A Ti-6242 alloy ring forging beta forging method and device

Abstract

The present invention belongs to the technical field of titanium alloy hot processing, and relates to a β forging method and device for a Ti-6242 alloy ring forging. The method comprises: step 1, performing conventional α+β zone forging on a Ti-6242 alloy bar to obtain a prefabricated Ti-6242 alloy ring blank; step 2, heating and sheathing the Ti-6242 alloy ring blank at a temperature range of 25 to 35°C at a phase transition point; step 3, rolling the heated and sheathed Ti-6242 alloy ring blank at a phase transition point, and the control points thereof include: a) controlling the furnace transfer time within 40s; b) controlling the rolling ring speed increase at 8mm / s to 10mm / s, Control to complete 70% to 80% of the total reserved deformation, and control the rolling time to 15s to 20s; Step 4, rolling the rolled Ti-6242 alloy ring billet at the phase change point, and the control points include: a) pausing for 5 to 10s after rolling; b) rolling to the final size of the ring at a ring speed of 4mm / s to 6mm / s after the pause, completing the remaining 20% ​​to 30% deformation, and controlling the rolling time to 10s to 15s, ensuring that the entire furnace forging process time is controlled within 90s.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy hot processing, and relates to a Ti-6242 alloy ring forging beta forging method and device. Background Art

[0002] Ti-6242 alloy is a near-α-type titanium alloy. It is based on Ti-Al-based α solid solution, with Sn and Zr added at the same time. The high-temperature creep resistance of the alloy is significantly improved through solid solution strengthening. Under the combined effect of Al, Sn and Zr, the alloy obtains good high-temperature strength, and has a high strength up to 540℃. It is mainly used to manufacture compressor casings, drums and discs of aircraft engines.

[0003] Ti-6242 alloy forgings for engines are usually forged in the two-phase zone, and after forging, near-β heat treatment + air cooling are used to obtain dual-state structure. In recent years, studies have found that dual-state structure Ti-6242 alloy forgings have load-keeping fatigue sensitivity under compressor working conditions, which greatly limits the application of this alloy in aero-engine forgings. In order to reduce the load-keeping fatigue sensitivity, it is urgent to develop a Ti-6242 alloy β forging process that can obtain a basketweave structure. The α+β forging technology of Ti-6242 alloy has been widely used in the aviation field, and the process maturity is high. However, the β forging process, especially the β forging of ring forgings, is still blank in China. The wall thickness of the ring forging is small, the β forging heating temperature is high, the temperature drop is fast, the forging window is narrower, and the structure control is more difficult. Summary of the invention

[0004] The purpose of the present invention is to realize the beta forging basket structure control technology of Ti-6242 alloy drum ring forgings to avoid the occurrence of dual-state structure and Widmanstatten structure.

[0005] To solve this technical problem, the technical solution of the present invention is:

[0006] A Ti-6242 alloy ring forging β forging method, comprising:

[0007] Step 1: Perform conventional α+β zone forging on the Ti-6242 alloy bar to obtain a prefabricated Ti-6242 alloy ring blank; the Ti-6242 alloy ring blank reserves 40% to 50% deformation for the final β ring rolling forging;

[0008] Step 2: heating and jacketing the Ti-6242 alloy ring blank at a temperature range of 25 to 35° C. above the phase transition point;

[0009] Step 3, rolling the heated and jacketed Ti-6242 alloy ring billet at the phase change point, wherein the control points include: a) the furnace transfer time is controlled within 40s; b) the rolling ring speed is controlled within 8mm / s to 10mm / s, and 70% to 80% of the total reserved deformation is completed, and the rolling time is controlled within 15s to 20s;

[0010] Step 4: rolling the rolled Ti-6242 alloy ring billet at the phase transformation point, and the control points include: a) pausing for 5 to 10 seconds after completing step 3; b) rolling the ring billet to the final size of the ring at a ring speed increase of 4 mm / s to 6 mm / s after the pause, completing the remaining 20% ​​to 30% deformation, and controlling the rolling time to 10s to 15s to ensure that the entire furnace forging process time is controlled within 90s.

[0011] Further, the heating coefficient of step 2 is 0.7 min / mm to 0.9 min / mm;

[0012] Furthermore, in step 2, a 10 mm thick aluminum silicate thermal insulation cotton is used for soft packaging, and after the packaging is completed, the product is returned to the furnace and kept at the original temperature for 45 to 60 minutes.

[0013] Furthermore, the heating temperature for conventional α+β zone forging is 30°C to 50°C below the phase transformation point.

[0014] A Ti-6242 alloy ring forging β forging device, comprising:

[0015] The conventional forging unit is used to perform conventional α+β zone forging on the Ti-6242 alloy bar to obtain a prefabricated Ti-6242 alloy ring blank; the Ti-6242 alloy ring blank reserves 40% to 50% of deformation for the final fire β ring rolling forging;

[0016] A heating and jacketing unit is used to heat and jacket the Ti-6242 alloy ring blank within a temperature range of 25 to 35°C above the phase transition point;

[0017] The first rolling unit is used to roll the heated and jacketed Ti-6242 alloy ring billet at the phase change point, and its control points include: a) the furnace transfer time is controlled within 40s; b) the rolling ring speed is controlled at 8mm / s to 10mm / s, and the total reserved deformation is controlled to be 70% to 80%, and the rolling time is controlled at 15s to 20s;

[0018] The second rolling unit is used to roll the rolled Ti-6242 alloy ring billet at the phase change point, and its control points include: a) pausing for 5 to 10 seconds after completing step three; b) rolling to the final size of the ring at a ring speed increase of 4 mm / s to 6 mm / s after the pause, completing the remaining 20% ​​to 30% deformation, and controlling the rolling time to 10s to 15s to ensure that the entire furnace forging process time is controlled within 90s.

[0019] Further, the heating coefficient of the heating and jacketing unit is 0.7min / mm to 0.9min / mm;

[0020] Furthermore, the heating and jacketing unit is soft-wrapped with aluminum silicate insulation cotton with a thickness of 10 mm. After the jacketing is completed, the unit is returned to the furnace and kept at the original temperature for 45 to 60 minutes.

[0021] Furthermore, the heating temperature for conventional α+β zone forging is 30°C to 50°C below the phase transformation point.

[0022] The beneficial effect of the present invention is that: through the above steps, a uniform basket-structure Ti-6242 alloy ring forging can be obtained, in which all original β grain boundaries are broken and there is no straight and coarse grain boundary α phase. After conventional solid solution + aging heat treatment, the forging has room temperature and high temperature tensile properties equivalent to those of dual-structure Ti-6242 alloy forgings, and higher fracture toughness and thermal creep resistance, while reducing the load-holding fatigue sensitivity of the Ti-6242 alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a low-power image of the forging structure;

[0024] Figure 2 This is a 100x diagram of the forging structure;

[0025] Figure 3 This is a 200x diagram of the forging structure;

[0026] Figure 4 This is a 500x picture of the forging structure. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Step 1: Forge the Ti-6242 alloy bar in the conventional α+β zone at 30℃~50℃ below the phase transformation point, and complete the processes of upsetting, punching, pre-expansion, etc. The pre-expansion process must control the size of the forging billet to reserve 40%~50% of the deformation for the final fire β ring rolling forging.

[0029] Step 2: Heat the Ti-6242 alloy ring blank that has completed two-phase zone forging within a temperature range of 25 to 35°C at the phase transition point, with a heating coefficient of 0.7 min / mm to 0.9 min / mm. After this process is completed, use 10 mm thick aluminum silicate insulation cotton for soft wrapping. After wrapping, return to the furnace and keep it at the original temperature for 45 to 60 minutes.

[0030] Step 3: Roll the Ti-6242 alloy billet that has been heated and jacketed in step 2 at the phase change point. The main control points are: a) the furnace transfer time is controlled within 40s; b) the rolling ring speed increase is controlled at 8mm / s to 10mm / s, and 70% to 80% of the total reserved deformation is completed, and the rolling time is controlled at 15s to 20s.

[0031] Step 4: Roll the billet rolled at the phase transformation point in step 3 below the phase transformation point, with the main control points being: a) pause the rolling for 5 to 10 seconds after completing step 3; b) roll the billet to the final size of the ring at a ring speed of 4 mm / s to 6 mm / s after the pause, and complete the remaining 20% ​​to 30% deformation. The rolling time is controlled within 10 to 15 seconds to ensure that the entire furnace forging process is controlled within 90 seconds.

[0032] Example 1

[0033] The compressor drum for a certain type of engine is made of Ti-6242 titanium alloy. The outer dimensions of the forging are Φ560×Φ440×125, and the blanking weight is ~60Kg.

[0034] By adopting the present invention, a Φ230×315 specification bar is subjected to three-time forging at 35°C below the phase transition point to complete the processes of upsetting, punching and pre-forging. After pre-forging, the size of the blank is Φ405×Φ200×125.

[0035] The β ring rolling forging process is as follows: the forging billet is heated by a soft jacket at 30°C at the phase transformation point; the rolling transfer time is 35s; the first stage of rolling at the phase transformation point adopts an 8mm / s ring speed increaser to roll to a size of ~Φ500×Φ355×127, pauses for 8s, and then changes to a 5mm / s ring speed increaser to roll to ~Φ560×Φ440×128. The final forging structure is shown in Figure 1-4 , performance is shown in Table 1.

[0036] Table 1 Mechanical properties of typical parts

[0037]

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A Ti-6242 alloy ring forging β forging method, characterized in that: include: Step 1: Perform conventional α+β zone forging on the Ti-6242 alloy bar to obtain a prefabricated Ti-6242 alloy ring blank; The Ti-6242 alloy ring blank reserves 40% to 50% deformation for the final β ring rolling forging; Step 2: heating and jacketing the Ti-6242 alloy ring blank at a temperature range of 25 to 35°C above the phase transition point; the heating coefficient is 0.7 min / mm to 0.9 min / mm; Step 3: rolling the heated and jacketed Ti-6242 alloy ring billet at the phase change point, wherein the control points include: a) the furnace transfer time is controlled within 40 seconds; b) the rolling ring speed is controlled within 8 mm / s to 10 mm / s, 70% to 80% of the total reserved deformation is completed, and the rolling time is controlled within 15 seconds to 20 seconds; Step 4: rolling the rolled Ti-6242 alloy ring billet at the phase transformation point, and the control points include: a) pausing for 5 to 10 seconds after completing step 3; b) rolling the ring billet to the final size of the ring at a ring speed increase of 4 mm / s to 6 mm / s after the pause, completing the remaining 20% ​​to 30% deformation, and controlling the rolling time to 10s to 15s to ensure that the entire furnace forging process time is controlled within 90s.

2. The method according to claim 1, characterized in that The heating temperature for conventional α+β zone forging is 30℃~50℃ below the phase transformation point.

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