Ni30 superalloy and method of heat treating the same

Abstract

The application provides a heat treatment method of a Ni30 high-temperature alloy, and comprises the following steps: S1: producing an electrode bar: according to the chemical composition of the Ni30 alloy, metal raw materials are loaded into a non-vacuum induction furnace, current heating is carried out to melt at 1500-1600 DEG C, then pouring is carried out in an ingot mold, mold cooling is carried out, then demolding is carried out, and then air cooling is continuously carried out to room temperature, so that a solid solution electrode bar is obtained; S2: high-temperature solid solution: the solid solution electrode bar obtained in the step S1 is loaded into a heating furnace, heating is carried out to 1050-1150 DEG C, and then holding is carried out for 4-8 hours, then the furnace is discharged, and water cooling is carried out to room temperature, so that a solid solution electrode bar is obtained; S3: electroslag remelting smelting: the solid solution electrode bar obtained in the step S2 is subjected to electroslag remelting smelting, so that an electroslag ingot is obtained, and preparation is completed. Through the application, the problem that the Ni30 high-temperature alloy electrode bar prepared by the conventional heat treatment method has large stress, the process parameters are unstable in the electroslag remelting process, the quality of the electroslag ingot is unstable, and the material yield of forging is low is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal heat treatment, in particular to a Ni30 high-temperature alloy and a heat treatment method thereof. BACKGROUND

[0002] Ni30 alloy is an age hardening type high-temperature alloy gas valve material invented by Japan Hitachi Metal. After the patent expired in 2014, domestic related manufacturers began to trial-produce the material.

[0003] In the preparation of Ni30 high-temperature alloy, the conventional process adopts non-vacuum induction + electroslag remelting process to smelt the alloy electrode rod. There is a problem that the quality of the electroslag ingot is unstable due to large fluctuation of the process parameters in the electroslag remelting process. Cracks occur in the forging process, resulting in very low yield of Ni30 high-temperature alloy.

[0004] Through analysis, it is considered that the content of Al and Ti in Ni30 alloy is as high as 4.5% or more, which forms γ' phase with Ni element to have age hardening effect. The stress generated by the precipitation of γ' phase in the cooling process of the electrode rod affects the stability of the process parameters in the electroslag process. There is no stress removal process for the electrode rod of Ni30 high-temperature alloy in the conventional technology, resulting in unstable quality of the electroslag ingot of Ni30 high-temperature alloy produced by the conventional method, and high crack scrap rate in the forging process. Therefore, a suitable process for removing the stress of the electrode rod of Ni30 high-temperature alloy needs to be found. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a heat treatment method for the electrode rod of Ni30 high-temperature alloy, so as to solve the problems of unstable quality of the electroslag ingot of Ni30 high-temperature alloy prepared by the conventional process, and high crack scrap rate and low material yield in the forging process.

[0006] To solve the above problems, the present application provides a heat treatment method for the electrode rod of Ni30 high-temperature alloy, comprising the following steps:

[0007] S1: producing an electrode rod: according to the chemical composition of Ni30 alloy, metal raw materials are loaded into a non-vacuum induction furnace, and power is supplied to heat to 1500-1600℃ for melting, then poured into an ingot mold, and after mold cooling, the mold is removed, and then air cooling is continued to room temperature to obtain a solid solution electrode rod;

[0008] The chemical composition of the Ni30 alloy comprises:

[0009] C: ≤0.08%; Mn: ≤0.50%; Si: ≤0.50%; S: ≤0.015%; P: ≤0.015%;

[0010] Cr: 13.50%-15.50%; B: ≤0.01%; Cu: ≤0.2%; Al: 1.6%-2.2%; Ti: 2.30%-2.90%; Nb: 0.40%-0.90%; Mo: 0.40%-1.00%; Ni: 29.5%-33.5%; the balance being iron and other inevitable impurities;

[0011] S2: high-temperature solid solution: the electrode rod to be solid-solved obtained in the step S1 is loaded into a heating furnace, heated to 1050-1150°C, and kept for 4-8 hours, then discharged and cooled to room temperature to obtain a solid-solution electrode rod.

[0012] S3: electroslag remelting smelting: the solid-solution electrode rod obtained in the step S2 is subjected to electroslag remelting smelting to obtain an electroslag steel ingot, and the preparation is completed.

[0013] As a preferred scheme, in the step S1, the temperature of the electric heating is 1500-1540°C.

[0014] As a preferred scheme, in the step S1, the time of the belt mold cooling is greater than 4 hours.

[0015] As a preferred scheme, in the step S1, the chemical composition of the Ni30 alloy comprises:

[0016] C: ≤0.05%; Mn: ≤0.30%; Si: ≤0.30%; S: ≤0.010%; P: ≤0.010%;

[0017] Cr: 14.00%-15.00%; B: ≤0.005%; Cu: ≤0.1%; Al: 1.8%-2.0%; Ti: 2.40%-2.80%; Nb: 0.50%-0.70%; Mo: 0.50%-0.80%; Ni: 30.5%-32.5%; the balance being iron and other inevitable impurities;

[0018] As a preferred scheme, in the step S1, the chemical composition of the Ni30 alloy comprises:

[0019] C: ≤0.05%; Mn: ≤0.20%; Si: ≤0.25%; S: ≤0.005%; P: ≤0.008%;

[0020] Cr: 14.50; B: ≤0.005%; Cu: ≤0.05%; Al: 1.95%; Ti: 2.70%; Nb: 0.60%; Mo: 0.60%; Ni: 31.48%; the balance being iron and other inevitable impurities.

[0021] As a preferred scheme, in the step S2, the temperature of the heat preservation is 1080 DEG C, and the time is 6 hours.

[0022] As a preferred scheme, in the step S2, the temperature of the heat preservation is 1080 DEG C, and the time is 6 hours.

[0023] Another technical problem to be solved by the present application is to provide a Ni30 high-temperature alloy electrode rod to solve the problems of unstable quality of Ni30 high-temperature alloy electroslag ingot produced by conventional processes and low material yield of forging.

[0024] To solve the above problems, the present application provides a Ni30 high-temperature alloy prepared by the above heat treatment method.

[0025] Compared with the prior art, the present application has the following innovative points:

[0026] The present application adopts a solid solution heat treatment process of high temperature 1050 DEG C-1150 DEG C and heat preservation for 4-8 hours, so that the gamma prime phase in the Ni30 high-temperature alloy is fully dissolved, and the stress generated by the precipitation of the gamma prime phase in the electrode rod is eliminated; and further, the method of water cooling is adopted to achieve the purpose of rapidly cooling the electrode rod to be solid solution, reduce the precipitation amount of the gamma prime phase in the electrode rod to be solid solution in the range of 800-600 DEG C, and finally achieve the purpose of eliminating (or greatly reducing) the organizational stress, solving the problems of large stress of the Ni30 high-temperature alloy electrode rod prepared by the conventional method, low material yield, and many crack waste products. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The JmatPro software is used to simulate the equilibrium phase diagram of the Ni30 alloy.

[0028] Figure 2 The figure is a comparison chart of the electroslag remelting curves of the Ni30 alloy electrode rod before and after the high-temperature solid solution process.

[0029] Figure 2 In the figure, the left graph is before improvement, and the right graph is after improvement. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] The present application provides a heat treatment method of a Ni30 high-temperature alloy electrode rod, comprising the following steps:

[0032] S1: producing electrode bar: according to the chemical composition of Ni30 alloy, a certain proportion of metal raw materials is loaded into a non-vacuum induction furnace, and is heated to 1500-1600 DEG C by power supply to melt, and then is poured into an ingot mold, and after mold cooling, the mold is removed, and then continues to be air cooled to room temperature, to obtain a solid solution electrode bar to be prepared;

[0033] The chemical composition of the Ni30 alloy comprises:

[0034] C: ≤0.08%; Mn: ≤0.50%; Si: ≤0.50%; S: ≤0.015%; P: ≤0.015%;

[0035] Cr: 13.50%-15.50%; B: ≤0.01%; Cu: ≤0.2%; Al: 1.6%-2.2%; Ti: 2.30%-2.90%; Nb: 0.40%-0.90%; Mo: 0.40%-1.00%; Ni: 29.5%-33.5%; the balance is iron and other inevitable impurities;

[0036] S2: high-temperature solid solution: the solid solution electrode bar obtained in the step S1 is loaded into a heating furnace, and is heated to 1050-1150 DEG C and kept for 4-8 hours, and then is discharged and cooled to room temperature, to obtain a solid solution electrode bar.

[0037] S3: electroslag remelting smelting: the solid solution electrode bar obtained in the step S2 is subjected to electroslag remelting smelting, to obtain an electroslag steel ingot, and the preparation is completed.

[0038] Preferably, in the step S1, the temperature of the power heating is 1500-1540 DEG C.

[0039] Preferably, in the step S1, the time of the mold cooling is greater than 4 hours.

[0040] Preferably, the chemical composition of the Ni30 alloy in the step S1 comprises:

[0041] C: ≤0.05%; Mn: ≤0.30%; Si: ≤0.30%; S: ≤0.010%; P: ≤0.010%;

[0042] Cr: 14.00%-15.00%; B: ≤0.005%; Cu: ≤0.1%; Al: 1.8%-2.0%; Ti: 2.40%-2.80%; Nb: 0.50%-0.70%; Mo: 0.50%-0.80%; Ni: 30.5%-32.5%; the balance is iron and other inevitable impurities;

[0043] Preferably, the chemical composition of the Ni30 alloy comprises:

[0044] C: ≤0.05%; Mn: ≤0.20%; Si: ≤0.25%; S: ≤0.005%; P: ≤0.008%;

[0045] Cr: 14.50; B: ≤0.005%; Cu: ≤0.05%; Al: 1.95%; Ti: 2.70%; Nb: 0.60%; Mo: 0.60%; Ni: 31.48%; the balance is iron and other inevitable impurities.

[0046] Preferably, in the step S2, the temperature of the heat preservation is 1080℃, and the time is 6 hours.

[0047] Preferably, in the step S2, the mode of the out-of-furnace cooling is water cooling, and the temperature of the electrode rod before water cooling is greater than or equal to 880℃.

[0048] The application also provides a Ni30 high-temperature alloy prepared by the heat treatment method.

[0049] The following provides examples to further expand the above technical solutions of the application:

[0050] Example 1:

[0051] The embodiment provides a heat treatment method of a Ni30 high-temperature alloy, including the following steps:

[0052] S1: producing an electrode rod: according to the chemical composition of the Ni30 alloy, metal raw materials are loaded into a non-vacuum induction furnace, and power is supplied to heat to 1500-1600℃ for melting, then poured into an ingot mold, and after mold cooling for more than 4 hours, the mold is removed, and then air cooling is continued to room temperature, to obtain a solid solution electrode rod;

[0053] The chemical composition of the Ni30 alloy includes:

[0054] C: ≤0.08%; Mn: ≤0.50%; Si: ≤0.50%; S: ≤0.015%; P: ≤0.015%;

[0055] Cr: 13.50%-15.50%; B: ≤0.01%; Cu: ≤0.2%; Al: 1.6%-2.2%; Ti: 2.30%-2.90%; Nb: 0.40%-0.90%; Mo: 0.40%-1.00%; Ni: 29.5%-33.5%; the balance is iron and other inevitable impurities;

[0056] S2: high temperature solid solution: the electrode rod to be solid-solved obtained in the step S1 is loaded into a heating furnace, heated to 1080 DEG C and kept for 6 hours, then discharged and water-cooled to room temperature, the temperature of the solid-solution electrode rod before water-cooling is greater than or equal to 880 DEG C, and a solid-solution electrode rod is obtained.

[0057] S3: electroslag remelting smelting: the solid-solution electrode rod obtained in the step S2 is subjected to remelting smelting, and an electroslag steel ingot is obtained, and the preparation is completed.

[0058] Preferably, in the step S1, the chemical composition of the Ni30 alloy comprises:

[0059] C: 0.05%; Mn: 0.20%; Si: 0.25%; S: 0.005%; P: 0.006%; Cr: 14.50; B: 0.005%; Cu: 0.01%; Al: 1.95%; Ti: 2.70%; Nb: 0.60%; Mo: 0.60%; Ni: 31.48%; and the balance is iron and other inevitable impurities.

[0060] Preferably, in the step S1, the ingot mold is a Φ330mm ingot mold; and in the step S3, the electroslag steel ingot is a Φ500mm electroslag steel ingot.

[0061] The embodiment also provides a Ni30 high-temperature alloy prepared by the above-mentioned heat treatment method.

[0062] As shown in Figure 1 the above-mentioned embodiment of the present application, the JmatPro software is used to simulate the equilibrium phase diagram of the Ni30 alloy to understand the dissolution temperature of the γ'(GAMMA-PRIME in the figure) phase.

[0063] According to Figure 1 the JmatPro software simulating the dissolution temperature of the γ'(GAMMA-PRIME in the figure) phase in the equilibrium phase diagram of the Ni30 alloy, the solid-solution process is determined, including the process parameters such as holding temperature, holding time and cooling medium.

[0064] Figure 1 The curve composed of the middle gray blocks (GAMMA-PRIME) is GAMMA-PRIME (i.e. γ' phase).

[0065] The simulation results show that: in the heating process, the γ' phase is dissolved above 880 DEG C. At a temperature greater than 880 DEG C, the purpose of dissolving the γ' phase is achieved. Therefore, the solid-solution of the Ni30 alloy electrode rod at any temperature greater than 880 DEG C belongs to the protection scope of the present application.

[0066] During the cooling process, water cooling is used to achieve rapid cooling, which reduces the precipitation of the γ' phase in the range of 800-600℃, and ultimately eliminates (or significantly reduces) the structural stress. Other cooling methods, such as oil cooling or other cooling methods with a cooling rate greater than that of air cooling, are also within the scope of protection of this invention.

[0067] pass Figure 1 As can be seen, the phase dissolution temperature of γ' (GAMMA-PRIME in the figure) is around 880℃. Considering that the electrode needs time for processes such as unloading from the furnace, transportation, and immersion in water after being held at high temperature for a certain period of time, the surface temperature of the electrode rod will drop. Based on the actual time used and the measured surface temperature drop data, the holding temperature is determined to be 1050℃-1150℃ for 4-8 hours (preferably 1080℃ for 6 hours). This ensures that the surface temperature of the electrode is not less than 880℃ before immersion in water, achieving a solid solution effect. To ensure uniform heating of the Φ330mm electrode rod and complete dissolution of γ', the holding time is determined to be 6 hours. To achieve rapid cooling and reduce γ' precipitation when the electrode rod cools below 880℃, water is selected as the cooling medium.

[0068] Example 2:

[0069] This embodiment provides a heat treatment method for Ni30 high-temperature alloy, including the following steps:

[0070] S1: Production of electrode rods: According to the chemical composition of Ni30 alloy, a certain proportion of metal raw materials are loaded into a non-vacuum induction furnace, heated to 1500℃ and melted, then poured into an ingot mold, cooled with the mold for more than 4 hours, demolded, and then air-cooled to room temperature to obtain the electrode rod to be solidified.

[0071] The chemical composition of the Ni30 alloy includes:

[0072] C: ≤0.05%; Mn: ≤0.30%; Si: ≤0.30%; S: ≤0.010%; P: ≤0.010%;

[0073] Cr: 14.00%; B: ≤0.005%; Cu: ≤0.1%; Al: 1.8%; Ti: 2.40%; Nb: 0.50%; Mo: 0.50%; Ni: 30.5%; balance is iron and other unavoidable impurities.

[0074] S2: High-temperature solid solution: The electrode rod to be solidified obtained in step S1 is placed into a heating furnace, heated to 1050°C and kept at that temperature for 8 hours, and then removed from the furnace and cooled to room temperature with water. The temperature of the electrode rod to be solidified in water before water cooling is greater than or equal to 880°C, thus obtaining the solidified electrode rod.

[0075] S3: Electroslag remelting smelting: the solid solution electrode rod obtained in the step S2 is subjected to electroslag remelting smelting to obtain an electroslag steel ingot, and the preparation is completed.

[0076] The embodiment further provides a Ni30 high-temperature alloy prepared by the heat treatment method.

[0077] Embodiment 3:

[0078] The embodiment provides a heat treatment method of a Ni30 high-temperature alloy, including the following steps.

[0079] S1: Production of electrode rod: according to the chemical composition of the Ni30 alloy, a certain proportion of metal raw materials is loaded into a non-vacuum induction furnace, and is heated to 1500-1600 DEG C by power supply to melt, and then is poured into an ingot mold, and is taken out after mold cooling for more than 4 hours, and is continuously air-cooled to room temperature to obtain a solid solution electrode rod;

[0080] The chemical composition of the Ni30 alloy includes:

[0081] C: ≤0.08%; Mn: ≤0.50%; Si: ≤0.50%; S: ≤0.015%; P: ≤0.015%;

[0082] Cr: 15.50%; B: ≤0.01%; Cu: ≤0.2%; Al: 2.2%; Ti: 2.90%; Nb: 0.90%; Mo: 1.00%; Ni: 33.5%; the balance is iron and other inevitable impurities;

[0083] S2: High-temperature solid solution: the solid solution electrode rod obtained in the step S1 is loaded into a heating furnace, is heated to 1150 DEG C and is kept for 4 hours, and then is taken out and water-cooled to room temperature, and the temperature of the solid solution electrode rod before water cooling is greater than or equal to 880 DEG C to obtain a solid solution electrode rod.

[0084] S3: Electroslag remelting smelting: the solid solution electrode rod obtained in the step S2 is subjected to electroslag remelting smelting to obtain an electroslag steel ingot, and the preparation is completed.

[0085] Preferably, in the step S1, the chemical composition of the Ni30 alloy includes:

[0086] The embodiment further provides a Ni30 high-temperature alloy prepared by the heat treatment method.

[0087] As described above, the present application makes the γ' phase fully dissolve by adopting high-temperature solid solution treatment and heat preservation, eliminates the stress in the electrode rod due to the precipitation of the γ' phase; adopts the method of water cooling to achieve the purpose of rapid cooling, reduces the precipitation amount of the γ' phase in the range of 800-600 ℃, and finally achieves the purpose of eliminating (or greatly reducing) the organizational stress, and improves the final Ni30 high-temperature alloy yield.

[0088] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present disclosure.

Claims

1. A method of heat treatment of a Ni30 superalloy, characterized in that: The method comprises the following steps: S1: producing an electrode rod: according to the chemical composition of the Ni30 alloy, metal raw materials are loaded into a non-vacuum induction furnace, and current heating is performed to melt at 1500-1600 DEG C, and then the molten metal is poured into an ingot mold, the mold is cooled, and then the electrode rod is taken out of the mold and further air-cooled to room temperature to obtain a solid solution electrode rod; the chemical composition of the Ni30 alloy comprises: C: ≤0.08%; Mn: ≤0.50%; Si: ≤0.50%; S: ≤0.015%; P: ≤0.015%; Cr: 13.50%-15.50%; B: ≤0.01%; Cu: ≤0.2%; Al: 1.6%-2.2%; Ti: 2.30%-2.90%; Nb: 0.40%-0.90%; Mo: 0.40%-1.00%; Ni: 29.5%-33.5%; and the balance is iron and other inevitable impurities; S2: high-temperature solid solution: the solid solution electrode rod obtained in the step S1 is loaded into a heating furnace, heated to 1050-1150 DEG C, and kept for 4-8 hours, and then taken out of the furnace and cooled to room temperature to obtain a solid solution electrode rod; S3: electroslag remelting smelting: the solid solution electrode rod obtained in the step S2 is subjected to electroslag remelting smelting to obtain an electroslag ingot, and the preparation is completed. In the step S2, the mode of the furnace cooling is water cooling, and the temperature of the solid solution electrode rod before water cooling is greater than or equal to 880 DEG C.

2. The heat treatment method of a Ni30 superalloy according to claim 1, characterized in that: In the step S1, the temperature of the current heating is 1500-1540 DEG C.

3. The method of heat treatment of a Ni30 superalloy according to claim 1, characterized in that: In the step S1, the time of the mold cooling is greater than 4 hours.

4. The method of heat treatment of Ni30 superalloys according to claim 1, characterized in that: In the step S1, the chemical composition of the Ni30 alloy comprises: C: ≤0.05%; Mn: ≤0.30%; Si: ≤0.30%; S: ≤0.010%; P: ≤0.010%; Cr: 14.00%-15.00%; B: ≤0.005%; Cu: ≤0.1%; Al: 1.8%-2.0%; Ti: 2.40%-2.80%; Nb: 0.50%-0.70%; Mo: 0.50%-0.80%; Ni: 30.5%-32.5%; and the balance is iron and other inevitable impurities.

5. The heat treatment method of a Ni30 superalloy according to claim 4, characterized in that: The chemical composition of the Ni30 alloy comprises: C: ≤0.05%; Mn: ≤0.20%; Si: ≤0.25%; S: ≤0.005%; P: ≤0.008%; Cr: 14.50%; B: ≤0.005%; Cu: ≤0.05%; Al: 1.95%; Ti: 2.70%; Nb: 0.60%; Mo: 0.60%; Ni: 31.48%; and the balance is iron and other inevitable impurities.

6. The method of heat treating a Ni30 superalloy according to claim 1, wherein: In the step S2, the temperature of the heat preservation is 1080 DEG C, and the time is 6 hours.

7. A Ni30 superalloy characterized by: The high-temperature alloy is prepared by the heat treatment method in any one of claims 1-6.

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