Method for improving grain uniformity of nickel-based superalloy ring piece

Abstract

The invention relates to a method for improving grain uniformity of a nickel-based superalloy ring piece, which is characterized by comprising the following steps of: preheating a nickel-based superalloy bar blanked according to specifications at the temperature of 1070-1180 DEG C, pressing by a press, punching and trimming to obtain a round billet; preheating the round billet under the temperature condition of 1020-1100 DEG C, and then carrying out ring rolling to enlarge an inner hole; the blank is preheated under the temperature condition of 1020-1100 DEG C, then continuous ring rolling is carried out for three times, and the ring rolling ratio of each fire is 7-9%, 12-14% and 16-19% in sequence; the special-shaped ring is subjected to annealing treatment under the temperature condition of 800-900 DEG C; and carrying out solution treatment on the special-shaped ring and then carrying out ring expansion again. By the adoption of the process, waste of die materials during machining is greatly reduced, and the manufacturing cost of the bulging die is reduced.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a ring-shaped part, and particularly to a method for improving the grain uniformity of a nickel-based superalloy ring-shaped part. Background Art

[0002] Currently, a superalloy bar is usually heated to the deformation temperature and then upset into a solid billet. A central hole of the solid billet is punched out with a punch to obtain a hollow billet. The hollow billet is heated to the deformation temperature and then rolled into a ring billet with a rectangular cross-section. Then, the ring billet with a rectangular cross-section is heated to the deformation temperature and placed into the outer die of a bulging die on a die bottom plate. Pressure is applied to squeeze the inner die and the outer die of the bulging die to close the die, and the ring billet with a rectangular cross-section deforms and fills the cavity of the bulging die, and then demolding obtains a ring billet with a special-shaped cross-section. This method solves the forming technology of forming a ring billet with a formed cross-section from a gold bar through upsetting, punching, and rolling. However, when using this method to produce a ring billet with a rectangular cross-section, such as in the process of producing a ring billet with a rectangular cross-section of a nickel-based superalloy, it is easy to cause defects such as tissue variation, grain coarsening, and cracks due to the increase in temperature during ring rolling of the alloy. In severe cases, even rejects may occur.

[0003] Chinese invention patent CN1586754A discloses a method for rolling and forming a ring-shaped part with an outer stepped cross-section. The longitudinal cross-section of the ring-shaped part is a non-rectangular outer stepped shape, that is, the ring-shaped part belongs to a special shape of a special-shaped ring forging. This method includes blanking, billet making, rolling, and subsequent processing, and solves the technical problems of forming a special-shaped ring forging from blanking, billet making to rolling and forming. However, when using this method to roll a special-shaped ring forging of a nickel-based superalloy, from the alloy bar to the final rolling of the special-shaped ring forging, the deformation amount of the alloy has a great influence on the structure and performance of the ring forging. If the deformation amount is not selected accurately, it will cause defects such as coarse grains, rolling damage, rolling cracks, and easy generation of flash on the ring forging, thus affecting the delivery and use of the forging. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a complete forging process flow. While ensuring an appropriate ring rolling deformation amount for each heating, control the starting forging and final forging temperatures for each ring rolling, accurately control the final rolling size, cancel the sizing process of the ring expanding machine, and add a pre-stabilization treatment process before solution treatment to precipitate β-phase at the grain boundaries, so as to solve the problem of accidentally coarse grains in the local cross-section of the forging, and the crystal grains of the whole cross-section of the part are uniformly fine, the mechanical properties are excellent, and the part size is accurate.

[0005] To solve the above technical problems, the method for improving the grain uniformity of a nickel-based superalloy ring-shaped part according to the present invention is characterized by including the following steps:

[0006] a. Preheat the nickel-based superalloy bar blanked according to specifications at a temperature of 1070°C to 1180°C, press with a press, and punch and trim to obtain a round blank;

[0007] b. Preheat the round blank obtained in step a at a temperature of 1020°C to 1100°C, and then perform ring rolling to expand the inner hole;

[0008] c. Preheat the blank obtained in step b at a temperature of 1020°C to 1100°C, and then continuously perform ring rolling for three heats. The ring rolling ratios for each heat are 7 - 9%, 12 - 14%, and 16 - 19% in sequence; the final rolling temperature is 890°C to 950°C;

[0009] d. Anneal the profiled ring obtained in step c at a temperature of 800°C to 900°C;

[0010] e. After solution treatment of the profiled ring obtained in step d, perform ring expansion again; during this step of ring expansion, use a profiled tooling to expand the ring to the corresponding shape.

[0011] Preferably, the ring rolling ratio during the ring expansion treatment in step e is 1%.

[0012] Preferably, the annealing treatment in the above step d is carried out for 4 - 7 h.

[0013] Preferably, the solution treatment in the above step e is to hold the profiled ring at a temperature of 1100°C to 1180°C for 1 hour, and then air cool.

[0014] Preferably, the nickel - based superalloy bar is GH4169 alloy.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The method for improving the grain uniformity of nickel - based superalloy rings of the present invention adopts medium - low temperature rapid ring rolling. The pre - rolling heating temperature is 1070°C to 1180°C, and the final rolling temperature is about 890°C to 950°C. Due to the relatively fast rolling speed and short rolling time, the temperature of the ring - shaped part during the rolling process is guaranteed. The test results show that within this rolling temperature range, the grains are fine and uniform, and can be controlled within the range of ASTM# such as 7 - 10. By adjusting the forging temperature during the forging process, precisely controlling the final rolling size, canceling the profiling process of the ring expander, and adding a pre - stabilization treatment process before solution treatment, the present invention solves the problem of accidentally coarse grains in the local cross - section of the forging, and the grain size of the entire cross - section of the ring - shaped part is uniformly fine, with excellent mechanical properties and precise part dimensions. Specific Embodiments

[0017] To implement the method for improving the grain uniformity of nickel - based superalloy rings of the present invention, a forging heating furnace, a quick forging machine, and a hole - expanding machine are required. The specific embodiments are as follows:

[0018] a. Preheat the nickel - based superalloy bar cut according to the specifications at a temperature of 1070°C to 1180°C, press it with a press, and perform punching and trimming to obtain a round blank;

[0019] b. Preheat the round blank obtained in step a at a temperature of 1020°C to 1100°C, and then perform ring rolling to expand the inner hole.

[0020] c. Preheat the blank obtained in step b at a temperature of 1020°C to 1100°C, and then perform continuous ring rolling for three heats. The ring rolling ratios for each heat are 7 - 9%, 12 - 14%, and 16 - 19% respectively; the final rolling temperature is 890°C to 950°C.

[0021] d. Anneal the profiled ring obtained in step c at a temperature of 800°C to 900°C.

[0022] e. After solution treatment of the profiled ring obtained in step d, perform ring expansion again; when performing ring expansion in this step, use a profiled tooling to expand the ring to the corresponding shape.

[0023] Preferably, the ring rolling ratio during the ring expansion treatment in step e is 1%.

[0024] Preferably, the annealing treatment in step d above is carried out for 4 to 7 hours.

[0025] Preferably, the solution treatment in step e above is to hold the profiled ring at a temperature of 1100°C to 1180°C for 1 hour, and then air cool.

[0026] Preferably, the nickel - based superalloy bar is GH4169 alloy.

Claims

1. A method for improving the grain uniformity of nickel-based superalloy rings, characterized in that, It includes the following steps: a. Preheat the nickel-based superalloy bar cut according to specifications at a temperature of 1070°C to 1180°C, press it with a press, and punch and trim the edges to obtain a round blank; b. Preheat the round blank obtained in step a at a temperature of 1020°C to 1100°C, and then perform ring rolling to expand the inner hole; c. Preheat the blank obtained in step b at a temperature of 1020°C to 1100°C, and then perform continuous ring rolling for three heats. The ring rolling ratios for each heat are 7-9%, 12-14%, and 16-19% in sequence; the final rolling temperature is 890°C to 950°C; d. Anneal the profiled ring obtained in step c at a temperature of 800°C to 900°C; e. After solution treatment of the profiled ring obtained in step d, expand the ring again; when expanding the ring in this step, use a profiled tooling to expand the ring to the corresponding shape.

2. The method for improving the grain uniformity of a nickel-based superalloy ring according to claim 1, wherein The ring rolling ratio during the ring expansion treatment in step e is 1%.

3. The method for improving the grain uniformity of nickel-based superalloy rings according to claim 1, characterized in that, The annealing treatment in step d is carried out for 4 to 7 hours.

4. The method for improving the grain uniformity of a nickel-based superalloy ring according to claim 1, characterized in that The solution treatment in step e is to hold the profiled ring at a temperature of 1100°C to 1180°C for 1 hour, and then air cool it.

5. The method for improving the grain uniformity of a nickel-based superalloy ring according to claim 1, characterized in that, The nickel-based superalloy bar is GH4169 alloy.