CN102896267A - Isothermal forging method of TC17 titanium alloy disc-shaped forge piece - Google Patents

Abstract

The invention relates to a forging method of a titanium alloy disc forging, in particular to an isothermal forging method of a TC17 titanium alloy disc forging. The process is as follows: heating the titanium alloy ingot to 40°C to 50°C below the phase transition point, heating the upper and lower flat dies to 40°C to 50°C below the phase transition point, and moving the upper flat die down so that the ingot can be heated at a temperature of 0.001s ^-1 ~ The strain rate of 0.01s ^-1 is subjected to the first fire isothermal upsetting to form a primary cake base, and then the second fire isothermal upsetting is performed at a strain rate of 0.001s ^-1 to 0.01s ^-1 to form a secondary cake base, with a deformation of 30 ~50%; heat the secondary cake base to 20°C-30°C below the phase transition point, heat the upper and lower cavity molds to 20°C-30°C below the phase transition point, press the secondary cake base to forge it in 0.001s The strain rate of ^-1 ~ 0.01s ^-1 forms the forging after the deformation in the cavity mold reaches 30 ~ 50%; the heat treatment of the forging after forging adopts solid solution + aging treatment. The disk-shaped forgings forged by this method have ideal equiaxed structure and high performance, and are suitable for manufacturing forgings such as compressor disks and turbine disks of aero-engines.

Description

A kind of isothermal forging method of TC17 titanium alloy disc forging

technical field

The invention relates to a forging method of a titanium alloy disc forging, in particular to an isothermal forging method of a TC17 titanium alloy disc forging.

Background technique

Titanium alloy has the characteristics of high strength, light weight and good corrosion resistance. It has important applications in the field of aviation and aerospace, especially the compressor discs and turbine discs of aero-engines. Due to the harsh working environment and complex stress, they are often It is formed by forging α+β type two-phase titanium alloy with excellent comprehensive performance. The disc forged with α+β two-phase titanium alloy has a series of advantages such as high strength, good fracture toughness, high hardenability and wide forging temperature range, which can meet the needs of loss tolerance design and high structure, high reliability and low manufacturing cost requirements. The change of microstructure has a significant impact on mechanical properties, and the above-mentioned excellent comprehensive properties must be guaranteed by the ideal microstructure of forgings.

"Shanghai Iron and Steel Research" published an article titled "Titanium Alloy Blisk Isothermal Forging Technology" in February 2006. The article studied the forging diagram of the TC17 alloy blisk, the shape of the forging blank, the mold structure and the isothermal forging process. , and produce titanium alloy blisk isothermal forgings through isothermal forging process. The isothermal forging of the TC17 disc described in this article is the same type of material disc isothermal forging as described in this patent, but the article does not describe the forming process of the forging. Different forming process methods have different effects and economic benefits.

In the research of α + β titanium alloy forging, four types of microstructures can be obtained due to different hot deformation processes. With the increasingly higher requirements for engine performance, various performance design indicators continue to improve, and a lot of research work has been invested in To obtain the basket structure, CN1403622A discloses a titanium alloy quasi-β forging process. When using this process to perform quasi-β forging on α+β-type titanium alloys, the titanium alloy blank is heated to a region near the temperature of the β phase transition point, that is, the phase transition Forging is carried out in the range of 10°C below the transformation point temperature to 10°C above the transformation point temperature. When heating in this area, due to the cooling of the billet after it is released from the furnace, the deformation of the forging is actually carried out in the α+β area. The structure of the basket structure The primary alpha phase is within 15. However, this method is forging by hot die forging, which cannot effectively control the forging deformation temperature, so there is no stability in the control of the structure of the forging.

Patent CN101804441A "Near-isothermal Forging Method of TC17 Two-phase Titanium Alloy Disc Forging", the method adopts the "low-high-low" process to make billets, that is, the TC17 titanium alloy ingot is heated to 30°C to 75°C below the phase transition point , upsetting; reheating to 20°C-60°C above the phase transition point, elongated; reheating to 30°C-75°C below the phase transition point, upsetting and punching to obtain a circular blank with α equiaxed distribution, and then The ring blank is heated to 20°C to 60°C above the phase transition point, and the forging die is heated to 10°C to 20°C below the phase transition point to prepare a forging with a full mesh and basket structure. Although this method is also a forging method for TC17 titanium alloy disc forgings, it produces a forging with a full mesh and basket structure. If a forging with a two-state structure is to be obtained, this method cannot be realized.

Contents of the invention

The technical problem to be solved by the present invention is to provide an isothermal forging method for a TC17 titanium alloy disc forging whose internal microstructure is about 20% equiaxed α-phase and uniformly distributed bimodal structure. Technical solution of the present invention is,

Cut the TC17 titanium alloy bar into an ingot according to the specifications, heat the ingot to 40°C-50°C below the phase transition point of the alloy, and keep it warm according to the effective thickness of the ingot at 0.6-1min/mm; heat the upper and lower flat dies to phase Put the ingot into the flat die at 40°C-50°C below the change point, and press the ingot to forge the ingot to make it deform in the flat die at a strain rate of 0.001s ^- 1-0.01s ^-1 to 30%-50 %Formed into a primary cake base, take out the primary cake base from the flat mold, return to the furnace while it is hot to heat and keep it warm;

The heat preservation time of returning to the furnace is calculated according to the temperature after reaching the temperature, and the heat preservation time is halved according to the first heat preservation time; With a strain rate of 0.001s ^-1 ~0.01s ^-1 , the deformation in the flat die reaches 30% to 50% to form a secondary cake base, and the secondary cake base is taken out from the flat die and air-cooled;

Heat the above-mentioned secondary cake base to 20°C-30°C below the phase transition point, and keep warm according to the effective thickness of the secondary cake base of 0.6-1min/mm; heat the upper and lower cavity molds to 20°C-30°C below the phase transition point Finally, put the secondary cake blank into the cavity mold, press the secondary cake blank to forge the secondary cake blank at a strain rate of 0.001s ^-1 ~ 0.01s ^-1 in the cavity mold, and then form the forging after the deformation reaches 30% ~ 50%. , take out the forging from the cavity mold and air cool;

After forging, the forgings are heat treated, and the forgings are heat treated after forging. The heat treatment system is 780℃～820℃×4 hours, water cooling; 590℃～650℃×8 hours, air cooling.

The heat treatment system of the forging is 800°C±10°C×4 hours, water cooling; 620°C±10°C×8 hours, air cooling.

For the convenience of taking molds, the ingot and cake base are preheated to 200°C-300°C before heating and loading, and then spray glass lubricant on the surface; the flat mold and cavity mold are molded on the ingot Before spraying glass lubricant on the surface of the mold.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The present invention adopts the ingot two-firing isothermal upsetting process to make the billet, that is, the TC17 titanium alloy ingot is heated to 40°C-50°C below the phase transition point, and the flat die is heated to 40°C-50°C below the phase transition point. In the flat die, the ingot is subjected to two-fire upsetting with a strain rate of 0.001s ^-1 to 0.01s ^-1 and a deformation of 30% to 50%, so as to ensure that the ingot is carried out in the two-phase region, and the obtained The fine and evenly distributed equiaxed α-structure cake lays the foundation for subsequent forging forming.

Heat the cake base to 20°C to 30°C below the phase transition point, heat the cavity mold to 20°C to 30°C below the phase transition point, and make the cake base in the cavity mold at a strain rate of 0.001s ^-1 to 0.01s In the range of ^-1 , the deformation reaches 30% to 50% to form forgings, to ensure that the forging blank is carried out in the two-phase region, and to obtain a two-state structure with an equiaxed α content of about 20%, so as to obtain the best fracture toughness and Plastic matching fully meets the needs of loss tolerance design.

The invention has the advantages of isothermal forging in the conventional α+β two-phase forging zone, that is, isothermal upsetting + isothermal die forging, small deformation resistance, easy forming, good stability, high yield, and avoiding the excessive fire in the current process The high cost and long period brought about by the secondary free forging to forging billet greatly increase the economic benefits while meeting the design requirements.

The forgings forged by this method have ideal comprehensive properties after heat treatment, and the ultrasonic detection clutter level of 150mm thick forgings can meet the requirements of 0.8-12DB.

Description of drawings

Figure 1 is a process flow chart of forming a disc forging by two times of isothermal upsetting and one time of isothermal forging of titanium alloy.

Figure 2 is a photo of the metallographic structure at the R/2 position of the longitudinal section cut along the center line of the forging formed by isothermal forging of TC17 titanium alloy.

Detailed ways

α+β type two-phase titanium alloy, for example: titanium alloy with Chinese material designation TC17.

The near-isothermal forging process steps of TC17 titanium alloy are given below:

Step 1: Detect that the phase transition point temperature of the TC17 titanium alloy material used is 895°C.

Step 2: As shown in Figure 1, the TC17 titanium alloy round bar is cut into the ingot 1 according to the forging specification, and the ingot 1 is preheated to 300°C and then sprayed with a special lubricant on its surface, and then the ingot 1 Put it in the forging heating furnace and heat it to 855°C below the phase transition point of the titanium alloy, and keep it warm. The holding time is calculated based on the effective thickness of the ingot of 0.6min/mm.

Step 3: Heat the upper flat die 2 and the lower flat die 3 to 855°C below the phase transition point of the titanium alloy. If it is more convenient to take the die, you can spray glass lubricant on the surface of the upper flat die 2 and the lower flat die 3. Heating is carried out through the ring mold heating furnace 8 installed on the forging press, and then the ingot 1 heated in step 1 is loaded into the flat die, and the ingot 1 is subjected to isothermal upsetting through the upper flat die to form a cake base 4 . Once the cake base 4 is returned to the furnace while it is hot. The deformation of the primary cake base 4 is 33%, and the forging strain rate of the primary cake base 4 in the forging process is 0.001s ^{- 1} ~0.01s ^-1 .

Step 4: heat the above-mentioned primary cake blank 4 returned to the furnace while it is hot to 855° C. below the phase transition point of the titanium alloy, keep it warm, and keep the keep time halved by step 2.

Step 5: Take out the primary cake blank 4 from the forging heating furnace, put it on the forging press and perform the second fire upsetting to obtain the secondary cake blank 5, and air cool after forging. The deformation of the secondary cake base 5 is 36%, and the forging strain rate of the secondary cake base 5 in the forging process is 0.001s ^-1 ~0.01s ^-1 .

Step 6: Preheat the secondary cake base 5 to 300°C, spray glass lubricant on its surface, then heat the cake base to 865°C below the phase transition point of the titanium alloy, keep it warm, and keep the heat preservation time according to the effective thickness of the cake base 0.6min/mm calculation.

Step 7: Heat the upper cavity mold 6 and the lower cavity mold 7 to 865°C below the titanium alloy phase transition point. If it is more convenient when taking the mold, you can heat the upper cavity mold 6 and the lower cavity mold 7. The surface is sprayed with glass lubricant, heated by the ring mold heating furnace 8 installed on the forging press, and then the cake base 5 heated in step 5 is loaded into the cavity mold, and the pressure is applied by the forging press to make the upper cavity mold 6 Descending, close the mold with the lower cavity mold 7 and forge and press the cake blank 5 to form the forging 9 at one time, and the forging 9 is released from the mold and air-cooled. The deformation of the forging 9 is 33%, and the forging strain rate of the forging 9 in the forging process is 0.001s ⁻¹ to 0.01s ⁻¹ .

Step 8: The forging 9 is heat treated, that is, solution + aging treatment, wherein the solution treatment is to heat the forging 9 to 800°C±10°C, keep it warm for 4 hours, and then put it into water to cool it rapidly (water quenching); The forged piece 9 after the solution treatment is heated to 620° C.±10° C., held for 8 hours, and then air-cooled.

Claims (4)

1. the isothermal forging method of a TC17 titanium alloy disk forge piece is characterized in that, may further comprise the steps:

The TC17 titanium alloy rod bar is become excellent ingot by the specification blanking, heat this rod ingot to below the alloy phase height 40 ℃～50 ℃, by this rod ingot effective thickness 0.6～1min/mm insulation;

Heat upper and lower flat-die and after below the transformation temperature 40 ℃～50 ℃ described excellent ingot is put into flat-die, press forges and presses excellent ingot makes it with 0.001s ^-1～0.01s ^-1Strain rate after flat-die internal strain amount reaches 30%～50%, obtain one time biscuit, take out and to melt down while hot;

Biscuit melts down temperature retention time while hot by calculating after temperature, temperature retention time reduces by half, and after insulation finishes, biscuit flat-die of packing into is carried out the second fire and is upset as the secondary biscuit, and press forges and presses a biscuit makes it with 0.001s ^{- 1}～0.01s ^-1Strain rate reach 30%～50% rear taking-up air cooling in flat-die internal strain amount;

Heat described secondary biscuit to following 20 ℃～30 ℃ of transformation temperature, by this secondary biscuit effective thickness 0.6～1min/mm insulation; Heat upper and lower swaging die after below the transformation temperature 20 ℃～30 ℃ the described secondary biscuit swaging die of packing into, press forging and pressing secondary biscuit makes it with 0.001s ^-1～0.01s ^-1Strain rate reach 30%～50% postforming forging in swaging die internal strain amount;

Forging is heat-treated after forging, and its heat treating regime is for being 780 ℃～820 ℃ * 4 hours, water-cooled; 590 ℃～650 ℃ * 8 hours, air cooling.

2. according to the isothermal forging method of TC17 titanium alloy forging claimed in claim 1, it is characterized in that: described excellent ingot is preheating to 200 ℃～300 ℃ before adding the hot charging mould after at its surface spraying glass lubricant.

3. according to the isothermal forging method of TC17 titanium alloy forging claimed in claim 1, it is characterized in that: described flat-die and swaging die before described excellent ingot dress mould at the mould surface spraying glass lubricant.

4. according to the isothermal forging method of TC17 titanium alloy forging claimed in claim 1, it is characterized in that: described forging heat treating regime is 800 ℃ ± 10 ℃ * 4 hours, water-cooled; 620 ℃ ± 10 ℃ * 8 hours, air cooling.

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