Method for forging Cr-Mn-N non-magnetic steel step shaft through radial forging machine

Abstract

The invention relates to the technical field of metal material forging, in particular to a method for forging a Cr-Mn-N non-magnetic steel step shaft through a radial forging machine, develops a non-magnetic steel step shaft product through the forging technology of a hot forging and warm forging mode, a water cooling mode and operation vehicle positioning of small-specification Cr-Mn-N non-magnetic steel, solves the problem that the radial forging machine cannot directly cog and form the non-magnetic steel step shaft, and improves the yield of the non-magnetic steel step shaft. And the high-quality, efficient and stable supply requirements of the variety are met.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material forging, in particular to a method for forging a Cr-Mn-N non-magnetic steel stepped shaft with a radial forging machine. Background Art

[0002] Cr-Mn-N non-magnetic steel is a high-strength austenitic steel with excellent low magnetic permeability, high mechanical strength, excellent pitting resistance, good intergranular corrosion resistance, and excellent wear resistance. It is widely used in the manufacture of non-magnetic components in industries such as petroleum and coal mining. However, due to its high manganese and nitrogen content, this material has poor thermoplasticity and high hot strength. This makes it prone to surface spiral defects and excessive forging forces during forging, seriously affecting product quality and production efficiency.

[0003] The production process for TISCO's Cr-Mn-N non-magnetic steel stepped shafts is as follows: electroslag ingots → heating → forging on an 1800-ton radial forging machine → remelting for holding → hot and warm forging to form the finished product. 710 round electroslag ingots are conventionally used, and the finished product diameters range from φ170 to φ350mm. All non-magnetic steel stepped shafts for centralizers are non-magnetic. Controlling the length of each step during the forging process and precisely controlling each step during warm forging present challenges, especially when the equipment cannot automatically execute the program. Therefore, the production of non-magnetic steel stepped shafts for centralizers consists of three main steps: cutting and sizing, hot forging the steps, and warm forging the steps. Leveraging existing equipment with innovative forging methods, the resulting product boasts high strength, a smooth surface, and excellent straightness.

[0004] The purpose of this invention is to study the hot forging process and warm forging process of the non-magnetic steel step shaft forging link for the centralizer, accurately control the length and size of the forging step, and use the radial forging machine to independently complete the proprietary production technology of the non-magnetic steel blanking and finished product for the centralizer. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems and provide a method for forging a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine.

[0006] The object of the present invention is achieved as follows: A method for forging a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine, comprising the following steps: Step 1: Raw material preparation: Select a Cr-Mn-N non-magnetic steel electroslag ingot that meets the standard, whose nitrogen content is 5500-6000ppm and the ingot diameter is 700-720mm; Step 2: Heating treatment: Heat the electroslag ingot to 1200-1250°C, and the holding temperature is 2000-2500°C. The holding temperature increases with the increase of the diameter of the electroslag ingot, and the holding time is 4-7 hours; Step 3: Forging blanking: Use a radial forging machine to open the blank, and the diameter of the intermediate blank is controlled at 350-380mm; Step 4: Intermediate blank processing: Forge the electroslag ingot into an intermediate blank. After the blank is formed, it is divided into blocks according to the size requirements of the finished product on a hot saw machine. After dividing, it is kept warm at 1150-1200℃ for 2-3 hours; Step 5: Hot forging of the step shaft: hot forging is carried out with a 30-50mm reduction. According to the diameter and length of the finished product, the feed length of the intermediate blank is calculated, and the feed speed of the intermediate blank is controlled at 2-3m / min; Step 6: Hot and warm forging of the step shaft: after the step shaft is hot forged, it is water-cooled online for 30-50S, the forging temperature is controlled to 600-750℃, and a reduction of 12-15mm is used for forging. The entire shaft is warm forged to the finished product size in one go; Step 7: Cooling and subsequent processing: after forging is completed, it is water-cooled online for 5-10 minutes and then air-cooled to room temperature.

[0007] The chemical composition and mass percentage of the Cr-Mn-N non-magnetic steel electroslag ingot that meets the standards in step 1 are: C≤0.05%, Si≤1.2%, Mn: 17-23%, P≤0.05%, S≤0.02%, Cr: 16-19%, Ni: 0.6-1%, Mo: 0.5-1%, Cu: 0.6-0.8%.

[0008] The formula for calculating the feed length of the intermediate billet in step 5 is as follows: L1=(R2*R2) / (R1*R1)*L2, L1 is the feed length of the intermediate billet, mm; R1 is the diameter of the intermediate billet, mm; L2 is the length of the finished product, mm; R2 is the diameter of the finished product, mm.

[0009] The beneficial effects of the present invention are: 1. The independent forging of a single device from blanking to finished product of the Cr-Mn-N non-magnetic steel stepped shaft diameter forging machine is completed, achieving a breakthrough in the market share of non-magnetic steel for stabilizers; 2. Improving production efficiency: The optimized process flow realizes high-quality, efficient and stable production. 3. According to the yield rate of finished products, inspection results and user evaluation of the products, the production plan is further optimized to form a mature and stable production process. 4. Through the improvement of production plans and on-site management, the machine-hour output of non-magnetic steel for stabilizers is further improved, and various indicators such as surface quality, non-destructive testing, performance, and straightness are fully controlled by the process. 5. The development of Cr-Mn-N non-magnetic steel stepped shafts has achieved the goal of increasing profits by 2,000 yuan / ton per ton of steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0011] The present invention adopts hot forging into step shafts, online water cooling, warm forging step forming and other technologies to realize the independent forging of non-magnetic steel step shafts by radial forging machines, and has three main innovations: 1. It breaks the forging mode of fast forging + radial forging of non-magnetic steel step shafts, and adopts the forging mode of independent blanking + forming of materials by radial forging machines, which greatly improves the machine hourly output and the surface quality after forging; 2. The radial forging machine is manually operated, and the position of the operating vehicle is combined with the deformation amount to control the length of each step of the forging, so that the length of the forging can be controlled in the manual state of radial forging; 3. The warm forging technology with rapid online water cooling is adopted to solve the problem of high forging force and large impact on equipment in warm forging of non-magnetic steel step shafts.

[0012] A method for producing a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine includes the following steps: 1. Raw material preparation: Selecting standard Cr-Mn-N non-magnetic steel electroslag ingots with a nitrogen content of no less than 5500 ppm. The standard Cr-Mn-N non-magnetic steel electroslag ingot is designated TWZ-2, and its chemical composition by mass is: C ≤ 0.05%, Si ≤ 1.2%, Mn: 17-23%, P ≤ 0.05%, S ≤ 0.02%, Cr: 16-19%, Ni: 0.6-1%, Mo: 0.5-1%, and Cu: 0.6-0.8%.

[0013] 2. Heating treatment: Heat the electroslag ingot to 1200-1250℃. The holding time is determined according to the diameter of the electroslag ingot to ensure uniform temperature.

[0014] 3. Forging blanking: Use 1800-ton diameter forging machine for blanking, and the diameter of the intermediate blank is controlled at 350-380mm.

[0015] 4. Intermediate billet processing: After forging, the intermediate billet is divided into blocks according to the finished product size requirements, and then kept warm at 1150-1200℃.

[0016] 5. Hot forging of stepped shafts: Use a 30-50mm reduction for hot forging. Calculate the intermediate billet feed length based on the post-forging compression ratio of the intermediate billet, depending on the diameter and length of the finished product. Control the intermediate billet feed speed at 2-3m / min. The calculation formula is as follows: L1 = (R2*R2) / (R1*R1)*L2, where L1 is the intermediate billet feed length, mm; R1 is the intermediate billet diameter, mm; L2 is the finished product length, mm; and R2 is the finished product diameter, mm.

[0017] 6. Hot forging of stepped shaft: After hot forging, water cool for 30-50S, control the forging temperature to 600-750℃, use 12-15mm pressure reduction for forging, and warm forge the entire shaft to the finished product size in one step.

[0018] 7. Cooling and subsequent treatment: After forging, use online water cooling for 10 minutes and then air cooling to room temperature to ensure material performance. Example 1

[0019] This method is implemented in an 1800-ton radial forging machine to forge TWZ-2 non-magnetic steel stepped shaft. The diameter of the electroslag ingot used is ￠710, the electroslag ingot is cut to ￠380, and the finished forging specification is ￠200*L+￠320*L+￠200*L. The specific implementation process steps are as follows: 1. The electroslag ingot is heated in a chamber furnace at a heating temperature of 1240℃ and kept warm for 5 hours to forge the electroslag ingot into a round billet with a diameter of 380mm.

[0020] 2. Cut the intermediate billet into pieces with hot saw and return to the furnace. Heat the furnace to 1200℃ and keep it warm for 2 hours.

[0021] 3. Cart A grips the north end of the forged material and begins forging. When the material enters the hammer, the forging begins (the material ends and the hammer end cross-section are aligned). The forging dimension is R1. Cart A advances 700mm and records Cart A's position, L1. It then draws and forges to R2. Cart A then advances to L1 and, after idling, travels 1300mm north. The hammer performs R1 forging. Cart A then advances 750mm north and records L2. Cart A then forges southward to R2. Cart A then advances to L2 and repeats the steps in parentheses. This process records four positions, L1-L4.

[0022] 4. Use clamps to lift and water-cool for 30 seconds. After cooling, load the material from the north side and perform two passes of warm forging (12 + 5mm) on the south end. Observe the conditions below and the forging force to confirm whether the transition point has been reached. Then, based on the distance left for the large-size section of turn A (1300mm) and the position of turn B, perform warm forging. After warm forging the small-size section, warm forge the large-size section of the entire section. After warm forging, cool the section in water for 10 minutes. After cooling, measure the entire section and adjust its length.

[0023] 5. After online water cooling, place on cooling bed and air cool to room temperature.

[0024] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by any technician in this field within the scope of the present invention are included in the patent scope of the present invention.

Claims

1. A method for forging a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine, characterized in that: The following steps are involved: Step 1: Raw material preparation: Select standard Cr-Mn-N non-magnetic steel electroslag ingots with a nitrogen content of 5500-6000ppm and an ingot diameter of 700-720mm; Step 2: Heating treatment: Heat the electroslag ingot to 1200-1250℃, and keep it at 2000-2500℃. The holding temperature increases with the diameter of the electroslag ingot, and the holding time is 4-7 hours. Step 3: Forging: Use a radial forging machine to forge the blank, and the diameter of the intermediate blank is controlled at 350-380mm; Step 4: Intermediate billet processing: After the electroslag ingot is forged into the intermediate billet, it is cut into pieces according to the finished product size requirements on a hot saw machine. After cutting, the pieces are kept at 1150-1200℃ for 2-3 hours; Step 5: Hot forging of stepped shaft: hot forging is performed with a reduction of 30-50mm. The feed length of the intermediate blank is calculated based on the diameter and length of the finished product. The feed speed of the intermediate blank is controlled at 2-3m / min. Step 6: Hot forging of stepped shaft: After hot forging, the stepped shaft is water-cooled online for 30-50 seconds, the forging temperature is controlled to 600-750℃, and forging is performed with a 12-15mm reduction. The entire shaft is warm forged to the finished size in one step. Step 7: Cooling and subsequent treatment: After forging is completed, use online water cooling for 5-10 minutes and then air cooling to room temperature.

2. The method for forging a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine according to claim 1, characterized in that: The chemical composition and mass percentage of the Cr-Mn-N non-magnetic steel electroslag ingot that meets the standards in step 1 are: C≤0.05%, Si≤1.2%, Mn: 17-23%, P≤0.05%, S≤0.02%, Cr: 16-19%, Ni: 0.6-1%, Mo: 0.5-1%, Cu: 0.6-0.8%.

3. The method for forging a Cr-Mn-N non-magnetic steel stepped shaft using a radial forging machine according to claim 1, characterized in that: The formula for calculating the feed length of the intermediate billet in step 5 is as follows: L1=(R2*R2) / (R1*R1)*L2, L1 is the feed length of the intermediate billet, mm; R1 is the diameter of the intermediate billet, mm; L2 is the length of the finished product, mm; R2 is the diameter of the finished product, mm.

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