A high-performance 4130 forging for deep-sea equipment and its production method

Abstract

The present application belongs to the technical field of forging production, and particularly relates to a production process of 4130 high-performance forging for deep-sea equipment; the main steps are as follows: controlling the initial forging temperature to be 1100-1220 DEG C, the final forging temperature to be 800 DEG C-900 DEG C, and the forging ratio to be greater than or equal to 4:1; heating to 1200-1240 DEG C for 3-5 hours, normalizing the obtained forging, air cooling after 880-920 DEG C for 3-7 hours, then quenching, water cooling after 860-900 DEG C for 3-6 hours, finally tempering, air cooling after 600-620 DEG C for 3-6 hours, and obtaining the final material. The present application adopts the combination of component design, forging and heat treatment process, and achieves the purposes of refining grains, improving hardenability and improving comprehensive mechanical properties; the prepared forging has high strength, and also improves the comprehensive properties such as corrosion resistance, pressure resistance, low-temperature toughness, impact resistance and fatigue resistance.

Description

Technical Field

[0001] This invention belongs to the field of forging production technology, specifically relating to a production process for 4130 high-performance forgings for deep-sea equipment. Background Technology

[0002] 4130 is a low-alloy steel generally used in onshore oil wellhead equipment, and rarely in deep-sea oil production equipment. This is because the inherent hardenability of 4130 results in lower hardness, yield strength, tensile strength, and low-temperature impact toughness in forgings compared to other deep-sea forging materials. Therefore, improving 4130 forgings to achieve higher overall performance is an urgent technical challenge. Strict control over the microalloying ratio of raw materials, forging, and heat treatment is crucial during the production of 4130 forgings. Summary of the Invention

[0003] The purpose of this invention is to overcome the technical defects existing in the prior art and to develop a high-performance 4130 forging for deep-sea equipment.

[0004] To achieve the above objectives, the present invention first provides a 4130 high-performance forging for deep-sea equipment, which is composed of the following components by weight percentage:

[0005] C: 0.27-0.33%, Si: 0.15-0.35%, Mn: 0.30-0.80%, P: ≤0.010%, S: ≤0.005%, Cr: 0.75-1.10%, Mo: 0.15-0.25%, Ni: 0-0.50%, Al 0-0.055%, V: ≤0.03%, H: ≤2ppm, O: ≤2ppm, N: ≤120ppm.

[0006] Composition design: Refer to the 4130 material composition in ASTM A29 standard, and improve and control the content of alloying elements in the material to reach the required upper limit, and control harmful elements such as arsenic, selenium, and antimony to minimize them, so as to improve the hardenability of the material and enhance mechanical properties such as hardness, yield strength, tensile strength, and impact energy.

[0007] This invention specifies the Cr content as 0.75-1.10%, preferably 1.04-1.08%, and the Ni content as 0.40-0.50%. Appropriate amounts of chromium (Cr) can improve the hardenability and wear resistance of steel, and enhance its corrosion resistance and oxidation resistance. Combined with the use of Mo, it is a strong carbide-forming element, forming Mo₂C with C, which can inhibit austenite grain growth. Simultaneously, Mo is an element that prevents temper embrittlement of type II, greatly contributing to improved impact toughness after high-temperature tempering. Ni (preferably 0.45-0.48%) can improve the strength and toughness of steel, increase hardenability, significantly alter some physical properties of steel and alloys, and improve the corrosion resistance of steel. Furthermore, V is a strong carbide-forming element; adding V further refines the grains, improves strength and tempering stability, but the amount should not be too high, so the V content is controlled at V: ≤0.03% (preferably 0.012%-0.014%).

[0008] This invention also provides a manufacturing process for 4130 high-performance forgings for deep-sea equipment, comprising the following steps:

[0009] (1) Forging process:

[0010] The initial forging temperature is controlled at 1100-1200℃, and the final forging temperature is 800℃~900℃. The forging ratio must be ≥4:1. During the forging process, the temperature is heated to 1200~1240℃ and held for 3-5 hours. Finally, the forging is taken out of the furnace and forged. After repeated upsetting and drawing by the press and forging hammer, the forging is finally formed and obtained.

[0011] Preferably, the final forging temperature in step (1) is 850°C.

[0012] (2) Post-forging heat treatment (normalizing treatment):

[0013] The forgings obtained in step (1) are subjected to normalizing treatment. The furnace temperature is ≤350℃, the heating rate is ≤150℃ / h, and the furnace is held at 880-920℃ for 3-7 hours before air cooling to obtain the normalized forgings.

[0014] Preferably, the furnace temperature in step (2) is 200-350℃ and the heating rate is 100-150℃ / h.

[0015] (3) Performance heat treatment: Quenching followed by high-temperature tempering (quenching and tempering):

[0016] (a) The forgings after normalizing in step (2) are first quenched. The furnace temperature of the forgings is controlled to be ≤350℃, the heating rate is ≤150℃ / h, and the forgings are held at 860-900℃ for 3-6 hours and then water-cooled to obtain the quenched forgings.

[0017] (b) The forgings quenched in step (a) are tempered, and the furnace temperature is controlled to be ≤350℃, the heating rate is ≤150℃ / h, and the forgings are held at 600-620℃ for 3-6 hours and then air-cooled to obtain 4130 forgings for deep-sea equipment.

[0018] Preferably, in step (3) (a), the furnace temperature is 180℃~200℃ and the heating rate is 120~150℃ / h;

[0019] Preferably, in step (3) (b), the furnace temperature is 180℃~200℃ and the heating rate is 120~150℃ / h.

[0020] The advantages and technical effects of this invention are:

[0021] (1) The 4130 material prepared by this invention is a low alloy steel. By adjusting the microalloy content, the hardenability of the material is improved. However, to obtain a product with high comprehensive performance, a reasonable forging process, post-forging heat treatment process and performance heat treatment process are also required. Therefore, by combining composition design with forging process and heat treatment process, the purpose of refining grains, improving hardenability and improving comprehensive mechanical properties is achieved. The prepared 4130 forgings have high strength, and at the same time, the comprehensive properties such as corrosion resistance, pressure resistance, low temperature toughness, impact resistance and fatigue resistance are also improved.

[0022] (2) In the present invention, the initial forging temperature is 1100-1200℃. Exceeding 1250℃ can easily cause overheating or even burning. The holding time is determined according to the size of the billet. The reasonable holding time is the basis for ensuring that the grains are not coarse. The final forging temperature is 800-900℃. Too low a final forging temperature will cause the parts to crack, and too high a temperature will also cause the grains to become coarse.

[0023] (3) The forging ratio of the present invention must be ≥4:1. This ensures that the structure is compact after forging, and can break up the coarse austenite grains, disperse the inclusions, eliminate the banded structure, and reduce anisotropy. After repeated upsetting and drawing by the press and forging hammer, the grains can be made finer, which lays the foundation for improving mechanical properties.

[0024] (4) The tempering treatment temperature of the present invention is 600-620℃. The purpose is to make the steel parts have a good combination of strength and toughness, with both high strength and excellent low temperature toughness and impact resistance. The temperature should not be too high, otherwise it will lead to a decrease in the hardness of the forgings, and thus the yield strength and tensile strength will also decrease. Attached Figure Description

[0025] Figure 1 This is a low-magnification microstructure image of the material prepared in Example 1.

[0026] Figure 2 The image shows the grain size of the material prepared in Example 1.

[0027] Figure 3 The image shows the microstructure of the material prepared in Example 1 under a 100x microscope.

[0028] Figure 4 The image shows the microstructure of the material prepared in Example 1 under a 500x microscope.

[0029] Figure 5 This is a diagram of the non-metallic inclusions in the material prepared in Example 1. Detailed Implementation

[0030] The present invention will be described in detail below with reference to examples. In the examples, the preferred forging ratio is 7 to 25:1.

[0031] Example 1:

[0032] The forging material composition consists of the following components by weight percentage:

[0033] C: 0.32%, Si: 0.31%, Mn: 0.74%, P: 0.009%, S: ≤0.001%, Cr: 1.05%, Mo: 0.23%, Ni: 0.45%, Al: 0.025%, V: 0.014%, H: 0.9ppm, O: 12ppm, N: 24ppm

[0034] The specific steps are as follows:

[0035] (1) Forging process: The steel billet with the above composition is used as raw material and heated for forging. The initial forging temperature is 1130℃ and the final forging temperature is 850℃. The forging ratio must be 25:1. During the forging process, the temperature is heated to 1220℃ and held for 4 hours. Finally, it is taken out of the furnace for forging. After repeated upsetting and drawing by the press and forging hammer, it is finally formed and the forging is obtained.

[0036] (2) Post-forging heat treatment:

[0037] The forgings obtained in step (1) are subjected to normalizing treatment. The forgings are fed into the furnace at a temperature of 210°C, with a heating rate of 120°C / h. After holding at 900°C for 3 hours, they are air-cooled.

[0038] (3) Performance heat treatment:

[0039] Quenching: The forgings after normalizing in step (2) are first quenched. The furnace temperature of the forgings is 180℃, the heating rate is 120℃ / h, and after holding at 880℃ for 3 hours, they are water-cooled to obtain the quenched forgings.

[0040] Tempering: The forgings after quenching are tempered. The forgings are fed into the furnace at a temperature of 180℃, with a heating rate of 120℃ / h. After holding at 610℃ for 4 hours, they are air-cooled to obtain 4130 forgings for deep-sea oil and gas equipment.

[0041] Example 2:

[0042] The forging material composition consists of the following components by weight percentage:

[0043] C: 0.32%, Si: 0.26%, Mn: 0.76%, P: 0.009%, S: ≤0.004%, Cr: 1.04%, Mo: 0.22%, Ni: 0.48%, Al: 0.022%, V: 0.013%, H: 0.9ppm, O: 13ppm, N: 34ppm

[0044] The specific steps are as follows:

[0045] (1) Forging process: Take the steel billet with the above composition as raw material, heat it and forge it. The initial forging temperature is 1120℃ and the final forging temperature is 850℃. The forging ratio must be 7:1. During the forging process, heat it to 1220℃ and hold it for 4 hours. Finally, take it out of the furnace for forging. After repeated upsetting and drawing by the press and forging hammer, it is finally formed and a forging is obtained.

[0046] (2) Post-forging heat treatment:

[0047] The forgings obtained in step (1) are subjected to normalizing treatment. The forgings are fed into the furnace at a temperature of 210°C, with a heating rate of 120°C / h. After holding at 900°C for 4 hours, they are air-cooled.

[0048] (3) Performance heat treatment:

[0049] Quenching: The forgings after normalizing in step (2) are first quenched. The furnace temperature of the forgings is 180℃, the heating rate is 120℃ / h, and after holding at 880℃ for 4.5 hours, they are water-cooled to obtain the quenched forgings.

[0050] Tempering: The forgings after quenching are tempered. The forgings are fed into the furnace at a temperature of 180℃, with a heating rate of 120℃ / h. After holding at 610℃ for 5 hours, they are air-cooled to obtain 4130 forgings for deep-sea oil and gas equipment.

[0051] Example 3:

[0052] The forging material composition consists of the following components by weight percentage:

[0053] C: 0.31%, Si: 0.25%, Mn: 0.78%, P: 0.008%, S: ≤0.005%, Cr: 1.08%, Mo: 0.23%, Ni: 0.48%, Al: 0.022%, V: 0.012%, H: 1.2ppm, O: 18ppm, N: 39ppm

[0054] The specific steps are as follows:

[0055] (1) Forging process: The steel billet with the above composition is taken as raw material and put into the preheated forging furnace for forging. The initial forging temperature is 1150℃ and the final forging temperature is 850℃. The forging ratio must be 16:1. During the forging process, the temperature is heated to 1220℃ and held for 4 hours. Finally, the forging is taken out of the furnace and forged. After repeated upsetting and drawing by the press and forging hammer, the forging is finally formed and obtained.

[0056] (2) Post-forging heat treatment:

[0057] The forgings obtained in step (1) were normalized. The furnace temperature of the forgings was 210℃, the heating rate was 120℃ / h, and the furnace was held at 905℃ for 3.5 hours before air cooling.

[0058] (3) Performance heat treatment:

[0059] Quenching: The forgings after normalizing in step (2) are first quenched. The furnace temperature of the forgings is 180℃, the heating rate is 120℃ / h, and after holding at 875℃ for 3 hours, they are water-cooled to obtain the quenched forgings.

[0060] Tempering: The forgings after quenching are tempered. The forgings are fed into the furnace at a temperature of 180℃, with a heating rate of 120℃ / h. After holding at 610℃ for 4 hours, they are air-cooled to obtain 4130 forgings for deep-sea oil and gas equipment.

[0061] The mechanical properties of the forgings produced in Examples 1-3 were tested, and the results are shown in Table 1.

[0062] Table 1 Results of Mechanical Property Tests

[0063]

[0064] This invention improves the steel forging process in three aspects: formulation, forging process, and heat treatment process. First, it strengthens the grains by refining the formulation. Second, it eliminates cracks by forging. When the forging temperature is close to the final forging temperature, a light-hammering and fast-forging process is used to make the grains even finer. Finally, it improves the mechanical properties by combining heat treatment process. This solves the current technical problems and obtains high-performance 4130 forgings for deep-sea oil and gas equipment that meet NACE standards.

[0065] Further testing was conducted on the material prepared in Example 1:

[0066] Figure 1 The image shows the low-magnification microstructure of the forging material (testing standard: ASTM E381-20). As can be seen from Table 2, the selection of the forging ratio is very important, and the forging conditions selected in this invention are suitable, resulting in a very dense low-magnification microstructure of the material.

[0067] Table 2 Results of low-magnification tissue analysis

[0068]

[0069] Figure 2 The image shows the grain size of the forging material, tested according to the ASTM E112-13(2021) comparative method. The image shows that the grain size is very fine, at grade 9. Grain size reflects the quality of the forging during actual heat treatment and hot working, and directly affects the microstructure and properties of the product obtained after the steel cools.

[0070] Microstructural testing is based on: ASTM E407-07(2015)e1; Figure 3 The image shows the microstructure of the forging material under a 100x microscope, indicating that the microstructure is uniformly distributed under the microscope. Figure 4 The image shows the microstructure of the forging material under a 500x microscope, which reveals granular tempered sorbite.

[0071] Figure 5 Table 3 shows the non-metallic inclusions in the forging material and the detection results of non-metallic inclusions. As can be seen from the figures, the non-metallic inclusions in the material of this invention are well controlled and the detection results are excellent.

[0072] Table 3 Results of Non-metallic Inclusion Detection

[0073]

[0074] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing 4130 high-performance forgings for deep-sea equipment, characterized in that, The 4130 high-performance forging for deep-sea equipment is characterized by being composed of the following components by mass percentage: C: 0.27-0.33%, Si: 0.15-0.35%, Mn: 0.30-0.80%, P: ≤0.010%, S: ≤0.005%, Cr: 0.75-1.10%, Mo: 0.15-0.25%, Ni: 0-0.50%, Al 0-0.055%, V: ≤0.03%, H: ≤2ppm, O: ≤2ppm, N: ≤120 ppm; The method includes the following steps: (1) Forging process: The initial forging temperature is controlled at 1100-1200℃, the final forging temperature is 800℃~900℃, and the forging ratio is 7~25:

1. During the forging process, the temperature is heated to 1200~1240℃ and held for 3-5 hours. Finally, the forging is taken out of the furnace and forged. After repeated upsetting and drawing by the press and forging hammer, the forging is finally formed and obtained. (2) Post-forging heat treatment: The forgings obtained in step (1) are subjected to normalizing treatment. The furnace temperature is ≤350℃, the heating rate is ≤150℃ / h, and the forgings are held at 880-920℃ for 3-7 hours and then air-cooled to obtain the normalized forgings. (3) Performance heat treatment: (a) The forgings after normalizing in step (2) are first quenched. The furnace temperature of the forgings is controlled to be ≤350℃, the heating rate is ≤150℃ / h, and the forgings are held at 860-900℃ for 3-6 hours and then water-cooled to obtain the quenched forgings. (b) The forgings quenched in step (a) are tempered, and the furnace temperature is controlled to be ≤350℃, the heating rate is ≤150℃ / h, and the forgings are held at 600-620℃ for 3-6 hours and then air-cooled to obtain 4130 forgings for deep-sea equipment.

2. The method for producing 4130 high-performance forgings for deep-sea equipment according to claim 1, characterized in that, The final forging temperature in step (1) is 850℃.

3. The method for producing 4130 high-performance forgings for deep-sea equipment according to claim 1, characterized in that, In step (2), the furnace temperature is 200~350℃ and the heating rate is 100~150℃ / h.

4. The method for producing 4130 high-performance forgings for deep-sea equipment according to claim 1, characterized in that, In step (3) (a), the furnace temperature is 180℃~200℃ and the heating rate is 120~150℃ / h.

5. The method for producing 4130 high-performance forgings for deep-sea equipment according to claim 1, characterized in that, In step (3) (b), the furnace temperature is 180℃~200℃ and the heating rate is 120~150℃ / h.

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