Preparation method of energy storage system high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material

Abstract

The invention discloses a preparation method of an energy storage system high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material. The method comprises the following steps: a, producing and preparing 30Cr2Ni4MoV steel, wherein the 30Cr2Ni4MoV steel comprises the following components in percentage by weight: 0.30 to 0.36 percent of C, 0.15 to 0.35 percent of Si, 0.40 to 0.60 percent of Mn, less than or equal to 0.012 percent of P, less than or equal to 0.012 percent of S, 1.4 to 1.8 percent of Cr, 0.37 to 0.47 percent of Mo, 3.3 to 3.6 percent of Ni, 0.02 to 0.04 percent of Al and 0.10 to 0.14 percent of V; the blank steel is used as a raw material; and b, the initial forging temperature is 1100-1180 DEG C, upsetting and square drawing are conducted, air cooling is conducted to 800 DEG C after upsetting and square drawing are conducted again, and then remelting is conducted. Upsetting, changing a jaw and a cutting board, drawing out, and then drawing out the star anise at the furnace temperature of 1050 + / -10 DEG C for 3 hours; carrying out rolling and material distribution at the furnace temperature of 1000 + / -10 DEG C for 0.5-1 hour, wherein the two ends need to be concave as much as possible; upsetting and rolling on an upper die at the furnace temperature of 1000 + / -10 DEG C; and finally, the thick end is pulled out at the furnace temperature of 950 + / -10 DEG C, and the thin end is pulled out for several times, straightened, shaped and formed. The forging ratio is not less than 4: 1; and c, through thermal refining and high-temperature tempering heat treatment, the tensile strength of the material is larger than or equal to 1200 MPa, and the yield strength of the material is larger than or equal to 1100 MPa.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of forging, and particularly relates to a preparation method of high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for an energy storage system. BACKGROUND

[0002] The flywheel energy storage is a system for storing kinetic energy by rotating the rotor at high speed, and belongs to clean energy storage technology, which can help power grid regulation and stabilization, renewable energy storage and the like. The rotor speed of the system core component can reach tens of thousands of revolutions per minute, and the flywheel rotor requires that the material has ultra-high strength, low density and fatigue resistance, and the manufacturing process is strict, and needs to meet the requirements of small deformation, long service life and reduced fracture risk during high-speed operation. The material performance and manufacturing process of the rotor are a great challenge to the manufacturing industry. The flywheel energy storage system of Beacon Power Company in the United States has begun commercial application. The high-strength alloy steel is combined with the mature forging and heat treatment technology to produce a durable and reliable rotor. The ultra-pure 30Cr2Ni4MoV rotor steel forging of high-strength steel has been industrialized in China, but the precision control of the forging process, the control of the residual stress of the heat treatment and the consistency of the products in large-scale production still need to be solved. SUMMARY

[0003] The application aims to solve the technical problem of providing a preparation method of high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for an energy storage system.

[0004] To solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for an energy storage system, which comprises the following steps:

[0005] a. Production and preparation process of X46Cr13 steel material: mainly including electric furnace smelting technology (EF) or electric arc furnace smelting technology (EAF), ladle refining furnace refining technology (LF) and vacuum refining technology (VD). The specific method is as follows:

[0006] Electric furnace smelting technology (EF) or electric arc furnace smelting technology (EAF): through a series of processes such as furnace charging, melting, oxidation and reduction, the processed material 1 is produced.

[0007] Ladle refining furnace refining technology (LF): deoxidizing and desulfurizing catalyst materials are added to the processed material 1, and chemical reactions are generated by heating to realize desulfurization and deoxidization, so as to produce the processed material 2.

[0008] Vacuum refining technology (VD): in order to further deaerate, deoxidize, desulfurize and stir the processed material 2, reduce the hydrogen and nitrogen content in the steel, and uniform the composition and temperature, the processed material 3 is produced.

[0009] Electroslag Remelting (ESR): The material to be processed 3 as electrode, put into the slag pool remelted to form 30Cr2Ni4MoV forging raw material.

[0010] Take the weight components as C: 0.30-0.36%, Si: 0.15-0.35%, Mn: 0.40-0.60%, P: ≤0.012%, S: ≤0.012%, Cr: 1.4-1.8%, Mo: 0.37-0.47%, Ni: 3.3-3.6%, Al: 0.02-0.04%, V: 0.10-0.14%. The remaining Fe and other residual elements of the billet steel are used as raw materials to enter the preheated forging furnace and heated to 800-1220℃, and the forging is started.

[0011] b. Forging process: the initial forging temperature is 1100-1180℃, the final forging temperature is 850-950℃, and in the initial forging process, after upsetting and square bar drawing, it is air cooled to 800℃ and then returned to the furnace. At 1050±10℃ furnace temperature for 3h, it is upset and square bar drawn; at 1000±10℃ furnace temperature for 0.5-1h, it is rolled and divided, and the two ends need to be as concave as possible; at 1000±10℃ furnace temperature, the upper die is upset and rolled; finally, at 950±10℃ furnace temperature, one end is drawn out, straightened, shaped and formed. The forging ratio is ≥4:1, and light hitting and fast forging process is used when approaching the final forging temperature.

[0012] c. 30Cr2Ni4MoV has good hardenability, and through quenching and tempering and high temperature tempering heat treatment, fine and uniform structure and good comprehensive performance can be obtained.

[0013] Further, in step a, increasing the content of C, Cr, Ni, Mo and V elements can improve the hardenability, strength, hardness, toughness and corrosion resistance of the material, and improve the comprehensive physicochemical properties. C is an element that improves hardness, Cr, Ni, Mo and V are elements that improve hardenability and corrosion resistance, and the addition of C, Ni, Mo and V is more obvious in improving hardenability. At the same time, Ni can greatly improve the impact toughness at low temperature. During smelting, it is necessary to ensure that non-metallic inclusions and harmful elements in the steel are minimized.

[0014] Further, in step b, the initial forging temperature of X46Cr13 is 1100-1180℃, and exceeding 1180℃ can easily cause grain coarsening.

[0015] Further, in step b, the method determines through experiments that the appropriate final forging temperature is 850-950℃, and too low final forging temperature will cause the possibility of cracking of the part, and too high final forging temperature will also cause grain coarsening.

[0016] Further, in step b, the forging ratio must be ensured to be ≥4:1, so as to ensure that the structure is compact after forging, and the coarse austenite grains are broken, the inclusions are dispersed, the banded structure is eliminated, and the anisotropy is reduced.

[0017] Further, in step c, the tempering treatment and high-temperature tempering heat treatment are adopted, the tempered sorbite is obtained after the quenching and tempering treatment and high-temperature tempering, and the steel has excellent comprehensive mechanical properties.

[0018] The 30Cr2Ni4MoV flywheel rotor raw material prepared by the method has a tensile strength ≥1200 MPa, a yield strength ≥1100 MPa, an elongation ≥10%, a reduction of area ≥30%, an impact toughness ≥1125 KV2, and a hardness of 360-420 HB. DETAILED DESCRIPTION

[0019] The specific embodiments of the present application are described in detail below.

[0020] A preparation method of a high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for an energy storage system. The steps are as follows:

[0021] a. Production and preparation process of 30Cr2Ni4MoV steel material: mainly including electric furnace smelting technology (EF) or electric arc furnace smelting technology (EAF), ladle refining furnace refining technology (LF), vacuum refining technology (VD). The specific method is as follows:

[0022] Electric furnace smelting technology (EF) or electric arc furnace smelting technology (EAF): through a series of processes such as furnace repair, charging, melting, oxidation, and reduction, the processed material 1 is produced.

[0023] Ladle refining furnace refining technology (LF): for the processed material 1, add deoxidizing and desulfurizing catalyst materials, heat to produce chemical reactions to realize desulfurization and deoxidization, thereby producing the processed material 2.

[0024] Vacuum refining technology (VD): for the processed material 2, in order to further deaerate, deoxidize, desulfurize, stir, reduce the hydrogen and nitrogen content in the steel, and uniform the composition and temperature, the processed material 3 is produced.

[0025] Electric slag remelting technology (ESR): the processed material 3 is used as an electrode and is placed in a slag pool to be remelted to form a 30Cr2Ni4MoV forging raw material.

[0026] The weight components are C: 0.30-0.36%, Si: 0.15-0.35%, Mn: 0.40-0.60%, P: ≤0.012%, S: ≤0.012%, Cr: 1.4-1.8%, Mo: 0.37-0.47%, Ni: 3.3-3.6%, Al: 0.02-0.04%, V: 0.10-0.14%. The remaining Fe and other residual elements are used as the raw material to enter the preheated forging furnace and heated to 800-1220°C, and then the forging is started.

[0027] b. The forging process: the initial forging temperature is 1100-1180°C, and the final forging temperature is 850-950°C. In the initial forging process, the upsetting and square bar drawing are performed, and then the blank is air-cooled to 800°C and returned to the furnace. The upsetting and square bar drawing are performed at 1050±10°C for 3h, the rolling and the material division are performed at 1000±10°C for 0.5-1h, the two ends need to be concave as much as possible, the upsetting and rolling are performed at 1000±10°C, and the one end is drawn out at 950±10°C, and then the straightening, shaping and forming are performed. The forging ratio is ≥4:1, and the light hitting and fast forging process is used when the temperature is close to the final forging temperature.

[0028] c. The hardenability of 30Cr2Ni4MoV is good, and through the quenching and tempering treatment and the high-temperature tempering heat treatment, the fine and uniform structure and the good comprehensive performance can be obtained.

[0029] The mechanical property indexes of the forged pieces after the heat treatment of the raw material according to the method are as follows:

[0030] Index item Design target value Index value Tensile strength Rm / MPa ≥1200 ≥1200 Yield strength Rp0.2 / MPa ≥1100 ≥1100 Elongation A / % ≥10 ≥10 Area reduction Z / % ≥30 ≥30 Impact toughness KV2 ≥25 ≥25 Hardness / HB 360-420 360-420

[0031] The above examples only exemplarily illustrate the principles and effects of the present application, and part of the applied examples, and are not used to limit the present application; it should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application.

Claims

1. A method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for an energy storage system, characterized in that... Includes the following steps: a. 30Cr2Ni4MoV steel is prepared using electric furnace smelting technology or electric arc furnace smelting technology, ladle refining furnace refining technology, vacuum degassing refining technology for molten steel, and electroslag remelting technology. The weight composition is as follows: C: 0.30-0.36%, Si: 0.15-0.35%, Mn: 0.40-0.60%, P: ≤0.012%, S: ≤0.012%, Cr: 1.4-1.8%, Mo: 0.37-0.47%, Ni: 3.3-3.6%, Al: 0.02-0.04%, V: 0.10-0.14%. The billet steel, with the remainder being Fe and other residual elements, is used as raw material and is heated to 800-1220℃ in a preheated forging furnace to begin forging. b. Forging Process: The initial forging temperature is 1100-1180℃, and the final forging temperature is 850-950℃. During the initial forging process, after upsetting and square drawing, and then upsetting and square drawing again, the material is air-cooled to 800℃ before being returned to the furnace. At a furnace temperature of 1050±10℃, the material is upsetting for 3 hours, followed by changing the jaws and anvil, lengthening, and then drawing an octagon. At a furnace temperature of 1000±10℃, the material is rounded and divided for 0.5-1 hours, with both ends concave as much as possible. At a furnace temperature of 1000±10℃, the material is upsetting again using the upper die and rounded. Finally, at a furnace temperature of 950±10℃, the rough end is drawn out, and the thin end is drawn out in stages, straightened, shaped, and formed. The forging ratio is ≥4:1, and a light-hammering, fast-forging process is used near the final forging temperature. c.30Cr2Ni4MoV has good hardenability. Only through quenching and tempering and high-temperature tempering can a fine and uniform microstructure and good comprehensive properties be obtained.

2. The preparation process according to claim 1, specifically the method is as follows: Electric furnace smelting technology (EF) or electric arc furnace smelting technology (EAF): The material to be processed is produced through a series of processes including furnace repair, charging, melting, oxidation, and reduction. Ladle refining furnace (LF) technology: For the material to be processed 1, deoxidation and desulfurization catalyst is added, and heating produces a chemical reaction to achieve desulfurization and deoxidation, thereby producing the material to be processed 2; Vacuum refining technology (VD): For the material to be processed 2, in order to further degas, deoxidize, desulfurize, and stir, reduce the hydrogen and nitrogen content in the steel, and homogenize the composition and temperature, so as to produce the material to be processed 3. Electroslag Remelting (ESR): The material to be processed, 3, is used as an electrode and placed in a slag pool for remelting to form the raw material for 30Cr2Ni4MoV forgings.

3. The method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for energy storage systems as described in claim 1, characterized in that: In step 2, after initial forging, the furnace is air-cooled to 800°C and then returned to the furnace.

4. The method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for energy storage systems as described in claim 1, characterized in that: In step 2, during the first forging stage at 1000±10℃, flat ends are not allowed; the rounded ends must be used to avoid stress concentration.

5. The method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for energy storage systems as described in claim 1, characterized in that: In step 2, during the second forging stage at 1000±10℃, the material should be roughened and rolled in stages, and rolled along with the mold. Pay attention to clearing the corners, and after demolding, draw the small round piece according to the dimensions.

6. The method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for energy storage systems as described in claim 1, characterized in that: In step 3, the tempering treatment involves heating the forging to 860±10℃ at an average rate of ≤200℃ / h when the temperature is ≤200℃, holding it at that temperature for 14~14.5h, and then water cooling. Alternatively, heating the forging to 560±10℃ at an average rate of ≤60℃ / h when the temperature is ≤200℃, holding it at that temperature for 22~22.5h, and then air cooling to room temperature.

7. The method for preparing high-strength alloy steel 30Cr2Ni4MoV flywheel rotor raw material for energy storage systems as described in claim 1, characterized in that: In step 3, during high-temperature tempering, the forging is heated to 540±5℃ at an average rate of ≤100℃ / h when it is ≤200℃, held for 22~22.5h, and then air-cooled.