GH625 forged rod and preparation method thereof

Abstract

The invention discloses a GH625 forged rod and a preparation method thereof, and belongs to the technical field of metallurgy. The preparation method of the GH625 forged rod comprises the following steps that a consumable ingot is subjected to homogenization treatment; the consumable ingot obtained after homogenization treatment is forged; and the homogenization treatment comprises the following steps: preserving heat for 10-30 hours at the temperature of 1100-1150 DEG C and preserving heat for 10-80 hours at the temperature of 1150-1220 DEG C. According to the preparation method of the GH625 forged rod, through the combination of the homogenization treatment and the forging deformation process, segregation and shrinkage porosity formed in the preparation process of the oversized GH625 forged rod can be efficiently reduced, and the product yield and the qualified rate are increased.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a GH625 forged rod and a preparation method thereof. Background Art

[0002] GH625 alloy is a solid solution strengthened nickel-based deformable high temperature alloy with molybdenum and niobium as the main strengthening elements. It has good corrosion resistance and oxidation resistance, and has good tensile and fatigue properties from low temperature to high temperature 980℃. At the same time, GH625 nickel-based high temperature alloy is also one of the main materials for manufacturing the hot end rotating parts of the new generation of aircraft engines, among which turbine blades are an important component of the hot end rotating parts. Because this high temperature alloy has excellent mechanical properties and structural stability, it can work stably for a long time under extreme conditions, so it has become one of the materials for the new generation of high temperature alloys for turbine blades.

[0003] However, as aircraft engines continue to develop towards a high thrust-to-weight ratio, turbine blades have to withstand higher temperatures and stresses, and the working environment has become more deteriorating. This has put forward more stringent requirements on the high-temperature alloy forging rods used to manufacture turbine blades, that is, to achieve large-scale materials for manufacturing turbine blades. For example, the weight of the forging rods used to prepare the overall casing of a certain aircraft engine reaches 1.2 tons, the weight of the single forging rods used for shipborne gas turbines reaches 1.5 tons, and the weight of the single forging rods used for ground-based gas turbines reaches more than 6 tons. However, in the aviation field, the weight of GH625 high-temperature alloy forging rods is often less than 1 ton, and the size is less than ≤Φ250mm.

[0004] In addition, the large-scale production of GH625 high-temperature alloy forging rods also puts forward higher requirements for the yield strength, grain size, carbide, low-temperature performance and other indicators of the forgings, which is very technically difficult. In order to solve the disadvantages brought about by the large-scale production of GH625 high-temperature alloy forging rods for turbine blades, it is necessary to use appropriate forging processes and heat treatment methods to make the carbides and grain size of the forgings meet the requirements, thereby improving the strength and low-temperature plasticity of the alloy.

[0005] Therefore, the development of an ultra-large-sized nickel-based high-temperature alloy GH625 forging rod and its preparation method has important theoretical and engineering guiding significance for improving the economy and reliability in the preparation process of ultra-large-sized GH625 high-temperature alloy forging rods, and even for improving the quality of high-temperature alloy components. Summary of the invention

[0006] The purpose of the present invention is to provide a GH625 forged rod and a preparation method thereof, so as to solve the technical problems in the prior art that large-size GH625 forged rod alloy is difficult to produce and the prepared large-size GH625 forged rod alloy has poor strength and low-temperature plasticity.

[0007] To achieve the above object, an embodiment of the present invention provides a method for preparing a GH625 forged rod, comprising the following steps:

[0008] The consumable ingots are homogenized;

[0009] Forging the consumable ingot after homogenization treatment;

[0010] The homogenization treatment includes: keeping warm at 1100°C-1150°C for 10h-30h and keeping warm at 1150°C-1220°C for 10h-80h.

[0011] In one of the preferred solutions of the present invention, the forging includes a first fire forging, wherein the consumable ingot after homogenization treatment is upset, and after upsetting, the ingot is kept at 1150° C.-1190° C. for 2 h-6 h.

[0012] In one of the preferred solutions of the present invention, the forging further comprises a second fire forging, wherein the steel ingot after the first fire forging treatment is upset and stretched, and after stretching, the steel ingot is kept at 1150° C.-1190° C. for 2 h-6 h.

[0013] In one of the preferred solutions of the present invention, the forging further comprises a third fire forging, wherein the steel ingot after the second fire forging treatment is upset and stretched, and after stretching, the steel ingot is kept at 1150° C.-1190° C. for 15 h-25 h.

[0014] In one of the preferred solutions of the present invention, the forging further comprises a fourth fire forging, wherein the steel ingot after the third fire forging treatment is upset, and after upset, the steel ingot is kept at 1100° C.-1190° C. for 2 h-6 h.

[0015] In one of the preferred solutions of the present invention, the forging further comprises a fifth fire forging, wherein the steel ingot after the fourth fire forging treatment is stretched, and after stretching, the steel ingot is kept at 1150° C.-1190° C. for 2 h-6 h.

[0016] In one of the preferred schemes of the present invention, the forging further comprises a sixth fire forging, wherein the steel ingot after the fifth fire forging treatment is upset, and after upsetting, the steel ingot is kept at 1100°C-1190°C for 2h-6h, and after the insulation is completed, the steel ingot is sheathed, and after the sheathing treatment, the steel ingot is kept warm for 2h-6h.

[0017] In one of the preferred schemes of the present invention, the forging further includes a seventh fire forging, wherein the steel ingot after the sixth fire forging treatment is stretched, and after stretching, it is kept at 1100℃-1190℃ for 2h-6h, and after the insulation is completed, the steel ingot is sheathed, and after the sheathing treatment, it is kept warm for 2h-6h.

[0018] In one of the preferred solutions of the present invention, the forging further comprises an eighth fire forging, wherein the steel ingot treated by the seventh fire forging is stretched and air-cooled after the stretching.

[0019] The invention also discloses a GH625 forged rod, which is prepared by adopting the above-mentioned method for preparing the GH625 forged rod.

[0020] In summary, the beneficial effects of the present invention are:

[0021] 1. The preparation method of the GH625 forged rod of the present invention can effectively reduce the segregation and shrinkage holes formed in the preparation process of the oversized GH625 forged rod by combining the homogenization treatment and the forging deformation process, and improve the product yield and qualified rate.

[0022] 2. GH625 alloy is a nickel-based alloy containing 9.0% Mo and 3.7% Nb. When the diameter of the steel ingot is expanded from the conventional Φ450mm and Φ550mm to Φ810mm, the high content of Mo and Nb elements causes the alloy to have a significantly increased degree of segregation during solidification. The generation of segregation will deteriorate the hot working performance of the alloy on the one hand, and is also extremely unfavorable to the performance of the final product on the other hand. The present invention adopts an appropriate homogenization process to eliminate the carbide segregation of the steel ingot and reduce the segregation of the second phase in the forged rod to the maximum extent, so that the precipitated phase is evenly distributed.

[0023] 3. GH625 is a fine-grained strengthened alloy. In order to make the yield strength of GH625 reach above 410Mpa, the grain size must be controlled to be equal to or finer than level 6. For this reason, the present invention adopts the method of "multiple upsetting and drawing + step-by-step cooling + soft packaging + high-temperature homogenization of intermediate billet" to obtain a forged rod with a grain size finer than level 6 and a yield strength ≥410Mpa.

[0024] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by implementing the present invention. The purpose and other advantages of the present invention can be described by the effects described in the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the head grains of the GH625 forged rod prepared in Example 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the tail grains of the GH625 forged rod prepared in Example 1 of the present invention;

[0027] Figure 3 This is a schematic diagram of the head grains of the GH625 forged rod prepared in Example 2 of the present invention;

[0028] Figure 4 This is a schematic diagram of the tail grains of the GH625 forged rod prepared in Example 2 of the present invention;

[0029] Figure 5This is a schematic diagram of the head grains of a GH625 forged rod prepared in a comparative example of the present invention;

[0030] Figure 6 Schematic diagram of the tail grains of the GH625 forged rod prepared in the comparative example of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0032] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0033] The present invention provides a method for preparing a GH625 forged rod, comprising the following steps:

[0034] Step (1): homogenizing the consumable ingot; specifically, homogenizing the Φ810 mm consumable ingot obtained by smelting, igniting and heating, keeping the temperature at 1100°C-1150°C for 10h-30h, then heating to 1150°C-1220°C, and keeping the temperature for 10h-80h; the original microstructure and precipitate distribution diagram of the consumable ingot are shown in Figure 1, and the microstructure and precipitate distribution diagram of the consumable ingot after homogenization are shown in Figure 2. Figure 2 As shown;

[0035] Step (2): forging the consumable ingot after homogenization treatment; specifically, forging is carried out by adopting the method of "four upsetting and four drawing + step-by-step cooling + soft bag + intermediate fire and long time homogenization", which includes the following steps:

[0036] Step (201): First fire forging: After the homogenized consumable ingot is taken out from the heating furnace, it is upset to Φ800mm*2100mm, octagonal, and then kept at 1150℃-1190℃ for 2h-6h;

[0037] Step (202): Second fire forging: the steel ingot after the first fire forging treatment is taken out from the heating furnace, upset to Φ940mm*1700mm, then immediately stretched to Φ830mm*2150mm, chamfered, and kept at 1150℃-1190℃ for more than 2h-6h;

[0038] Step (203): Third forging: the steel ingot after the second forging treatment is taken out from the heating furnace, upset to Φ1150mm*1200mm, then immediately stretched to Φ830mm*2150mm, chamfered, and kept at 1150℃-1190℃ for 15h-25h;

[0039] Step (204): Fourth forging: taking the steel ingot after the third forging treatment out of the heating furnace, upsetting it to 1200mm*Φ1150mm, chamfering it, and keeping it at 1100℃-1190℃ for more than 2h-6h;

[0040] Step (205): Fifth fire forging: the steel ingot after the fourth fire forging treatment is taken out from the heating furnace, stretched to Φ830mm*2150mm, and continued to be kept at 1150℃-1190℃ for more than 2h-6h;

[0041] Step (206): Sixth forging: taking the steel ingot after the fifth forging treatment out of the heating furnace, upsetting it to H=1200 mm, chamfering it, and keeping it at 1100°C-1190°C for more than 2h-6h, then covering the steel ingot with a jacket, and keeping it at this temperature for more than 2h-6h;

[0042] Step (207): Seventh forging: the steel ingot after the sixth forging treatment is taken out from the heating furnace, stretched to Φ750mm*2320mm, a clamp handle is made at the tail, and the steel ingot is kept at 1100℃-1190℃ for more than 2h-6h, and then the steel ingot is covered and kept for more than 2h-6h;

[0043] Step (208): Eighth forging: The steel ingot after the seventh forging treatment is taken out from the heating furnace, stretched to Φ550mm*4000mm, and finally air-cooled to room temperature.

[0044] The present invention also discloses a GH625 forged rod, which is prepared by adopting the above-mentioned method for preparing a GH625 forged rod. The specifications of the prepared GH625 forged rod include: a diameter of Φ440mm-Φ550mm, and a length of 4000mm-6000mm.

[0045] The grain size of GH625 forged rods is required to be no less than grade 3, and the grain size difference in the same field of view shall not exceed 3 grades. After heat treatment of the forged rods, the grain size is measured to be grade 7.0, which is qualified.

[0046] Example 1

[0047] A method for preparing a GH625 forged rod comprises the following steps:

[0048] a. Homogenization process: put the Φ810mm consumable ingot into a chamber furnace for homogenization treatment, ignite and heat up, and heat the furnace temperature from room temperature to 1135℃ after 12 hours, keep it warm for 25 hours, heat it to 1165℃ after 5 hours, keep it warm for 25 hours, heat it to 1220℃ after 6 hours, keep it warm for 80 hours, cool it to 190℃ with the furnace, and cool it to room temperature after unloading the furnace;

[0049] b. Forging process:

[0050] First fire: heat the consumable ingot to 1170℃ and keep it for 12h. After taking it out of the heating furnace, upset it to H=2100mm, chamfer it, and then keep it at 1170℃ for 6h.

[0051] Second fire (upsetting and pulling): the steel ingot after the first fire treatment is taken out from the heating furnace, upset to H = 1700mm, then immediately pulled to Φ820mm, octagonal, and kept at 1170℃ for 6h;

[0052] The third fire (two upsetting and two drawing): the steel ingot after the second fire treatment is taken out from the heating furnace, upset to H = 1200mm, then immediately drawn to Φ820mm, inverted octagonally, and kept at 1190℃ for 20h;

[0053] Fourth fire (three upsetting): take the steel ingot after the third fire treatment out of the heating furnace, upset to H = 1100mm, chamfer, and continue to keep it at 1170℃ for 6h;

[0054] Fifth fire (three pulls): take the steel ingot after the fourth fire treatment out of the heating furnace, pull it to Φ820mm, turn it into an octagonal shape, and continue to keep it at 1150℃ for 6h;

[0055] Sixth fire (four upsetting + soft bagging): the steel ingot after the fifth fire treatment is taken out from the heating furnace, upsetting to H = 1100mm, chamfering, and then keeping it at 1100℃ for 6h, and then the steel ingot is covered and kept for another 4h;

[0056] The seventh fire (four-drawing + soft bag): take the steel ingot after the sixth fire treatment out of the heating furnace, draw it to Φ750mm, clamp it at the tail, keep it at 1100℃ for 6h, then cover it and keep it for more than 4h;

[0057] Eighth fire (drawing to a foot): Take the steel ingot treated in the seventh fire out of the heating furnace, draw it to Φ550mm*4000mm, and finally air cool it to room temperature.

[0058] The preparation process of the above embodiment 1 is finally used to obtain a Φ550mm ultra-large size nickel-based high-temperature alloy GH625 forged rod; the grain size of the head of the Φ550mm forged rod is as follows Figure 1 As shown, the grain size at the tail of Φ550mm forged rod Figure 2 The mechanical properties of Φ550mm forged rod are shown in Table 1.

[0059] Table 1: Mechanical properties of GH625 forged rods prepared in Example 1

[0060]

[0061] It can be seen from Table 1 that the GH625 forged rod prepared in Example 1 has excellent mechanical properties.

[0062] Example 2

[0063] a. Homogenization process: put the Φ810mm consumable ingot into a chamber furnace for homogenization treatment, ignite and heat up, and heat the furnace temperature from room temperature to 1140℃ after 12 hours, keep it warm for 24 hours, heat it up to 1160℃ after 6 hours, keep it warm for 24 hours, heat it up to 1220℃ after 6 hours, keep it warm for 80 hours, cool it down to 220℃ with the furnace, and cool it down to room temperature after unloading the furnace;

[0064] b. Forging process:

[0065] First fire: heat the consumable ingot to 1170℃ and keep it for 12h. After taking it out of the chamber heating furnace, upset it to H=2000mm, chamfer it, and then keep it at 1170℃ for 6h.

[0066] Second fire (upsetting and pulling): the steel ingot after the first fire treatment is taken out from the heating furnace, upset to H = 1600mm, then immediately pulled to Φ830mm, octagonal, and kept at 1170℃ for 6h;

[0067] The third fire (two upsetting and two drawing): the steel ingot after the second fire treatment is taken out from the heating furnace, upset to H = 1100mm, then immediately drawn to Φ830mm, inverted octagonally, and kept at 1190℃ for 20h;

[0068] Fourth fire (three upsetting): take the steel ingot after the third fire treatment out of the heating furnace, upset to H = 1100mm, chamfer, and continue to keep it at 1170℃ for 6h;

[0069] Fifth fire (three pulls): take the steel ingot after the fourth fire treatment out of the heating furnace, pull it to Φ830mm, turn it into an octagonal shape, and continue to keep it at 1150℃ for 6h;

[0070] Sixth fire (four upsetting + soft bagging): the steel ingot after the fifth fire treatment is taken out from the heating furnace, upsetting to H = 1100mm, chamfering, and then keeping it at 1100℃ for 6h, and then the steel ingot is covered and kept for another 4h;

[0071] The seventh fire (four-drawing + soft bag): the steel ingot after the sixth fire treatment is taken out of the heating furnace, drawn to Φ830mm, octagonal, and kept at 1100℃ for 6h, and then the steel ingot is covered and kept for another 4h;

[0072] Eighth fire: The steel ingot after the seventh fire treatment is taken out from the heating furnace, stretched to 600mm octagonal, clamped at the tail, then returned to the furnace and kept at 1100℃ for 6h, taken out and covered, and kept warm for another 4h;

[0073] Ninth fire: Take the steel ingot after the eighth fire treatment out of the heating furnace, stretch it to 450mm octagonal, roll it to Φ440mm, and air cool it to room temperature after forging.

[0074] The preparation process of the above-mentioned embodiment 2 is finally used to obtain a Φ440mm ultra-large size nickel-based high-temperature alloy GH625 forged rod; the grain size of the head of the Φ440mm forged rod is as follows: Figure 3 As shown, the grain size at the tail of the Φ440mm forged rod is as follows: Figure 4 The mechanical properties of Φ440mm forged rod are shown in Table 2.

[0075] Table 2: Mechanical properties of GH625 forged rods prepared in Example 2

[0076]

[0077] It can be seen from Table 3 that the GH625 forged rod prepared in Example 2 has excellent mechanical properties.

[0078] Comparative Example

[0079] Different from Example 1 and Example 2, in the comparative example, the homogenization process was not subjected to a long-term heat preservation at 1220° C., the forging process was not subjected to a long-term heat preservation at 1190° C. after the third tempering (second upsetting and second drawing), and the fourth upsetting and fourth drawing were not performed. The preparation of the forged rod included the following steps:

[0080] a. Homogenization process: put the Φ810mm consumable ingot into a chamber furnace for homogenization treatment, ignite and heat up, and heat the furnace temperature from room temperature to 1135℃ after 12 hours, keep it warm for 25 hours, heat it to 1165℃ after 5 hours, keep it warm for 25 hours, heat it to 1180℃ after 6 hours, keep it warm for 72 hours, cool it to 190℃ with the furnace, and cool it to room temperature after unloading the furnace;

[0081] b. Forging process:

[0082] First fire: heat the consumable ingot to 1170℃ and keep it for 12h. After taking it out of the chamber heating furnace, upset it to H=2100mm, chamfer it, and then keep it at 1170℃ for 6h.

[0083] Second fire (upsetting and pulling): the steel ingot after the first fire treatment is taken out from the heating furnace, upset to H = 1700mm, then immediately pulled to Φ820mm, octagonal, and kept at 1170℃ for 6h;

[0084] The third fire (two upsetting and two drawing): the steel ingot after the second fire treatment is taken out from the heating furnace, upset to H = 1100mm, then immediately drawn to Φ820mm, inverted octagonally, and kept at 1170℃ for 6h;

[0085] Fourth fire (three upsetting): take the steel ingot after the third fire treatment out of the heating furnace, upset to H = 1100mm, and continue to keep it at 1170℃ for 6h;

[0086] Fifth fire (three pulls): take the steel ingot after the fourth fire treatment out of the heating furnace, pull it to Φ750mm, make a clamp handle at the tail, and then keep it at 1100℃ for 6h before covering the steel ingot;

[0087] Sixth fire: Take the steel ingot after the fifth fire treatment out of the heating furnace, stretch it to 560mm octagonal, roll it to Φ550mm, and air cool it to room temperature after forging.

[0088] The above comparative example preparation process is used to finally obtain a Φ550mm ultra-large size nickel-based high-temperature alloy GH625 forged rod; the grain size of the Φ550mm forged rod head is as follows Figure 5 As shown, the grain size at the tail of Φ550mm forged rod Figure 6 The mechanical properties of Φ550mm forged rod are shown in Table 3.

[0089] Table 3: Mechanical properties of GH625 forged rods prepared in comparative example

[0090]

[0091] It can be seen from Table 3 that the room temperature section shrinkage, high temperature elongation and section shrinkage of the GH625 forging rod prepared in the comparative example are unqualified.

[0092] In summary, the preparation method of the GH625 forged rod of the present invention can effectively reduce the segregation and shrinkage holes formed in the preparation process of the oversized GH625 forged rod by combining the homogenization treatment and the forging deformation process, and improve the product yield and qualified rate.

[0093] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a GH625 forged rod, characterized in that: The following steps are involved: The consumable ingots are homogenized; Forging the consumable ingot after homogenization treatment; The homogenization treatment includes: keeping warm at 1100° C.-1150° C. for 10 h-30 h and keeping warm at 1150° C.-1220° C. for 10 h-80 h.

2. The method for preparing a GH625 forged rod according to claim 1, characterized in that: The forging includes first fire forging, in which the consumable ingot after homogenization treatment is upset, and after upsetting, the ingot is kept at 1150° C.-1190° C. for 2 h-6 h.

3. The method for preparing a GH625 forged rod according to claim 2, characterized in that: The forging also includes a second fire forging, in which the steel ingot treated by the first fire forging is upset and stretched, and after stretching, the steel ingot is kept at 1150° C.-1190° C. for 2 h-6 h.

4. A method for preparing a GH625 forged rod as claimed in claim 3, characterized in that: The forging also includes a third fire forging, in which the steel ingot treated by the second fire forging is upset and stretched, and after stretching, the steel ingot is kept at 1150° C.-1190° C. for 15h-25h.

5. The method for preparing a GH625 forged rod according to claim 4, characterized in that: The forging also includes a fourth fire forging, in which the steel ingot treated by the third fire forging is upset, and after upset, the steel ingot is kept at 1100° C.-1190° C. for 2 h-6 h.

6. A method for preparing a GH625 forged rod as claimed in claim 5, characterized in that: The forging also includes a fifth fire forging, in which the steel ingot treated by the fourth fire forging is stretched and then kept at 1150° C.-1190° C. for 2 h-6 h.

7. A method for preparing a GH625 forged rod as claimed in claim 6, characterized in that: The forging also includes a sixth fire forging, in which the steel ingot treated by the fifth fire forging is upset, and after upsetting, the steel ingot is kept at 1100° C.-1190° C. for 2 h-6 h. After the insulation is completed, the steel ingot is sheathed, and after the sheathing, the steel ingot is kept warm for 2 h-6 h.

8. The method for preparing a GH625 forged rod according to claim 7, characterized in that: The forging also includes a seventh fire forging, in which the steel ingot after the sixth fire forging treatment is stretched, and then kept at 1100°C-1190°C for 2h-6h after stretching. After the insulation is completed, the steel ingot is sheathed, and then kept warm for 2h-6h after the sheathing treatment.

9. A method for preparing a GH625 forged rod as claimed in claim 8, characterized in that: The forging also includes an eighth fire forging, in which the steel ingot treated by the seventh fire forging is stretched and then air-cooled.

10. A GH625 forged rod, characterized in that: The GH625 forged rod is prepared by the preparation method of any one of claims 1 to 9.

11. A GH625 forged rod as claimed in claim 10, characterized in that: The specifications of the GH625 forged rod include: diameter of Φ440mm-Φ550mm, length of 4000mm-6000mm.

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