A 120Mn13 high manganese steel square steel forging method

Abstract

The application provides a 120Mn13 high manganese steel square steel forge piece forging method, controls deformation temperature and deformation amount to expand a plastic deformation temperature range of the 120Mn13 high manganese steel square steel forge piece, reduces an edge crack tendency of the forge piece, improves surface quality, refines austenite grains, realizes a 120Mn13 high manganese steel square steel forge piece forging forming process, and comprises the following steps: 1) heating; 2) radial forging of round steel; 3) reheating; 4) radial forging of square steel; and 5) air cooling after forging. The method is simple and convenient to operate, does not need to add forging equipment, solves the problem that 120Mn13 high manganese steel cannot be forged due to poor hot workability, widens the content range of raw materials and the deformation temperature range of forging, reduces smelting difficulty and production cost of the raw materials, solves the internal porosity problem of the cast 120Mn13 high manganese steel, improves the metal compactness of the steel, improves the organization form, refines the austenite grains, improves the mechanical properties of the forge piece, shortens the production cycle, and improves the production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic forming technology, specifically relating to a forging method for 120Mn13 high manganese steel square steel forgings. Background Technology

[0002] 120Mn13 high manganese steel, with its excellent wear resistance, high toughness, and non-magnetic properties, is widely used in various fields such as mining, building materials, coal, metallurgy, power, chemical industry, agricultural machinery, and military industry. However, due to the difficulty in forging 120Mn13 high manganese steel, it has long been mainly used in cast form, and forged high manganese steel has not achieved widespread application. Various casting defects are unavoidable in the casting process of 120Mn13 high manganese steel, such as porosity, shrinkage cavities, microcracks, coarse grains, and compositional segregation. These defects lead to premature failures such as cracking, collapse, and spalling during use, reducing its service life.

[0003] Studies have shown that forging 120Mn13 high-manganese steel can not only reduce the inhomogeneity of its cast metal structure and defects such as weld porosity and looseness, but also significantly increase the density, hardness, plasticity, and impact toughness of the metal after forging. Due to the difficulty of forging 120Mn13 high-manganese steel, its production has long been dominated by casting, and forged high-manganese steel has remained in the research and experimental stage, without widespread application. Some literature suggests that forging high-manganese steel can be achieved by controlling the phosphorus and sulfur content (wt%) in the steel to below 0.01% and the forging temperature range of 900℃ to 1180℃.

[0004] The shortcomings of the above-mentioned precautions are as follows: Controlling the phosphorus and sulfur content (wt%) in 120Mn13 high-manganese steel to below 0.01% places extremely stringent requirements on the raw materials and smelting process, making it difficult to achieve in mass industrial production and resulting in high smelting costs. Furthermore, the forging temperature range proposed by this method is narrow, making temperature control during forging difficult, especially for 120Mn13 high-manganese steel square forgings. During forging, the edges of the square steel cool down rapidly, significantly reducing plasticity and making them highly susceptible to cracking, thus preventing further forging. Repeated reheating in the furnace leads to grain growth and coarse microstructure within the forging, increasing production costs and extending the production cycle. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned methods and provide a forging method for 120Mn13 high-manganese steel square steel forgings by using a radial forging machine to expand the plastic deformation temperature range of 120Mn13 high-manganese steel square steel forgings by changing the material deformation mode, controlling the deformation temperature and deformation amount, reducing the tendency of forging edge cracks, improving surface quality, refining austenite grains, and realizing the forging process of 120Mn13 high-manganese steel square steel forgings.

[0006] The technical solution of this invention is implemented as follows:

[0007] A forging method for 120Mn13 high manganese steel square forgings includes the following steps:

[0008] Step 1) Heating: During forging production, the billet is loaded into the heating furnace and preheated at 300℃~450℃ for 2h~4h. Then, the furnace temperature is raised to 1050±50℃ at a heating rate of ≤100℃ / h and heated for 3h~5h. After that, the temperature is continuously raised to 1210±30℃ at the maximum heating rate of the heating furnace equipment and held for 0.5h~1h to make the billet reach the plastic deformation temperature.

[0009] Step 2) Radial Forging of Round Steel: After exiting the furnace, the billet is quickly transferred to the radial forging machine. The A-side control mechanism of the radial forging machine holds the billet and moves it towards the radial forging machine during circumferential rotation, pushing the billet to the center of the hammer head of the radial forging machine. The radial forging machine uses round steel hammer heads, and each hammer head starts forging simultaneously according to the set hammer weight. When the length of the billet after forging is sufficient to be held by the B-side control mechanism, the B-side control mechanism holds the billet and begins to pull and forge it during circumferential rotation. The forging frequency is controlled between 90 times / min and 240 times / min. During the forging process, the A-side control mechanism and the B-side control mechanism repeatedly exchange pull and forge, repeatedly pulling and forging the billet along the axial direction to lengthen it to the process size, thus completing the round steel forging.

[0010] Step 3) Reheating: The forged round steel is reheated in the furnace. The furnace temperature is reduced to 1000℃~1100℃ and held for 2h~3h.

[0011] Step 4) Radial Forging of Square Steel: After the forged round steel is heated twice and kept warm, it is taken out of the furnace and transferred to the radial forging machine. The A-side control mechanism of the radial forging machine holds the billet and keeps it stationary in the circumference without rotating. It moves towards the radial forging machine and pushes the billet to the center of the hammer head of the radial forging machine. The radial forging machine uses square hammer heads. The hammer heads of opposite groups start forging simultaneously according to the set hammer weight. When the length of the billet after forging is sufficient to be held by the B-side control mechanism, the B-side control mechanism holds the billet and pulls it while keeping it stationary in the circumference without rotating. The forging frequency is controlled at 90 times / min to 240 times / min. The action of Step 4) is repeated for each pass. The forming process is completed entirely by pulling and pulling with the B-side control mechanism. Before the last pass, a forging allowance of 2mm to 6mm is reserved in the width and thickness directions of the 120Mn13 high manganese steel square steel forging. The surface is finished in the last pass. The billet is pulled and pulled repeatedly along the axial direction on one side to be forged and lengthened to the finished size of the forging, thus completing the forging of the square steel forging.

[0012] Step 5) Air cooling after forging: After forging, the forging is air cooled to room temperature to complete the forging process of 120Mn13 high manganese steel square steel forging.

[0013] The billet for the 120Mn13 high manganese steel square forging is a die-cast round steel ingot, a die-cast octagonal steel ingot, an electroslag round ingot, or a continuously cast round billet.

[0014] The chemical composition (wt%) of the 120Mn13 high manganese steel square forging is as follows: C: 0.90%~1.30%, Si: 0.30%~1.00%, Mn: 11.00%~14.00%, P≤0.060%, S≤0.040%, with the balance being Fe and other unavoidable impurities.

[0015] The thickness of the 120Mn13 high manganese steel square forging ranges from 70mm to 250mm, the width ranges from 120mm to 350mm, and the length ranges from 2000mm to 15000mm.

[0016] The radial forging machine includes two control mechanisms and one forging box. Four forging hammers are installed in the forging box on the same vertical plane and are evenly distributed at 90° intervals.

[0017] The radial forging machine has a total of 4 round steel hammers, each with the same shape and structure. When forging round steel, all 4 hammers are adjusted simultaneously, and each hammer has the same hammering amount.

[0018] The radial forging machine has four square hammers in total, with two different shapes. Two hammers arranged opposite each other form a group, and their structures and shapes are identical. The forging working part of the first group of hammers is at the center of the hammer, while the forging working part of the second group of hammers is on both sides of the hammer. During forging, the hammer depth of the two groups is adjusted according to the deformation requirements, and the hammer depth of the two opposite hammers in each group is the same.

[0019] The positive effects of the technical solution of the present invention are as follows: The method of the present invention is simple and easy to operate. It adopts a radial forging machine to change the previous method of directly forging square parts to a deformation method of first forging into round steel forgings and then forging into square steel forgings. The hammering amount and pulling speed of the radial forging machine realize the forging and forming of 120Mn13 high manganese steel square steel forgings. The method of this invention for forging 120Mn13 high manganese steel square forgings can broaden the range of phosphorus content (wt%) in the raw materials to ≤0.060% and sulfur content (wt%) to ≤0.040%, and broaden the deformation temperature range of the forging process to 780℃~1240℃. This reduces the difficulty of raw material smelting and production costs, and solves the problems of poor hot workability, severe surface cracks, and inability to forge 120Mn13 high manganese steel. It also solves the problem of internal porosity in cast 120Mn13 high manganese steel, improves the internal metal density of the steel, improves the microstructure, refines the austenite grains, improves the mechanical properties of 120Mn13 high manganese steel square forgings, improves product quality, shortens the production cycle, and improves production efficiency. Detailed Implementation

[0020] The technical solution of the present invention is described below with specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0021] Example 1: The chemical composition (wt%) of the 120Mn13 high-manganese steel square forging in Example 1 is: C: 1.12%, Si: 0.60%, Mn: 13.38%, P: 0.045%, S: 0.028%, with the balance being Fe and other unavoidable impurities; the product specifications are 130mm × 200mm × 6000mm. The forging process is as follows:

[0022] Step 1) During forging production, the billet is loaded into the heating furnace and preheated at 400℃±10℃ for 3 hours. Then, the furnace temperature is raised to 1040±10℃ at a heating rate of 90℃ / h and heated for 5 hours. After that, the temperature is continuously raised to 1200±10℃ at the maximum heating rate of the heating furnace equipment. After holding at this temperature for 1 hour, the billet is taken out of the furnace for forging.

[0023] Step 2) After exiting the furnace, the billet is quickly transferred to the radial forging machine using a crane. The A-side manipulator of the radial forging machine holds the billet and moves it towards the radial forging machine while rotating circumferentially, pushing the billet to the center of the hammer head. The radial forging machine uses round steel hammer heads, and each hammer head starts forging simultaneously according to the set hammer weight. When the length of the billet reaches 2000mm after forging, the B-side manipulator holds the billet and begins pull forging while rotating circumferentially. The forging frequency is set to 180 times / min. During the forging process, the A-side manipulator and the B-side manipulator are repeatedly switched 3 times to perform pull forging, repeatedly pulling and forging the billet along the axial direction to lengthen it to a diameter of Φ250mm, completing the round steel forging.

[0024] Step 3) The forged round steel is returned to the furnace for secondary heating. The furnace temperature is reduced to 1100℃ and held for 3 hours.

[0025] Step 4) After the forged round steel is heated twice and kept warm, it is taken out of the furnace and transferred to the radial forging machine. The A-side control mechanism of the radial forging machine holds the billet and keeps it stationary in the circumference without rotating. It moves towards the radial forging machine and pushes the billet to the center of the radial forging machine hammer. The radial forging machine uses square hammers. The opposite set of hammers start forging at the same time according to the set hammer amount. When the length of the billet reaches 1800mm after forging, the B-side control mechanism holds the billet and pulls it while keeping it stationary in the circumference without rotating. The forging frequency is controlled at 180 times / min. The B-side manipulator repeatedly pulls and forges three times, ensuring that the entire forming process is completed using the B-side manipulator pull method. Before the last pass, a forging allowance of 3mm and 5mm is reserved in the width and thickness directions of the 120Mn13 high manganese steel square steel forging, respectively. The last pass is controlled at 240 times / min for surface finishing. The billet is drawn along the axial direction by the B-side manipulator single-side pull forging to the finished size of the forging, thus completing the forging of the square steel forging.

[0026] Step 5) After forging, the forging is air-cooled to room temperature to complete the forging process of 120Mn13 high manganese steel square steel forging.

[0027] The above method enabled the production of 120Mn13 high-manganese steel square forgings with high phosphorus and sulfur content, as described in Example 1. The actual forging temperature range in Example 1 was 780℃~1200℃, and the forging process was completed in two passes. Post-forging testing showed uniform internal structure with a grain size of grade 7. The mechanical property test results were: Rp0.2=532MPa, Rm=1050MPa, A=53%, Z=43%, KU2=235J. This method not only reduces the difficulty of smelting and producing 120Mn13 high-manganese steel square forgings but also expands the forging temperature range, enabling two-pass forging. Furthermore, the post-forging material exhibits uniform structure, refined grain size, and significantly improved mechanical properties compared to cast 120Mn13 high-manganese steel, ultimately extending the product's service life.

Claims

1. A forging method for 120Mn13 high-manganese steel square forgings, characterized in that, Includes the following steps: Step 1) Heating: During forging production, the billet is loaded into the heating furnace and preheated at 300℃~450℃ for 2h~4h. Then, the furnace temperature is raised to 1050±50℃ at a heating rate of ≤100℃ / h and heated for 3h~5h. After that, the temperature is continuously raised to 1210±30℃ at the maximum heating rate of the heating furnace equipment and held for 0.5h~1h to make the billet reach the plastic deformation temperature. Step 2) Radial Forging of Round Steel: After exiting the furnace, the billet is quickly transferred to the radial forging machine. The A-side control mechanism of the radial forging machine holds the billet and moves it towards the radial forging machine during circumferential rotation, pushing the billet to the center of the hammer head of the radial forging machine. The radial forging machine uses round steel hammer heads, and each hammer head starts forging simultaneously according to the set hammer weight. When the length of the billet after forging is sufficient to be held by the B-side control mechanism, the B-side control mechanism holds the billet and begins to pull and forge it during circumferential rotation. The forging frequency is controlled between 90 times / min and 240 times / min. During the forging process, the A-side control mechanism and the B-side control mechanism repeatedly exchange pull and forge, repeatedly pulling and forging the billet along the axial direction to lengthen it to the process size, thus completing the round steel forging. Step 3) Reheating: The forged round steel is reheated in the furnace. The furnace temperature is reduced to 1000℃~1100℃ and held for 2h~3h. Step 4) Radial Forging of Square Steel: After the forged round steel is heated twice and kept warm, it is taken out of the furnace and transferred to the radial forging machine. The A-side control mechanism of the radial forging machine holds the billet and keeps it stationary in the circumferential direction without rotating. It moves towards the radial forging machine and pushes the billet to the center of the hammer head of the radial forging machine. The radial forging machine uses square hammer heads. The hammer heads of opposite groups start forging simultaneously according to the set hammer weight. When the length of the billet after forging is sufficient to be held by the B-side control mechanism, the B-side control mechanism holds the billet and pulls it while keeping it stationary in the circumferential direction without rotating. The forging frequency is controlled at 90 times / min to 240 times / min. The action of Step 4) is repeated for each pass. The forming process is completed entirely by pulling and pulling with the B-side control mechanism. Before the last pass, a forging allowance of 2mm to 6mm is reserved in both the width and thickness directions of the 120Mn13 high manganese steel square steel forging. The surface is finished in the last pass. The billet is pulled and pulled repeatedly along the axial direction on one side to be forged and lengthened to the finished size of the forging, thus completing the forging of the square steel forging. Step 5) Air cooling after forging: After forging, the forging is air cooled to room temperature to complete the forging process of 120Mn13 high manganese steel square steel forging.

2. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The billet for the 120Mn13 high manganese steel square forging is a die-cast round steel ingot, a die-cast octagonal steel ingot, an electroslag round ingot, or a continuously cast round billet.

3. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The chemical composition (wt%) of the 120Mn13 high manganese steel square forging is as follows: C: 0.90%~1.30%, Si: 0.30%~1.00%, Mn: 11.00%~14.00%, P≤0.060%, S≤0.040%, with the balance being Fe and other unavoidable impurities.

4. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The thickness of the 120Mn13 high manganese steel square forging ranges from 70mm to 250mm, the width ranges from 120mm to 350mm, and the length ranges from 2000mm to 15000mm.

5. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The radial forging machine includes two control mechanisms and one forging box. Four forging hammers are installed in the forging box on the same vertical plane and are evenly distributed at 90° intervals.

6. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The radial forging machine has a total of 4 round steel hammers, each with the same shape and structure. When forging round steel, all 4 hammers are adjusted simultaneously, and each hammer has the same hammering amount.

7. The forging method for a 120Mn13 high-manganese steel square forging according to claim 1, characterized in that, The radial forging machine has a total of 4 square hammers, with two different shapes and structures. Two hammers that are opposite each other form a group, and their structures and shapes are the same. The forging working part of the first group of hammers is in the center of the hammer, and the forging working part of the second group of hammers is on both sides of the hammer. During forging, the hammering amount of the two groups of hammers is adjusted according to the deformation requirements, and the hammering amount of the two opposite hammers in each group is the same.