;

Step 3, melting obtains to contain the titan alloy casting ingot of wild phase TiB and TiC for twice to three times;

Step 4, at the β phase region ingot casting of titanium alloy being carried out cogging forges, carrying out routine at the alpha+beta two-phase region subsequently forges, after forging is finished, utilize machining apparatus to remove oxide skin and shrinkage cavity, segregation and the inclusion defect of titanium alloy surface, promptly get the high strength and high elastic modulus titanium alloy of complex intensifying.

5, the preparation method of the high strength and high elastic modulus titanium alloy of complex intensifying according to claim 4 is characterized in that, described wild phase TiB and TiC, and its mol ratio is 1:20～4:1, its volume fraction summation is controlled between 4%～6%.

6, the preparation method of the high strength and high elastic modulus titanium alloy of complex intensifying according to claim 4 is characterized in that, described cogging is forged, and its deflection surpasses 50%, and operating temperature range is 1080 ℃～1200 ℃.

7, the preparation method of the high strength and high elastic modulus titanium alloy of complex intensifying according to claim 4 is characterized in that, described conventional the forging, and its deflection surpasses 75%, and operating temperature range is 980 ℃～1050 ℃.