阅读说明：本技术 GH4720Li合金盘件锻后控温冷却方法和应用 (Temperature-controlled cooling method for GH4720Li alloy disc part after forging and application ) 是由 史玉亭 曲敬龙 杜金辉 孟令胜 安腾 谷雨 毕中南 秦鹤勇 于 2020-07-31 设计创作，主要内容包括：本发明提供了一种GH4720Li合金盘件锻后控温冷却方法和应用,涉及镍基高温合金加工领域,GH4720Li合金盘件锻后控温冷却方法包括以下步骤：将等温模锻得到的GH4720Li合金盘锻件进行空冷,空冷至650℃-800℃,冷却时间为10-20min；对空冷后的GH4720Li合金盘锻件以0.005-0.015℃/s的冷速冷却至室温。GH4720Li合金盘件在锻后冷却过程中使用该控温冷却方法,可获得晶粒度细小(晶粒度8级或更细)、γ′强化相分布均匀的组织。(The invention provides a post-forging temperature-control cooling method and application of a GH4720Li alloy disc, and relates to the field of nickel-based high-temperature alloy processing, wherein the post-forging temperature-control cooling method of the GH4720Li alloy disc comprises the following steps: air-cooling the GH4720Li alloy disc forging obtained by isothermal die forging to 650-800 ℃ for 10-20 min; and cooling the GH4720Li alloy disc forging subjected to air cooling to room temperature at a cooling speed of 0.005-0.015 ℃/s. The GH4720Li alloy disk can obtain a structure with fine grain size (grain size is 8-grade or smaller) and uniform gamma' strengthening phase distribution by using the temperature-controlled cooling method in the cooling process after forging.)

1. A temperature-controlled cooling method for a GH4720Li alloy disc piece after forging is characterized by comprising the following steps:

air-cooling the GH4720Li alloy disc forging obtained by isothermal die forging to 650-800 ℃ for 10-20 min;

and cooling the GH4720Li alloy disc forging subjected to air cooling to room temperature at a cooling speed of 0.005-0.015 ℃/s.

2. The method for controlling the temperature and cooling of the GH4720Li alloy disc after forging according to claim 1, wherein the air-cooled GH4720Li alloy disc forging is cooled to room temperature at a cooling rate of 0.01 ℃/s.

3. The method for controlling the temperature and cooling of the GH4720Li alloy disc forging after forging according to claim 1, wherein a second jacket is arranged on the surface of the GH4720Li alloy disc forging after air cooling so as to cool the GH4720Li alloy disc forging after air cooling to room temperature at a cooling rate of 0.005-0.015 ℃/s.

4. The method of claim 3, wherein the second jacket comprises insulating cotton.

5. The GH4720Li alloy disc after forging temperature-controlled cooling method of claim 4, wherein the thermal insulation cotton comprises refractory alumina silicate fibers;

preferably, the thickness of the heat insulation cotton is matched with the cooling rate, and one or more layers of heat insulation cotton can be used.

6. The method for cooling the GH4720Li alloy disc after forging at a controlled temperature of claim 1, wherein a bar or disc blank is subjected to isothermal die forging to obtain a GH4720Li alloy disc forging;

preferably, the bar or disc blank is closed before isothermal forging.

7. The method for cooling the GH4720Li alloy disc after forging at a controlled temperature according to claim 1, wherein the bar or disc blank is transferred from a high temperature furnace to a hydraulic forging machine, and the bar or disc blank is subjected to an isothermal die forging process to obtain the GH4720Li alloy disc forging.

8. The post-forging temperature-controlled cooling method for the GH4720Li alloy disc of any one of claims 1-7, wherein the method is air-cooled to 680-770 ℃;

preferably, air-cooled to 750 ℃;

preferably, the air cooling time is 15 min.

9. The method for cooling the GH4720Li alloy disc after forging at a controlled temperature according to claim 7, wherein when the bar or disc blank is transferred from a high temperature furnace to a hydraulic forging machine, a first sheath is wrapped on the surface of the GH4720Li alloy bar or disc blank during the transfer, and the first sheath is removed after the air cooling of the disc forging obtained from the bar or disc blank is finished.

10. Use of the post-forging temperature-controlled cooling method of GH4720Li alloy disc forging of any of claims 1-9 in the preparation of GH4720Li superalloy disc forging.

Technical Field

The invention relates to the technical field of nickel-based superalloy processing, in particular to a temperature-controlled cooling method and application of a GH4720Li alloy disc piece after forging.

Background

As a typical hard-to-deform superalloy, the GH4720Li has high alloying degree, poor thermoplasticity and extreme sensitivity to hot working temperature, and the temperature change and residual stress distribution during forging and cooling of a disc forging are complicated. The large residual stress difference between the center and the edge of the disc forging can cause the cracking of the forging in the cooling process after forging, the deformation in subsequent processing and the reduction of the service fatigue life of parts. The forging process also requires that the structure with fine crystal grains and uniformly distributed gamma' strengthening phases is realized on the basis of ensuring the forming size and no cracking. This requires that strict temperature control processes and parameters be set for the structure evolution process and the residual stress distribution during forging and cooling after forging.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a post-forging temperature-control cooling method for GH4720Li alloy disc parts, which is used in the post-forging cooling process of GH4720Li alloy disc parts and can obtain a structure with fine grain size (8-grade or finer grain size) and uniform gamma' strengthening phase on the premise of ensuring that the disc forging parts are not cracked.

The invention provides a temperature-controlled cooling method for a GH4720Li alloy disc part after forging, which comprises the following steps:

air-cooling the GH4720Li alloy disc forging obtained by isothermal die forging to 650-800 ℃ for 10-20 min;

and cooling the GH4720Li alloy disc forging subjected to air cooling to room temperature at a cooling speed of 0.005-0.015 ℃/s.

Further, the GH4720Li alloy disc forging after air cooling is cooled to room temperature at a cooling speed of 0.01 ℃/s.

Further, a second sheath is arranged on the surface of the air-cooled GH4720Li alloy disc forging, so that the air-cooled GH4720Li alloy disc forging can be cooled to room temperature at a cooling speed of 0.005-0.015 ℃/s.

Further, the second cover comprises heat preservation cotton.

Further, the heat insulation cotton comprises refractory aluminum silicate fibers;

preferably, the thickness of the heat insulation cotton is matched with the cooling rate, and one or more layers of heat insulation cotton can be used.

Further, carrying out isothermal die forging on the bar billet or the disc billet to obtain a GH4720Li alloy disc forging;

preferably, the bar or disc blank is closed before isothermal forging.

And further transferring the bar stock or the disc stock from a high-temperature furnace to a hydraulic forging machine, and carrying out an isothermal forging procedure on the bar stock or the disc stock to obtain the GH4720Li alloy disc forging.

Further, air cooling to 680-770 ℃;

preferably, air-cooled to 750 ℃;

preferably, the air cooling time is 15 min.

Further, when the bar billets or the disc billets are transferred to a hydraulic forging machine from a high-temperature furnace, a first sheath is wrapped on the surfaces of the GH4720Li alloy bar billets or the disc billets in the transferring process, and the first sheath is removed after air cooling of disc forgings obtained by the bar billets or the disc billets is finished.

The application of the post-forging temperature-control cooling method for the GH4720Li alloy disc forging in the preparation of the GH4720Li high-temperature alloy disc forging.

Compared with the prior art, the invention can at least obtain the following beneficial effects:

the cooling method is used in the temperature-controlled cooling process of the GH4720Li alloy disc after forging, so that a structure with fine grain size (8-grade or finer grain size) and uniform gamma' strengthening phase can be obtained; according to the invention, two sheath processes are adopted in the isothermal die forging process, and the GH4720Li disc forging obtained by matching two cooling rates is adopted, the internal residual stress value is small at 0.005-0.015 ℃/s, the residual stress distribution is uniform, the disc body can be prevented from deforming and cracking due to the over-high cooling speed, and the stable control of the structure and the residual stress of the disc forging is realized. In addition, the temperature-controlled cooling method after forging is simple in operation process and low in requirements on equipment conditions, and can be realized in batch production of GH4720Li alloy disc forgings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1a is a drawing of a finished GH4720Li alloy disc forging produced according to example 1 of the invention;

FIG. 1b is a metallographic structure diagram of a GH4720Li alloy disc forging prepared according to example 1 of the invention;

FIG. 2 shows a GH4720Li alloy disc forging finished product prepared by the comparative example 1 of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

In one aspect of the invention, the invention provides a post-forging temperature-controlled cooling method for a GH4720Li alloy disc, and the post-forging temperature-controlled cooling method for the GH4720Li alloy disc comprises the following steps:

air-cooling the GH4720Li alloy disc forging obtained by isothermal die forging to 650-800 ℃ (for example, 650 ℃, 700 ℃, 750 or 800 ℃) for 10-20min (for example, 10min, 15min or 20 min);

and cooling the GH4720Li alloy disc forging after air cooling to room temperature at a cooling speed of 0.005-0.015 ℃/s (for example, 0.015 ℃/s, 0.01 ℃/s or 0.005 ℃/s).

The temperature control cooling method is used in the cooling process of the GH4720Li alloy disc after forging, so that a structure with fine grain size (8-grade or finer grain size) and uniformly distributed gamma' strengthening phases can be obtained; the GH4720Li alloy disc forging is cooled to room temperature at a cooling rate of 0.005-0.015 ℃/s, the value of the residual stress in the GH4720Li alloy disc forging is small, the residual stress is uniformly distributed, the disc body can be prevented from deforming and cracking due to the over-high cooling rate, and the stable control of the structure and the residual stress of the disc forging is realized. In addition, the temperature-controlled cooling method after forging is simple in operation process and low in requirements on equipment conditions, and can be realized in batch production of GH4720Li alloy disc forgings.

The purpose of the first stage of cooling air is to control the phase distribution of gamma' precipitation in the cooling process at a higher cooling speed, pin and fix a deformation structure and prevent crystal grains from excessively growing; an infrared thermometer can be used for monitoring the cooling temperature and recording the temperature and time of the cooling process.

If the temperature after air cooling is lower than 650 ℃, the temperature difference between the center and the edge of the disc forging is large, the residual stress difference is high, and the disc forging deforms and cracks; if the temperature after air cooling is higher than 800 ℃, the precipitation of the gamma' phase is insufficient, the capability of pinning and fixing the deformation structure is insufficient, and the crystal grains grow up. If the cooling speed of the GH4720Li alloy disc forging in the second-stage temperature-controlled cooling process is higher than 0.015 ℃/s, the GH4720Li disc forging is very sensitive to temperature drop, the cooling speed after forging is too high, the residual stress value in the GH4720Li disc forging is large, the residual stress is distributed unevenly, the disc forging is easy to deform or even crack, and the size and the yield of finished products are affected.

The slower the cooling speed of the GH4720Li alloy disc forging in the second-stage temperature-controlled cooling process is, the smaller the residual stress value is, and the more uniform the residual stress distribution is. The purpose of the cotton cooling process in the cooling process is to balance thermal stress and structural stress, reduce the residual stress value in the disc forging and avoid deformation and cracking.

In the present invention, room temperature is a temperature in a general sense, and means 20 to 25 ℃. In the invention, the first-stage air cooling and the second-stage temperature-controlled cooling to room temperature are both carried out in a room-temperature environment.

In some preferred embodiments of the invention, the GH4720Li alloy disc forgings after air cooling (first stage) are cooled to room temperature at a cooling rate of 0.01 ℃/s.

In some embodiments of the invention, a second jacket is provided on the surface of the air-cooled GH4720Li alloy disc forging to facilitate cooling the air-cooled GH4720Li alloy disc forging to room temperature at a cooling rate of 0.005-0.015 ℃/s. Therefore, the operation is simple and convenient, and the cooling speed of the GH4720Li alloy disc forging subjected to air cooling is easily controlled within 0.015 ℃/s.

In some embodiments of the invention, the second sheath comprises thermal cotton. The temperature-controlled cooling mode that the air cooling is combined with the arrangement of the heat-preservation cotton on the surface of the disc forging piece effectively prevents the deformation and cracking of the disc forging piece due to the large gradient residual stress distribution caused by the uneven temperature drop of the GH47 4720Li alloy disc forging piece, and the obtained structure with fine grain size and uniform gamma' strengthening phase realizes the stability control of the structure and the performance of the GH47 4720Li alloy disc forging piece.

In some embodiments of the invention, the air-cooled GH4720Li alloy disc forging is sheathed by heat-insulating cotton, and one or more layers of heat-insulating cotton can be used for sheathing, so that the GH4720Li alloy disc forging is completely in the heat-insulating cotton and is uniformly wrapped without being in direct contact with the outside air in the cotton cooling process.

In some embodiments of the invention, the thermal insulation wool comprises refractory alumina-silicate fibers; the thickness of the heat insulation cotton is matched with the cooling rate, and one or more layers of heat insulation cotton can be used.

In some embodiments of the invention, isothermal die forging of a billet or disc billet yields a GH4720Li alloy disc forging; preferably, the bar or disc blank is closed before isothermal forging, for example, by closing all doors and windows in the forging. Therefore, the influence of indoor and outdoor temperature difference and wind speed on the temperature in the forging process and the cooling process can be avoided.

In some embodiments of the invention, the bar stock or disc stock is transferred from the high temperature furnace to a hydraulic forging machine, and the bar stock or disc stock is subjected to an isothermal forging process to obtain the GH4720Li alloy disc forging.

In some embodiments of the invention, air cooled to 680 ℃ -770 ℃; preferably, air-cooled to 750 ℃; preferably, the air cooling time is 15 min.

Further, when the bar billet or the disc billet is transferred to a hydraulic forging machine from a high-temperature furnace, a first sheath is wrapped on the surface of the GH47 4720Li alloy disc forging in the transfer process, the first sheath is removed from the disc forging obtained by the bar billet or the disc billet through the forging process after air cooling is finished, in some specific embodiments, heat insulation cotton pressed in the isothermal forging process is attached to the surface of the GH47 4720Li alloy disc forging in the transfer process, and all residual heat insulation cotton is removed after the air cooling is finished.

In some embodiments of the invention, the GH4720Li alloy disc forgings are air cooled in a cooling zone. And air cooling is carried out in a cooling area, all surfaces of the GH4720Li alloy disc forging are required to be in uniform contact with air as much as possible, the cooling rate is the same, and synchronous cooling of all parts of the GH4720Li alloy disc forging is ensured. In the cooling zone, the finish forging temperature of the GH4720Li alloy disc forging was measured and recorded using an infrared thermometer, while the dimensions of the GH4720Li alloy disc forging were measured and recorded.

In some embodiments of the invention, the post-forging temperature-controlled cooling method for the GH4720Li alloy disc piece comprises the following steps:

1) and closing all doors and windows in the forging field before isothermal forging of the GH4720Li alloy bar billet or disc billet. The influence of temperature difference on the forging process and the cooling process is avoided;

2) transferring the GH4720Li alloy bar billet or disc billet from a high-temperature furnace to a hydraulic forging machine, and carrying out an isothermal forging process on the GH4720Li alloy bar billet or disc billet to obtain a GH4720Li alloy disc forging;

in the transferring process, the bar blank or the plate blank needs to be sheathed for the first time by using heat-preservation cotton;

3) the GH4720Li alloy disc forging obtained by isothermal forging is transferred to a cooling area from a hydraulic forging machine for air cooling, the GH4720Li alloy disc forging can be isolated from the ground by using heat-resistant bricks, the disc forging is erected and does not contact with the ground, so that all surfaces are ensured to be in contact with air as far as possible, the cooling rate is the same, and the cooling effect is uniform;

4) measuring and recording the finish forging temperature of the GH4720Li alloy disc forging by using an infrared thermometer;

5) air-cooling the GH4720Li alloy disc forging to 680-770 ℃ for 10-20 min; the purpose of air cooling is to control the phase distribution of gamma' precipitation in the cooling process at a higher cooling speed, pin and fix a deformation structure and prevent crystal grains from excessively growing; monitoring the cooling temperature by using an infrared thermometer, and recording the temperature and time in the cooling process;

6) sheathing the air-cooled GH4720Li alloy disc forging by using refractory aluminum silicate fiber heat-insulating cotton, and continuously cooling the heat-insulating cotton to room temperature; one or more layers of heat insulation cotton can be used for sheathing, the GH4720Li alloy disc forging is quickly transferred onto the heat insulation cotton for sheathing, and the GH4720Li alloy disc forging is completely in the heat insulation cotton in the cotton cooling process and is uniformly wrapped without contacting with external air; the thickness of the heat insulation cotton is determined according to the actual condition and the cooling rate, and one or more layers can be used; after the sheath is sheathed, the cooling rate of the GH4720Li alloy disc forging piece is 0.005-0.015 ℃/s; the purpose of the cotton cooling process in the cooling process is to balance thermal stress and structural stress, reduce the residual stress value in the disc forging and avoid deformation and cracking;

7) and taking out the cooled GH4720Li alloy disc forging from the heat-insulating cotton, and carrying out subsequent processes after factory inspection and recording are carried out on the disc forging.

In another aspect of the invention, the invention provides application of the post-forging temperature-controlled cooling method for the GH4720Li alloy disc forging in preparation of the GH4720Li high-temperature alloy disc forging.

Some embodiments of the present invention will be described in detail below with reference to specific embodiments. The embodiments described below and the features of the embodiments can be combined with each other without conflict.