Preparation method of high-alloying easy-to-crack nickel-based wrought superalloy cast ingot

Abstract

The invention discloses a preparation method of a high-alloying easy-to-crack nickel-based wrought superalloy cast ingot, which specifically comprises the following steps: adopting a higher runner preheating temperature, a higher ingot mold preheating temperature, a lower pouring temperature, a lower pouring speed and a shorter vacuum cooling time in an induction melting process to reduce thermal stress when the cast ingot is cooled; in the thermal annealing process, a low heating rate and a high annealing temperature are selected, thermal stress and structural stress in the cast ingot are reduced, the purpose of improving the cracking defect of the cast ingot is achieved, and finally the induction cast ingot which is good in surface quality and free of melting speed fluctuation in the duplex consumable smelting process is obtained. By means of the preparation method, the problems that a high-alloying large-size induction ingot is prone to cracking and the melting speed of consumable smelting is unstable are solved, the metallurgical quality of the deformed high-temperature alloy is improved, and a foundation is laid for preparing large-specification bars and large-size forgings.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-based high-temperature alloy smelting, and in particular relates to a method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot. Background Art

[0002] Nickel-based deformable superalloys are a type of metal material that can withstand stress for a long time and maintain stable operation under extreme ambient temperature conditions of 600°C or higher. They are mainly used to produce key components such as turbine disks, turbine blades, and bolts that need to withstand high temperature environments for aircraft engines. In recent years, with the increasing demand for high thrust-to-weight ratio aircraft engines, there is an urgent need to develop high-performance deformable superalloys. As a result, the alloying degree of nickel-based deformable superalloys has been continuously improved, and the performance of the alloy has been improved by adding a large amount of precipitation strengthening elements (Al, Ti, Nb, etc.) and solid solution strengthening elements (Co, Cr, Mo, W, etc.).

[0003] With the development trend of high alloying of nickel-based deformable high-temperature alloys, it is inevitable that serious component segregation, more hard and brittle phases will be precipitated between grains, and the content of γ′ phase can reach up to 50%, which makes it very easy to crack during the cooling process of induction casting, and the cracking tendency will increase further as the ingot shape expands. For double-melting alloys, these cracks will directly affect the subsequent remelting process, and it is very easy to cause large fluctuations in process parameters such as voltage, current, melting rate and droplet during the consumable melting process, causing disturbance of the metal molten pool flow, which may cause macroscopic defects such as black spots and white spots in the material, resulting in the scrapping of the material. At present, there are few reports on the control methods of cracking defects in high-alloyed ingots, which greatly limits the expansion of high-alloyed ingot shapes and the improvement of industrial production efficiency. The preheating temperature of the launder and ingot mold, the pouring temperature and pouring rate of the molten steel, the vacuum cooling time and the subsequent annealing process are closely related to the comprehensive quality of the induction casting, and further affect the stability of the melting rate during the subsequent remelting process. Therefore, selecting appropriate launder and ingot mold preheating temperature, molten steel pouring temperature and pouring speed, vacuum cooling time and thermal annealing system can effectively reduce the thermal stress and structural stress of high-alloyed ingots prone to cracking, thereby achieving the effect of improving ingot cracking defects. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot, comprising the following steps:

[0006] Step 1, vacuum induction melting: according to the alloy composition requirements, weigh the alloy raw materials, and then put the high-temperature alloy raw materials into the vacuum induction furnace according to a specific feeding order for vacuum induction melting;

[0007] Step 2: Preheating the launder and ingot mold:

[0008] 2.1. Before vacuum induction melting, place the launder in the preheating station and keep it at a certain temperature for a certain period of time;

[0009] 2.2. During the vacuum induction melting process, the ingot mold is placed in a preheating station and kept at a certain temperature for a certain period of time;

[0010] Step 3, pouring: at the end of vacuum induction melting, after adjusting the molten steel to a certain pouring temperature, the preheated launder and ingot mold are placed in the launder chamber and ingot mold chamber respectively, and pouring is performed at a certain pouring speed;

[0011] Step 4, induction ingot cooling: after pouring, the ingot is vacuum cooled in the ingot mold chamber for a certain period of time and then demolded;

[0012] Step 5, hot annealing of the ingot: the induction ingot removed from the ingot mold is sent to the annealing furnace, the ingot is heated to a certain temperature at a certain heating rate, and kept warm for a certain period of time, finally obtaining a vacuum induction ingot with good surface quality.

[0013] Preferably, the composition of the high-alloyed easy-to-cracking nickel-based deformable high-temperature alloy is, in terms of mass percentage, C: 0.10% to 0.20%, Al: 4.2% to 5.0%, Ti: 1.0% to 2.2%, Mo: 4.0 to 5.8, Co: 19.5 to 22.0, Cr: 14.0 to 16.0, B: 0.002 to 0.009, Zr: 0.05 to 0.18, and the rest is Ni.

[0014] Preferably, the launder preheating temperature in step 2.1 is 1100-1200° C., and the preheating time is 8-12 hours.

[0015] Preferably, the preheating temperature of the ingot mold in step 2.2 is 400-550° C., and the preheating time is 2-4 hours.

[0016] Preferably, the pouring temperature in step 3 is 1440-1460° C., and the pouring speed is 180-210 kg / min.

[0017] Preferably, the vacuum cooling time in step 4 is 25 to 40 minutes.

[0018] Preferably, the ingot thermal annealing heating heating rate in step 5 is 50-80°C / min, the annealing temperature is 900-1100°C, the holding time is 6-10h, and the ingot is cooled to 250-350°C in the furnace and air-cooled out of the furnace.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention adopts a higher launder and ingot mold preheating temperature, a lower pouring temperature and pouring speed, and a shorter vacuum cooling time, and reduces the temperature difference between the melt and the ingot mold to minimize the thermal stress generated when the induction ingot is cooled in the ingot mold, thereby reducing the number of cracks inside and outside the ingot and improving the overall quality of the induction ingot;

[0021] (2) The present invention adopts a lower annealing heating rate and a higher annealing temperature, which can significantly reduce the structural stress and thermal stress in the induction ingot, thereby obtaining an induction ingot without cracks and with good surface quality, and significantly improving the melting rate fluctuation problem in the subsequent consumable smelting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a high alloy nickel-based deformable high temperature alloy vacuum induction ingot corresponding to the present invention;

[0023] Figure 2 is the melting rate of the high-alloyed nickel-based deformed high-temperature alloy corresponding to the present invention during the consumable melting process;

[0024] Figure 3 The vacuum induction cast ingot of high alloy nickel-based deformed high temperature alloy corresponding to the cracking in Comparative Example 1;

[0025] Figure 4 The melting rate fluctuation during the consumable melting process of the high-alloyed nickel-based deformed high-temperature alloy corresponding to Comparative Example 1;

[0026] Figure 5 The vacuum induction cast ingot of high alloy nickel-based deformed high temperature alloy corresponding to the cracking in Comparative Example 2;

[0027] Figure 6 The melting rate fluctuation during the consumable melting process of the high-alloyed nickel-based deformed high-temperature alloy corresponding to Comparative Example 2;

[0028] Figure 7 The present invention is a flow chart of the preparation method. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] See also Figure 1-Figure 6 The present invention provides a technical solution: a method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot, which specifically comprises the following steps:

[0031] Step 1, Vacuum Induction Melting

[0032] According to the alloy composition requirements, the alloy raw materials are weighed, and then the high-temperature alloy raw materials are placed in a vacuum induction furnace according to a specific charging sequence for vacuum induction melting;

[0033] Step 2: Preheating the launder and ingot mold

[0034] 2.1. Before vacuum induction melting, place the launder in the preheating station and preheat at 1100-1200℃ for 8-12h;

[0035] 2.2. During the vacuum induction melting process, place the ingot mold in the ingot mold preheating station and preheat it at 400-550°C for 2-4 hours;

[0036] Step 3, pouring

[0037] At the end of vacuum induction melting, the temperature of the molten steel is adjusted to 1440-1460°C, and then the preheated launder and ingot mold are respectively loaded into the launder chamber and ingot mold chamber, and the molten steel is poured into the ingot mold at a speed of 180-210 kg / min;

[0038] Step 4: Induction ingot cooling

[0039] The induction casting ingot is vacuum cooled in the ingot mold chamber for 25 to 40 minutes and then demolded;

[0040] Step 5: Ingot thermal annealing

[0041] The ingot removed from the ingot mold is sent to the annealing furnace, heated to 900-1100°C at a heating rate of 50-80min / °C, kept warm for 6-10h, then cooled to 250-350°C and air-cooled, completing the preparation of the vacuum induction ingot.

[0042] Embodiment 1 comprises the following steps:

[0043] Step 1, Vacuum Induction Melting

[0044] According to the alloy composition requirements, the alloy raw materials are weighed, and then the high-temperature alloy raw materials are placed in a vacuum induction furnace according to a specific charging sequence for vacuum induction melting;

[0045] Step 2: Preheating the launder and ingot mold

[0046] 2.1. Preheat the launder at 1100°C for 10 hours;

[0047] 2.2. Preheat the ingot mold at 400°C for 4 hours;

[0048] Step 3, pouring

[0049] Adjust the temperature of the molten steel to 1450°C, place the preheated launder and ingot mold in the launder chamber and ingot mold chamber respectively, and pour the molten steel into the ingot mold at a pouring speed of 190-200 kg / min;

[0050] Step 4: Induction ingot cooling

[0051] The induction casting ingot was vacuum cooled in the ingot mold chamber for 30 min and then demoulded;

[0052] Step 5: Ingot thermal annealing

[0053] The ingot is sent to the annealing furnace, heated to 1000℃ at a heating rate of 60℃ / min and kept at this temperature for 6h, and finally cooled to 350℃ and then taken out of the furnace for air cooling. Figure 1 As shown, a vacuum induction ingot with good surface quality is obtained; the induction ingot is subsequently subjected to self-consumable smelting, such as Figure 2 As shown in the figure, the melting rate is stable without obvious fluctuation during the smelting process.

[0054] Embodiment 2 comprises the following steps:

[0055] Step 1, Vacuum Induction Melting

[0056] According to the alloy composition requirements, the alloy raw materials are weighed, and then the high-temperature alloy raw materials are placed in a vacuum induction furnace according to a specific charging sequence for vacuum induction melting;

[0057] Step 2: Preheating the chute and ingot mold

[0058] 2.1. Preheat the launder at 1150°C for 8 hours;

[0059] 2.2. Preheat the ingot mold at 500°C for 2h;

[0060] Step 3, pouring

[0061] At the end of smelting, the temperature of the molten steel is adjusted to 1440°C, the preheated launder and ingot mold are respectively placed in the launder chamber and ingot mold chamber, and the molten steel is poured into the ingot mold at a pouring speed of 180-190 kg / min;

[0062] Step 4: Induction ingot cooling

[0063] The induction cast ingot was vacuum cooled in the ingot mold chamber for 35 min and then removed;

[0064] Step 5: Ingot thermal annealing

[0065] The ingot was put into the annealing furnace, heated to 1050℃ at a heating rate of 50℃ / min and kept warm for 8h. Finally, it was cooled to 300℃ and air-cooled to obtain a vacuum induction ingot with good surface quality. The vacuum induction ingot was subjected to consumable melting, and the melting rate was stable without melting rate fluctuation problem.

[0066] Comparative Example 1 comprises the following steps:

[0067] Step 1, Vacuum Induction Melting

[0068] According to the alloy composition requirements, the alloy raw materials are weighed, and then the high-temperature alloy raw materials are placed in a vacuum induction furnace according to a specific charging sequence for vacuum induction melting;

[0069] Step 2: Preheating the launder and ingot mold

[0070] 2.1. Preheat the launder at 1000°C for 6 hours;

[0071] 2.2. Preheat the ingot mold at 300°C for 4 hours;

[0072] Step 3, pouring

[0073] At the end of smelting, adjust the temperature of molten steel to 1470℃, load the preheated launder and ingot mold into the launder chamber and ingot mold chamber respectively, and pour at a speed of 240-250kg / min;

[0074] Step 4: Induction ingot cooling

[0075] The induction cast ingot was vacuum cooled in the ingot mold chamber for 40 min and then removed;

[0076] Step 5: Ingot thermal annealing

[0077] The demoulded ingot was sent to the annealing furnace, heated to 700℃ at a heating rate of 60℃ / min and kept at this temperature for 10h, and finally cooled to 400℃ and air-cooled. Obvious cracks were found on the surface of the vacuum induction ingot, such as Figure 3 As shown, the induction ingot was subjected to vacuum consumable melting, and it was found that the melting rate fluctuated during the melting process, such as Figure 4 shown.

[0078] Comparative Example 2 comprises the following steps:

[0079] Step 1, Vacuum Induction Melting

[0080] According to the alloy composition requirements, the alloy raw materials are weighed, and then the high-temperature alloy raw materials are placed in a vacuum induction furnace according to a specific charging sequence for vacuum induction melting;

[0081] Step 2: Preheating the ingot mold

[0082] 2.1. Preheat the launder at 800°C for 10 hours;

[0083] 2.2. Preheat the ingot mold at 350°C for 8 hours;

[0084] Step 3, pouring

[0085] At the end of smelting, adjust the temperature of molten steel to 1480℃, load the preheated launder and ingot mold into the launder chamber and ingot mold chamber respectively, and pour at a speed of 230-240kg / min;

[0086] Step 4: Induction ingot cooling

[0087] The induction cast ingot was vacuum cooled in the ingot mold chamber for 45 min and then removed;

[0088] Step 5: Ingot thermal annealing

[0089] The demoulded ingot was sent to an annealing furnace, heated to 900°C at a heating rate of 100°C / min and kept at this temperature for 8 hours, and finally cooled to 300°C and air-cooled to obtain a vacuum induction ingot with obvious cracks on the surface (such as Figure 5 As shown), the vacuum induction ingot was subjected to consumable melting, and it was found that the melting rate fluctuated during the melting process (as shown Figure 6 shown).

[0090] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot, characterized in that: The following steps are involved: Step 1, vacuum induction melting: according to the alloy composition requirements, weigh the alloy raw materials, and then put the high-temperature alloy raw materials into the vacuum induction furnace according to a specific feeding order for vacuum induction melting; Step 2: Preheating the launder and ingot mold: 2.

1. Before vacuum induction melting, place the launder in the preheating station and keep it at a certain temperature for a certain period of time; 2.

2. During the vacuum induction melting process, the ingot mold is placed in a preheating station and kept at a certain temperature for a certain period of time; Step 3, pouring: at the end of vacuum induction melting, after adjusting the molten steel to a certain pouring temperature, the preheated launder and ingot mold are placed in the launder chamber and ingot mold chamber respectively, and pouring is performed at a certain pouring speed; Step 4, induction ingot cooling: after pouring, the ingot is vacuum cooled in the ingot mold chamber for a certain period of time and then demolded; Step 5, hot annealing of the ingot: the induction ingot removed from the ingot mold is sent to the annealing furnace, the ingot is heated to a certain temperature at a certain heating rate, and kept warm for a certain period of time, finally obtaining a vacuum induction ingot with good surface quality.

2. The method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot according to claim 1, characterized in that: The components of the high-alloyed easy-to-crack nickel-based deformable high-temperature alloy are, in terms of mass percentage, C: 0.10%-0.20%, Al: 4.2%-5.0%, Ti: 1.0%-2.2%, Mo: 4.0-5.8%, Co: 19.5-22.0%, Cr: 14.0-16.0%, B: 0.002-0.009, Zr: 0.05-0.18, and the rest is Ni.

3. The method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot according to claim 1, characterized in that: The launder preheating temperature in step 2.1 is 1100-1200° C., and the preheating time is 8-12 hours.

4. The method for preparing a high-alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot according to claim 1, characterized in that: The ingot mold preheating temperature in step 2.2 is 400-550° C., and the preheating time is 2-4 hours.

5. The method for preparing a high alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot according to claim 1, characterized in that: The pouring temperature in step 3 is 1440-1460° C., and the pouring speed is 180-210 kg / min.

6. The method for preparing a high alloyed easy-to-crack nickel-based deformable high temperature alloy ingot according to claim 1, characterized in that: The vacuum cooling time in step 4 is 25 to 40 minutes.

7. The method for preparing a high alloyed easy-to-crack nickel-based deformable high-temperature alloy ingot according to claim 1, characterized in that: The ingot hot annealing heating heating rate in step 5 is 50-80°C / min, the annealing temperature is 900-1100°C, the holding time is 6-10h, and the ingot is cooled to 250-350°C and then air-cooled out of the furnace.

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