Heat treatment process for rapid aging of large-size GH4738 alloy forge piece

An aging treatment, large-scale technology, applied in the field of heat treatment technology, can solve the problems of inability to eliminate tissue differences, long production cycles, and large differences in γ' phase content, so as to shorten the aging treatment time, improve strength uniformity, and reduce production. cost effect

Active Publication Date: 2021-10-29
UNIV OF SCI & TECH BEIJING
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

However, it should be noted that for large-sized GH4738 alloy forgings, especially for large-sized forged turbine disks with a diameter greater than 1000mm and a thickness greater than 200mm, it is difficult to completely suppress the precipitation and growth of the γ′ phase even with oil cooling after solution treatment. , resulting in a large difference in the γ′ phase content between the edge and the center of the forging after solution treatment
Subsequent aging treatment cannot eliminate this structural difference, which eventually leads to large fluctuations in the strength of the alloy forging body and a low pass rate of mechanical properties.
In addition, the existing aging treatment takes a long time (the total aging time of the two stages is as long as 20h), the production cycle is long, the energy consumption is high, and the efficiency is low
[0006] Current research on large-scale GH4738 alloy forgings mainly focuses on the processing technology of the forging itself. For example, the patent (patent number: CN105177478A) proposes a method for opening a large ingot of GH4738 superalloy; the patent (patent number: CN103341586A) A forming method to realize the GH4738 nickel-based superalloy turbine disk is proposed, but there are few studies on the heat treatment process of the forging after forming

Method used

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  • Heat treatment process for rapid aging of large-size GH4738 alloy forge piece
  • Heat treatment process for rapid aging of large-size GH4738 alloy forge piece
  • Heat treatment process for rapid aging of large-size GH4738 alloy forge piece

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Experimental program
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Effect test

Embodiment 1

[0025] 1) Put the large-sized GH4738 alloy forging into the heating furnace for solution treatment: the heating furnace first raises the temperature to 830°C at a heating rate of 5°C / min, and keeps it for 40 minutes; then raises the temperature to 960°C at a heating rate of 8°C / min , keep warm for 50min; then raise the temperature to 1020℃ at a heating rate of 5℃ / min, and keep warm for 60min; after that, air is introduced into the heating furnace, and after cooling to below 500℃ at a rate of 110-130℃ / min, the alloy forging is taken out and air-cooled to room temperature.

[0026] 2) Put the GH4738 alloy forging after the solution treatment in step 1) into the heating furnace for aging treatment: the heating furnace first raises the temperature to 700°C at a heating rate of 5°C / min, and keeps it for 40min; The heating rate was raised to 750°C, kept for 6 hours, and then taken out and air-cooled to room temperature.

[0027] figure 2 , image 3 They are the γ′ phase distribu...

Embodiment 2

[0032] 1) Put the large-sized GH4738 alloy forging into the heating furnace for solution treatment: the heating furnace first raises the temperature to 820°C at a heating rate of 6°C / min, and keeps it for 50 minutes; then raises the temperature to 970°C at a heating rate of 5°C / min , hold for 40 minutes; then raise the temperature to 1030°C at a heating rate of 3°C / min, and hold for 40 minutes; after that, air is introduced into the heating furnace, and after cooling to below 500°C at a rate of 130-150°C / min, the alloy forging is taken out and air-cooled to room temperature.

[0033] 2) Put the GH4738 alloy forging after solution treatment in step 1) into a heating furnace for aging treatment: the heating furnace first raises the temperature to 710°C at a heating rate of 6°C / min, and keeps it for 30min; then heats it at a heating rate of 5°C / min The heating rate was raised to 760°C, kept for 8 hours, and then taken out and air-cooled to room temperature.

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Abstract

The invention discloses a heat treatment process for rapid aging of a large-size GH4738 alloy forge piece, and belongs to the technical field of heat treatment of nickel-based high-temperature alloy. The process comprises the steps of firstly, carrying out solution treatment on the large-size GH4738 alloy forge piece, and carrying out cooling in a mode that the large-size GH4738 alloy forge piece is cooled in a furnace at first and then is cooled in air; and then carrying out aging treatment on the large-size GH4738 alloy forge piece in a heating furnace under the conditions that the aging treatment temperature ranges from 740 DEG C to 760 DEG C and the heat preservation time ranges from 4 h to 8 h, and cooling the large-size GH4738 alloy forge piece in air after the large-size GH4738 alloy forge piece is taken out. According to the heat treatment process, by optimizing the cooling speed of alloy obtained after solution treatment and cooperating with short-time aging treatment, a dispersed and evenly-distributed gamma' phase is promoted to be formed in a GH4738 alloy matrix. The treatment process has an unexpected effect on improving the strength uniformity of the alloy forge piece at the room temperature. The tensile strength difference corresponding to the edge and the core area of the forge piece at the room temperature is reduced to be within 15 MPa from about 40 MPa, and the yield strength difference is reduced to be within 15 MPa from about 50 MPa. Meanwhile, compared with traditional aging treatment, the heat treatment process has the advantages that the aging treatment time is greatly shortened, the production efficiency is improved, the production cost is reduced and important production and application value is achieved.

Description

technical field [0001] The invention relates to the technical field of heat treatment of nickel-based superalloys, in particular to a heat treatment process for rapid aging of large-sized GH4738 alloy forgings. Background technique [0002] Superalloys, also known as heat-resistant alloys or superalloys, have excellent mechanical properties and stability in high-temperature environments. Among them, GH4738 is a Ni-Cr-Co-based precipitation hardening deformation superalloy, which has good plastic deformation ability at high temperature, and has high strength, fatigue resistance and corrosion resistance at high temperature of 760-870 °C , is currently widely used in aviation and energy fields. [0003] In many applications, GH4738 alloy is widely used to make forgings such as large-size turbine disks due to its good processing plasticity and stable microstructure and properties. The flue gas turbine uses flue gas as the working medium to convert the heat and pressure energy ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22F1/10C21D1/78C21D11/00
CPCC22F1/10C21D1/78C21D11/005Y02P10/20
Inventor 郑磊刘红亮赵鑫董建孟晔
Owner UNIV OF SCI & TECH BEIJING
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