Forging method of large TC18 titanium alloy right trapezoid free forge piece

Abstract

The invention belongs to the field of titanium alloy forging, and particularly relates to a forging method for a large TC18 titanium alloy right-trapezoid free forge piece. The method comprises the following steps: first heating number: upsetting a TC18 titanium alloy phi 400 specification bar until the deformation in the length direction reaches 20-50% to obtain a forging stock; chamfering and broadening the forging stock; in the second heating number, the width of the forging stock is reduced along the bevel edge of the right trapezoid, then the thickness size is finished, and the deformation is controlled to be 20%-50%; the length of the widened forging stock is not greater than that of the forge piece; the third heating number is that the forging stock subjected to width reduction correction is forged and pressed in the thickness direction, and the deformation is controlled to be 25%-35%; and the fourth heating number is that the forged and pressed forging stock is trimmed to the size required by the drawing, and the deformation is controlled to be 5%-10%.

Description

Technical Field

[0001] The invention belongs to the field of titanium alloy forging, and in particular relates to a forging method for a large TC18 titanium alloy "right-angle trapezoidal" free forging. Background Art

[0002] Titanium alloys are widely used in aerospace, medical equipment and other fields due to their advantages such as low density, high strength and corrosion resistance. Ultra-high-strength titanium alloys represented by TC18 titanium alloy have excellent comprehensive properties and occupy an important position in the materials used in large aircraft manufacturing. They are often used to manufacture large load-bearing structural parts such as beams, trusses and reinforcement frames.

[0003] At present, titanium alloy aircraft structural parts are mainly formed by forging technology. Due to the special working environment, in the design and manufacturing process of aircraft components, the main technical indicators are to enhance the strength and rigidity of the structural parts and improve the stress corrosion resistance and fracture toughness of the structural parts. In the initial stage of aircraft research and development, titanium alloy forgings were mostly used in the form of free forgings, which facilitated structural optimization and changes and flexible adjustments. In order to save materials, free forgings are often designed and used according to the shape of parts, breaking the inherent thinking mode of traditional free forgings "rectangular shape", but this brought high challenges to free forging. Summary of the invention

[0004] The purpose of the present invention is to provide a forging method for large-scale TC18 titanium alloy "right-angled trapezoidal" free forgings, the forgings weighing more than 1000kg, while ensuring the forging forming, avoiding the instability of the forging structure, thereby improving the uniformity and stability of the product structure and performance.

[0005] Technical solution:

[0006] A forging method for a large TC18 titanium alloy "right-angle trapezoidal" free forging is provided, comprising:

[0007] First firing: Roughen the TC18 titanium alloy φ400 bar until the deformation in the length direction reaches 20%-50% to obtain a forging blank; widen the chamfer of the forging blank;

[0008] Second fire: widen the forging billet along the hypotenuse of the "right-angle trapezoid", and then trim the thickness, and control the deformation within 20%-50%; the length of the forging billet after widening shall not be greater than the length of the forging;

[0009] The third fire: forging the forging blank after width correction along the thickness direction, and the deformation is controlled within 25%-35%;

[0010] Fourth fire: trim the forging billet after forging to the size required by the drawing, and control the deformation within 5%-10%.

[0011] Furthermore, the entire forging furnace transfer process is required to be completed within 50 seconds; the heating temperature range for the first, second and fourth fires is 30-35°C below the phase change point, and the heating temperature range for the third fire is 12-15°C above the phase change point; the heating and insulation time for cold materials is calculated as 1.5-2.5min / mm; the insulation time for hot materials returning to the furnace is calculated as 0.8-1.5min / mm.

[0012] Furthermore, the third heating process does not allow hot material to be returned to the furnace.

[0013] Furthermore, special measuring tools are made according to the size requirements of the drawings to measure the target size in real time during the forging process.

[0014] Furthermore, the forging process of the first, second and fourth fires is required to be completed within 5-10 minutes, and the forging process of the third fire is required to be completed within 3-5 minutes. After the forging is completed, the final forging temperature is greater than or equal to 720°C.

[0015] Furthermore, during the entire forging process, the feed amount each time is ≤ 2 / 3 of the hammer anvil.

[0016] Furthermore, the amount of pressure per hammer is 100-200 mm.

[0017] Furthermore, the pressing speed is 5 to 10 mm / s.

[0018] Beneficial effects:

[0019] Through the three-stage forging of the technical solution, it is possible to ensure that the material structure is qualified and stable while meeting the "right-angle trapezoid" size requirements of the forging. The structure of the material is a key factor in determining the material performance. Only when the structure of the forging is qualified can the performance of the forging be guaranteed to be qualified, and then the qualified forging finished product can be guaranteed. The present invention can meet the above two requirements at the same time, the mechanical properties of the forging are also qualified, and a good match of strength and plasticity can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the final size of the forging.

[0021] Figure 2 Organize photos for high magnification

[0022] Figure 3 Organize photos for low magnification DETAILED DESCRIPTION

[0023] Example:

[0024] 1) Cutting material: Φ400×1887mm Material grade: TC18

[0025] Marking: smelting furnace number or code, ingot section number, material grade, and suffix of forging drawing number.

[0026] 2) Forging:

[0027] First fire: Forging size Φ400×1887, roughing to Φ500×~1200, then stretching and squared to 640×246×~1506;

[0028] Second fire: Forging size 640×246×~1506 squared and shaped to 640(506)×246×~1690

[0029] The third fire: Forging size: press 246 in the thickness direction to 172, and use a special sample to compare the slope size;

[0030] The fourth fire: trim the size to the final size of the forging 640 (455) × 172 × ~ 2340, such as Figure 1 shown.

[0031] Equipment: 45MN fast forging machine

[0032] Heating equipment: electric furnace.

[0033] The first heating temperature is 30℃ below the phase change point and kept warm for 320min;

[0034] The second heating temperature is 30℃ below the phase change point and kept warm for 200min;

[0035] The third heating temperature is 30℃ below the phase change point, and the temperature is kept for 200min. The temperature is raised with the furnace to 15℃ above the phase change point, and the temperature is kept for 90min.

[0036] The fourth heating temperature is 30℃ below the phase transition point and kept warm for 140min;

[0037] Forging technical requirements:

[0038] a) Preheat the hammer, anvil and tools to 150-350℃ before forging;

[0039] b) Billet transfer time ≤ 60s;

[0040] c) 4 fire completed;

[0041] d) Final forging temperature ≥720℃.

[0042] 3) Heat treatment: Performed according to special heat treatment process

[0043] Primary annealing: 830±10℃×180±15min, furnace cooling to 750±10℃ and keeping temperature for 180±15min, then air cooling after being taken out of the furnace;

[0044] Secondary annealing: 616±5℃×360±15min, air cooling.

[0045] 4) Physical and chemical: Conduct physical and chemical tests according to the sampling diagram.

[0046] 2.3 Trial production results

[0047] 1) H content (wt. / %): 0.0015.

[0048] 2) High magnification: It is composed of strip-shaped and spherical α phase and β transformation organization, which meets the standard Figure 2 Level 6. High-magnification tissue photos such as Figure 2 shown.

[0049] 3) Low magnification: Low magnification streamline distribution is basically along the shape, without throughflow and severe eddy current. Low magnification has no shrinkage, pores, stratification, segregation, cracks, metal and non-metal inclusions and other metallurgical defects. Low magnification meets the standard Figure 1 Level 4, low-power tissue such as Figure 3 shown.

[0050] 4) Mechanical properties

[0051]

Claims

1. A forging method for large TC18 titanium alloy "right-angle trapezoidal" free forgings, characterized in that: include: First firing: Roughen the TC18 titanium alloy φ400 bar until the deformation in the length direction reaches 20%-50% to obtain a forging blank; widen the chamfer of the forging blank; Second fire: widen the forging billet along the hypotenuse of the "right-angle trapezoid", and then trim the thickness, and control the deformation within 20%-50%; the length of the forging billet after widening shall not be greater than the length of the forging; The third fire: forging the forging blank after width correction along the thickness direction, and the deformation is controlled within 25%-35%; Fourth fire: trim the forging billet after forging to the size required by the drawing, and control the deformation within 5%-10%.

2. The method according to claim 1, characterized in that The entire forging furnace transfer process is required to be completed within 50 seconds; the heating temperature range for the first, second and fourth fires is 30-35℃ below the phase change point, and the heating temperature range for the third fire is 12-15℃ above the phase change point; the heating and insulation time for cold materials is calculated as 1.5-2.5min / mm; the insulation time for hot materials returning to the furnace is calculated as 0.8-1.5min / mm.

3. The method according to claim 1, characterized in that The third heating process does not allow hot material to be returned to the furnace.

4. The method according to claim 1, characterized in that Make special measuring tooling according to the size requirements of the drawing, and measure the target size in real time during the forging process.

5. The method according to claim 2, characterized in that The forging process of the first, second and fourth fires is required to be completed within 5-10 minutes, and the forging process of the third fire is required to be completed within 3-5 minutes. After forging, the final forging temperature is greater than or equal to 720℃.

6. The method according to claim 2, characterized in that During the entire forging process, the feed amount each time is ≤2 / 3 of the hammer and anvil.

7. The method according to claim 4, characterized in that The pressing amount of each hammer is 100-200mm.

8. The method according to claim 5, characterized in that The pressing speed is 5 to 10 mm / s.

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