Non-magnetic steel retaining ring and preparation process thereof

Abstract

The invention relates to the technical field of generator retaining ring preparation, in particular to a non-magnetic steel retaining ring and a preparation process thereof. Comprising the steps that S1, forging and pressing are conducted, specifically, a non-magnetic steel blank is heated to 1080-1150 DEG C, heat preservation is conducted for 1-2 hours, and a retaining ring blank is obtained after forging and punching; s2, ring rolling is conducted, specifically, the retaining ring blank is heated to 950-1050 DEG C for ring rolling, heat preservation is conducted for 30-50 min, and the ring rolling deformation is controlled to range from 20% to 40%; and S3, heat treatment is conducted, specifically, the retaining ring blank subjected to ring rolling is heated to 900-1100 DEG C, heat preservation is conducted for 2-4 hours, then the retaining ring blank is cooled to the room temperature, and the non-magnetic steel retaining ring is obtained. By means of the process, the mechanical property and the yield of the non-magnetic steel retaining ring can be remarkably improved, and meanwhile the defects of cracks and uneven structures are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of generator retaining ring preparation, and in particular to a non-magnetic steel retaining ring and a preparation process thereof. Background Art

[0002] As a key component that secures the end coils of a generator's rotor windings, retaining rings operate in an extremely harsh environment, exposed to strong magnetic fields and corrosive media. Under these conditions, retaining rings are prone to stress corrosion, brittle cracking, and fatigue fracture, seriously impacting the safe and stable operation of the generator.

[0003] In order to meet the requirements of the performance and service environment of the guard ring, high-strength non-magnetic steel guard rings are currently widely used. As a functional steel material, non-magnetic steel is a low-magnetic steel material that basically does not generate magnetic induction under the action of a magnetic field. Its room temperature microstructure is required to be stable austenite. Non-magnetic steel guard rings not only play an important role in the field of generators, but also have broad application prospects in aerospace, new energy vehicles and other fields. It has the characteristics of high strength, wear resistance, corrosion resistance, etc., and can effectively protect the internal weak magnetic metal materials from the influence of external magnetic fields. Among them, 50Mn18Cr5 is a typical manganese-chromium non-magnetic steel with high strength, plasticity and low magnetic permeability. It is a commonly used material for the preparation of guard rings.

[0004] However, my country faces significant challenges in the manufacturing process of retaining rings for high-power generators. Currently, the manufacturing process for retaining rings for high-power generators in my country often relies on imports, while there is a huge domestic demand for retaining rings. Traditional retaining ring production processes primarily utilize forging and hydraulic cold bulging, which are difficult to manufacture and have a low yield rate. During the forging process, multiple fires and multiple deformations are typically used, which can easily lead to coarse grains and low toughness in forgings. Furthermore, due to stress concentration, cracks are more likely to occur during the forging process, further reducing product quality and production efficiency.

[0005] In addition, some existing technologies, such as patent CN113969337B, use a solution treatment, recrystallization, forging, quenching and tempering, and low-temperature tempering to prepare the retaining ring. Although this process improves the performance of the retaining ring to a certain extent, the process has problems such as complicated procedures and low yield rate, which not only increases production costs but also reduces production efficiency.

[0006] With the continuous development of high-power generator sets, higher requirements are being placed on the performance indicators of retaining ring materials, such as strength, toughness, and magnetic properties, to ensure their safe operation. At the same time, to achieve mass production of retaining rings, it is urgent to research and develop a new retaining ring preparation process to solve the problems existing in the existing technology. Summary of the Invention

[0007] In order to solve the above technical problems existing in the prior art, the present invention provides a non-magnetic steel guard ring and a preparation process thereof.

[0008] The technical solution of the present invention to solve the above technical problems is as follows: A first aspect of the present invention is to provide a process for preparing a non-magnetic steel retaining ring, comprising the following steps: S1. Forging: Heat the non-magnetic steel blank to 1080~1150℃, keep it warm for 1~2 hours, and then forge and punch to obtain the retaining ring blank; S2. Ring rolling: heat the retaining ring blank to 950~1050℃ for ring rolling, keep it warm for 30~50 minutes, and control the ring rolling deformation to 20%~40%; S3. Heat treatment: heating the ring-rolled retaining ring blank to 900-1100° C., keeping the temperature for 2-4 hours, and then cooling it to room temperature to obtain the non-magnetic steel retaining ring.

[0009] The preparation process of the non-magnetic steel guard ring provided by the present invention adopts a ring rolling process and combines it with other processes, which can reasonably control the processing allowance and greatly improve the yield rate; at the same time, it can refine the grains, increase the grain boundary area and hinder the movement of dislocations and the expansion of cracks, and also reduce defects and unevenness in the guard ring, so that mechanical properties such as tensile strength and yield strength are significantly improved.

[0010] On the basis of the above technical solution, the present invention can also make the following improvements: Furthermore, the non-magnetic steel blank is 50Mn18Cr5.

[0011] Furthermore, in step S1, a roughening process is further performed between the forging and the punching, and a hole enlarging process is further performed after the punching, and the inner diameter of the hole after the enlarging is φ150 mm.

[0012] Furthermore, after forging, a round rod with a diameter of 110-130 mm and a height of 145-155 mm is obtained; after roughening, the diameter of the round rod is 50±5 mm.

[0013] Furthermore, in step S1, a die with a diameter of 120 mm is used for punching.

[0014] Furthermore, in step S2, the retaining ring blank is rotated and fed during the ring rolling process, and the rotation speed is controlled to be 20-50 RPM and the feed speed is controlled to be 1.0-2.0 mm / rev.

[0015] The beneficial effect of adopting the above-mentioned further technical solution is that the guard ring blank is continuously rotated and fed during rolling, which causes the grains to be broken and refined to varying degrees. When the deformation reaches a certain level, the lattice is distorted and the dislocation density increases, which causes the grains to undergo dynamic recrystallization, thereby achieving the strengthening effect of improving grain refinement and grain homogenization.

[0016] Furthermore, in step S3, water cooling is used for cooling.

[0017] Another aspect of the present invention is to provide a non-magnetic steel retaining ring, which is prepared using the above-mentioned preparation process of the non-magnetic steel retaining ring.

[0018] Compared with the prior art, the present invention has the following technical effects: The preparation process of the non-magnetic steel retaining ring provided by the present invention can significantly improve the mechanical properties and yield rate of the non-magnetic steel retaining ring, while reducing defects such as cracks and uneven structure; By adopting the ring rolling process and combining it with other processes, the processing allowance can be reasonably controlled, greatly improving the yield rate. At the same time, the hot processing method of hot ring rolling improves the structure of the retaining ring, making the grains more uniform and refining the grains. The grain boundary area is increased and the movement of dislocations and the expansion of cracks are hindered, reducing the generation of cracks and defects. It also reduces defects and unevenness in the retaining ring, resulting in a significant improvement in mechanical properties such as tensile strength and yield strength. By controlling the deformation amount of ring rolling, the strengthening effect of improving grain refinement and grain homogenization is achieved, thereby improving the mechanical properties of the retaining ring; during the ring rolling process, high temperature heating and low strain rate deformation methods are used to prepare retaining rings with refined and uniform grains; Through the solution heat treatment process, the carbides in the alloy are fully dissolved to form a uniform austenite structure, which significantly improves the strength and hardness of the non-magnetic steel retaining ring; The preparation process is simplified, and the cerclage improves the outer dimensions and uniformity of the retaining ring, which not only reduces the processing allowance but also improves the yield rate. The preparation difficulty is low and it is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart showing a process for preparing a non-magnetic steel guard ring according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] The following is an explanation of the embodiments of the present invention by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will contain many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0021] Example 1 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 20%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 900°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0022] Example 2 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 30%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 900°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0023] Example 3 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 40%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 900°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0024] Example 4 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 20%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 1000°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0025] Example 5 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 30%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 1000°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0026] Example 6 The preparation process of the non-magnetic steel guard ring includes the following steps: S1. Forging: Heat the non-magnetic steel billet 50Mn18Cr5 to 1100℃, keep it warm for 1 hour, and forge it into a round bar of φ120*150mm. Then upset it to 50±5mm, punch it with a φ120mm die, and finally expand it with a horse bar. After expansion, the inner diameter of the hole is φ150mm, and the retaining ring blank is obtained. S2, Ring rolling: Heat the retaining ring blank to 1050℃, keep it warm for 30 minutes, and control the ring rolling deformation to 40%; S3. Solution heat treatment: heat the non-magnetic steel guard ring blank to 1000°C, keep it warm for 2 hours, and then water-cool it to obtain the non-magnetic steel guard ring.

[0027] The performance data of the non-magnetic steel guard rings prepared in various embodiments are shown in Table 1.

[0028] Table 1 Performance data of non-magnetic steel guard rings prepared in various embodiments

[0029] According to the JB / T 1268-2002 standard, the retaining ring prepared at a solution temperature of 1000°C and a deformation of 30% meets the strength level of Grade I forgings.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A preparation process of a non-magnetic steel guard ring, characterized in that: The following steps are involved: S1. Forging: Heat the non-magnetic steel blank to 1080~1150℃, keep it warm for 1~2 hours, and then forge and punch to obtain the retaining ring blank; S2. Ring rolling: heat the retaining ring blank to 950~1050℃ for ring rolling, keep it warm for 30~50 minutes, and control the ring rolling deformation to 20%~40%; S3. Heat treatment: heating the ring-rolled retaining ring blank to 900-1100° C., keeping the temperature for 2-4 hours, and then cooling it to room temperature to obtain the non-magnetic steel retaining ring.

2. The preparation process of the non-magnetic steel retaining ring according to claim 1, characterized in that: The non-magnetic steel blank is 50Mn18Cr5.

3. The preparation process of the non-magnetic steel retaining ring according to claim 1 or 2, characterized in that: In step S1, a roughening process is further performed between the forging and the punching, and a hole enlarging process is further performed after the punching.

4. The preparation process of the non-magnetic steel retaining ring according to claim 3, characterized in that: After forging, a round rod with a diameter of 110-130 mm and a height of 145-155 mm is obtained; after roughening, the height of the round rod is 50±5 mm.

5. The preparation process of the non-magnetic steel retaining ring according to claim 1 or 2, characterized in that: In step S1, a die with a diameter of 120 mm is used for punching.

6. The process for preparing the non-magnetic steel retaining ring according to claim 1 or 2, characterized in that: In step S2, the retaining ring blank is rotated and fed during the ring rolling process, and the rotation speed is controlled to be 20-50 RPM and the feed speed is controlled to be 1.0-2.0 mm / rev.

7. The process for preparing the non-magnetic steel retaining ring according to claim 1 or 2, characterized in that: In step S3, cooling is performed by water cooling.

8. A non-magnetic steel guard ring, characterized in that: The non-magnetic steel guard ring is prepared using the preparation process of any one of claims 1 to 7.

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