阅读说明：本技术 GH4720Li合金及其冶炼方法、GH4720Li合金零部件和航空发动机 (GH4720Li alloy and smelting method thereof, GH4720Li alloy part and aeroengine ) 是由 曲敬龙 谷雨 杨树峰 杜金辉 安腾 陈正阳 毕中南 秦鹤勇 唐超 王民庆 史玉亭 于 2019-12-06 设计创作，主要内容包括：本发明提供了一种GH4720Li合金及其冶炼方法、GH4720Li合金零部件和航空发动机,涉及冶炼技术领域,GH4720Li合金的冶炼方法包括：对GH4720Li合金的原料进行真空感应熔炼；其中,在所述真空感应熔炼的精炼期采用100-150KW的工频搅拌功率进行搅拌,在精炼过程中测量真空感应熔炼系统的漏气率,若相邻两次测量到的漏气率的变化率的绝对值小于等于7％,则停止所述精炼。该冶炼方法可以有效降低冶炼时合金液中有害气体元素的含量,降低夹杂物数量分布,使获得的GH4720Li合金纯净度高,冶金质量高。(The invention provides a GH4720Li alloy and a smelting method thereof, GH4720Li alloy parts and aeroengines, and relates to the technical field of smelting, wherein the smelting method of the GH4720Li alloy comprises the following steps: carrying out vacuum induction melting on a raw material of the GH4720Li alloy; stirring with power frequency stirring power of 100-150KW in the refining period of the vacuum induction smelting, measuring the gas leakage rate of the vacuum induction smelting system in the refining process, and stopping refining if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7%. The smelting method can effectively reduce the content of harmful gas elements in the alloy liquid during smelting, and reduce the quantity distribution of inclusions, so that the obtained GH4720Li alloy has high purity and high metallurgical quality.)

1. A smelting method of GH4720Li alloy is characterized by comprising the following steps: carrying out vacuum induction melting on a raw material of the GH4720Li alloy;

stirring with power frequency stirring power of 100-150KW in the refining period of the vacuum induction smelting, measuring the gas leakage rate of the vacuum induction smelting system in the refining process, and stopping refining if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7%.

2. The smelting method according to claim 1, wherein the refining is stopped if an absolute value of a rate of change in the leak rates of two adjacent passes is 5% or less.

3. The smelting method according to claim 1, characterized in that the stirring is performed at a power frequency of 115-135KW in the refining period.

4. A smelting process according to any one of claims 1 to 3, wherein the time interval between two consecutive measurements of the gas leakage rate is 5 to 10 min.

5. A smelting process according to any one of claims 1 to 3, wherein the time for each measurement of the leak rate is from 30 to 60 s.

6. The method as claimed in claim 1, wherein the temperature of refining is 1500-;

preferably, the vacuum degree during vacuum induction melting is greater than 0 and less than or equal to 50 Pa.

7. The smelting method according to claim 1, further comprising, after the vacuum induction smelting, electroslag remelting and/or vacuum arc remelting;

preferably, after the vacuum induction melting, electroslag remelting and vacuum arc remelting are sequentially carried out.

8. A GH4720Li alloy obtained by smelting according to any one of claims 1-7.

9. A GH4720Li alloy part characterized in that at least a portion of the GH4720Li alloy part is prepared from the GH4720Li alloy of claim 8;

preferably, the GH4720Li alloy part comprises at least one of an aircraft engine turbine disk, an aircraft engine compressor disk, an aircraft engine blade, and an aircraft engine gas disk.

10. An aircraft engine comprising the GH4720Li alloy part of claim 9.

Technical Field

The invention relates to the technical field of smelting, in particular to a GH47 4720Li alloy, a smelting method thereof, GH4720Li alloy parts and an aero-engine.

Background

At present, when the GH4720Li alloy is smelted, the refining period of vacuum induction smelting lacks scientific and reasonable operation criteria and judgment standards, and only depends on the fluidity of an operator on the surface of alloy liquid in a crucible or the refining duration as the refining finishing basis, so that the stability control of the purity and the metallurgical quality of the GH47 4720Li alloy is not facilitated, and the further improvement of the purity of the GH4720Li alloy is limited. Therefore, upgrading the smelting process in the refining period is important for further improving the purity and mechanical properties of the GH4720Li alloy.

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

Disclosure of Invention

The invention aims to provide a smelting method of GH4720Li alloy, which can effectively reduce the content of harmful gas elements in an alloy liquid during smelting, reduce the quantity distribution of inclusions, and ensure that the obtained GH4720Li alloy has high purity and high metallurgical quality.

The invention provides a smelting method of GH4720Li alloy, which comprises the following steps: carrying out vacuum induction melting on a raw material of the GH4720Li alloy;

stirring with power frequency stirring power of 100-150KW in the refining period of the vacuum induction smelting, measuring the gas leakage rate of the vacuum induction smelting system in the refining process, and stopping refining if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7%.

Further, if the absolute value of the change rate of the air leakage rate of two adjacent times is less than or equal to 5%, the refining is stopped.

Further, the stirring is carried out by adopting power frequency stirring power of 115-135KW in the refining period.

Further, the time interval between two adjacent air leakage rate measurements is 5-10 min.

Further, the time for each measurement of the air leakage rate is 30-60 s.

Further, the refining temperature is 1500-;

preferably, the vacuum degree during vacuum induction melting is greater than 0 and less than or equal to 50 Pa.

Further, after the vacuum induction melting, electroslag remelting and/or vacuum arc remelting are/is further included;

preferably, after the vacuum induction melting, electroslag remelting and vacuum arc remelting are sequentially carried out.

GH4720Li alloy obtained by smelting according to the smelting method.

A GH4720Li alloy part, at least a portion of the GH4720Li alloy part being made from the GH4720Li alloy described above;

preferably, the GH4720Li alloy part comprises at least one of an aircraft engine turbine disk, an aircraft engine compressor disk, an aircraft engine blade, and an aircraft engine gas disk.

An aircraft engine comprising the GH4720Li alloy component as defined above.

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

in the refining period of vacuum induction melting, stirring with low power of 100-150KW can replace the original power-off film-forming operation, effectively increase the stirring effect of the alloy liquid, improve the uniformity of the alloy liquid, facilitate the removal of harmful gas elements (such as O, N and H), and facilitate the reduction of the impurity content in the alloy liquid; when harmful gas elements are eliminated, a certain gas leakage rate can be generated in the vacuum induction melting system, the gas leakage rate of the vacuum induction melting system is measured for many times in a refining period, if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7%, the escape amount of the harmful gas in the alloy liquid is very small, the purity of the alloy liquid meets the process requirement, the removal of the harmful gas elements and impurities is favorably and accurately controlled, and further, the GH47 4720Li alloy obtained by smelting has very high purity, extremely high quality and long fatigue life.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In one aspect of the invention, the invention provides a smelting method of GH4720Li alloy, which comprises the following steps: carrying out vacuum induction melting on a raw material of the GH4720Li alloy;

stirring with a power frequency stirring power of 100-150KW in the refining period of the vacuum induction smelting, measuring the gas leakage rate of the vacuum induction smelting system in the refining process, and stopping refining if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7% (for example, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0).

It is understood that during the refining period, the raw materials of the GH4720Li alloy are all melted to form the molten alloy.

In the refining period of vacuum induction melting, stirring with 100-150KW (for example, 100KW, 110KW, 120KW, 130KW, 140KW or 150 KW) low power can replace the original power-off film-forming operation, so that the stirring effect of the alloy liquid can be effectively increased, the uniformity of the alloy liquid is improved, harmful gas elements (for example, O, N and H) can be favorably removed, and the impurity content in the alloy liquid can be favorably reduced; when harmful gas elements are eliminated, a certain gas leakage rate can be generated in the vacuum induction melting system, the gas leakage rate of the vacuum induction melting system is measured for many times in a refining period, if the absolute value of the change rate of the gas leakage rate measured in two adjacent times is less than or equal to 7%, the escape amount of the harmful gas in the alloy liquid is very small, the purity of the alloy liquid meets the process requirement, the removal of the harmful gas elements and impurities is favorably and accurately controlled, and further, the GH47 4720Li alloy obtained by smelting has very high purity, extremely high quality and long fatigue life. If the absolute value of the change rate of the air leakage rate measured in two adjacent times is more than 7%, the content of harmful elements in the alloy liquid is high, and the refining time should be prolonged. For above-mentioned power frequency stirring power scope, when the stirring power of adopting was too high when refining, then caused unnecessary energy waste, when the stirring power of adopting was crossed lowly when refining, then can reduce the effect of degasifying.

Compared with the mode of film forming by power failure in the refining period, the stirring effect of the alloy liquid can be reduced by the film forming operation by power failure, so that harmful gas elements (O, N, H) are not favorably removed, the collision aggregation and growth of impurities are influenced, and the impurity content in the alloy liquid is increased; according to the invention, the refining mode of low-power stirring is adopted, which is beneficial to the removal of harmful gas elements, the stirring effect and the uniform mixing effect of the alloy liquid are increased, the alloy liquid is more uniform, the effect of collision, aggregation and growth of inclusions is improved, the impurity content in the alloy liquid is further reduced, and the purity and the quality of the GH47 4720Li alloy are improved.

In the refining period, effective dehydrogenation can be carried out by means of lower vacuum degree, but O, N is different from H, O is deoxidized by means of reaction with C to generate CO, and N is removed in the deoxidizing process, so that the content of harmful gas elements in the alloy liquid is reduced.

In some embodiments of the present invention, the change rate of the air leakage rate is: let the leakage rate measured in two adjacent times be the leakage rate L measured in the Nth time (where N is a natural number of 1 or more)_NAnd the leak rate L measured at the N +1 th time_N+1Then, the change rate of the leak rate of the adjacent two times of the nth and the N +1 th times can be calculated by the following formula: (L)_N-L_N+1)/L_NThe absolute values of the change rates of the leak rates at the Nth and N +1 th adjacent times are | (L)_N-L_N+1)|/L_N。

In other embodiments of the present invention, the vacuum leakage rate may be expressed by a change rate of a vacuum degree, and specifically, the vacuum induction melting system is always vacuumized during the vacuum induction melting process, so that the vacuum degree in the vacuum induction melting system is maintained at the same vacuum degree P when the vacuum leakage rate is not measured₀When the leakage rate is measured for the Nth time, the vacuum pumping is stopped for a predetermined time t, and the vacuum degree of the system is assumed to rise to P_NThe change rate of the vacuum degree in the predetermined time is | P₀-P_NI/t, when the air leakage rate is measured for the (N + 1) th time, stopping vacuumizing for a predetermined time t (the same as the predetermined time for the Nth time), and assuming that the vacuum degree of the system is increased to P_N+1The change rate of the vacuum degree in the predetermined time is | P₀-P_N+1I/t, the change rate of the nth and N +1 th adjacent air leakage rates can be calculated by the following formula: (| P)₀-P_N|/t)-(|P₀-P_N+1|/t))/(|P₀-P_NI/t), the absolute value of the change rate of the leak rate of the adjacent two times of Nth and (N + 1) th is | ((| P)₀-P_N|/t)-(|P₀-P_N+1|/t))|/(|P₀-P_NI/t). Thus, the change rate of the leak rate is reflected by the degree of vacuumThe method is simple and convenient to operate and easy to realize. The predetermined time t may be 30s, 60s, or other convenient measurement time, and may be specifically selected according to actual conditions.

It should be noted that the description "| |" used herein indicates an absolute value.

It can be understood that the reason for the change of the vacuum degree may include that the amount of harmful gas generated during the removal of the harmful elements enters the vacuum induction melting system to change the vacuum degree of the vacuum induction melting system, or that external air enters the vacuum induction melting system to change the vacuum degree of the vacuum induction melting system.

In some preferred embodiments of the present invention, the refining is stopped if the absolute value of the rate of change of the leak rates of two adjacent passes is 5% or less. Therefore, the gas leakage rate difference between two adjacent times is smaller, the quantity of harmful gas elements and impurities in the alloy liquid is smaller, and the purity, the quality and the fatigue life of the GH4720Li alloy obtained by smelting are improved more favorably.

The inclusions may include carbon-nitrogen inclusions, silicon carbide inclusions, and the like, and the number and distribution of the inclusions may be observed and counted by using a Scanning Electron Microscope (SEM) and Image Pro plus software.

In some preferred embodiments of the invention, the stirring is carried out during the refining period using a line frequency stirring power of 115-135 KW. Therefore, the method is more beneficial to the removal of harmful gas elements, the reduction of inclusions, the improvement of the purity, the quality and the fatigue life of the GH47 4720Li alloy obtained by smelting, and the higher metallurgical quality.

In some embodiments of the present invention, the time interval between two adjacent air leakage rate measurements is 5-10min (e.g., 5min, 6min, 8min, or 10min, etc.). Therefore, the time interval is proper, and the measured change rate of the air leakage rate of two adjacent measurements can accurately judge whether the refining can be finished.

In some embodiments of the invention, the time for each leak rate measurement is 30-60s (e.g., may be 30s, 40s, 50s, or 60s, etc.). Therefore, the air leakage rate measured each time is relatively accurate.

In some embodiments of the invention, the temperature of the refining is 1500-; the degree of vacuum during the vacuum induction melting is not less than 0 and not more than 50Pa (for example, 10Pa, 20Pa, 30Pa, 40Pa, or 50 Pa). Therefore, the refining effect is better.

In some embodiments of the invention, the vacuum induction melting is performed in a vacuum induction melting furnace, and the entire vacuum induction melting furnace may be regarded as a vacuum induction melting system.

In some embodiments of the invention, the distribution of the number of inclusions in the GH4720Li alloy obtained after completion of Vacuum Induction Melting (VIM) may be as low as 3548N/mm²The cycle number increased to 6315 when the fatigue life of the GH4720Li alloy was tested at 455 ℃.

In some embodiments of the invention, after the vacuum induction melting, electroslag remelting and/or vacuum arc remelting is further included. Therefore, the quality of the GH4720Li alloy is further improved.

In some preferred embodiments of the present invention, after the vacuum induction melting, electroslag remelting (ESR) and Vacuum Arc Remelting (VAR) are sequentially performed.

It is to be understood that the electroslag remelting and vacuum arc remelting are conventional electroslag remelting and vacuum arc remelting, and will not be described in detail herein.

In some embodiments of the present invention, the above-mentioned smelting method comprises the steps of: batching → stock preparation → charging → power supply → high vacuum → alloy material full melting → temperature measurement → power reduction → refining → side gas leakage rate → sampling → seasoning → temperature measurement → argon filling → microelement addition → sampling → temperature measurement → conjunctiva → power supply → pouring.

In other embodiments of the present invention, the above-mentioned smelting method comprises the steps of:

1. preparing materials: calculating the use amount of each element raw material according to the control requirement of GH4720Li alloy components by mass percent;

2. preparing materials: selecting metal nickel (such as a nickel plate), metal cobalt (such as a cobalt plate), metal chromium, metal molybdenum (such as a molybdenum strip), metal tungsten (such as a tungsten strip), ferroboron, a graphite electrode and the like, wherein all raw materials need to be clean and free of oil stains;

3. charging: nickel plates, cobalt plates and the like are randomly arranged at the bottom of the furnace, tungsten strips, molybdenum strips and the like are distributed at the middle layer position of a crucible of the vacuum induction furnace, and intermediate alloys (comprising Ni, Co, Cr and the like) are arranged on the intermediate layers;

4. and (3) high vacuum pumping: vacuumizing the vacuum induction furnace to 0-50 Pa;

5. melting period: the full melting temperature of the alloy material is 1400-1590 ℃;

6. and (3) refining period: after the alloy material is completely melted, entering a refining period, adjusting melting power, stirring by adopting power frequency stirring power of 100-150KW, adding alloy elements Al and Ti, starting to measure gas leakage rate after entering the refining period for 90min, controlling refining temperature to be 1500-1600 ℃, judging whether the refining period is finished or not by comparing the change rate of two adjacent gas leakage rates, and stopping refining if the absolute value of the change rate of the gas leakage rate measured by two adjacent times is less than or equal to 7%;

7. filling argon: argon is filled into the smelting chamber after the refining period is finished;

8. introducing argon, mixing trace alloy elements (including Zr, B and the like), adding the mixture into a crucible, and stirring the trace alloy elements to melt to obtain an alloy finished product sample;

9. pouring of the alloy: and (3) pouring the alloy liquid obtained in the step (8) to obtain GH4720Li alloy, wherein the pouring temperature is 1420-1500 ℃, and the time for pouring the phi 360mm electrode is 11-15 min (the time range refers to the time for pouring 2 electrodes, and if one electrode is poured, the time is halved).

In another aspect of the invention, the invention provides GH4720Li alloy obtained by smelting according to the smelting method. The GH4720Li alloy has high purity and long fatigue life.

In another aspect of the invention, the invention provides a GH4720Li alloy part, at least a part of the GH4720Li alloy part is prepared by using the GH4720Li alloy.

In some embodiments of the invention, the GH4720Li alloy part comprises at least one of an aircraft engine turbine disk, an aircraft engine compressor disk, an aircraft engine blade, and an aircraft engine gas disk.

In another aspect of the invention, the invention provides an aircraft engine comprising an aircraft engine blade as hereinbefore described.

It should be noted that, besides the aero-engine blade described above, the aero-engine may also include structures that a conventional aero-engine should have, such as an air intake duct and a combustion chamber, and therefore, redundant description is not repeated herein.

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