A guard ring forging and a method for manufacturing the same

Abstract

The application discloses a guard ring forge piece and a preparation method thereof, and belongs to the technical field of guard ring forge piece manufacturing, and solves the problem of insufficient basic yield strength of the guard ring forge piece in the prior art. The preparation method of the guard ring forge piece comprises the following steps: step 1, smelting electrode blank and electric-shock remelting steel ingot, and peeling processing; step 2, homogenizing treatment is performed on the steel ingot; step 3, the steel ingot is forged and bloomed, and air cooling is performed after forging; and step 4, solid solution treatment is performed on the forged blank to obtain the guard ring forge piece. The strength of the guard ring forge piece prepared by the method is excellent after hot forging and solid solution treatment.

Description

Technical Field

[0001] This invention relates to the field of retaining ring forging technology, and particularly to a retaining ring forging and its preparation method. Background Technology

[0002] Retaining ring forgings are core components of generator sets. They belong to the category of large, thin-walled ring forgings. Because they are located at both ends of the generator set, the material needs to be non-magnetic, and austenitic stainless steel forgings are typically used. Due to the austenitic structure of this type of steel, its strength cannot be increased through heat treatment. Instead, work hardening generated during cold deformation or warm forging is used, sacrificing some plasticity to significantly improve the material's strength. In engineering production, with the increasing demand for larger forging sizes, especially for large forgings, cold deformation or warm forging requires large equipment, space, and specialized molds, impacting manufacturing cycles and costs. To reduce the amount of deformation required for work hardening, or to eliminate the need for cold deformation or semi-hot forging, providing a retaining ring forging that achieves a high basic yield strength (e.g., after hot forging or solution treatment) has become a pressing issue. Summary of the Invention

[0003] In view of the above, the present invention aims to provide a retaining ring forging and its preparation method to solve the problem of insufficient basic yield strength of existing retaining ring forgings.

[0004] The objective of this invention is mainly achieved through the following technical solutions:

[0005] This invention provides a method for preparing a retaining ring forging, comprising:

[0006] Step 1: Smelt electrode billets + electroslag remelted steel ingots, and peel off the outer layer;

[0007] Step 2: Homogenize the steel ingots;

[0008] Step 3: Forge the steel ingot into a billet, and then cool it with blast air after forging;

[0009] Step 4: Perform solution treatment on the forging billet to obtain the retaining ring forging.

[0010] Furthermore, in step 2, the homogenization process includes the following steps:

[0011] S201. Heat the steel ingot to 600-650℃ and hold for 1-1.2 hours per 100mm.

[0012] S202. Heat to 800-850℃ and hold for 1-1.2 hours per 100mm.

[0013] S203, heat to 1150~1180℃, hold for 2h~3h / 100mm; the heating rate in S202 is less than the heating rate in S203.

[0014] Furthermore, in S202, the heating rate is below 40℃ / h.

[0015] Furthermore, in S203, the heating rate is above 70℃ / h.

[0016] Furthermore, in step 3, the forging process is completed by lightly drawing the ingot body, upsetting and drawing it longer, punching holes, and expanding the holes.

[0017] Furthermore, in step 3, the initial forging temperature of the forging blanking process of light drawing and upsetting of the ingot body is 1150-1180℃.

[0018] Furthermore, in step 4, the solution treatment includes: loading the forging billet into the furnace at a furnace temperature ≤500℃ and rapidly heating it to 1080~1100℃, holding it at that temperature for 2~2.5h / 100mm, and then water cooling it after it is removed from the furnace.

[0019] Furthermore, the composition of the retaining ring forging, by mass percentage, includes: C 0.08%–0.11%, Si 0.40%–1.2%, Mn 18.5%–21.0%, Cr 18%–19.5%, Ni 0.5%–3%, V 0.35%–0.95%, N 0.68%–0.75%, Nb 0.005%–0.03%, Cu ≤0.01%, Al

[0020] ≤0.01%, P≤0.010%, S≤0.010%, balance is Fe and unavoidable trace impurities.

[0021] The present invention also provides a retaining ring forging, which is prepared by the above-described preparation method.

[0022] Furthermore, the microstructure of the retaining ring forging consists of austenite and dispersed nitrides, with a grain size of level 6 or higher and uniform grain size.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] a) The preparation method of the retaining ring forging of the present invention adopts smelting, forging and solution treatment. By precisely controlling the homogenization treatment steps and parameters of each step, combined with the precise control of forging process parameters, the basic strength of the retaining ring forging can be significantly improved, the amount of deformation for processing and strengthening can be reduced, and even the performance requirements can be met without the need for cold deformation or warm forging deformation, thereby reducing manufacturing steps and costs.

[0025] b) The retaining ring forging of the present invention improves the solid solution strengthening effect of the alloy by precisely controlling the content of carbon, silicon, vanadium, niobium and nickel; and reduces hot forging cracks by synergistically controlling manganese and chromium and matching them with other alloying elements to control the ε phase precipitation temperature; in addition, the addition of each alloying element can increase the solid solubility of nitrogen in the matrix under normal pressure smelting, ensuring that the nitrogen content in normal pressure smelting can reach more than 0.68%; by precisely controlling the content of O, S, P and Al, the content of inclusions in the alloy can be reduced, which can improve the purity of the alloy and reduce the probability of hot forging cracks, and ensure grain uniformity and the precipitation and distribution of grain boundaries.

[0026] c) The composition of the retaining ring forging of the present invention is conducive to the formation of dispersed nitrides in the austenitic structure, which plays a role in refining the grains and improving the strength of the matrix.

[0027] d) The retaining ring forgings of the present invention exhibit excellent strength after hot forging and solution treatment. For example, the properties of the forging blank are as follows: tensile strength σ b The yield strength is above 950 MPa, for example, 956–1110 MPa; 0.2 The tensile strength is above 690 MPa, for example, 690–840 MPa; the elongation is above 35%, for example, 35%–46%; the reduction of area is above 60%, for example, 60%–69%; and the impact energy is above 56 J, for example, 56–135 J. The properties after solution treatment are as follows: tensile strength σ b The yield strength is above 920 MPa, for example, 920–984 MPa; 0.2 The strength is 620 MPa or higher, for example, 620 to 675 MPa; the elongation is 38% or higher, for example, 38% to 52%; the area reduction is 59% or higher, for example, 59% to 70%; and the impact energy is 70 J or higher, for example, 70 to 138 J.

[0028] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 The grain size of the retaining ring forging after solution treatment in Example 1;

[0031] Figure 2 The microstructure of the retaining ring forging after solution treatment in Example 1;

[0032] Figure 3This is a schematic diagram of the heating and temperature rise curve of the homogenization treatment in the preparation method of the retaining ring forging of the present invention. Detailed Implementation

[0033] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0034] This invention provides a method for preparing a retaining ring forging, comprising:

[0035] Step 1: Smelt electrode billets + electroslag remelted steel ingots, and peel off the outer layer;

[0036] Step 2: Homogenize the steel ingots;

[0037] Step 3: Forge the steel ingot into a billet, and then cool it with blast air after forging;

[0038] Step 4: Perform solution treatment on the forging billet to obtain the retaining ring forging.

[0039] Specifically, in step 1 above, the electrode billet is melted and cast in an electric arc furnace, and then the steel ingot is obtained by electroslag remelting. In step 1 above, atmospheric pressure smelting is used.

[0040] Specifically, in step 1 above, the electric arc furnace melting and casting of electrode billets may include the following steps: roughing molten steel in an electric arc furnace; refining molten steel in a refining ladle, adjusting the alloy composition, VOD operation, nitrogen blowing and stirring, adding manganese nitride to adjust N in batches, using Cr nitride to adjust N for any remaining deficiency, and finally using manganese and chromium to adjust manganese and chromium; after the composition is qualified, switching to argon stirring, with the tapping temperature at 1460℃~1490℃; and completing the casting of the electrode billet under argon protection.

[0041] Specifically, in step 1 above, electroslag remelting may include the following steps: electroslag remelting a set of electrode blanks in a crystallizer, selecting CaF2 50%–70%, Al2O3 20%–40%, and CaO 0%–20% for slag formation, and the electroslag remelting rate is 0.8T / h–1.2T / h.

[0042] Specifically, in step 1 above, the surface of the steel ingot needs to be peeled to remove surface cracks and slag.

[0043] Specifically, in step 2 above, the homogenization process includes the following steps:

[0044] S201. Heat the steel ingot to 600-650℃ and hold it for 1-1.2 hours per 100mm.

[0045] S202. The first heating should be carried out at a rate of less than 40℃ / h to 800-850℃, and the holding time should be 1h-1.2h / 100mm.

[0046] S203. The second heating is carried out at a rate of not less than 70℃ / h to 1150~1180℃, and the heat is held for 2h~3h / 100mm for homogenization treatment.

[0047] like Figure 3 The figure shows the heating curve in step 2, taking a steel ingot with a diameter of 1000mm as an example.

[0048] Specifically, in S202 above, considering that high-nitrogen austenitic stainless steel has low thermal conductivity at low temperatures and the heat transfer from the outer surface of the ingot to the core is slow, it is necessary to avoid excessively fast heating rates, which would lead to large temperature differences inside the ingot, generate internal tensile stress, and easily cause cracking of the ingot. Appropriately reducing the heating rate can ensure the temperature uniformity of the ingot after the first heating and avoid the generation of cracks. Therefore, the heating rate is controlled to be below 40℃ / h, for example, 30~40℃ / h.

[0049] Specifically, in the S203 described above, after holding at 800–850℃, the temperature inside and outside the steel ingot becomes uniform. Continued heating allows for rapid heating because of the good high-temperature plasticity; even if there is a temperature difference between the inside and outside during the heating process, there is no need to worry about the effect of temperature stress. Furthermore, this allows high-nitrogen austenitic stainless steel to quickly pass through the sensitive temperature range for brittle phase precipitation, reducing the brittle phases in the high-nitrogen austenitic stainless steel, improving the plasticity of the stainless steel, and reducing surface cracks or edge cracking during hot working. Therefore, the heating rate is 70℃ / h or higher, for example, 70–100℃ / h.

[0050] Specifically, in step 2 above, the purpose of the long-term homogenization treatment at 1150–1180℃ is to remelt the harmful phases from the solidification process of the steel ingot and to diffuse easily segregated alloying elements at high temperatures. Therefore, the homogenization treatment is carried out at a holding time of 2–3 hours per 100 mm.

[0051] Specifically, in step 3 above, considering that the precipitation temperature of the harmful phase δ at high temperatures can easily cause cracking and overheating and burning of grain boundaries, the initial forging temperature is controlled at 1150–1180℃. In addition, considering the precipitation of the harmful phase ε at low temperatures and the poor plasticity and high tensile strength at low temperatures, the final forging temperature is controlled at 950℃ or higher, for example, 960–970℃.

[0052] Specifically, in step 3 above, the forging process involves light drawing, upsetting and lengthening of the ingot, punching, and reaming to complete the forging blank. The initial forging temperature for the light drawing and upsetting and lengthening of the ingot is between 1150 and 1180°C, and the initial forging temperature for the punching and reaming processes is between 1100 and 1150°C. The final forging temperature is controlled above 950°C.

[0053] Specifically, in step 3 above, considering the poor high-temperature plasticity of the retaining ring forging material, narrow forging temperature range, and severe cracking tendency, a multi-stage, small-deformation-amount hot deformation method is adopted. Considering that excessive deformation may lead to mixed grain structure and cracking in the large deformation zone, while insufficient deformation may result in incomplete grain breakage and recrystallization, the deformation amount for each upsetting is controlled at 30%–50%, and the deformation amount for each elongation is controlled at 15%–25%. The specific hot forging process and the number of deformation passes can be designed according to the final shape and size of the forging, and will not be detailed here. After hot forging, the forging is cooled by forced air.

[0054] Specifically, in step 4 above, the solution treatment includes: loading the forging billet into the furnace at a furnace temperature ≤500℃ and rapidly heating it to 1080~1100℃, holding it at that temperature for 2~2.5h / 100mm, and then water cooling it after it is removed from the furnace.

[0055] Specifically, in step 4 above, the heating rate is above 70℃ / h.

[0056] Specifically, the composition of the aforementioned retaining ring forging, by mass percentage, includes: C 0.08%–0.11%, Si 0.40%–1.2%, Mn 18.5%–21.0%, Cr 18%–19.5%, Ni 0.5%–3%, V 0.35%–0.95%, N 0.68%–0.75%, Nb 0.005%–0.03%, Cu≤0.01%, Al≤0.01%, P≤0.010%, S≤0.010%, with the balance being Fe and unavoidable trace impurities.

[0057] The following details the function and dosage selection of the components contained in this invention:

[0058] Nitrogen (N): Nitrogen has a strong solid solution strengthening ability; as the N content increases, the strength of steel continuously improves, but its fracture toughness does not decrease significantly. Nitrogen is an austenite stabilizing element, which can inhibit the formation of ferrite and strain-induced martensite in steel. In addition, Nitrogen is very beneficial to improving the pitting corrosion resistance and stress corrosion resistance of steel. However, the dissolution of Nitrogen into austenite under normal pressure is affected by the alloy composition. Therefore, this invention ensures that the Ni content is 0.68% to 0.75% by adjusting the alloy composition.

[0059] Cr: Cr is one of the most important alloying elements in austenitic stainless steel. Adding Cr to high-nitrogen, chromium-manganese austenitic stainless steel and dissolving it into the iron matrix can effectively increase the electrode potential of the matrix. Under the action of an oxidizing medium, a Cr-rich oxide film forms on the surface, preventing anodic reactions and thus improving its corrosion resistance. Cr can increase the solubility of C and reduce Cr depletion; therefore, increasing the Cr content is beneficial to the resistance of austenitic stainless steel to intergranular corrosion. Cr can effectively improve the steel's resistance to pitting and crevice corrosion; this effectiveness is greatly enhanced when N is also present in the steel. Increasing the Cr content in austenitic stainless steel can lower the martensitic transformation temperature (M). s The Cr content decreases, thus increasing the stability of the austenitic matrix. Therefore, high-chromium austenitic stainless steel is difficult to martensite even after cold working and low-temperature treatment. However, the Cr content cannot be too high, because Cr is a strong ferrite-forming / stabilizing element, i.e., it can shrink the austenitic region. With the increase of Cr content in steel, ferrite (δ) structure can appear in austenitic stainless steel. In austenitic stainless steel, with the increase of Cr content, the tendency of some intermetallic phases (such as σ phase) to form increases. If the steel contains Mo, the increase of Cr content will also promote the formation of χ phase. The precipitation of these intermetallic phases not only significantly reduces the plasticity and toughness of the steel, but also reduces the corrosion resistance of the steel under some conditions. When stainless steel maintains a completely austenitic structure without the formation of δ ferrite, simply increasing the Cr content will not have a significant impact on its mechanical properties. Therefore, after in-depth research, this invention controls the Cr content to be 18% to 19.5%.

[0060] Mn: In high-nitrogen, chromium-manganese austenitic stainless steel, the main role of Mn is to stabilize austenite and increase the solubility of N. In Ni-saving stainless steels, Mn is a very important alloying element, and it is mainly added to the steel in combination with austenite-forming elements. Mn is a relatively weak austenite-forming element, but it has a strong austenite-stabilizing effect; Mn itself contributes very little to improving the corrosion resistance of the steel. To increase the solubility of N, this invention controls the Mn content at 18.5%–21.0%.

[0061] C: C is a strong austenite-forming and stabilizing element in stainless steel, and it significantly improves the strength of austenitic stainless steel through interstitial solid solution strengthening. C can also improve the stress corrosion resistance of austenitic stainless steel in high-concentration chloride solutions (such as 42% MgCl2 boiling solution). However, C is sometimes considered a harmful element in austenitic stainless steel. For example, C can form high-chromium M with Cr in the steel. 23C6-type carbides lead to localized chromium depletion in the steel, reducing its corrosion resistance, especially its resistance to intergranular corrosion. Therefore, not only should the C content be controlled as low as possible during the smelting of austenitic stainless steel, but subsequent hot and cold working and heat treatment processes should also prevent C accumulation on the stainless steel surface to avoid the precipitation of Cr carbides. Therefore, this invention, through in-depth research, controls the C content to 0.08%–0.11% primarily to improve the strength of austenitic stainless steel. 23 C6 type carbides can be eliminated by solution treatment.

[0062] Vanadium (V): The atomic size of vanadium (V) is comparable to that of Fe, it has high solid solubility, its addition amount is easy to control, and it is insensitive to segregation bands. In high-nitrogen chromium-manganese austenitic stainless steel, V can play a nitrogen-fixing role because V has a strong affinity for nitrogen in steel. The formation of V(C,N) significantly reduces the content of "free N" in the steel. V mainly affects the microstructure and properties of steel through the precipitation of V(C,N). During hot working, it can inhibit the recrystallization of austenite and prevent grain growth, thereby refining the grains and improving the strength and toughness of the steel. It can also effectively avoid strain aging in steel. Nitrogen in steel can enhance the strengthening effect of V. The precipitation strengthening effect of V(C,N) becomes more pronounced as the nitrogen content in the steel increases. At higher temperatures (above 1000℃), V(C,N) can dissolve in γ-Fe; therefore, vanadium mainly strengthens through interphase precipitation during the γ-α transformation process and precipitation in ferrite. This invention, through in-depth research, controls the V content to be 0.35%–0.95%.

[0063] Nb: Nb has a larger atomic size than Fe and a higher diffusion coefficient in austenite. Therefore, Nb tends to segregate at high-energy sites such as grain boundaries and dislocation lines. This strongly drags down dislocation climb and grain boundary movement, inhibiting recrystallization nucleation and thus increasing the material's recrystallization time. Nb is an austenite stabilizing element and can form carbides / nitrides with elements such as C / N in steel, preventing or reducing M... 23 The formation of C6-type carbides prevents the generation of sensitized intergranular corrosion. Nb compounds have a high complete solution temperature, generally above 1100℃, which helps pin dislocations and prevent grain boundary migration, thus refining austenite grains. Generally, the higher the amount added, the higher the complete solution temperature. Therefore, when formulating the processing technology for Nb microalloyed steel, the ratio of Nb dissolved to precipitated amounts, as well as the size range of the precipitated phase particles, should be strictly controlled to achieve the effect of grain refinement. As a microalloying element, this invention, through in-depth research, controls the Nb content to be between 0.005% and 0.03%.

[0064] Si: Si is a strong ferrite-forming element. As the Si content increases, the ferrite content increases, and the formation of intermetallic phases also accelerates and increases. However, increasing Si content will increase the yield strength. This invention, through in-depth research, controls the Si content to be between 0.40% and 1.2%.

[0065] Mo: Some high-nitrogen, chromium-manganese austenitic stainless steels typically contain a small amount of Mo, whose main function is to improve the steel's resistance to reducing media corrosion, pitting corrosion, and crevice corrosion. However, Mo is an element that forms and stabilizes ferrite and expands the ferrite region, and promotes the formation of intermetallic phases, thus reducing the steel's plasticity and toughness. This invention, through in-depth research, strictly limits the addition of Mo.

[0066] Ni: Ni is a crucial alloying element in austenitic stainless steel, primarily responsible for forming and stabilizing austenite, thus improving the steel's thermodynamic stability. Ni, along with Si, can also influence the high-temperature precipitation temperature of δ-Fe. Nickel and iron are infinitely soluble, with nickel expanding the austenite region of iron and being a major alloying element for austenite formation and stabilization. Nickel and carbon do not form carbides; nickel can increase the strength of steel without affecting its plasticity and toughness, and it can also improve the steel's corrosion resistance. Although increasing the N content can replace nickel in high-nitrogen steel, further increases in N require special methods such as pressurization. This invention, through in-depth research, controls the Ni content to be between 0.5% and 3%.

[0067] As harmful elements, P and S are controlled to ≤0.010% and ≤0.010% in this invention, taking into account actual manufacturing costs and processes. At the same time, Cu content is controlled to ≤0.010%, and Al content is also strictly controlled to avoid the formation of AlN inclusions in high-nitrogen steel, which are prone to cracking during hot forging. The Al content must also be ≤0.010%.

[0068] To further improve the overall performance of the aforementioned retaining ring forgings, the composition of the retaining ring forgings, by mass percentage, can be: C 0.09%–0.11%, Si 0.50%–1.2%, Mn 18.5%–20.0%, Cr 18.5%–19.4%, Ni 0.5%–2.1%, V 0.40%–0.95%, N 0.68%–0.75%, Nb 0.01%–0.03%, Cu≤0.006%, Al≤0.008%, P≤0.010%, S≤0.010%, with the balance being Fe and unavoidable trace impurities.

[0069] To further improve the overall performance of the aforementioned retaining ring forgings, the mass percentage of carbon in the composition of the aforementioned retaining ring forgings is 0.095% to 0.11%.

[0070] To further improve the overall performance of the aforementioned retaining ring forgings, the mass percentage of Mn in the composition of the aforementioned retaining ring forgings is 18.6% to 19.5%.

[0071] To further improve the overall performance of the aforementioned retaining ring forgings, the mass percentage of Cr in the composition of the aforementioned retaining ring forgings is 18.7% to 19.2%.

[0072] To further improve the overall performance of the aforementioned retaining ring forgings, the mass percentage of Ni in the composition of the aforementioned retaining ring forgings is 0.5% to 2.1%.

[0073] The present invention also provides a retaining ring forging prepared by the above method. The microstructure of the retaining ring forging is austenite + dispersed nitride, and the grain size can reach level 6 or above, for example, level 6 to 9. The grains are uniform, for example, the grain size difference is below level 0.5.

[0074] Specifically, the aforementioned retaining ring forgings exhibit excellent strength after hot forging and solution treatment. For example, the properties of the forging blank are as follows: tensile strength σ b The yield strength is above 950 MPa, for example, 956–1110 MPa; 0.2 The tensile strength is above 690 MPa, for example, 690–840 MPa; the elongation is above 35%, for example, 35%–46%; the reduction of area is above 60%, for example, 60%–69%; and the impact energy is above 56 J, for example, 56–135 J. The properties after solution treatment are as follows: tensile strength σ b The yield strength is above 920 MPa, for example, 920–984 MPa; 0.2 The strength is 620 MPa or higher, for example, 620 to 675 MPa; the elongation is 38% or higher, for example, 38% to 52%; the area reduction is 59% or higher, for example, 59% to 70%; and the impact energy is 70 J or higher, for example, 70 to 138 J.

[0075] Specifically, after solution treatment, the basic strength of the aforementioned retaining ring forgings is sufficient to meet the requirements of some yield strength and tensile strength, without the need for cold deformation or semi-hot forging strengthening. Even if further cold deformation or semi-hot forging strengthening is required, the deformation rate is relatively small, and the cold deformation or semi-hot forging strengthening process will not be described here.

[0076] Examples 1-4

[0077] Examples 1-4 of the present invention provide a retaining ring forging and its preparation method. The chemical composition of the examples is shown in Table 1. The microstructure of the retaining ring forgings of Examples 1-4 is shown in Table 2. Figure 1 The grain size of the retaining ring forging after solution treatment in Example 1; Figure 2The microstructure of the retaining ring forging in Example 1 after solution treatment is shown in Table 3. The main performance test results of the examples are shown in Table 3.

[0078] The preparation method of Example 1 includes:

[0079] Step 1: Melt and cast electrode billets using an electric arc furnace, then remelt 10,000 kg of steel ingots using electroslag remelting;

[0080] The process of melting and casting electrode billets in an electric arc furnace may include the following steps: roughing molten steel in an electric arc furnace; refining the molten steel in a refining ladle, adjusting the alloy composition, using VOD operation, stirring with nitrogen, adding manganese nitride in batches to adjust N, and using Cr nitride to adjust N for any remaining insufficient N, until the N content reaches 0.7%; finally, adjusting manganese and chromium with metallic manganese and metallic chromium; after the composition is qualified, switching to argon stirring, and tapping the steel at a temperature of 1470℃; and completing the casting of the electrode billets under argon protection.

[0081] Electroslag remelting may include the following steps: electroslag remelting a set of electrode blanks in a crystallizer, selecting CaF2 60%, Al2O3 20%, CaO 20% for slag formation, and the electroslag remelting melting rate is 1T / h;

[0082] The surface of the electroslag ingot is peeled to remove surface cracks and slag.

[0083] Step 2: Homogenize the steel ingot:

[0084] S201. Heat the steel ingot to 650℃ and hold for 10 hours;

[0085] S202, First, raise the temperature to 850℃ at a rate of 30℃ / h and hold for 10 hours;

[0086] S203. The second heating is carried out at 80℃ / h to 1180℃, and the heat is held for 30h to homogenize the temperature.

[0087] Step 3: Forge the steel ingot into a billet, and perform multiple heating upsetting and drawing deformations at a heating temperature of 1180℃ and a final forging temperature of 960℃; then punch and expand the hole, with an initial forging temperature of 1150℃. After the hole is expanded, the retaining ring forging billet has a wall thickness of 240mm and is then cooled by forced air.

[0088] Step 4: The forging billet is placed into a furnace at 450℃ and heated at 80℃ / h until it reaches 1080℃. It is then held at this temperature for 5 hours, removed from the furnace, and water-cooled to obtain a solution-treated retaining ring forging.

[0089] The preparation method of Example 2 is largely the same as that of Example 1, except that:

[0090] In step 2: the steel ingot undergoes homogenization treatment.

[0091] S201. Heat the steel ingot to 600℃ and hold for 10 hours;

[0092] S202, First, raise the temperature to 830℃ at a rate of 40℃ / h and hold for 8 hours;

[0093] S203. The second heating is carried out at 100℃ / h to 1180℃, and the temperature is held for 25h to homogenize the product.

[0094] The preparation method of Example 3 is largely the same as that of Example 1, except that:

[0095] Step 3: Forge the steel ingot into a billet, and perform multiple heating upsetting and drawing deformations at a heating temperature of 1160℃ and a final forging temperature of 950℃; then punch and expand the hole, with the initial forging temperature of punching and expanding the hole at 1130℃. After the hole is expanded, the wall thickness of the retaining ring forging billet is 180mm, and it is then cooled by forced air.

[0096] Step 4: The forging billet is placed into a furnace at 500℃ and heated at 70℃ / h until it reaches 1100℃. It is then held at this temperature for 4 hours, removed from the furnace, and water-cooled to obtain a solution-treated retaining ring forging.

[0097] The preparation method of Example 4 is largely the same as that of Example 1, except that:

[0098] Step 1: The electrode billet is melted and cast in an electric arc furnace, and then 7000 kg of steel ingot is smelted by electroslag remelting. The tapping temperature of the electric arc furnace is 1460℃. The slag for electroslag remelting is 70% CaF2, 10% Al2O3, and 10% CaO. The melting rate of electroslag remelting is 1.1T / h.

[0099] The surface of the electroslag ingot is peeled to remove surface cracks and slag.

[0100] Table 1 Chemical composition, wt%

[0101]

[0102] Table 2 Microstructure

[0103]

[0104]

[0105] Table 3 Performance test results

[0106]

[0107] The inventors conducted extensive experimental research during the research process, and some schemes with lower basic yield strength are now used as comparative examples.

[0108] Comparative Example 1

[0109] This comparative example provides a retaining ring forging, the composition of which is shown in Table 4 below. The preparation method is the same as that in Example 1, and will not be repeated here.

[0110] Comparative Example 2

[0111] This comparative example provides a retaining ring forging, the composition of which is shown in Table 4 below. The preparation method is the same as that in Example 1, and will not be repeated here.

[0112] Comparative Example 3

[0113] This comparative example provides a retaining ring forging, the composition of which is shown in Table 4 below. The preparation method is the same as that in Example 1, and will not be repeated here.

[0114] Comparative Example 4

[0115] This comparative example provides a retaining ring forging, the composition of which is shown in Table 4 below. The preparation method is the same as that in Example 1, and will not be repeated here.

[0116] The main performance test results of the comparative retaining ring forgings are shown in Table 5.

[0117] Table 4 Chemical composition, wt%

[0118] Comparative Example C Si Mn S P Cr Ni Nb V N Cu Al 1 0.10 0.08 20.23 0.009 0.020 19.44 0.02 0.003 0.02 0.8 0.03 0.005 2 0.078 0.074 18.86 0.008 0.020 19.45 0.02 0.003 0.005 0.68 0.008 0.008 3 0.10 0.055 18 0.006 0.025 18.17 0.02 0.003 0.005 0.5 0.007 0.006 4 0.11 0.45 17.5 0.002 0.012 18.7 0.17 0.003 0.005 0.58 0.06 0.002

[0119] Table 5 Comparative Performance Test Results

[0120]

[0121]

[0122] As can be seen from the comparative examples and comparative embodiments, the retaining ring forging of the present invention exhibits excellent strength after hot forging and solution treatment.

[0123] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a retaining ring forging, characterized in that, include: Step 1: Smelt electrode billets + electroslag remelted steel ingots, and peel off the outer layer; Step 2: Homogenize the steel ingots; Step 3: Forge the steel ingot into a billet, and then cool it with blast air after forging; Step 4: Perform solution treatment on the forging billet to obtain the retaining ring forging; In step 2, the homogenization process includes the following steps: S201. Heat the steel ingot to 600~650℃ and hold for 1h~1.2h / 100mm. S202. Heat to 800~850℃ and hold for 1h~1.2h / 100mm. S203: Heat to 1150~1180℃, hold for 2h~3h / 100mm; the heating rate in S202 is less than the heating rate in S203. In S202, the heating rate is below 40℃ / h; In the S203, the heating rate is above 70℃ / h; In step 3, the forging blank is completed through light drawing, upsetting and elongation, punching, and reaming of the ingot body; the initial forging temperature of the light drawing and upsetting and elongation forging blank is 1150~1180℃, and the final forging temperature is controlled above 950℃; the deformation amount of each upsetting is controlled to be 30%~50%, and the deformation amount of each elongation is controlled to be 15%~25%; The components of the retaining ring forging, by mass percentage, include: C 0.08%~0.11%, Si 0.40%~1.2%, Mn 18.5%~21.0%, Cr 18%~19.5%, Ni 0.5%~3%, V 0.35%~0.95%, N 0.68%~0.75%, Nb 0.005%~0.03%, Cu ≤0.01%, Al ≤0.01%, P ≤0.010%, S ≤0.010%, with the balance being Fe and unavoidable trace impurities; The microstructure of the retaining ring forging consists of austenite and dispersed nitrides, with a grain size of grade 6 or higher, uniform grain size, and a grain size difference of less than 0.

5. The yield strength σ of the solution-treated retaining ring forging 0.2 It is above 620 MPa.

2. The preparation method according to claim 1, characterized in that, In S202, the heating rate is 30~40℃ / h.

3. The preparation method according to claim 1, characterized in that, In the S203, the heating rate is 70~100℃ / h.

4. The preparation method according to claim 1, characterized in that, In step 4, the solution treatment includes: loading the forging billet into the furnace at a furnace temperature ≤500℃ and rapidly heating it to 1080~1100℃, holding it at that temperature for 2~2.5h / 100mm, and then water cooling it after it is removed from the furnace.

5. The preparation method according to claim 1, characterized in that, The components of the retaining ring forging, by mass percentage, include: C 0.09%~0.11%, Si 0.50%~1.2%, Mn 18.5%~20.0%, Cr 18.5%~19.4%, Ni 0.5%~2.1%, V 0.40%~0.95%, N 0.68%~0.75%, Nb 0.01%~0.03%, Cu ≤0.006%, Al ≤0.008%, P ≤0.010%, S ≤0.010%, with the balance being Fe and unavoidable trace impurities.

6. A retaining ring forging, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 5.

7. The retaining ring forging according to claim 6, characterized in that, The microstructure of the retaining ring forging is austenite plus dispersed nitrides.

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