阅读说明：本技术 一种可实现低成本轧制的变形TiAl合金材料 (Deformed TiAl alloy material capable of realizing low-cost rolling ) 是由 刘奎 李小兵 马颖澈 高明 舒磊 张孟殊 于 2020-04-16 设计创作，主要内容包括：本发明公开了一种可实现低成本轧制的变形TiAl合金材料,属于TiAl合金技术领域。按原子百分含量计,该合金成分：Al 42-44％,Mn 2.0-4.0％,Mo 0.5-1.0％,B 0.08-0.3％,C 0.1-0.3％,O≤0.07wt.％,H≤0.005wt.％,N≤0.01wt.％,余量Ti。该合金熔炼、预锻造变形,再轧制成棒材,锻造和轧制工序无包套和等温处理。制备的棒材室温强度和塑性均超过目前国外已应用的Ti-42Al-5Mn、Ti-43Al-4Nb-1Mo-0.1B(TNM)合金。本发明合金800℃高温下组织稳定,长期时效不析出ω、Laves等有害相。(The invention discloses a deformed TiAl alloy material capable of realizing low-cost rolling, belonging to the technical field of TiAl alloys. The alloy comprises the following components in percentage by atom: 42-44% of Al, 2.0-4.0% of Mn, 0.5-1.0% of Mo, 0.08-0.3% of B, 0.1-0.3% of C, less than or equal to 0.07 wt% of O, less than or equal to 0.005 wt% of H, less than or equal to 0.01 wt% of N and the balance of Ti. The alloy is smelted, pre-forged to deform, rolled into bar, and the forging and rolling processes are non-sheathed and isothermal treatment. Prepared by)

1. A deformed TiAl alloy material capable of realizing low-cost rolling is characterized in that: the alloy comprises the following chemical components in percentage by atom:

42 to 44 percent of Al, 2.0 to 4.0 percent of Mn, 0.5 to 1.0 percent of Mo, 0.08 to 0.3 percent of B, 0.1 to 0.3 percent of C, and the balance of Ti and inevitable impurities.

2. The wrought TiAl alloy material capable of realizing low-cost rolling of the material as claimed in claim 1, wherein: in the deformed TiAl alloy material, the content of O is less than or equal to 0.07 wt.%, the content of H is less than or equal to 0.005 wt.%, and the content of N is less than or equal to 0.01 wt.%.

3. The wrought TiAl alloy material capable of realizing low-cost rolling according to claim 1 or 2, wherein: in the chemical components of the deformed TiAl alloy material, Al accounts for 42.5-44 at.%, Mn accounts for 2.6-3.8 at.%, and Mo accounts for 0.6-0.9 at.%.

4. The wrought TiAl alloy material capable of realizing low-cost rolling according to claim 1 or 2, wherein: in the chemical components of the deformed TiAl alloy material, B accounts for 0.08-0.2 at.%, and C accounts for 0.1-0.2 at.%.

5. The wrought TiAl alloy material capable of realizing low-cost rolling according to claim 1 or 2, wherein: the preparation process of the deformed TiAl alloy material comprises the following steps:

(1) proportioning according to alloy components, and directly smelting into an ingot in a vacuum induction smelting furnace by adopting a CaO crucible;

(2) and forging the alloy ingot into a bar with the diameter of 30-60 mm, and then carrying out hot rolling to obtain the bar with the diameter of 10-18 mm.

6. The wrought TiAl alloy material capable of realizing low-cost rolling of the alloy material of claim 5, wherein: in the step (2), the forging initial deformation temperature is 1300-1350 ℃, and the final deformation temperature is more than 1100 ℃; in the hot rolling process, the rolling pass is one or more times, and the rolling initial deformation temperature is 1300-1350 ℃.

7. The wrought TiAl alloy material capable of realizing low-cost rolling of the alloy material of claim 5, wherein: in order to ensure that the alloy has higher tensile strength at 750-800 ℃, the bar obtained by hot rolling is subjected to heat treatment, wherein the heat treatment system is as follows: 1230-0 ℃ solid solution for 0.5-1 h, air cooling, and then keeping the temperature at 760-800 ℃ for 3 h for aging treatment.

Technical Field

The invention relates to the technical field of TiAl alloy, in particular to a deformed TiAl alloy material capable of realizing low-cost rolling.

Background

TiAl-based alloys having low density (-4 g/cm)³) The high-temperature-resistant composite material has the advantages of high specific strength, good oxidation resistance and the like, is expected to replace high-temperature alloy in a temperature range of 600-900 ℃, can be used for preparing certain aerospace structural components and ground power system rotating or reciprocating motion structural components, greatly improves the thrust weight ratio and the fuel efficiency, and is considered as a new-generation light-weight high-temperature-resistant structural material with application potential. Among a plurality of TiAl alloys, the deformed TiAl alloy has greatly reduced metallurgical defects and peritectic segregation, and has fine and uniform structure and higher room temperature and high temperature strength. Meanwhile, the good thermomechanical processing property can ensure that workpieces in various shapes can be processed by the alloy at lower manufacturing cost. Therefore, the deformed TiAl alloy has become a focus and hot spot of research in the field of the TiAl alloy in recent years. At present, typical deformed TiAl comprises Ti-43Al-4Nb-1Mo-0.1B (TNM for short) developed by Germany and Austria, Ti-45Al-8.5Nb (high Nb-TiAl for short) developed by northern China, Ti-42Al-5Mn developed by Japan and the like, wherein the TNM and the Ti-42Al-5Mn have been respectively applied to low-pressure turbine blades of aero-engines and valve materials of racing engines. In contrast, in the wrought alloy, Ti-42Al-5Mn can realize the non-sheath and non-isothermal forging deformation with large deformation rate under the atmosphere, and has low deformation component and wide application prospect. However, researches show that the alloy has the problems of insufficient oxidation resistance, low strength, aging precipitation of Laves harmful phases and the like when the alloy is in service at the temperature of more than 700 ℃, and the industrial application of the alloy is severely restricted. In order to utilize the strong effects of the Mn element such as beta phase stability, low cost, omega brittle phase precipitation inhibition and the like, the development of a novel alloy is necessary to break through the problems existing in TiAl-Mn series alloys at the temperature of more than 700 ℃.

Disclosure of Invention

The invention aims to provide a deformed TiAl alloy material capable of realizing low-cost rolling and a preparation process thereof, the alloy is a beta-solidification gamma-TiAl alloy added with Mn, Mo and B on the basis of TiAl, can realize non-sheath, non-isothermal and low-cost rolling deformation by optimizing alloy components, a deformed bar has excellent room temperature strength and moderate plasticity, and the numerical values of the two exceed deformation alloys such as TNM, Ti-42Al-5Mn and the like; has good tissue stability, and does not precipitate Laves, omega and other harmful brittle phases at 800 ℃.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the deformed TiAl alloy material capable of realizing low-cost rolling comprises the following chemical components in atomic percentage: 42 to 44 percent of Al, 2.0 to 4.0 percent of Mn, 0.5 to 1.0 percent of Mo, 0.08 to 0.3 percent of B, 0.1 to 0.3 percent of C, and the balance of Ti and inevitable impurities.

In the deformed TiAl alloy material, the content of O is less than or equal to 0.07 wt.%, the content of H is less than or equal to 0.005 wt.%, and the content of N is less than or equal to 0.01 wt.%.

In the chemical composition of the deformed TiAl alloy material, the content of Al is preferably 42.5 to 44 at.%, the content of Mn is preferably 2.6 to 3.8 at.%, and the content of Mo is preferably 0.6 to 0.9 at.%.

In the chemical composition of the deformed TiAl alloy material, the content of B is preferably 0.08-0.2 at.%, and the content of C is preferably 0.1-0.2 at.%.

The preparation process of the deformed TiAl alloy material comprises the following steps:

(1) proportioning according to alloy components, and directly smelting into an ingot in a vacuum induction smelting furnace by adopting a CaO crucible;

(2) forging the alloy ingot into a bar with the diameter of 30-60 mm, and then carrying out hot rolling to obtain a bar with the diameter of 8-18 mm; the initial deformation temperature of forging is 1300-1350 ℃, and the final deformation temperature is more than 1100 ℃; in the hot rolling process, the rolling pass is one or more times, and the rolling initial deformation temperature is 1300-1350 ℃.

In order to ensure that the alloy has higher tensile strength at 750-800 ℃, the bar obtained by hot rolling is subjected to heat treatment, wherein the heat treatment system is as follows: 1230-0 ℃ solid solution for 0.5-1 h, air cooling, and then keeping the temperature at 760-800 ℃ for 3 h for aging treatment.

The design mechanism of the deformed TiAl alloy material is as follows:

according to the alloy, the contents of Al and Mn are synergistically controlled by adding Mo, and the contents of O, H, N and other elements are strictly controlled, so that the thermal deformation capability, the oxidation resistance and the structural stability of the alloy are improved, and the Laves brittle phase precipitation in the aging process is inhibited.

The alloy of the invention is added with a proper amount of B, and the content of B is required to be 0.1-0.3 at.%, so as to improve the room and high temperature strength of the alloy.

The alloy of the invention is added with proper amount of C, and the C content is required to be 0.1-0.3 at.%, so as to improve the creep property of the alloy and ensure that the alloy can obtain a near-lamellar structure.

In order to ensure that the alloy has higher tensile strength at 750-800 ℃, the heat treatment system of the deformed alloy is as follows: 1230-0 ℃ solid solution for 0.5-1 h, air cooling, and then keeping the temperature at 760-800 ℃ for 3 h for aging treatment.

The invention has the following advantages and beneficial effects:

1. the components of the deformed TiAl alloy can be accurately controlled, the production cost is relatively low under the conditions of Mn raw material cost and vacuum induction melting, the production process has strong practicability, and the material can be produced in large batch;

2. the deformed TiAl alloy belongs to a TiAl alloy capable of being thermally deformed at low cost, Hot Isostatic Pressing (HIP) is not needed before the alloy ingot is thermally deformed, the forging and rolling processes are both arranged in an atmospheric environment, and sheathing and isothermal treatment are also not needed, wherein the rolling is performed by adopting a Y-shaped rolling mill for multi-pass forming with one fire, the deformation cost is low, and the material utilization rate is high;

3. the deformed TiAl alloy has excellent high-temperature oxidation resistance and tissue thermal stability at the high temperature of 800 ℃, the high-temperature oxidation resistance is superior to that of Ti-42Al-5Mn, and no Laves brittle phase is precipitated in the tissue in the long-term aging process;

4. rolled of TiAl alloy of the inventionThe yield strength of the thin bar at room temperature is 1033MPa, the tensile strength is 1258MPa, the elongation is 0.63%, and the strength and the plasticity are both higher than those of the Ti-42Al-5Mn and TNM alloys which are applied abroad at present.

Drawings

FIG. 1 shows the macroscopic morphology of the alloy of the present invention and Ti-42Al5Mn alloy after cyclic oxidation at 800 deg.C/1 h for 100 h; wherein: (a) ti-42Al5Mn alloy; (b) the alloy of the present invention.

FIG. 2 is a graph showing the oxidation kinetics of the alloy of the present invention and Ti-42Al5Mn alloy after 100h of cyclic oxidation at 800 deg.C/1 h.

FIG. 3 shows the alloy of the present invention rolledThe microstructure before and after heat treatment of the bar; wherein: (a) before heat treatment of the bar; (b) after the bar material is thermally treated.

FIG. 4 shows the comparative results of the Laves brittle phase precipitation in the structure of the alloy of the present invention and the Ti-42Al5Mn alloy after 30 days of aging treatment at 800 deg.C, respectively; wherein: (a) the detection result of the Ti-42Al5Mn alloy electronic probe; (b) the electron back scattering diffraction detection result of the Ti-42Al5Mn alloy; (c) the alloy electronic probe of the invention detects the result; (d) the invention provides an alloy electron backscattering diffraction detection result.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The invention provides a deformed TiAl alloy material capable of realizing low-cost rolling, which comprises the following steps of proportioning alloy components according to the following table 1, and smelting the alloy components into ingots in a vacuum induction smelting furnace by adopting a CaO crucible; by utilizing the vacuum electromagnetic stirring capability, the unmelted metal inclusions in the alloy are reduced, the composition segregation is avoided to be large, and the alloy ingot is sampled and tested at the temperature of 1100-1300 ℃ and the strain rate of 10s^-1And 0.1s^-1A thermal compression stress-strain curve under conditions; performing 100-cycle oxidation resistance experiments under the oxidation condition of 800 ℃/heat preservation time of 1h to judge the high-temperature oxidation performance of the alloy; the alloy cast ingot is made into a bar through the processes of forging and hot rolling, and the diameter of the bar isSampling from a hot rolling rod, detecting the alloy structure and structure by using SEM, EPMA, EBSD and TEM, and performing a room-temperature and high-temperature tensile test on a stretcher to evaluate the comprehensive mechanical properties of the alloy;

after the hot rolled bar is subjected to heat treatment, the precipitation of Laves harmful phases of the alloy after long-term aging at the high temperature of 800 ℃ is analyzed, and the thermal stability of the service structure of the alloy is evaluated.

Examples 1 to 3:

three batches of the alloy ingots of the present invention, example 1 (first batch, No.1), example 2 (second batch, No.2), and example 3 (third batch, No.3), were melted in a vacuum induction furnace according to the alloy chemical compositions in table 1. The first batch of cast ingots are 20kg centrifugal ingots subjected to vacuum induction and centrifugal casting and are used for compression, oxidation experiments and thermophysical parameter measurement; the second and third batches of cast ingots are 20kg of vacuum induction and gravity castingAnd the cylindrical ingot is used for rolling deformation. The chemical compositions of the three batches of material are shown in table 1.

The samples obtained from the first batch of centrifugal ingots were measured for the thermal physical properties such as alloy thermal diffusion, specific heat, thermal conductivity, Young's modulus, shear modulus, Poisson's ratio, etc., and are shown in tables 2 and 3.

Cutting series from first batch centrifugal cast ingotThe samples were tested in a Gleeble-3800 thermal simulation tester at 1100 deg.C, 1150 deg.C, 1200 deg.C, 1250 deg.C, 1300 deg.C and a strain rate of 10s^-1And 0.1s^-1The thermal compression stress-strain curves under the conditions and the maximum rheological resistance data of the samples are shown in table 4.

A series of 10mm multiplied by 5mm experimental samples are cut and prepared from a first batch of cast ingots, oxidized under the condition of 800 ℃ of atmosphere, cooled to room temperature after heat preservation for 1h, and circulated for many times, according to the rules of aviation industry standard-oxidation resistance test method (HB52580-2000) of steel and high temperature alloy, the total cycle of oxidation is 100 times (100h), the oxidation weight gain and the oxide film shedding weight are measured after cooling, and the instrument is an electronic balance, and the precision is 0.1 mg. The macroscopic morphology and the oxidation kinetics of the alloys of the invention after oxidation are shown in figures 1 and 2. As can be seen from the figure, the oxide film formed on the surface of the alloy of the invention does not fall off at the temperature of 800 ℃, the adhesiveness is good, and the oxidation resistance is excellent.

Will be secondThree batches ofThe cast ingot is drawn out and forged into the section diameter by multiple timesThe forging stock has the forging initial deformation temperature of 1300-1350 ℃ and the final deformation temperature of more than 1100 ℃. And then rolling the mixture into a bar with the diameter of 18-10 mm by a Y-shaped rolling mill for multiple passes at one time, wherein the rolling initial deformation temperature is 1300-1350 ℃. Samples were taken from the rods and tested for room, high temperature tensile testing and the data are given in Table 5.

The heat treatment system of the alloy is solid solution at 1230-1280 ℃ for 0.5-1 h, air cooling and then aging treatment at 760-800 ℃ for 3 h. Table 6 sets forth the chamber, high temperature tensile properties data after the rolled heat treatment of the alloys of this invention. The microstructure of the alloy of the invention before and after heat treatment is shown in FIG. 3.

FIG. 4 shows the corresponding Laves precipitation after 30 days aging at 800 ℃ for the alloys of the invention and Ti-42Al-5 Mn. As can be seen from the data in the figure, the alloy has good performance stability at 800 ℃, and harmful phases such as omega, Laves and the like are not precipitated.

TABLE 1 chemical composition of alloy of the invention in three batches smelted in a vacuum induction furnace

TABLE 2 thermal diffusion, specific heat, thermal conductivity and density of the alloys of the invention

TABLE 3 Young's modulus, shear modulus, Poisson's ratio of the alloys of the present invention

TABLE 4 maximum rheological stress (MPa) at different temperatures (. degree. C.) for the alloys of the invention

TABLE 5 room temperature and high temperature instantaneous tensile properties of bars of different dimensions of the new alloys

TABLE 6 room temperature and high temperature instantaneous tensile Properties of the New alloys after Heat treatment