Preparation method of nickel-based high-temperature alloy GH625 (N06625) large-size steel ingot

Abstract

The invention provides a preparation method of a nickel-based high-temperature alloy steel ingot. According to the smelting process of the nickel-based superalloy GH625 large-size vacuum arc furnace steel ingot, the vacuum induction furnace (VIM) and the vacuum arc furnace (VAR) are adopted for duplex smelting to produce the GH625 superalloy large-size steel ingot, and the large-size steel ingot which is phi 810 mm, free of macrosegregation, shallow in shrinkage cavity and good in plasticity can be obtained. According to the method, a 12t vacuum induction furnace is adopted to smelt about 12t electrode bars, a 12t vacuum arc furnace is adopted to remelt a consumable ingot with the diameter of 810mm, and the high-temperature alloy consumable ingot with the diameter of about 12t is prepared. The smelting process of the high-temperature alloy large forge piece material is broken through, the problems that a large-size steel ingot needed by a large forge piece is prone to segregation, the pipe shrinkage depth is large and the like are solved, and the market competitiveness is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nickel-based superalloy smelting, and relates to a preparation method of a nickel-based superalloy steel ingot, in particular to a preparation method of a large-sized steel ingot of nickel-based superalloy GH625 (N06625). Background Art

[0002] Alloy GH625 is a solid-solution strengthened nickel-based wrought superalloy with molybdenum and niobium as the main strengthening elements. It has good corrosion resistance and oxidation resistance, and has good tensile properties and fatigue properties from low temperature to 980 °C. Therefore, it can be widely used in the manufacture of aeroengine components, aerospace structural components and chemical equipment. The alloy has good processing and welding properties, and various plates, bars and forgings can also be supplied.

[0003] At present, the GH625 alloy steel ingots produced by the domestic vacuum induction melting (VIM) + electroslag remelting (ESR) or vacuum induction furnace (VIM) + vacuum arc furnace (VAR) melting processes have a relatively light weight and a relatively small diameter. While alloy GH625 is a nickel-based alloy containing 9.0% Mo and 3.7% Nb, when the diameter of the steel ingot is enlarged from the conventional Φ450 mm and Φ550 mm to Φ810 mm, the relatively high contents of Mo and Nb elements lead to a significantly increased segregation degree during the solidification of the alloy. On the one hand, the generation of segregation will deteriorate the hot working performance of the alloy, and on the other hand, it is also extremely unfavorable to the performance of the final product. Therefore, there is no report showing that the weight of the steel ingot reaches 12 tons and the diameter reaches Φ810 mm, which cannot meet the requirements of large-sized forgings for large-sized steel ingots.

[0004] Therefore, how to find a more suitable method to prepare large-sized GH625 alloy steel ingots and solve the above problems existing in the prior art has become one of the focuses widely concerned by many front-line researchers in the industry. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a preparation method of a nickel-based superalloy steel ingot, in particular to a preparation method of a large-sized steel ingot of nickel-based superalloy GH625 (N06625). The present invention produces and prepares a large-sized steel ingot with Φ810 mm, having no low magnification segregation, a relatively shallow shrinkage cavity and good plasticity, through the vacuum induction furnace (VIM) + vacuum arc furnace (VAR) melting process. Moreover, the process is simple, the conditions are mild, and the controllability is good, which is more conducive to industrialized scale production and popularization and application.

[0006] The present invention provides a preparation method of a nickel-based superalloy steel ingot, comprising the following steps:

[0007] 1) The nickel-based superalloy raw materials are melted in a vacuum induction furnace and then tapped to cast a nickel-based superalloy ingot with a diameter of the first size.

[0008] The nickel-based superalloy is GH625 alloy.

[0009] 2) The nickel-based superalloy ingot obtained in the above step is heated and then forged to obtain a nickel-based superalloy bar with a diameter of the second size.

[0010] 3) The nickel-based superalloy bar obtained in the above step is used as an electrode bar and remelted by consumable electrode remelting with low melting rate in a vacuum arc furnace to obtain a nickel-based superalloy steel ingot with a diameter of the third size.

[0011] The third size is larger than the second size.

[0012] Preferably, the GH625 alloy, by its elemental content, includes:

[0013] Cr: 20.00wt% - 23.00wt%, Mo: 8.00wt% - 10.00wt%, Nb: 3.15wt% - 4.15wt%, C: ≤0.10wt%, Si: ≤0.50wt%, Mn: ≤0.50wt%, S: ≤0.015wt%, P: ≤0.015wt%, Al: ≤0.4wt%, Ti: ≤0.4wt%, Fe: ≤5.0wt%, Co: ≤1.0wt% and the balance Ni.

[0014] Preferably, the nickel-based superalloy raw materials include metal raw materials, or metal raw materials and return materials.

[0015] The mass dosage of the return materials in the raw materials is 10% - 80%.

[0016] Preferably, during the vacuum induction furnace melting process, the C content in the melting mother liquor is ≤0.015wt%.

[0017] During the vacuum induction furnace melting process, the Al content in the melting mother liquor is ≤0.20wt%.

[0018] During the vacuum induction furnace melting process, after alloying is completed, stirring continues for ≥20 min.

[0019] Preferably, the tapping temperature is 1450 - 1490 °C.

[0020] The first size is 840 mm.

[0021] The second size is 710 - 720 mm.

[0022] Preferably, the heating method includes heating in a chamber furnace.

[0023] The heating temperature is 1170 - 1180 °C;

[0024] The forging method includes forging with a 45 / 50MN quick forging machine.

[0025] Preferably, before consumable remelting, it also includes the step of cleaning the surface of the nickel-based superalloy bar;

[0026] The mass of the nickel-based superalloy bar is 9 - 12 tons.

[0027] Preferably, the consumable remelting process includes a melting stage and a feeding stage;

[0028] The melting rate in the melting stage is 5.5 - 4.2 kg / min;

[0029] The melting rate in the melting stage specifically decreases gradually;

[0030] The melting droplet in the melting stage is 0.3 - 1.5 s.

[0031] Preferably, the melting rate in the feeding stage is 4.0 - 2.0 kg / min;

[0032] The melting rate in the feeding stage specifically decreases gradually;

[0033] The feeding weight in the feeding stage is 800 - 1000 kg.

[0034] Preferably, during the consumable remelting process, after power failure, continue to evacuate the vacuum for in-furnace cooling;

[0035] The in-furnace cooling time ≥ 3 h;

[0036] The nickel-based superalloy ingot is a large-sized nickel-based superalloy ingot;

[0037] The third dimension is 810 mm.

[0038] The present invention provides a method for preparing a nickel-based superalloy steel ingot, which includes the following steps: First, the nickel-based superalloy raw materials are melted in a vacuum induction furnace and then tapped to cast a nickel-based superalloy ingot with a diameter of a first size; the nickel-based superalloy is GH625 alloy; then the nickel-based superalloy ingot obtained in the above step is heated and forged to obtain a nickel-based superalloy bar with a diameter of a second size; finally, the nickel-based superalloy bar obtained in the above step is used as an electrode bar, and self-consumable remelting is carried out by low melting rate smelting in a vacuum arc furnace to obtain a nickel-based superalloy steel ingot with a diameter of a third size; the third size is larger than the second size. Compared with the prior art, the present invention believes that when the diameter of the GH625 alloy steel ingot is enlarged to Φ810mm, there will be problems of macrosegregation of large ingot types and deeper shrinkage cavities.

[0039] The present invention particularly designs a method for preparing a nickel-based superalloy steel ingot with specific process steps and parameters, which is a smelting method for preparing large-size superalloys. By reasonably controlling the C and Al contents of the base metal electrode bar, adopting a low melting rate smelting process during self-consumable remelting, and using "melting rate + molten droplet" control during the melting stage, the set value of the melting rate is gradually reduced from 5.5→4.2 kg / min, and the set value of the molten droplet is 0.3 - 1.5S; during the feeding stage, melting rate control is adopted, the set value of the melting rate is gradually reduced from 5.2→2.0 kg / min, and the feeding weight is 800 - 1000 kg. After power-off, continue to evacuate, and cool in the furnace for ≥3h before demoulding. The smelting method provided by the present invention can obtain large steel ingots without macrosegregation, with shallower shrinkage cavities and better plasticity, and at the same time, the performance can meet the standard requirements of the material.

[0040] The smelting process of the nickel-based superalloy GH625 large-size vacuum arc furnace steel ingot provided by the present invention, the finished steel ingot specification is Φ810mm, and it is suitable for the double-smelting production of GH625 superalloy large-size steel ingots by "vacuum induction furnace (VIM) + vacuum arc furnace (VAR)". Through the vacuum induction furnace (VIM) + vacuum arc furnace (VAR) melting process, the present invention produces large-size steel ingots with Φ810mm without macrosegregation, shallower shrinkage cavities and better plasticity.

[0041] The present invention breaks through large-size superalloys, smelts electrode bars of about 12t with a 12t vacuum induction furnace, remelts a φ810mm self-consumable ingot with a 12t vacuum arc furnace, and prepares a self-consumable ingot of about 12t of superalloy. The present invention has opened up the smelting process of large forgings of superalloys, overcome problems such as easy segregation and deep shrinkage pipes of large-size steel ingots required for large forgings, and improved the market competitiveness. Description of the Drawings

[0042] Figure 1 It is a physical diagram of the Φ810mm self-consumable ingot of GH625 superalloy prepared in Example 1 of the present invention;

[0043] Figure 2 Cross-sectional view of the Φ810mm consumable ingot made in Example 1 of the present invention after cutting off 100mm from the filling end;

[0044] Figure 3 Cross-sectional view of the Φ550mm black bar forged from the Φ810mm consumable ingot made in Example 1 of the present invention;

[0045] Figure 4 Microstructure diagram of the Φ440mm bar forged from the Φ810mm consumable ingot made in Example 2 of the present invention;

[0046] Figure 5 Cross-sectional view of the Φ440mm bar forged from the Φ810mm consumable ingot made in Example 2 of the present invention. Detailed implementation manners

[0047] In order to further understand the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0048] For all raw materials of the present invention, there is no special limitation on their sources, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0049] For all raw materials of the present invention, there is no special limitation on their purity. The present invention preferably uses industrial purity or the conventional purity in the field of nickel-based superalloy preparation.

[0050] The present invention provides a method for preparing a nickel-based superalloy steel ingot, comprising the following steps:

[0051] 1) Melting the nickel-based superalloy raw materials in a vacuum induction furnace and then tapping the steel to cast a nickel-based superalloy ingot with a diameter of a first size;

[0052] The nickel-based superalloy is GH625 alloy;

[0053] 2) Heating the nickel-based superalloy ingot obtained in the above step and then forging it to obtain a nickel-based superalloy bar with a diameter of a second size;

[0054] 3) Using the nickel-based superalloy bar obtained in the above step as an electrode bar and performing consumable remelting by low melting rate smelting in a vacuum arc furnace to obtain a nickel-based superalloy steel ingot with a diameter of a third size;

[0055] The third dimension is greater than the second dimension.

[0056] In the present invention, the nickel-based superalloy raw material is first melted in a vacuum induction furnace and then tapped to cast a nickel-based superalloy ingot with a diameter of the first dimension.

[0057] The nickel-based superalloy is GH625 alloy.

[0058] In the present invention, the GH625 alloy, by its elemental content, includes:

[0059] Preferably, Cr: 20.00 wt% - 23.00 wt%, Mo: 8.00 wt% - 10.00 wt%, Nb: 3.15 wt% - 4.15 wt%, C: ≤ 0.10 wt%, Si: ≤ 0.50 wt%, Mn: ≤ 0.50 wt%, S: ≤ 0.015 wt%, P: ≤ 0.015 wt%, Al: ≤ 0.4 wt%, Ti: ≤ 0.4 wt%, Fe: ≤ 5.0 wt%, Co: ≤ 1.0 wt% and the balance Ni. More preferably, Cr: 20.50 wt% - 22.50 wt%, Mo: 8.40 wt% - 9.60 wt%, Nb: 3.17 wt% - 4.13 wt%, C: ≤ 0.09 wt%, Si: ≤ 0.40 wt%, Mn: ≤ 0.40 wt%, S: ≤ 0.013 wt%, P: ≤ 0.013 wt%, Al: ≤ 0.35 wt%, Ti: ≤ 0.35 wt%, Fe: ≤ 4.0 wt%, Co: ≤ 0.9 wt% and the balance Ni. Even more preferably, Cr: 21.00 wt% - 22.00 wt%, Mo: 8.80 wt% - 9.20 wt%, Nb: 3.19 wt% - 4.11 wt%, C: ≤ 0.08 wt%, Si: ≤ 0.30 wt%, Mn: ≤ 0.30 wt%, S: ≤ 0.01 wt%, P: ≤ 0.01 wt%, Al: ≤ 0.3 wt%, Ti: ≤ 0.3 wt%, Fe: ≤ 3.0 wt%, Co: ≤ 0.8 wt% and the balance Ni

[0060] In the present invention, the nickel-based superalloy raw material preferably includes metal raw materials, or metal raw materials and return materials.

[0061] In the present invention, the mass dosage of the return materials in the raw materials is preferably 10% - 80%, more preferably 20% - 70%, even more preferably 30% - 60%, and most preferably 40% - 50%.

[0062] In the present invention, during the melting process in the vacuum induction furnace, the C content in the molten mother liquid is preferably ≤ 0.015 wt%, more preferably ≤ 0.01 wt%, and even more preferably ≤ 0.005 wt%.

[0063] In the present invention, during the melting process of the vacuum induction furnace, the Al content in the molten mother liquid is preferably ≤0.20 wt%, more preferably ≤0.15 wt%, and even more preferably ≤0.1 wt%.

[0064] In the present invention, during the melting process of the vacuum induction furnace, after alloying is completed, continuous stirring is preferably ≥20 min, more preferably ≥22 min, and even more preferably ≥25 min.

[0065] In the present invention, the tapping temperature is preferably 1450 - 1490 °C, more preferably 1455 - 1485 °C, even more preferably 1460 - 1480 °C, and even more preferably 1465 - 1475 °C.

[0066] In the present invention, the first dimension is preferably 840 mm.

[0067] In the present invention, the second dimension is preferably 710 - 720 mm, more preferably 712 - 718 mm, and even more preferably 714 - 716 mm.

[0068] In the present invention, the nickel-based superalloy ingot obtained in the above steps is heated and then forged to obtain a nickel-based superalloy bar with a diameter of the second dimension.

[0069] In the present invention, the heating method preferably includes heating with a chamber furnace.

[0070] In the present invention, the heating temperature is preferably 1170 - 1180 °C, more preferably 1172 - 1178 °C, and even more preferably 1174 - 1176 °C.

[0071] In the present invention, the forging method preferably includes forging with a 45 / 50 MN quick forging machine.

[0072] Finally, in the present invention, the nickel-based superalloy bar obtained in the above steps is used as an electrode bar and remelted by consumable electrode melting in a vacuum arc furnace with low melting rate to obtain a nickel-based superalloy ingot with a diameter of the third dimension;

[0073] The third dimension is larger than the second dimension.

[0074] In the present invention, before the consumable electrode remelting, it preferably further includes the step of cleaning the surface of the nickel-based superalloy bar.

[0075] In the present invention, the mass of the nickel-based superalloy bar is preferably 9 - 12 tons, more preferably 9.5 - 11.5 tons, and even more preferably 10 - 11 tons.

[0076] In the present invention, the consumable electrode remelting process preferably includes a melting stage and a feeding stage.

[0077] In the present invention, the melting rate in the melting stage is preferably 5.5 - 4.2 kg / min, more preferably 5.3 - 4.4 kg / min, more preferably 5.1 - 4.6 kg / min, and more preferably 4.9 - 4.8 kg / min.

[0078] In the present invention, the melting rate in the melting stage is specifically preferably gradually decreased.

[0079] In the present invention, the melting droplet in the melting stage is preferably 0.3 - 1.5 s, more preferably 0.5 - 1.3 s, and more preferably 0.7 - 1.1 s.

[0080] In the present invention, the melting rate in the feeding stage is preferably 4.0 - 2.0 kg / min, more preferably 3.6 - 2.4 kg / min, and more preferably 3.2 - 2.8 kg / min.

[0081] In the present invention, the melting rate in the feeding stage is specifically preferably gradually decreased.

[0082] In the present invention, the feeding weight in the feeding stage is preferably 800 - 1000 kg, more preferably 840 - 960 kg, and more preferably 880 - 920 kg.

[0083] In the present invention, during the consumable remelting process, it is preferably to continue to evacuate the vacuum for in-furnace cooling after power failure.

[0084] In the present invention, the time for in-furnace cooling is preferably ≥ 3 h, more preferably ≥ 3.5 h, and more preferably ≥ 4 h.

[0085] In the present invention, the nickel-based superalloy steel ingot is preferably a large-sized nickel-based superalloy steel ingot.

[0086] In the present invention, the third dimension is preferably 810 mm.

[0087] In order to complete and refine the overall technical solution of the present invention, better ensure the stability and controllability of the preparation method, and further improve the quality of the large-sized steel ingot of the nickel-based superalloy GH625 (N06625), the preparation method of the large-sized steel ingot of the nickel-based superalloy GH625 (N06625) may specifically include the following content:

[0088] The preparation method of the nickel-based superalloy steel ingot provided by the present invention, wherein the diameter of the large-sized superalloy ingot is above Φ810mm. By mass percentage, the chemical composition of the large-sized superalloy ingot is: C: ≤0.10wt%, Si: ≤0.50wt%, Mn: ≤0.50wt%, S: ≤0.015wt%, P: ≤0.015wt%, Cr: 20.00 - 23.00wt%, Mo: 8.00 - 10.00wt%, Nb: 3.15 - 4.15wt%, Al: ≤0.4wt%, Ti: ≤0.4wt%, Fe: ≤5.0wt%, Co: ≤1.0wt%, and the balance is Ni.

[0089] The specific production process is as follows:

[0090] Raw material preparation

[0091] The return material is composed of the return from Benxi Steel, and the usage amount of the return material is 10% - 80%.

[0092] Key points of vacuum induction furnace smelting

[0093] According to the requirements of the designed alloy composition, pure metal raw materials or return materials are weighed as raw materials according to the elements required for the alloy per unit weight, and vacuum induction furnace melting is carried out. Control the C content in the melting mother liquor to be ≤0.015wt% and the A1 content to be ≤0.20wt%. After alloying, the power frequency stirring is ≥20min, the tapping temperature is: 1450 - 1490°C, and an electrode rod with a diameter of Φ840mm is cast.

[0094] Remaking the electrode rod

[0095] The ingot with a diameter of Φ840mm is heated in a chamber furnace and forged into an electrode rod with a diameter of Φ720mm on a 45 / 50MN quick forging machine.

[0096] Key points of vacuum arc furnace smelting

[0097] The surface of the electrode rod with a diameter of Φ720mm is fully peeled by polishing, with the requirement that there is no black skin on the surface. If there are deep and wide cracks, they must be polished clean, and the bottom of the electrode rod is cleaned.

[0098] Self-consumable remelting is carried out in a vacuum arc furnace. During the remelting process, helium cooling is adopted throughout, the helium flow rate is 0.15 - 0.20L / min, the electrode rod is kept vertical at the center of the mold, the diameter of the electrode rod is Φ720mm, and the size of the mold is Φ810mm.

[0099] In the above technical solution of the present invention, in order to solve the problems of macrosegregation and deep shrinkage cavity in large ingots, "melting rate + molten droplet" control is adopted in the melting stage. The set value of the melting rate is gradually reduced from 5.5 to 4.2 kg / min, and the set value of the molten droplet is 0.3 - 1.5 s; in the feeding stage, melting rate control is adopted, the set value of the melting rate is gradually reduced from 5.2 to 2.0 kg / min, the feeding weight is 800 - 1000 kg, and after power failure, evacuation continues, and the furnace is cooled for ≥3 h before demolding.

[0100] The above content of the present invention provides a method for preparing a large-sized ingot of nickel-based superalloy GH625 (N06625). The method for preparing a nickel-based superalloy steel ingot with specific process steps and parameters designed by the present invention is a smelting method for preparing large-sized superalloys. By reasonably controlling the C and Al contents of the base metal electrode rod and adopting a low melting rate smelting process during consumable remelting, "melting rate + molten droplet" control is adopted in the melting stage. The set value of the melting rate is gradually reduced from 5.5 to 4.2 kg / min, and the set value of the molten droplet is 0.3 - 1.5 s; in the feeding stage, melting rate control is adopted, the set value of the melting rate is gradually reduced from 5.2 to 2.0 kg / min, and the feeding weight is 800 - 1000 kg. After power failure, evacuation continues, and the furnace is cooled for ≥3 h before demolding. The smelting method provided by the present invention can obtain large steel ingots without macrosegregation, with shallow shrinkage cavities and good plasticity, and at the same time, the performance can meet the standard requirements of the material.

[0101] The smelting process of the large-sized vacuum arc furnace ingot of nickel-based superalloy GH625 provided by the present invention has a finished steel ingot specification of Φ810 mm and is applicable to the double melting production of large-sized steel ingots of GH625 superalloy by "vacuum induction furnace (VIM) + vacuum arc furnace (VAR)". Through the melting process of vacuum induction furnace (VIM) + vacuum arc furnace (VAR), the present invention produces large-sized steel ingots with a diameter of Φ810 mm without macrosegregation, with shallow shrinkage cavities and good plasticity.

[0102] The present invention breaks through large-sized superalloys. A 12t vacuum induction furnace is used to smelt an electrode rod of about 12t, and a 12t vacuum arc furnace is used to remelt a φ810mm consumable ingot to prepare a consumable ingot of about 12t of superalloy. The present invention has opened up the smelting process of large-sized forgings of superalloys, overcome the problems such as easy segregation and deep shrinkage pipe of large-sized steel ingots required for large-sized forgings, and improved the market competitiveness.

[0103] In order to further illustrate the present invention, a method for preparing a nickel-based high-temperature alloy steel ingot provided by the present invention is described in detail below in combination with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention, and the protection scope of the present invention is not limited to the following examples.

[0104] Example 1

[0105] A method for preparing a nickel-based high-temperature alloy steel ingot comprises the following steps:

[0106] a. Vacuum induction furnace smelting: vacuum induction furnace alloy smelting, with return steel, metal chromium, nickel plate, according to the composition design, add metal niobium, metal molybdenum, pure titanium raw materials, metal aluminum, ferroboron, nickel-magnesium alloy, metal cerium, high-purity graphite block for alloy smelting, the tapping temperature is controlled at 1460℃, after tapping, it is cast into Φ840mm electrode ingot;

[0107] The composition and weight percentage of the electrode ingot are mainly: C 0.0082%, Si 0.009%, Mn 0.005%, S0.0006%, P 0.0010%, Cr 21.79%, Mo 9.10%, B 0.005%, Ti 0.30%, Co0.009%, Al0.15%, Cu 0.021%, Fe 0.18%, and the balance is nickel alloy steel.

[0108] b. Remaking electrode rods: hot-process the electrode ingots at a temperature of 1000-1200°C, and forge them into Φ725mm on a fast forging machine. After cooling, the surface of the Φ725mm electrode rods is polished and peeled off to become Φ715mm electrode rods;

[0109] c. Vacuum arc furnace smelting: Φ715mm electrode rods are remelted in a Φ810mm crystallizer. Helium cooling is used during the remelting process. The helium flow rate is 0.15L / min, the average melting rate is 4.8kg / min, and the droplet setting value is 0.91S. The melting rate in the filling stage is gradually reduced from 4.5 to 1.8kg / min. The filling weight is 860kg, and the mold is demolded after cooling in the furnace for 3h.

[0110] The composition and weight percentage of the consumable ingot are mainly C 0.0081%, Si 0.009%, Mn 0.005%, S0.0006%, P 0.0010%, Cr 21.79%, Mo 9.10%, B 0.005%, Ti 0.28%, Co0.009%, Al0.16%, Cu 0.021%, Fe 0.18%, and the balance is nickel alloy steel.

[0111] See Figure 1 , Figure 1 which is a physical picture of a Φ810mm consumable ingot of GH625 superalloy prepared in Example 1 of the present invention.

[0112] See Figure 2 , Figure 2 which is a cross-sectional view of the Φ810mm consumable ingot of GH625 superalloy prepared in Example 1 of the present invention after cutting off 100mm at the filling end.

[0113] The Φ550mm bar forged from the Φ810mm consumable ingot of GH625 superalloy prepared in Example 1 of the present invention was tested.

[0114] Macroscopic inspection: The ingot type segregation is grade 0.5, the general porosity is grade 0.5, the central porosity is grade 0.5, the general punctiform segregation is grade 0, and the edge punctiform segregation is grade 0.

[0115] The Φ810mm consumable ingot prepared in Example 1 of the present invention was forged to obtain a Φ550mm bar.

[0116] See Figure 3 , Figure 3 which is a cross-sectional view of the Φ550mm black-skin bar forged from the Φ810mm consumable ingot prepared in Example 1 of the present invention. Among them, the upper figure is the macroscopic inspection figure of the head of the forged bar, and the lower figure is the macroscopic inspection figure of the tail of the forged bar.

[0117] Example 2

[0118] A preparation method of a nickel-based superalloy steel ingot includes the following steps:

[0119] a. Vacuum induction furnace smelting: Alloying smelting in a vacuum induction furnace, using returned steel, metallic chromium, nickel plates, and adding niobium metal, molybdenum metal, pure titanium raw materials, aluminum metal, ferroboron, nickel-magnesium alloy, cerium metal, and high-purity graphite blocks for alloying smelting according to the composition design. The tapping temperature is controlled at 1461°C, and after tapping, it is poured into a Φ840mm electrode ingot;

[0120] The composition and weight percentage of the electrode ingot are mainly C 0.0015%, Si 0.04%, Mn 0.005%, S 0.0007%, P 0.0011%, Cr 21.80%, Mo 8.92%, B 0.005%, Ti 0.26%, Co 0.02%, Al 0.16%, Cu 0.02%, Fe 0.18%, and the balance is nickel-based alloy steel.

[0121] b. Remodeling electrode rods: hot-processing the electrode ingots at a temperature of 1000-1200°C, forging them into Φ723mm on a fast forging machine, and then polishing the surface of the Φ723mm electrode rods to form Φ715mm electrode rods after cooling;

[0122] c. Vacuum arc furnace smelting: Φ715mm electrode rods are remelted in a Φ810mm crystallizer. Helium cooling is used during the remelting process. The helium flow rate is 0.16L / min, the average melting rate is 5.0kg / min, and the droplet setting value is 0.90S; the melting rate in the filling stage is gradually reduced from 4.4 to 1.78kg / min, the filling weight is 850kg, and the mold is removed after cooling in the furnace for 3 hours. The composition and weight percentage of the consumable ingot are mainly C 0.001%, Si 0.04%, Mn 0.005%, S 0.0007%, P 0.0011%, Cr 21.80%, Mo 8.92%, B 0.005%, Ti 0.27%, Co 0.02%, Al 0.16%, Cu 0.02%, Fe 0.18%, and the balance is nickel alloy steel.

[0123] The Φ810 mm consumable ingot prepared in Example 2 of the present invention was forged to obtain a Φ440 mm bar.

[0124] The Φ440 mm bar forged from the Φ810 mm consumable ingot of the GH625 high temperature alloy prepared in Example 2 of the present invention was characterized.

[0125] See also Figure 4 , Figure 4 This is the organizational diagram of the Φ440mm bar forged from the Φ810mm consumable ingot prepared in Example 2 of the present invention.

[0126] The Φ440 mm bar forged from the Φ810 mm consumable ingot of the GH625 high temperature alloy prepared in Example 2 of the present invention was tested.

[0127] Low magnification detection: ingot-shaped segregation level 0.5, general looseness level 0.5, central looseness level 0.5, general point segregation level 0, edge point segregation level 0.

[0128] See also Figure 5 , Figure 5 This is a cross-sectional view of a Φ440 mm bar forged from a Φ810 mm consumable ingot prepared in Example 2 of the present invention. The upper figure is a low-magnification inspection view of the head of the forged bar, and the lower figure is a low-magnification inspection view of the tail of the forged bar.

[0129] The above has introduced in detail the preparation method of a large-sized ingot of nickel-based superalloy GH625 (N06625) provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements approximately the same as the literal expression of the claims, or if they include equivalent structural elements that have no substantial difference from the literal expression of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing a nickel-based high-temperature alloy steel ingot, characterized in that: The following steps are involved: 1) melting the nickel-based high-temperature alloy raw material in a vacuum induction furnace, tapping the steel, and casting to obtain a nickel-based high-temperature alloy ingot having a diameter of a first size; The nickel-based high-temperature alloy is GH625 alloy; 2) heating the nickel-based high-temperature alloy ingot obtained in the above step and then forging it to obtain a nickel-based high-temperature alloy rod with a diameter of the second size; 3) using the nickel-based high-temperature alloy rod obtained in the above step as an electrode rod, and performing consumable remelting in a vacuum arc furnace by low melting rate smelting to obtain a nickel-based high-temperature alloy ingot with a diameter of the third size; The third size is greater than the second size.

2. The preparation method according to claim 1, characterized in that: The GH625 alloy, according to its element content, includes: Cr: 20.00wt% ~ 23.00wt%, Mo: 8.00wt% ~ 10.00wt%, Nb: 3.15wt% ~ 4.15wt%, C: ≤0.10wt%, Si: ≤0.50wt%, Mn: ≤0.50wt%, S: ≤0.015wt%, P: ≤0.015wt%, Al: ≤0.4wt%, Ti: ≤0.4wt%, Fe: ≤5.0wt%, Co: ≤1.0wt% and the balance of Ni.

3. The preparation method according to claim 1, characterized in that: The nickel-based high-temperature alloy raw material includes a metal raw material, or a metal raw material and a return material; The mass amount of the return material in the raw material is 10% to 80%.

4. The preparation method according to claim 1, characterized in that: During the vacuum induction furnace smelting process, the C content in the smelting mother liquor is ≤0.015wt%; During the vacuum induction furnace smelting process, the Al content in the smelting mother liquor is ≤0.20wt%; During the vacuum induction furnace melting process, after alloying is completed, stirring is continued for ≥20 minutes.

5. The preparation method according to claim 1, characterized in that: The temperature of the steel tapping is 1450-1490°C; The first size is 840mm; The second size is 710-720 mm.

6. The preparation method according to claim 1, characterized in that: The heating method includes heating in a chamber heating furnace; The heating temperature is 1170-1180°C; The forging method includes forging with a 45 / 50MN fast forging machine.

7. The preparation method according to claim 1, characterized in that: The consumable remelting also includes a step of cleaning the surface of the nickel-based high-temperature alloy rod; The mass of the nickel-based high-temperature alloy rod is 9 to 12 tons.

8. The preparation method according to claim 1, characterized in that: The consumable remelting process includes a smelting stage and a feeding stage; The melting rate in the melting stage is 5.5-4.2 kg / min; The melting rate in the smelting stage is specifically gradually reduced; The droplet duration in the smelting stage is 0.3 to 1.5 seconds.

9. The preparation method according to claim 8, characterized in that: The melting rate in the feeding stage is 4.0-2.0 kg / min; The melting rate in the feeding stage is specifically gradually reduced; The feeding weight in the feeding stage is 800-1000kg.

10. The preparation method according to claim 1, characterized in that: During the consumable remelting process, vacuuming is continued to cool the furnace after power failure; The cooling time in the furnace is ≥ 3h; The nickel-based high-temperature alloy steel ingot is a large-sized nickel-based high-temperature alloy steel ingot; The third dimension is 810 mm.

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