CN108977689B - Metastable beta titanium alloy plate and processing method thereof - Google Patents

Abstract

The invention relates to a metastable beta titanium alloy plate and a processing method thereof, belonging to the technical field of titanium alloy plate preparation. According to the invention, 0.05-0.2 wt.% of boron element is added into the alloy, so that the cogging forging process of the alloy ingot can be omitted, the alloy ingot is directly rolled above the phase-change temperature, an alloy intermediate plate can be obtained by single-fire-pass rolling and 3-5-pass rolling, and then the alloy plate is obtained by short-time solution treatment above the phase-change temperature. Compared with the prior art, the invention can obviously shorten the processing flow of the plate and reduce the processing cost.

Description

A kind of metastable beta titanium alloy sheet and its processing method

technical field

The invention relates to a metastable beta titanium alloy plate and a processing method thereof, belonging to the technical field of titanium alloy plate preparation. The microstructure of the metastable beta titanium alloy plate processed by the method is uniform, and the method has short process flow, low processing cost and high efficiency .

Background technique

Metastable beta titanium alloy is a kind of lightweight structural material with high strength, strong corrosion resistance and excellent processing performance. It is widely used in aerospace, ships, weapons and armor, chemical industry, sports equipment and other fields. Alloy is the most important product, accounting for about 80% of all products.

For metastable β-type titanium alloy sheets, the current production method is mainly to first perform billet forging of ingots in the β-phase region for multiple piers, and then perform multi-fire and multi-pass hot rolling in the two-phase region. , and finally heat-treated to obtain the desired properties of the sheet. Because the β grains in the as-cast structure of the titanium alloy are abnormally coarse (up to a centimeter level), and the structure cannot be refined by heat treatment, the alloy ingot will have defects such as cracking and uneven structure after rolling when it is directly rolled. Often multiple forgings are required to refine the beta grains. At the same time, due to the easy growth of β grains in the high temperature single-phase region, the processing performance is deteriorated and the microstructure after rolling is uneven. Metastable β-type alloys are generally rolled in the two-phase region. However, due to the low phase transformation point (usually below 900 °C), this type of alloy has a large deformation resistance and insufficient plasticity in the two-phase region, so that the single-pass and single-pass deformation of the alloy is low, usually requiring multiple fires. Multiple passes of rolling are required to obtain the desired size of the sheet. The complex thermal deformation process increases the processing cost of metastable beta titanium alloy sheets, which affects the wide application of alloy sheets.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to propose a metastable beta titanium alloy plate processed by a short process and a processing method thereof.

A metastable beta titanium alloy sheet processed by a short process of the present invention contains 0.05-0.2wt% of boron element in the composition of the titanium alloy sheet, that is to say, calculated based on the total mass of the titanium alloy sheet as 100%, the titanium alloy The mass content of boron element in the plate is 0.05%-0.2%.

A preparation method of a metastable beta titanium alloy sheet of the present invention, the steps of the method include:

(1) Smelting ingot

The raw materials are mixed by layered cloth or material mixing, pressed into electrodes, connected by argon arc welding, and smelted 2 to 3 times in a vacuum consumable arc melting furnace to obtain a titanium alloy ingot.

(2) Sheet rolling

The titanium alloy ingot obtained in step (1) is peeled, and then the slab is cut. The slab is subjected to heat preservation treatment, and then the intermediate plate is obtained by rolling through 3 to 5 passes of hot rolling equipment under one fire. Then, the plate is subjected to solution treatment for 20 minutes to 1 hour in a muffle furnace, and the cooling method is water quenching (WQ) or air cooling (AC) to obtain a titanium alloy plate with a uniform structure.

The raw materials in the step (1) include raw materials for preparing metastable beta titanium alloys and boron-containing intermediate alloys or boron powders.

The boron-containing intermediate alloy is AlTiB or FeB, wherein the mass fraction of Al element in AlTiB is not more than 10%, and the mass fraction of boron element in FeB is not less than 18%. When the metastable β-titanium alloy composition contains Fe element, FeB is preferred; when the metastable β-titanium alloy composition contains Al element, AlTiB is preferred; when the metastable β-titanium alloy composition contains neither Al element nor Fe element, choose boron powder.

In the step (1), the mass fraction of boron in the titanium alloy ingot is 0.05-0.2 wt.% (mass fraction).

In the step (2), the heat preservation treatment time of the slab is determined according to the thickness of the slab, and is specifically 1.0 to 2.0 min/mm; the heat preservation treatment temperature is T _β to T _β +100° C., and T _β is the phase transition temperature of the titanium alloy. .

In the step (2), the deformation amount of each pass of rolling is not less than 10%, and the total deformation amount of rolling is not less than 50%; the solution treatment temperature is T _β ~ T _β +50 ° C, and T _β is titanium alloy phase transition temperature.

beneficial effect

Compared with the prior art, the present invention has the following advantages: at present, the processing of the usual metastable beta titanium alloy hot-rolled sheet usually includes the process of pulling the alloy ingot for multiple times at high temperature (1000-1200°C). Billet forging, followed by multi-fire and multi-pass hot rolling at temperatures below the transformation point. In the present invention, 0.05-0.2wt.% of boron is added to the alloy, so that the alloy ingot can save the blanking and forging process, directly roll above the phase transformation temperature, and go through a single fire and 3-5 passes at the same time. The alloy intermediate plate can be obtained by rolling, and then a short-term solution treatment is performed above the transformation temperature to obtain an alloy plate. Compared with the prior art, the invention can significantly shorten the processing flow of the plate and reduce the processing cost. At the same time, compared with the traditional process of rolling below the transformation point, the rolling temperature and the solution treatment temperature of the present invention are above the transformation point, and the selection range is wide, making it easy to operate in production. By adding a trace amount of boron element to the alloy, the invention effectively shortens the processing flow of the alloy plate without affecting its mechanical properties.

Description of drawings

Fig. 1 is the traditional processing process flow of preparing metastable β-type titanium alloy hot-rolled sheet;

Fig. 2 is a short-process processing process flow for preparing a metastable β-type titanium alloy hot-rolled sheet in the present invention; it can be seen from Fig. 1 that the process flow of the present invention is significantly less than that of the traditional process, the processing cost is low, and the efficiency is high.

Figure 3a is the microstructure of the longitudinal section of the directly rolled 2A2F10B alloy sheet with a total deformation of 50% in Example 1 after solution treatment at 850°C/1h/WQ;

Figure 3b shows the microstructure of the longitudinal section of the directly rolled 2A2F alloy sheet with a total deformation of 50% in Example 1 after solution treatment at 850°C/1h/WQ;

Figure 4a shows the microstructure of the longitudinal section of the directly rolled 2A2F10B alloy sheet with a total deformation of 70% in Example 2 after solution treatment at 850°C/1h/WQ;

Figure 4b shows the microstructure of the longitudinal section of the directly rolled 2A2F alloy sheet with a total deformation of 70% in Example 2 after solution treatment at 850°C/1h/WQ;

Figure 5a shows the microstructure of the longitudinal section of the directly rolled 2A2F10B alloy sheet with a total deformation of 85% after solution treatment at 850°C/1h/WQ in Example 3;

Figure 5b shows the microstructure of the longitudinal section of the directly rolled 2A2F alloy sheet with a total deformation of 85% in Example 3 after solution treatment at 850°C/1h/WQ.

Detailed ways

The specific embodiments of the present invention will be described below by means of examples and accompanying drawings.

Example 1

S1. Alloy ingot smelting:

According to the composition requirements of Ti-2(wt.%)Al-9.2(wt.%)Mo-2(wt.%)Fe-0.1(wt.%)B alloy (2A2F10B), take the corresponding weight of AlMo55, MoFe50, FeB20 , Ti-32Mo master alloy and grade 0 sponge titanium, use layered cloth to press electrodes, and then use vacuum consumable arc melting equipment to smelt twice to obtain 32Kg alloy ingots to ensure uniform composition. The surface of the ingot was then peeled off, and the chemical composition of the ingot was tested by chemical methods (Table 1). The phase transition point was determined by quenching metallographic method to be 815±5℃.

Table 1 Chemical composition (mass content) of 2A2F10B alloy ingot

Al Mo Fe B Ti 2.03 9.32 2.09 0.096 margin

S2. Sheet rolling:

A rolled slab of 115 mm (length) x 80 mm (width) x 20 mm (thickness) was taken from the ingot obtained in step S1. The slab is kept in a heating furnace at 900 ° C for 20 minutes, and then sent to a hot rolling mill for 4 passes of unidirectional hot rolling. The deformation of each pass is 20%, 10%, 10%, and 10%. After room temperature, surface sandblasting was performed to obtain a hot-rolled intermediate plate with a thickness of 10 mm, and the edges of the plate were smooth and free of cracks. The intermediate plate was solution-treated at 850° C. for 30 minutes, and quenched with water to obtain an alloy plate. Observe the microstructure of the longitudinal section of the sheet and compare it with the Ti-2(wt.%)Al-9.2(wt.%)Mo-2(wt.%)Fe alloy (2A2F) sheet prepared under the same process, as shown in As shown in Fig. 3a and Fig. 3b, it can be seen that the structure of the plate obtained by the method of the present invention is obviously more uniform.

Example 2

S1. Alloy ingot smelting:

According to the composition requirements of Ti-2(wt%)Al-9.2(wt%)Mo-2(wt%)Fe-0.1(wt%)B alloy, take the corresponding weight of AlMo55, MoFe50, FeB20, Ti-32Mo master alloy and For grade 0 sponge titanium, the electrodes are pressed by layered cloth, and then smelted twice by vacuum consumable arc smelting equipment to obtain a 32Kg alloy flat ingot to ensure uniform composition. The surface of the ingot was then peeled off, and the chemical composition of the ingot was tested by chemical methods (Table 2). The phase transition point was determined by quenching metallographic method to be 815±5℃.

Table 2 Chemical composition (mass content) of 2A2F10B alloy ingot

Al Mo Fe B Ti 2.12 9.26 2.04 0.098 margin

S2. Sheet rolling:

A rolled slab of 115 mm (length) x 80 mm (width) x 20 mm (thickness) was taken from the ingot shown in step S1. The slab was kept in a heating furnace at 900 ° C for 20 minutes, and then sent to a hot rolling mill for 4 passes of unidirectional hot rolling. The deformation of each pass was 25%, 20%, 15%, and 10%. After room temperature, surface sandblasting was performed to obtain a hot-rolled intermediate plate with a thickness of 6 mm, and the edges of the plate were smooth and free of cracks. The intermediate plate was solution-treated at 850°C for 30 minutes, and then water quenched to obtain an alloy plate. The microstructure of the longitudinal section of the sheet was observed and compared with the longitudinal section of the Ti-2 (wt%) Al-9.2 (wt%) Mo-2 (wt%) Fe alloy sheet prepared under the same process, as shown in Figure 4a and As shown in Figure 4b, the microstructure of the plate obtained by the method of the present invention has uniform and fine grains, while the grain size in the microstructure of the 2A2F alloy plate is larger, and the uniformity of the structure is also worse than that of the 2A2F10B alloy.

Example 3

S1. Alloy ingot smelting:

According to the composition requirements of Ti-2(wt%)Al-9.2(wt%)Mo-2(wt%)Fe-0.1(wt%)B alloy, take the corresponding weight of AlMo55, MoFe50, FeB20, Ti-32Mo master alloy and For grade 0 sponge titanium, the electrodes are pressed by layered cloth, and then smelted twice by vacuum consumable arc smelting equipment to obtain a 32Kg alloy flat ingot to ensure uniform composition. The surface of the ingot was then peeled and the chemical composition of the ingot was tested by chemical method (Table 3). The phase transition point was determined by quenching metallographic method to be 815±5℃.

Table 32 Chemical composition (mass content) of 2A2F10B alloy ingot

Al Mo Fe B Ti 2.07 9.21 2.02 0.11 margin

S2. Sheet rolling:

A rolled slab of 115 mm (length) x 80 mm (width) x 20 mm (thickness) was taken from the ingot shown in step S1. The slab was kept in a heating furnace at 900 ° C for 20 minutes, and then sent to a hot rolling mill for 4 passes of unidirectional hot rolling. The deformation of each pass was 40%, 20%, 15%, and 10%. Surface sandblasting was performed after room temperature to obtain a hot-rolled intermediate plate with a thickness of 3 mm. The edge of the intermediate plate was smooth and no obvious cracks appeared. The plate was solution-treated at 850° C. for 30 minutes, and quenched with water to obtain an alloy plate. The microstructure of the longitudinal section of the sheet was observed and compared with the microstructure of the longitudinal section of the Ti-2Al-9.2Mo-2Fe alloy sheet prepared under the same process, as shown in Figures 5a and 5b. It can be seen that the microstructure of the plate obtained by the method of the present invention has small grain size, and the uniformity of the structure is obviously better than that of the 2A2F alloy plate. Take the plate-like tensile sample from the plate along the rolling direction, test its tensile mechanical properties according to GB/T228.1-2010, and compare the tensile mechanical properties of the 2A2F alloy plate obtained by the traditional plate preparation process, see Table 4 As shown, it can be seen that the tensile mechanical properties of the alloy prepared by the method of the present invention are equivalent to the same alloy plate obtained by the traditional plate preparation process.

Table 4 Tensile mechanical properties of the 2A2F10B alloy plate prepared by the present invention and the 2A2F alloy plate prepared by the traditional plate preparation process

alloy Yield strength/MPa Tensile strength/MPa Elongation at break (%) 2A2F10B 868 689 34 2A2F 850 680 35

Claims (10)

1. A metastable beta titanium alloy plate processed by a short process is characterized in that: the titanium alloy plate comprises 0.11-0.2 wt% of boron element;

the short-process preparation and processing method of the metastable beta titanium alloy plate comprises the following steps:

(1) mixing the raw materials, pressing the raw materials into electrodes, connecting the electrodes, and then smelting for 2-3 times to obtain a titanium alloy ingot;

(2) peeling the titanium alloy ingot obtained in the step (1), cutting the slab, carrying out heat preservation treatment on the slab, carrying out 3-5 passes of rolling by hot rolling equipment on the slab under one fire to obtain an intermediate plate, and carrying out solution treatment on the plate to obtain the titanium alloy plate.

2. The short-run preparation processing method of the metastable beta titanium alloy plate according to claim 1, characterized by comprising the following steps:

(1) mixing the raw materials, pressing the raw materials into electrodes, connecting the electrodes, and then smelting for 2-3 times to obtain a titanium alloy ingot;

(2) peeling the titanium alloy ingot obtained in the step (1), cutting the slab, carrying out heat preservation treatment on the slab, carrying out 3-5 passes of rolling by hot rolling equipment on the slab under one fire to obtain an intermediate plate, and carrying out solution treatment on the plate to obtain the titanium alloy plate.

3. The method of claim 2, wherein the method comprises the steps of: the time of the solution treatment in the step (2) is 20min-1 h.

4. The method of claim 2, wherein the method comprises the steps of: and (3) the cooling mode in the solid solution treatment in the step (2) is water quenching or air cooling.

5. The method of claim 2, wherein the method comprises the steps of: the raw materials in the step (1) comprise raw materials for preparing the metastable beta titanium alloy and boron-containing intermediate alloy or boron powder.

6. The method of claim 5, wherein the method comprises the steps of: the boron-containing intermediate alloy is AlTiB or FeB, wherein the mass fraction of Al element in the AlTiB is not more than 10%, and the mass fraction of boron element in the FeB is not less than 18%.

7. The method of claim 5, wherein the method comprises the steps of: when the metastable beta titanium alloy component contains Fe element, the raw material in the step (1) comprises raw material for preparing the metastable beta titanium alloy and FeB.

8. The method of claim 5, wherein the method comprises the steps of: when the metastable beta titanium alloy contains Al element, the raw material in the step (1) comprises the raw material for preparing the metastable beta titanium alloy and AlTiB.

9. The method of claim 5, wherein the method comprises the steps of: when the metastable beta titanium alloy composition contains neither Al element nor Fe element, the raw material in the step (1) includes a raw material for preparing the metastable beta titanium alloy and boron powder.

10. The method of claim 2, wherein the method comprises the steps of: the heat preservation treatment time of the plate blank in the step (2) is determined according to the thickness of the plate blank, and is specifically 1.0-2.0 min/mm; the heat preservation treatment temperature is T_β-T_β+100℃，T_βIs the titanium alloy phase transition temperature; the deformation of each pass of rolling is not less than 10 percent, and the total deformation of rolling is not less than 50 percent; the solution treatment temperature is T_β-T_β+50℃，T_βIs the phase transition temperature of the titanium alloy.

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