A forging method for obtaining TC18 forgings with basketweave structure

Abstract

The present invention discloses a forging method for obtaining a TC18 forging with a basketweave structure in the field of titanium alloy forging technology, comprising: (1) first heating: selecting a TC18 titanium alloy bar as a raw material, and heating the raw material to 5°C to 25°C below its β transformation temperature; (2) 1-fire forging: using a small forging device to upset the raw material after the first heating; (3) hot billet reheating: heating the raw material after 1-fire forging to 5°C to 25°C below its β transformation temperature; (4) 2-fire forging: using a small forging device to stretch the raw material obtained in step (3); (5) hot billet reheating: heating the raw material after 2-fire forging to 5°C to 25°C below its β transformation temperature; (6) 3-fire forging: using a small forging device to upset the raw material obtained in step (5). The present invention can forge a TC18 titanium alloy forging with a uniform basketweave structure by using a small forging device.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy forging, and in particular relates to a forging method for obtaining a TC18 forging with a basketweave structure. Background Art

[0002] TC18 titanium alloy is a near-β titanium alloy with high strength and high toughness. Its nominal chemical composition is Ti-5AI-5Mo-5V-1Cr-1Fe. It is suitable for manufacturing various large forgings in aircraft fuselages and landing gear structures. It is mainly used to produce support rods on aircraft landing gears. Therefore, high performance indicators of TC18 titanium alloy are required, among which the fracture toughness (KIC) must be greater than or equal to 60MPa. In order to meet the design requirements, the improvement of fracture toughness is mainly achieved by forging a uniform basketweave structure.

[0003] At present, TC18 titanium alloy can obtain excellent organization and comprehensive performance through a process that combines pressure processing (forging, rolling) with heat treatment. The forging of TC18 titanium alloy generally adopts the quasi-β forging process, which is suitable for manufacturing large parts that require high fracture toughness. The quasi-forging process is to heat and keep the titanium alloy within a certain range above the phase transformation point, and then deform it greatly below the phase transformation point and air-cool it to obtain a basket structure with higher fracture toughness and better comprehensive performance. This method requires large-scale forging equipment, high production equipment investment costs, and high requirements for heat treatment, and the process is relatively complicated. On the other hand, because the organization of TC18 titanium alloy is particularly sensitive to hot working technology, the grain structure of the forged forgings forged using a small device such as a 560Kg air hammer combined with existing forging methods is mainly Widmanstatten structure and the fracture toughness is only 50MPa The performance index is far below the design requirements.

[0004] Therefore, by optimizing the forging process and using small equipment such as a 560Kg air hammer to produce TC18 titanium alloy square forgings with uniform basketweave structure, it has a positive significance for reducing production costs. Summary of the invention

[0005] The present invention is intended to provide a forging method for obtaining TC18 forgings with a basketweave structure, so as to solve the problem that existing small-sized air hammer equipment is difficult to forge TC18 titanium alloy forgings with a uniform basketweave structure.

[0006] A forging method for obtaining a TC18 forging having a basketweave structure in this solution comprises the following steps:

[0007] (1) First heating: Select TC18 titanium alloy rod as raw material, heat the raw material to 5℃~25℃ below its β transformation temperature, and keep it warm for 50min~80min according to effective thickness × (0.5min / mm~0.8min / mm);

[0008] (2) 1-fire forging: Use small forging equipment to upset the raw material after the first heating, and control the deformation to 30% to 50%;

[0009] (3) Hot billet reheating: Heat the raw material after the first forging to 5℃~25℃ below its β transformation temperature, according to the effective thickness × (0.25min / mm~0.4min / mm), and keep it warm for 25min~40min;

[0010] (4) 2-fire forging: Use small forging equipment to stretch the raw material after the hot billet is returned to the furnace for heating in step (3), and the deformation amount is controlled to 50% to 80%;

[0011] (5) Hot billet reheating: Heat the raw material after 2-fire forging to 5°C to 25°C below its β transformation temperature, according to the effective thickness × (0.25min / mm to 0.4min / mm), and keep it warm for 25min to 40min;

[0012] (6) Fire forging: Use small forging equipment to upset the raw material after the hot billet is returned to the furnace for heating in step (5), and control the deformation amount to 30% to 50% to obtain the TC18 forging with basket structure.

[0013] Beneficial effects of this solution: By optimizing the forging process of TC18, this solution can also forge TC18 titanium alloy forgings with uniform basketweave structure when using small forging equipment; thereby greatly reducing the production equipment cost of TC18 titanium alloy, and also simplifying the heat treatment process, making the forging of TC18 titanium alloy forgings more efficient.

[0014] Furthermore, after the three-fire forging in step (6), the TC18 forging is further subjected to step (7) of hot billet reheating and step (8) of final forging, so that a TC18 square forging with a basket structure can be obtained, specifically:

[0015] (7) Hot billet reheating: Heat the raw material after 3-forging to 5°C to 25°C below its β transformation temperature, according to the effective thickness × (0.25min / mm to 0.4min / mm), and keep it warm for 25min to 40min;

[0016] (8) Final forging: Use small forging equipment to square the raw materials after the hot billet is returned to the furnace for heating in step (7).

[0017] The TC18 square forging with basket structure is obtained by controlling the deformation amount to 50% to 80%.

[0018] TC18 square forgings with basketweave structure can be quickly produced by reheating the hot billet and performing final forging.

[0019] Further, the small forging equipment is a 560kg air hammer or a 760kg air hammer. The present application takes the 560kg air hammer and the 760kg air hammer as the preferred ones, but the small forging equipment is not limited thereto.

[0020] Furthermore, before the first heating, a titanium alloy anti-oxidation coating with a thickness of 0.5 to 1 mm is uniformly coated on the surface of the raw material. General lithium-based grease, imported tolerance mechanical grease, etc. can be used as the titanium alloy anti-oxidation coating.

[0021] Furthermore, the raw material is rounded before being coated with the titanium alloy anti-oxidation coating, and the rounded corner radius is 5 to 10 mm. The rounded corner setting can increase the fluidity of the raw material and prevent the raw material from cracking due to stress concentration at the sharp corner.

[0022] Furthermore, the selected raw materials meet the Q / 11AJ06500-2013 standard. The selected raw materials meet the requirements of the Q / 11AJ06500-2013 standard on supply status and specifications, chemical composition, mechanical properties, ultrasonic testing, size and shape, and macrostructure and microstructure.

[0023] In the application documents, 5°C to 25°C below the β transition temperature refers to 25°C below the β transition temperature to 5°C below the β transition temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The blue mesh organization diagram of the TC18 forging prepared in Example 1 of the present invention;

[0025] Figure 2 Schematic diagram of sampling for TC18 forgings prepared in Example 1 of the present invention;

[0026] Figure 3 The hydrogen content test report of TC18 forgings prepared in Example 1 of the present invention (excerpt);

[0027] Figure 4 Macrocorrosion test report of TC18 forging prepared in Example 1 of the present invention (excerpt);

[0028] Figure 5 Microstructure test report of TC18 forging prepared in Example 1 of the present invention (excerpt);

[0029] Figure 6The tensile and impact properties test report of the TC18 forging prepared in Example 1 of the present invention (excerpt);

[0030] Figure 7 Fracture toughness test report of TC18 forging prepared in Example 1 of the present invention (excerpt);

[0031] Figures 8 to 14 It is Q / 11AJ06500-2013 standard (excerpt);

[0032] Figures 15 to 22 It is Q / 11AJ06501-2013 standard (excerpt). DETAILED DESCRIPTION

[0033] The following is further described in detail through specific implementation methods:

[0034] Instructions attached Figure 2 Explanation of the figure marks: (1-1, 1-2) are sampling positions for tensile performance testing, (2-1, 2-2) are sampling positions for impact performance testing, (4-1, 4-2) are sampling positions for fracture toughness testing, and 6-1 is the sampling position for hydrogen content testing.

[0035] Embodiment 1: A forging method for obtaining a TC18 forging having a basketweave structure, comprising the following steps:

[0036] (1) Raw material procurement and control: Purchase Φ100 TC18 titanium alloy bars as raw materials. The raw materials are re-tested for chemical composition, mechanical properties, macrostructure, fracture toughness, grain size, flaw detection (inspection of internal quality A grade), etc. to ensure that they meet the Q / 11AJ06500-2013 standard (see attached for details). Figures 8 to 14 );

[0037] (2) Cutting: Cutting size is Φ100×230mm;

[0038] (3) Machining: chamfering (raw material rounding R10mm);

[0039] (4) Coating: The surface of the raw material is evenly coated with a 0.8 mm thick titanium alloy anti-oxidation (hydrogen absorption) coating, and the coating is made of general lithium-based grease or imported tolerance mechanical grease;

[0040] (5) First heating: Heat the coated raw material in a box-type electric furnace to 15°C below the β-transformation temperature of the raw material, at the effective thickness × 0.6 min / mm, and keep warm for 70 min;

[0041] (6) 1-fire forging: the raw material after the first heating is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm;

[0042] (7) Hot billet reheating: The raw material after the first forging is heated in a box-type electric furnace to 15°C below the β-transformation temperature of the raw material, and the temperature is kept at effective thickness × 0.3min / mm for 30min;

[0043] (8) 2-fire forging: The hot billet from step (7) is returned to the furnace for heating and placed on a 560kg air hammer workbench for elongation. The elongated size is Φ100×245mm.

[0044] (9) Hot billet reheating: The raw material after the second forging is heated in a box-type electric furnace to 15°C below the β-transformation temperature of the raw material, and the temperature is kept at effective thickness × 0.3 min / mm for 230 min;

[0045] (10) 3-fire forging: The raw material after the hot billet is returned to the furnace for heating in step (9) is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm, and the TC18 forging with basket structure is obtained.

[0046] The difference between Example 2 and Example 1 is that it also includes step (11) hot billet reheating and step (12) final forging, specifically:

[0047] (11) Hot billet reheating: The raw material after 3-fire forging is heated in a box-type electric furnace to 15°C below the β-transformation temperature of the raw material, and kept warm for 30 minutes at the effective thickness × 0.3 min / mm.

[0048] (12) Final forging: The raw material after the hot billet is returned to the furnace for heating in step (11) is placed on a 560 kg air hammer workbench for drawing and forming. The size after drawing and forming is 83×59×272 mm, and a TC18 square forging with a basket structure is obtained.

[0049] Embodiment 3: A forging method for obtaining a TC18 forging having a basketweave structure, comprising the following steps:

[0050] (1) Raw material procurement and control: Purchase Φ100 TC18 titanium alloy bars as raw materials. The raw materials are re-tested for chemical composition, mechanical properties, macrostructure, fracture toughness, grain size, flaw detection (inspection of internal quality A grade), etc. to ensure that they meet the Q / 11AJ06500-2013 standard (see attached for details). Figures 8 to 14 );

[0051] (2) Cutting: Cutting size is Φ100×230mm;

[0052] (3) Machining: chamfering (raw material rounding R5mm);

[0053] (4) Coating: The surface of the raw material is evenly coated with a 1mm thick titanium alloy anti-oxidation (hydrogen absorption) coating, and the coating is made of general lithium-based grease or imported tolerance mechanical grease;

[0054] (5) First heating: Heat the coated raw material in a box-type electric furnace to 25°C below the β-transformation temperature of the raw material, at the effective thickness × 0.5 min / mm, and keep warm for 50 min;

[0055] (6) 1-fire forging: the raw material after the first heating is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm;

[0056] (7) Hot billet reheating: The raw material after the first forging is heated in a box-type electric furnace to 5°C below the β-transformation temperature of the raw material, and the temperature is kept at effective thickness × 0.4 min / mm for 40 min;

[0057] (8) 2-fire forging: The hot billet from step (7) is returned to the furnace for heating and placed on a 560kg air hammer workbench for elongation. The elongated size is Φ100×245mm.

[0058] (9) Hot billet reheating: The raw material after the second forging is heated in a box-type electric furnace to 25°C below the β-transformation temperature of the raw material, and the temperature is kept at effective thickness × 0.25min / mm for 25min;

[0059] (10) 3-fire forging: The raw material after the hot billet is returned to the furnace for heating in step (9) is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm, and the TC18 forging with basket structure is obtained.

[0060] Example 4: A forging method for obtaining a TC18 forging having a basketweave structure, comprising the following steps:

[0061] (1) Raw material procurement and control: Purchase Φ100 TC18 titanium alloy bars as raw materials. The raw materials are re-tested for chemical composition, mechanical properties, macrostructure, fracture toughness, grain size, flaw detection (inspection of internal quality A grade), etc. to ensure that they meet the Q / 11AJ06500-2013 standard (see attached for details). Figures 8 to 14 );

[0062] (2) Cutting: Cutting size is Φ100×230mm;

[0063] (3) Machining: chamfering (raw material rounding R5mm);

[0064] (4) Coating: The surface of the raw material is evenly coated with a 0.6 mm thick titanium alloy anti-oxidation (hydrogen absorption) coating, and the coating is made of general lithium-based grease or imported tolerance mechanical grease;

[0065] (5) First heating: Heat the coated raw material in a box-type electric furnace to 55°C below the β-transus temperature of the raw material, at the effective thickness × 0.8 min / mm, and keep warm for 80 min;

[0066] (6) 1-fire forging: the raw material after the first heating is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm;

[0067] (7) Hot billet reheating: The raw material after the first forging is heated in a box-type electric furnace to 25°C below the β-transformation temperature of the raw material, and kept warm for 25 minutes at the effective thickness × 0.25min / mm;

[0068] (8) 2-fire forging: The hot billet from step (7) is returned to the furnace for heating and placed on a 560kg air hammer workbench for elongation. The elongated size is Φ100×245mm.

[0069] (9) Hot billet reheating: The raw material after the second forging is heated in a box-type electric furnace to a temperature 5°C below the β-transformation temperature of the raw material, and the temperature is kept at effective thickness × 0.4 min / mm for 40 min;

[0070] (10) 3-fire forging: The raw material after the hot billet is returned to the furnace for heating in step (9) is placed on a 560kg air hammer workbench for upsetting. The size after upsetting is Φ125×150mm, and the TC18 forging with basket structure is obtained.

[0071] The difference between Example 5 and Example 4 is that it also includes step (11) hot billet reheating and step (12) final forging, specifically:

[0072] (11) Hot billet reheating: The raw material after 3-fire forging is heated in a box-type electric furnace to 25°C below the β-transformation temperature of the raw material, and kept warm for 25 minutes at the effective thickness × 0.4 min / mm.

[0073] (12) Final forging: The raw material after the hot billet is returned to the furnace for heating in step (11) is placed on a 560 kg air hammer workbench for drawing and forming. The size after drawing and forming is 83×59×272 mm, and a TC18 square forging with a basket structure is obtained.

[0074] Sampling and testing:

[0075] Sampling and testing: The square forgings prepared in Example 2 were sampled for grain size and fracture toughness testing, and all indicators were required to meet the requirements of the Q / 11AJ06501-2013 forging standard. The grain size test results are shown in the attached Figure 1 As shown, the average grain size of the forging is Q / 11AJ06501-2013 standard. Figure 2 The fracture toughness test result of the 4 types is 82.3MPa 81.5MPa Other properties meet the requirements of Q / 11AJ06501-2013 forging standard. For details on the test results of hydrogen content, macro corrosion, microstructure, tensile properties, impact properties and fracture toughness, please see the attached Figures 3 to 7 .

[0076] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A forging method for obtaining a TC18 forging having a basket structure, characterized in that: The following steps are involved: (1) First heating: Select TC18 titanium alloy rod as raw material, heat the raw material to 5℃~25℃ below its β transformation temperature, and keep it warm for 50min~80min according to effective thickness × (0.5min / mm~0.8min / mm); (2) 1-fire forging: Use small forging equipment to upset the raw material after the first heating, and control the deformation to 30% to 50%; (3) Hot billet reheating: Heat the raw material after the first forging to 5℃~25℃ below its β transformation temperature, according to the effective thickness × (0.25min / mm~0.4min / mm), and keep it warm for 25min~40min; (4) 2-fire forging: Use small forging equipment to stretch the raw material after the hot billet is returned to the furnace for heating in step (3), and the deformation amount is controlled to 50% to 80%; (5) Hot billet reheating: Heat the raw material after 2-fire forging to 5°C to 25°C below its β transformation temperature, according to the effective thickness × (0.25min / mm to 0.4min / mm), and keep it warm for 25min to 40min; (6) 3-fire forging: Use small forging equipment to uproot the raw material after the hot billet is returned to the furnace for heating in step (5), and control the deformation amount to 30% to 50% to obtain the TC18 forging with basket structure.

2. A forging method for obtaining a TC18 forging with a basket structure according to claim 1, characterized in that: After the three-fire forging in step (6), the TC18 forging with the basket structure is further subjected to step (7) of hot billet reheating and step (8) of final forging, so that the TC18 square forging with the basket structure can be obtained, specifically: (7) Hot billet reheating: Heat the raw material after 3-forging to 5°C to 25°C below its β transformation temperature, according to the effective thickness × (0.25min / mm to 0.4min / mm), and keep it warm for 25min to 40min; (8) Final forging: The raw material after the hot billet is returned to the furnace for heating in step (7) is subjected to square drawing using a small forging device, and the deformation amount is controlled to 50% to 80% to obtain the TC18 square forging with basket structure.

3. A forging method for obtaining a TC18 forging with a basket structure according to claim 1 or 2, characterized in that: The small forging equipment is a 560kg air hammer or a 760kg air hammer.

4. A forging method for obtaining a TC18 forging with a basket structure according to claim 3, characterized in that: Before the first heating, a titanium alloy anti-oxidation coating with a thickness of 0.5 to 1 mm is evenly coated on the surface of the raw material.

5. A forging method for obtaining a TC18 forging with a basket structure according to claim 4, characterized in that: The raw material is rounded before being coated with the titanium alloy anti-oxidation paint, and the fillet radius is 5 to 10 mm.

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