Forging method of high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb

Abstract

The invention belongs to the field of internal structure forming of forgings, and particularly relates to a forging method of a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb. The method includes the steps that firstly, the production heating number is determined according to the forge piece weight; 2, the deformation amount of each heating number is determined according to the weight of the forge piece; thirdly, the charging mode of each heating number is determined according to the weight of the forge piece; fourthly, the forging temperature is determined according to the weight of the forge piece; 5, the cooling mode of each heating number is determined according to the weight of the forge piece; 6, charging according to the determined charging mode of each heating number, heating to the forging temperature, preserving heat for preset time, forging according to the determined heating number and deformation, and cooling according to the determined cooling mode after forging of each heating number is finished; and seventhly, heat treatment is conducted after forging is finished.

Description

Technical Field

[0001] The invention belongs to the field of internal structure forming of forgings, and in particular relates to a forging method of a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb. Background Art

[0002] Ti-5Cr-5Mo-5V-4Al-1Nb is a high-strength and high-toughness titanium alloy that has been put into practical use on aircraft in recent years. The alloy not only has good oxidation resistance, deep hardenability, hot and cold processing performance, easy forging, rolling and welding, but also can be used for solid solution aging heat treatment process to obtain high mechanical properties and good strength and fracture toughness matching. It has high static strength, high fracture toughness and high damage tolerance, and is mainly used as important load-bearing parts such as aircraft landing gear and crossbeams. Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy is a new type of near-β titanium alloy developed by my country in cooperation with many domestic universities and research institutes. Its nominal composition is Ti-5Cr-5Mo-5V-4Al-1Nb. After heat treatment, the fracture toughness of the alloy is at the same level as that of traditional high-strength alloys, but its static strength is higher and it has good hardenability. After solution aging heat treatment, the strength of the alloy can reach more than 1300MPa, while its fracture toughness can be maintained at 70MPa×m 1 / 2 above.

[0003] The forging process of the commonly produced high-strength titanium alloy Ti-5Cr-5Mo-5V-4Al-1Nb forgings will cause the internal structure grain size of the forgings to gradually grow, the tensile strength and yield strength to first decrease and then increase, the elongation, KIC and impact to first increase and then decrease, and the cross-sectional shrinkage to continue to increase; with the increase of aging temperature, the interweaving distribution of the precipitated secondary α phase tends to be more dense, the secondary α phase is coarser, the tensile strength and yield strength continue to decrease, the elongation and cross-sectional shrinkage first decrease and then increase, and the KIC and impact gradually increase; it cannot meet the requirements of the final standard of forgings. Summary of the invention

[0004] Purpose of the invention: To provide a forging method for a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb, so that the forgings of the high-strength titanium alloy Ti-5Cr-5Mo-5V-4Al-1Nb meet the recrystallized β-state basketweave structure with an average grain size of 302um.

[0005] Technical solution:

[0006] A forging method for a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb, comprising:

[0007] Step 1: Determine the production number according to the weight of the forging;

[0008] Step 2: Determine the deformation amount for each fire according to the weight of the forging;

[0009] Step 3: Determine the furnace loading method for each fire according to the weight of the forgings;

[0010] Step 4: Determine the forging temperature according to the weight of the forging;

[0011] Step 5: Determine the cooling method for each fire according to the weight of the forging;

[0012] Step 6: Load the furnace according to the determined charging method for each fire and heat it to the forging temperature and keep it warm for a predetermined time, forge according to the determined fire times and deformation amount, and cool it according to the determined cooling method after each fire forging;

[0013] Step 7: Heat treatment is performed after forging.

[0014] Preferably, in step 1, the relationship between weight and firing order is:

[0015] Forging weight (Kg) G≤200 200＜G≤400 400＜G≤600 600＜G≤800 Fire times (N) 1 fire 2 fire 3 fire ≥4 fire

[0016] Preferably, in step 2, the relationship between weight and deformation is:

[0017] Forging weight (Kg) G≤200 200＜G≤400 400＜G≤600 600＜G≤800 Deformation (%) 30≤δ<35 25≤δ<30 20≤δ<25 15≤δ<20

[0018] Preferably, in step 3, the furnace loading method for each fire is:

[0019]

[0020]

[0021] Preferably, in step 4, the relationship between weight and forging temperature is:

[0022]

[0023] Preferably, in step 5, the cooling method for each firing is:

[0024]

[0025] Preferably, in step seven, the heat treatment method is:

[0026] Solution treatment: heating temperature is 865℃~880℃; holding time is 100min~150min; air cooling in a wind-proof place after taking out of the furnace;

[0027] Aging: Heating temperature is 520℃~535℃; insulation time is 220min~260min; after taking out of the furnace, keep it away from wind and air cool it.

[0028] Preferably, in step six, the insulation time is calculated according to the heating coefficient 1 min / mm.

[0029] Beneficial effects:

[0030] By using 2500T fast forging machine equipment, the forging temperature and deformation of the forging are optimized, and the deformation during forging, the number of fires in production, the forging temperature, the cooling method, and the matching of the technical parameters of the furnace setting method are combined to effectively improve the residual undeformed original grain structure of Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy forgings of different specifications during forging, and improve the production qualification rate of forgings and the qualification rate of the required internal organization. At the same time, the mutual matching relationship of the deformation technical parameters during forging of forgings is well controlled for forging production. And by comprehensively considering the heating temperature deformation amount and other factors required for forgings; the requirements for the final physical and chemical requirements of forgings are improved. As a result, the forging qualification rate of Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy is improved, and the scrap loss is reduced. Energy is saved and economic benefits are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a low-magnification structure of a lower anti-torsion arm according to an embodiment of the present invention;

[0032] Figure 2 It is a high-power organization of the lower anti-torsion arm according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] This paper studies the production conditions and the influence of different sizes of Ti-5Cr-5Mo-5V-4Al-1Nb forgings on their performance to explore the process of producing large-size forgings that meet the requirements, provide theoretical and experimental basis for the production of large-size new ultra-high strength and toughness titanium alloy free forgings, and enrich and improve the in-plant production of titanium alloy materials for aviation.

[0034] This paper explores the process of producing large-size forgings that meet the requirements and ultimately meet physical and chemical testing standards by restricting the production conditions for Ti-5Cr-5Mo-5V-4Al-1Nb forgings of different sizes.

[0035] The technical problem to be solved by the present invention is to make the high-strength titanium alloy Ti-5Cr-5Mo-5V-4Al-1Nb forgings produced by 2500T fast forging machine equipment meet the required internal structure requirements, the required internal structure is: recrystallized β-state basket structure, the average grain size is 302um, and the mechanical properties requirements (tensile strength ≥ 1300MPa):

[0036] Forging process conditions of forgings. Through research and analysis, under the same equipment production conditions, forgings of different weights are produced using different forging constraints to complete the production of high-strength titanium alloy Ti-5Cr-5Mo-5V-4Al-1Nb forgings on 2500T fast forging machine equipment, and finally achieve the required organization and mechanical properties.

[0037] To achieve the above object, the present invention provides a forging method of a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb, the method comprising the following steps:

[0038] Step 1: Determine the production fire order according to the weight of the forging:

[0039] Forging weight (Kg) G≤200 200＜G≤400 400＜G≤600 600＜G≤800 Fire times (N) 1 fire 2 fire 3 fire ≥4 fire

[0040] Step 2: Determine the deformation amount for each fire according to the weight of the forging:

[0041]

[0042] Step 3: Determine the furnace loading method for each fire according to the size of the forging:

[0043]

[0044] The thermal insulation coating may be CONDAT 312.

[0045] The thermal insulation cotton can be 5mm aluminum silicate.

[0046] Step 4: Determine and set the forging temperature according to the weight of the forging:

[0047]

[0048] Step 5: Determine the cooling method according to the weight of the forging:

[0049]

[0050]

[0051] Step 6: Load the furnace according to the determined charging method for each fire and heat it to the forging temperature and keep it warm for a predetermined time, forge according to the determined fire times and deformation amount, and cool it according to the determined cooling method after each fire forging;

[0052] Step 7, heat treatment: solution + aging

[0053] Solution treatment: heating temperature is 865℃~880℃; holding time is 100min~150min; air cooling in a wind-proof place after taking out of the furnace;

[0054] Aging: Heating temperature is 520℃~535℃; insulation time is 220min~260min; air-cooling in a wind-proof place after taking out of the furnace;

[0055] Step 8: Physical and chemical inspection: dissect one forging from each batch for physical and chemical inspection; perform the inspection according to the forging bar standard YMS1526A; physical and chemical items: chemical composition, mechanical properties, low and high magnification organization inspection, etc.

[0056] Step 9, machining: machining all end faces; surface roughness Ra3.2

[0057] Step 10, flaw detection: Flaw detection is carried out according to GB / T 5193, and the standard for grade A acceptance is 100% ultrasonic inspection

[0058] The above is a forming method for improving the uniformity of the structure of Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy forgings of different specifications on a 2500T fast forging machine. The method is a production method that combines the characteristics of the weight of the forgings to be produced, the amount of deformation required for production, the number of fires in production, the forging temperature, the cooling method, and the matching of the technical parameters of the furnace setting method to solve the problem of uneven low-magnification structure and unqualified mechanical properties of the forging billet caused by uneven deformation of the forging billet at high temperature.

[0059] The above is a forming method for improving the uniformity of the structure of Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy forgings of different specifications on a 2500T fast forging machine. Under the constraints of technical conditions such as deformation amount, production fire number, forging temperature, cooling method, and setting furnace loading method, different production methods are adopted for forgings of different weights to effectively improve the original grain structure remaining undeformed inside the forging, improve the forging production forging qualification rate and the required internal structure and performance indicators to meet the final requirements.

[0060] The above is a forming method for improving the uniformity of the structure of Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy forgings of different specifications on a 2500T fast forging machine. It can well control the deformation amount, production fire number, forging temperature, cooling method, and matching of technical parameters of the furnace setting method during forging. And by comprehensively considering the parameters required for forgings, production process control and other factors, the final physical and chemical requirements of the bars can be improved.

[0061] Example:

[0062] Production details: Part number: ZDJ-YS10-5825200001-001; Material: Ti-5Cr-5Mo-5V-4Al-1Nb titanium alloy; Specification: Φ250×700; Weight: 161.4Kg; Standard: YMS1526; Name: Lower anti-torsion arm; Bar specification: 155×280×≥725

[0063] Phase transition point: β = 808°C

[0064] Step 1: Forging:

[0065] First fire: Heating temperature and holding time: Load the furnace to the required temperature, the heating coefficient is calculated as 1min / mm, and the temperature is raised to 770℃×250min;

[0066] Technical requirements: The pressing speed of this process step is 15mm / s; the pressing amount is 80mm-100mm; the feeding amount is 20mm-50mm;

[0067] Forging: Φ250×700, axial upsetting: ~Φ295×500±15, then flattening and drawing to: 155+30×280+30×≥725;

[0068] Cooling method: air cooling.

[0069] Step 2: Heat treatment

[0070] Solution heat treatment: heating temperature is 870℃; holding time is 120min; air cooling in a wind-proof place after taking out of the furnace;

[0071] Aging heat treatment: heating temperature is 528℃; holding time is 240min; air cooling in a wind-proof place after taking out of the furnace;

[0072] Step 3: Physical and chemical inspection: dissect one piece from each batch for physical and chemical inspection; forging standard YMS1526 is implemented; physical and chemical items: chemical composition (transferred raw materials), hydrogen content, room temperature tensile properties, high magnification, low magnification, KIC, impact, hardness;

[0073] Step 4:

[0074] Machining: Machining according to special drawings; surface roughness Ra3.2

[0075] Flaw detection: GB / T 5193, Grade A acceptance: 100% ultrasonic flaw detection acceptance.

[0076] After the above-mentioned example experiments, the physical and chemical properties are qualified, and the high and low magnification structures are shown. Figure 1 and Figure 2 . The mechanical properties are all qualified.

[0077] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent changes made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A forging method for a high-strength titanium alloy Ti5Cr5Mo5V4Al1Nb, characterized in that: include: Step 1: Determine the production number according to the weight of the forging; Step 2: Determine the deformation amount for each fire according to the weight of the forging; Step 3: Determine the furnace loading method for each fire according to the weight of the forgings; Step 4: Determine the forging temperature according to the weight of the forging; Step 5: Determine the cooling method for each fire according to the weight of the forging; Step 6: Load the furnace according to the determined charging method for each fire and heat it to the forging temperature and keep it warm for a predetermined time, forge according to the determined fire times and deformation amount, and cool it according to the determined cooling method after each fire forging; Step 7: Heat treatment is performed after forging.

2. The method according to claim 1, characterized in that In step 1, the relationship between weight and fire number is:

3. The method according to claim 2, characterized in that In step 2, the relationship between weight and deformation is:

4. The method according to claim 1, characterized in that: In step 3, the furnace loading method for each fire is:

5. The method according to claim 1, characterized in that In step 4, the relationship between weight and forging temperature is:

6. The method according to claim 1, characterized in that In step 5, the cooling method for each fire is:

7. The method according to claim 1, characterized in that In step seven, the heat treatment method is: Solution treatment: heating temperature is 865℃~880℃; holding time is 100min~150min; air-cooling in a wind-proof place after taking out of the furnace; Aging: Heating temperature is 520℃~535℃; insulation time is 220min~260min; after taking out of the furnace, keep it away from wind and air cool it.

8. The method according to claim 1, characterized in that In step six, the holding time is calculated according to the heating coefficient of 1min / mm.

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