CN116618562A - Free forging preparation method of Ti55531 titanium alloy large-size square billet - Google Patents

Abstract

The invention discloses a method for preparing Ti55531 titanium alloy large-scale billet free forging, specifically performing "high-low-high" billet forging on the Ti55531 titanium alloy ingot in sequence, low-temperature forging in the two-phase region below the β temperature, lateral widening, and drawing. Flat square forming billet; the weight of the Ti55531 titanium alloy large-scale forging billet prepared by this method can reach 2T, the structure and mechanical properties of high and low magnification are good, which can meet the requirements of various standards and specifications, and can realize the preparation of large-scale Ti55531 titanium alloy forging billet It can meet the purpose of mass production and has important economic and military strategic significance.

Description

Preparation method of Ti55531 titanium alloy large-scale billet free forging

technical field

The invention belongs to the technical field of titanium alloy material processing, and relates to a method for preparing Ti55531 titanium alloy large-size billet free forging.

Background technique

In the aerospace industry, titanium alloy is one of the main structural materials of aircraft and engines; in order to meet the requirements of new aviation structural parts on material performance and process performance, the latest titanium alloy design development trend is towards the comprehensive combination of high strength and high toughness development direction; at present, traditional high-strength and high-toughness titanium alloys mainly include near-β-type titanium alloys Ti-1023 and BT22 (domestic brand TC18, nominal composition is Ti-5Al-5Mo-5V-1Fe-1Cr), etc.; With the rapid development of the industry, new high-strength and high-toughness titanium alloys are also being continuously developed. Among them, Ti55531 titanium alloy is a high-strength, toughness, metastable β-type titanium alloy developed by VSMPO and Airbus based on BT-22. Its Mo equivalent is 13.1, and its strength level in the annealed state can reach 1080MPa. After heat treatment, the tensile strength can exceed 1500MPa; the nominal composition of Ti55531 titanium alloy is Ti-5Al-5V-5Mo-3Cr-1Zr, and its chemical composition Contains a higher mass fraction of β-phase stable elements such as molybdenum, vanadium, chromium, etc., so the alloy can still maintain a complete β-phase after quenching, and has a lower α/β transformation temperature (the phase transition point ranges from about 820 to 860℃); Ti55531 alloy, as a class of high-performance light-weight and high-strength structural material, has lower smelting and processing costs than Ti-1023 alloy, does not produce obvious composition segregation, and has high specific strength, high tensile strength, Good fracture toughness, good hardenability (≥250mm), insensitivity to segregation, and a wide range of processing technology, etc., easy to achieve matching control of strength, toughness and other indicators, and has excellent comprehensive mechanical properties;

Ti55531 titanium alloy, as a class 1 high-performance light-weight and high-strength structural material, has received great attention in the aviation field. The connection device between the wing and the pylon of a large long-range wide-body passenger aircraft has been applied;

Contents of the invention

The purpose of the present invention is to provide a Ti55531 titanium alloy large-size billet free forging preparation method to realize the preparation of 2T-level large-size Ti55531 titanium alloy billet, which is convenient for subsequent forging and machining to form special-shaped structural parts with specific appearance specifications.

The technical solution adopted in the present invention is the preparation method of Ti55531 titanium alloy large-scale billet free forging, specifically performing "high-low-high" billet forging on the Ti55531 titanium alloy ingot in sequence, and low-temperature forging in the two-phase region below the β temperature , Horizontal widening, drawing and flattening square billets.

The present invention is also characterized in that:

Among them, the Ti55531 titanium alloy large-scale billet free forging preparation method is specifically implemented according to the following steps:

Step 1, "high-low-high" billet forging: the Ti55531 titanium alloy ingot is subjected to the first upsetting and drawing forging at 100 ° C ~ 300 ° C above the β transformation temperature. ℃～50℃ for the second upsetting forging, and then the third upsetting forging at 30℃～50℃ above the β transformation temperature, and air cooling after forging;

Step 2, low-temperature forging in the two-phase region below the β temperature: perform upsetting forging on the blank processed in step 1, and the heating temperature is 30°C to 60°C below the β transformation temperature, and use air cooling after upsetting forging;

Step 3, transverse widening: the billet processed in step 2 is subjected to transverse widening and deformation, and the heating temperature is 30°C to 60°C below the β transformation temperature, and air cooling is adopted after forging;

Step 4, flattening and square forming: performing flattening and square forming on the blank processed in step S3, and the heating temperature is 30°C to 60°C below the β transformation temperature, and air cooling is adopted after forging;

Among them, in step 1, when the blank is heated at 100°C to 300°C above the β transformation temperature, the alloy is first heated to 800°C and kept for 120 minutes, and then heated to the required temperature for heat preservation; during the first upsetting, the ingot The sawing surface needs to be riveted and upset. When upsetting, the upsetting method is used to upset half, turn over and then upset to size;

Among them, in step 1, the upsetting forging is carried out at 100°C to 300°C above the β transformation temperature for 2 to 4 times, and the deformation of each fire is controlled between 30% and 50%; the temperature below the β transformation temperature is 30°C to 50°C for 1 ～2 times of upsetting forging, the deformation is controlled between 30-50%; 1-2 times of upsetting forging is carried out at 30°C-50°C above the β transformation temperature, and the deformation is controlled between 30-50%;

Wherein in step 2, the billet processed in step 1 is subjected to upsetting and drawing forging for 3 to 5 times, and the deformation is controlled between 30 and 50%;

Wherein step 1 and step 2 in the upsetting and drawing forging, the drawing speed is not greater than 20mm/s, and the single reduction is not greater than 100mm;

Wherein, in step 3, the blank processed in step 2 is subjected to lateral widening and deformation for 1 to 3 times, and the deformation is controlled between 20 and 50%;

The transfer time of the billet from the heating furnace to the fast forging machine in step 2 and step 3 shall not exceed 40 seconds, and the final forging temperature shall not be less than 800°C;

Wherein in step 4, the billet processed in step 3 is flattened and square-shaped, and the amount of deformation is controlled between 15% and 40%;

Wherein in the step 4, the number of times of flattening and forming fires is no more than 2 fire times.

The beneficial effects of the present invention are:

Compared with the conventional forging billet, the method for preparing Ti55531 titanium alloy large-size square billet free forging of the present invention utilizes the forging pressure advantage of the 10000T large-tonnage fast forging machine to provide a large amount of deformation when the forging billet is widened and deformed, which can effectively reduce the number of fires , to improve production efficiency, the formed large-size billet can be subsequently modified for forging and machining to add special-shaped parts with specific size requirements. Therefore, the free forging preparation method of a Ti55531 titanium alloy large-size billet provided by the present invention can realize the preparation of a 2T-level large-size Ti55531 titanium alloy billet, which has important economic and military strategic significance.

Description of drawings

Fig. 1 is the flow chart of Ti55531 titanium alloy large size billet free forging preparation method of the present invention;

Fig. 2 is the Ti55531 titanium alloy large-size square billet R-state macroscopic appearance in the Ti55531 titanium alloy large-size square billet free forging preparation method of the present invention;

Fig. 3 is Ti55531 titanium alloy large-scale billet finished product morphology in the Ti55531 titanium alloy large-scale square billet free forging preparation method of the present invention;

Fig. 4 is the Ti55531 titanium alloy large-scale billet microstructure in the Ti55531 titanium alloy large-scale square billet free forging preparation method of the present invention;

Fig. 5 is the room temperature mechanical properties of Ti55531 titanium alloy large-size billet in solid solution aging state in the preparation method of Ti55531 titanium alloy large-size billet free forging of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The invention provides a Ti55531 titanium alloy large-scale billet free forging preparation method, which is specifically implemented according to the following steps: as shown in Figure 1, the Ti55531 titanium alloy ingot is sequentially subjected to "high-low-high" billet forging, β temperature Low-temperature forging, lateral widening, and flattening of square billets in the following two-phase areas;

Example 1

The method for preparing Ti55531 titanium alloy large-scale billet free forging specifically includes the following steps:

Step 1, "high-low-high" blank forging: the Ti55531 titanium alloy ingot is subjected to upsetting and drawing forging at 100°C to 300°C above the β transformation temperature for 3 times, and the deformation of each fire is controlled at 30% to 50%. In between, air cooling is used after forging, followed by two upsetting forgings at 30°C to 50°C below the β transformation temperature, and the deformation is controlled between 30% and 50%, and then at 30°C to 50°C above the β transformation temperature Carry out 2 times of upsetting and drawing forging, the amount of deformation is controlled between 30% and 50%, and air cooling is used after forging;

Step 2, low-temperature forging in the two-phase region below the β temperature: Carry out 4 times of upsetting and drawing forging on the billet processed in step S1, and the heating temperature is 30°C to 60°C below the β transformation temperature, and the deformation is controlled between 30% and 50%. After upsetting and forging, air cooling is adopted;

Step 3, transverse widening: carry out two times of transverse widening deformation on the billet processed in step S2, and the heating temperature is 30°C-60°C below the β transformation temperature, the deformation is controlled between 20-50%, and air cooling is used after forging ;

Step 4, flattening and square forming: the billet processed in step S3 is subjected to flattening and square forming for one heat, and the heating temperature is 30°C to 60°C below the β transformation temperature, and the deformation is controlled between 15% and 40%. Then use air cooling.

Example 2

Preferably, in step 1, when heating the cold blank at 100°C to 300°C above the β-transition temperature, it is first heated to 800°C and kept for 120 minutes, and then heated to the required temperature for heat preservation.

Preferably, in step 1, when upsetting for the first time, the sawn surface of the ingot needs to be riveted and upset, and the upsetting method is first half upset, turned over and then upset to size.

Preferably, in step 1 and step 2, the drawing speed is ≤20mm/s, and the single reduction is ≤100mm.

Preferably, in step 2 and step 3, the transfer time of the billet from the heating furnace to the fast forging machine is ≤40S, and the final forging temperature is ≥800°C.

Preferably, in step S4, the number of flattening and square forming fires is not more than 2 fires.

Example 3

Experimental results

As shown in Figure 2 and Figure 3, the Ti55531 titanium alloy large-scale square billet produced by a kind of Ti55531 titanium alloy large-scale square billet free forging preparation method of the present invention has a normal low-magnification structure and no metallurgical defects, as shown in Figure 4 As shown, the microstructures are all equiaxed α-structures on the β-transformation matrix. As shown in Figure 5, the overall structure performance is uniform, which can meet the requirements of batch production and has important economic and military strategic significance.

Claims (10)

1. The preparation method of Ti55531 titanium alloy large-scale billet free forging, which is characterized in that the Ti55531 titanium alloy ingot is sequentially subjected to "high-low-high" billet forging, low-temperature forging in the two-phase region below the β temperature, and lateral expansion , Flattened square billet. 2. the Ti55531 titanium alloy large-scale billet free forging preparation method according to claim 1 is characterized in that, specifically implement according to the following steps: Step 1, "high-low-high" billet forging: the Ti55531 titanium alloy ingot is subjected to the first upsetting and drawing forging at 100 ° C ~ 300 ° C above the β transformation temperature, and air cooling is used after forging, followed by 30 °C below the β transformation temperature. ℃～50℃ for the second upsetting forging, and then the third upsetting forging at 30℃～50℃ above the β transformation temperature, and air cooling after forging; Step 2, low-temperature forging in the two-phase region below the β temperature: perform upsetting forging on the blank processed in step 1, and the heating temperature is 30°C to 60°C below the β transformation temperature, and use air cooling after upsetting forging; Step 3, transverse widening: the billet processed in step 2 is subjected to transverse widening and deformation, and the heating temperature is 30°C to 60°C below the β transformation temperature, and air cooling is adopted after forging; Step 4, flattening and square forming: perform flattening and square forming on the blank processed in step S3, and the heating temperature is 30° C. to 60° C. below the β transformation temperature, and air cooling is adopted after forging. 3. The method for preparing Ti55531 titanium alloy large-size square billet free forging according to claim 2, characterized in that, in the step 1, when the blank is heated at 100° C. to 300° C. above the β transformation temperature, the alloy is first Heat to 800°C and keep it warm for 120 minutes, then raise the temperature to the required temperature to keep it warm; when upsetting for the first time, the sawed surface of the ingot needs to be riveted and upset. When upsetting, half of it is first upset, turned over and then upset to the size upsetting way. 4. The method for preparing Ti55531 titanium alloy large-scale billet free forging according to claim 2, characterized in that, in the step 1, 2 to 4 times of upsetting forging are carried out at 100° C. to 300° C. above the β transformation temperature , the amount of deformation per fire is controlled between 30-50%; 1-2 times of upsetting forging is carried out at 30°C-50°C below the β-transition temperature, and the deformation amount is controlled between 30-50%; 30°C above the β-transition temperature Upsetting and drawing forging is carried out at ~50°C for 1 to 2 fires, and the deformation is controlled between 30 and 50%. 5. The method for preparing Ti55531 titanium alloy large-scale billet free forging according to claim 2, characterized in that, in the step 2, the billet processed in the step 1 is subjected to upsetting and drawing forging for 3 to 5 times, and the deformation amount Control it between 30-50%. 6. The method for preparing Ti55531 titanium alloy large-scale billet free forging according to claim 2, characterized in that, the drawing speed in the upsetting and drawing forging of the steps 1 and 2 is not greater than 20mm/s, and the single press The lower amount is not more than 100mm. 7. The method for preparing Ti55531 titanium alloy large-scale billet free forging according to claim 2, characterized in that, in said step 3, the blank processed in step 2 is subjected to 1 to 3 times of transverse widening and deformation, and the amount of deformation is Control it between 20% and 50%. 8. The method for preparing Ti55531 titanium alloy large-scale billet free forging according to claim 2, characterized in that, the transfer time of the billet from the heating furnace to the fast forging machine in the step 2 and step 3 is not more than 40S, and the final forging The temperature is not less than 800°C. 9. The method for preparing Ti55531 titanium alloy large-size billet free forging according to claim 2, characterized in that in step 4, the billet processed in step 3 is flattened and square-shaped, and the deformation is controlled at 15-40 %between. 10. The method for preparing Ti55531 titanium alloy large-size billet free forging according to claim 9, characterized in that, in the step 4, the number of flattening fires is not more than 2 fires.