A method for improving the uniformity of the structure of large high-strength titanium alloy components

Abstract

The invention relates to the technical field of metal thermal processing, in particular to a method for improving the structural uniformity of a large high-strength titanium alloy component. The method comprises the following steps: S1: placing an ingot in a heating furnace and heating the ingot to a forging temperature; S2: performing multiple forging on the ingot to form a raw material; S3: performing multiple heating forging on the raw material to finally form a forging; S4: placing the forging in a heating furnace, heating the forging to Tβ+Δt, and keeping the temperature for 90 to 120 minutes; S5: after the temperature is kept, heating the forging to Tβ+Δn again, and keeping the temperature for 60 to 90 minutes; then adjusting the temperature of the heating furnace to an aging temperature, and performing aging and heat preservation for a third time; the method places the forging in a heating furnace, heats the forging to Tβ+Δt, and keeps the temperature for 90 to 120 minutes; completely transforms α grains in the forging into β grains, and then heats the forging to Tβ+Δn again, and keeps the temperature for 60 to 90 minutes; thus making the β grains grow uniformly and eliminating the contrast difference in the forging structure.

Description

Technical Field

[0001] The invention relates to the technical field of metal thermal processing, in particular to a method for improving the structural uniformity of a large high-strength titanium alloy component. Background Art

[0002] With the demand for lightweight aviation equipment, key load-bearing components are gradually developing in the direction of large-scale and integrated, which further increases the size of raw material bars. In the production process of large-scale raw material bars (diameter ≥ 400mm), large-scale ingots (diameter ≥ 700mm) are often used to produce raw materials. Due to the small forging ratio, the number of fires from ingots to large-scale raw materials is small, and the degree of deformation is insufficient, which will produce a large amount of incomplete recrystallization in the core. There will be a large number of small-angle grain boundaries in the incompletely recrystallized grains, which will cause a significant contrast difference between the incompletely recrystallized grains and the completely recrystallized grains ( Figure 1 ), resulting in uneven overall structure of forgings produced after traditional heat treatment, which will eventually be inherited by the forging structure. In addition, it is easy to have uneven overall structure, such as uneven distribution of size and volume fraction of α grains in various parts of the bar ( Figure 2 If the traditional heat treatment process is used, the core of the forging still has the primary α phase ( Figure 3 ), resulting in poor product performance.

[0003] When producing small-sized raw materials (diameter < 350mm), large-sized ingots (diameter ≥ 700mm) are also used to produce raw materials. However, during the forging process, the forging ratio is large, and multiple forgings will be performed in the middle. During the multiple forgings, the size of the large-sized ingots gradually decreases, and the deformation of the forgings during the forging process is more uniform, so that the α grains in the core of the forgings can also be uniformly deformed. The temperature can also be guaranteed to be uniform during the heat treatment process, which can eliminate the overall structural unevenness in the large-sized ingots and obtain raw materials with uniform overall structural morphology. Finally, the overall structural morphology of the forgings is also very uniform. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for improving the uniformity of the structure of large high-strength titanium alloy components, so as to eliminate the contrast difference in the forging structure.

[0005] The technical solution adopted by the present invention to solve the technical problem is a method for improving the uniformity of the structure of large high-strength titanium alloy components, comprising the following steps:

[0006] S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature;

[0007] S2: The ingot is forged in multiple rounds to form raw materials;

[0008] S3: The raw materials are heated and forged for multiple times to form forgings;

[0009] S4: Place the forging in a heating furnace, heat the forging to Tβ+Δt, Δt is -30 to -20°C, and keep warm for 90 to 120 minutes;

[0010] S5: After the insulation is completed, the forging is heated to Tβ+Δn, Δn is 15-30°C, and the insulation is carried out for 60-90 minutes; then the forging is subjected to aging insulation treatment.

[0011] S6: Turn off the heating furnace and allow the forging to air cool to room temperature.

[0012] Furthermore, in step S5, the aging and heat preservation process is as follows: the temperature of the heating furnace is adjusted to the aging temperature, the aging temperature is 540-590°, and the forging is placed in the heating furnace for aging and heat preservation for 6-8 hours.

[0013] Furthermore, in step S4, the forging is heated to Tβ+Δt, where Δt is -30°C to -20°C, and held at this temperature for 90 to 120 minutes to ensure that all α grains are completely dissolved and transformed into β grains. This promotes the dissolution of α grains and the conversion of low-angle grain boundaries into high-angle grain boundaries, weakening the contrast.

[0014] The beneficial effects of the present invention are as follows: by placing a forging in a heating furnace, heating the forging to Tβ+Δt, and keeping the temperature for a first time; α grains in the forging are completely transformed into β grains and promoting the transformation of small-angle grain boundaries into large-angle grain boundaries, thereby weakening the contrast; and then heating the forging to Tβ+Δn, where n is greater than t, and keeping the temperature for a second time; β grains are uniformly grown, ensuring uniform internal structure of the forging, avoiding excessive growth of β grains, and eliminating contrast differences in the forging structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a physical image of an ingot with contrast differences in the prior art;

[0016] Figure 2 yes Figure 1 Schematic diagram of the crystal phase in;

[0017] Figure 3 yes Figure 1 Schematic diagram of the crystal phase of the formed forging;

[0018] Figure 4 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0019] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0020] like Figure 1 As shown, the present invention provides a method for improving the uniformity of the structure of a large high-strength titanium alloy component, comprising the following steps:

[0021] S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature;

[0022] S2: The ingot is forged in multiple rounds to form raw materials;

[0023] S3: The raw materials are heated and forged for multiple times to form forgings;

[0024] S4: Place the forging in a heating furnace, heat the forging to Tβ+Δt, Δt is -30 to -20°C, and keep warm for 90 to 120 minutes;

[0025] S5: After the insulation is completed, the forging is heated to Tβ+Δn, Δn is 15-30°C, and the insulation is carried out for 60-90 minutes; then the forging is subjected to aging insulation treatment.

[0026] S6: Turn off the heating furnace and allow the forging to air cool to room temperature.

[0027] The ingot is a titanium alloy steel ingot with contrast differences, with a diameter of at least 700 mm. The raw material formed by forging the ingot has a diameter of at least 400 mm. During the processing from the ingot to the raw material, due to the small forging ratio, the raw material also exhibits contrast differences. This contrast difference is ultimately inherited into the forging structure, and the typical structure of the forging still exhibits contrast differences. Contrast differences are abnormalities in the central structure and uneven distribution of grain size and volume fraction. The forging is placed in a heating furnace and heated to Tβ+Δt, where Δt is -30 to -20°C, for 90 to 120 minutes. This promotes the dissolution of α grains and the conversion of low-angle grain boundaries to high-angle grain boundaries, weakening the contrast. The forging is then heated to Δn of 15 to 30°C for 60 to 90 minutes, allowing the β grains to grow uniformly, ensuring a uniform internal structure and eliminating contrast differences.

[0028] In step S5, the aging and heat preservation process is as follows: the temperature of the heating furnace is adjusted to the aging temperature, the aging temperature is 540-590°, and the forging is placed in the heating furnace for aging and heat preservation for 6-8 hours.

[0029] Furthermore, in step S4, the forging is heated to Tβ+Δt, where Δt is -30 to -20°C, and kept warm for 90 to 120 minutes to ensure that all α grains are completely dissolved and completely transformed into β grains, thereby promoting the dissolution of the α phase and the transformation of low-angle grain boundaries into high-angle grain boundaries, thereby weakening the contrast.

[0030] Example 1

[0031] S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature;

[0032] S2: The ingot is forged in multiple rounds to form raw materials;

[0033] S3: The raw materials are heated and forged for multiple times to form forgings;

[0034] S4: Place the forging in a heating furnace, heat the forging to (Tβ-30)°, and keep it warm for 90 minutes;

[0035] S5: After the insulation is completed, the forging is heated to Tβ+15° and kept warm for 60 minutes; then the heating furnace temperature is adjusted to 540° and aging is carried out for 6 hours;

[0036] S6: Turn off the heating furnace and allow the forging to air cool to room temperature.

[0037] Example 2

[0038] S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature;

[0039] S2: The ingot is forged in multiple rounds to form raw materials;

[0040] S3: The raw materials are heated and forged for multiple times to form forgings;

[0041] S4: Place the forging in a heating furnace, heat the forging to (Tβ-20)°, and keep it warm for 120 minutes;

[0042] S5: After the insulation is completed, the forging is heated to Tβ+30° and kept warm for 90 minutes; then the heating furnace temperature is adjusted to 590° and aging is carried out for 8 hours;

[0043] S6: Turn off the heating furnace and allow the forging to air cool to room temperature.

[0044] Comparative Example 1

[0045] S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature;

[0046] S2: The ingot is forged in multiple rounds to form raw materials;

[0047] S3: The raw materials are heated and forged for multiple times to form forgings;

[0048] S4: Turn off the heating furnace and allow the forging to air cool to room temperature.

[0049] The mechanical properties of the forgings formed in Example 1, Example 2 and Comparative Example 1 were tested, as shown in the following table.

[0050] serial number tensile strength Yield strength Elongation Sectional shrinkage Example 1 1170 1050 12 24 Example 2 1178 1058 11 22 Comparative Example 1 1120 1039 16 37

[0051] The mechanical properties test results show that the mechanical properties of the forgings treated by this method are significantly higher than those of the untreated forgings.

[0052] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the microstructure uniformity of large high-strength titanium alloy components, characterized by: The following steps are included: S1: Place the ingot in a heating furnace and heat it to the forging temperature until the core of the ingot reaches the temperature; S2: The ingot is forged in multiple rounds to form raw materials; S3: The raw materials are heated and forged for multiple times to form forgings; S4: Place the forging in a heating furnace, heat the forging to Tβ+Δt, Δt is -30~-20℃, and keep it warm for 90~120 minutes; S5: After the insulation is completed, the forging is heated to Tβ+Δn, Δn is 15~30℃, and the temperature is kept for 60~90 minutes; then the forging is subjected to aging insulation treatment; The aging and heat preservation process is as follows: the temperature of the heating furnace is adjusted to the aging temperature, the aging temperature is 540~590°, and the forging is placed in the heating furnace for aging and heat preservation for 6~8 hours; S6: Turn off the heating furnace and allow the forging to air cool to room temperature.

2. A method for improving the microstructure uniformity of a large high-strength titanium alloy component according to claim 1, characterized in that: In step S4, the forging is heated to Tβ+Δt, where Δt is -30 to -20°C, and kept warm for 90 to 120 minutes to ensure that all α grains are completely dissolved and completely transformed into β grains.

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