Ti-containing high-carbon high-chromium high-density grinding ball hot-rolled round steel and production process thereof

Abstract

The invention belongs to the field of material smelting, and relates to Ti-containing high-carbon high-chromium high-density grinding ball hot-rolled round steel and a production process thereof. The round steel comprises the following components: 1.0 to 1.10 percent of C, 0.15 to 0.40 percent of Si, 0.20 to 0.40 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.030 percent of S, 2.0 to 2.20 percent of Cr, 0.015 to 0.020 percent of Cu, 0.015 to 0.020 percent of Mo, 0.002 to 0.004 percent of Nb, less than or equal to 0.030 percent of V, 0.015 to 0.035 percent of Al, less than or equal to 0.25 percent of Ni, 0.010 to 0.025 percent of Ti, less than or equal to 1.5 ppm of H, less than or equal to 25 ppm of O, 0.005 to 0.010 percent of N and the balance of Fe and inevitable impurities. The components and the process are optimized, so that the round steel has excellent wear resistance and impact toughness, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the field of material smelting, and particularly relates to a hot-rolled round steel for grinding balls with high carbon, high chromium, high titanium and high density and its production process. Background Art

[0002] The main application scenarios of grinding ball steel include industries such as metallurgy, mining, building materials and electric power. Specifically, grinding ball steel can be used to manufacture the main vulnerable parts of the equipment required by these industries. The main properties required for grinding ball steel include high strength, high hardness, high wear resistance, good corrosion resistance and appropriate toughness. Due to the relatively harsh use environment of grinding ball steel, its service life usually does not exceed 8000 hours. The failure modes mainly include diameter reduction, cracking and other modes. To maintain the long life of grinding balls, the grinding balls need to have good wear resistance and excellent impact toughness. However, it is difficult for current steel grades to have both excellent wear resistance and impact toughness at the same time. Therefore, preparing steel with both excellent wear resistance and impact toughness has become a technical problem that urgently needs to be solved in this field.

[0003] In summary, designing a steel with excellent properties such as wear resistance and impact toughness has become a key problem that urgently needs to be solved in the steel industry of our country. Summary of the Invention

[0004] The purpose of the present invention is to overcome the technical defects existing in the prior art. Aiming at the technical problem that it is difficult for current steel grades to have both excellent wear resistance and impact toughness at the same time, the present invention provides a hot-rolled round steel for grinding balls with high carbon, high chromium, high titanium and high density and its production process. Through the effective combination of composition and process control, specifically through the setting of electric furnace, LF refining, VD and continuous casting parameters, a complete production process of hot-rolled round steel for grinding balls with high carbon, high chromium, high titanium and high density is formed, and a steel with excellent properties such as wear resistance and impact toughness is obtained.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions; First, a hot-rolled round steel for grinding balls with high carbon, high chromium, high titanium and high density is provided, which is composed of the following components by mass percentage: C: 1.0 - 1.10%, Si: 0.15 - 0.40%, Mn: 0.20 - 0.40%, P ≤ 0.020%, S: ≤ 0.030%, Cr: 2.0 - 2.20%, Cu: 0.015 - 0.020%, Mo: 0.015 - 0.020%, Nb: 0.002 - 0.004%, V: ≤ 0.030%, Al: 0.015 - 0.035%, Ni: ≤ 0.25%, Ti: 0.010 - 0.025%, H: ≤ 1.5 ppm, O: ≤ 25 ppm, N: 0.005 - 0.010%, and the balance is Fe and unavoidable impurities.

[0006] The hardness of the round steel is ≥62HRC, the impact performance is ≥8 J, the precipitation size of TiN is within 10 μm, and the standard requirement for sulfide inclusions is ≤0.5 grade.

[0007] Composition design: Aiming at the technical problem that it is difficult for the current steel grades to have excellent wear resistance and excellent impact toughness at the same time, the present invention first optimizes the alloy design composition, and the specific description is as follows: C: It can increase the pearlite ratio, strength and hardness, but too high content will reduce plasticity and toughness, and too low content of C will affect the strength of the hot-rolled round steel. Therefore, the content of C in the present invention is controlled at 1.0 - 1.10%.

[0008] Cr: A carbide-forming element, which increases the material hardness and prevents grain growth, but Cr should not be added too high, otherwise it will lead to a decrease in plastic toughness. Therefore, the content of Cr in the present invention is controlled at 2.0 - 2.20%.

[0009] Ti: It has the function of refining austenite grains, strong solid solution strengthening effect, improves tempering stability, and has a secondary hardening effect. The formation of dispersed TiN precipitates helps to improve the wear resistance of grinding balls. If it is too high, the precipitates will coarsen and reduce the fatigue life of grinding balls. Therefore, the content of Ti in the present invention is controlled at 0.010 - 0.025%.

[0010] Al: It has the function of refining austenite grains, strong solid solution strengthening effect, improves impact toughness. When combined with chromium and silicon, it can significantly improve the high-temperature scale resistance and high-temperature corrosion resistance of steel. AlN precipitates help to improve the wear resistance of grinding balls. If it is too high, the precipitates will coarsen and reduce the fatigue life of grinding balls. Therefore, the content of Al in the present invention is controlled at 0.015 - 0.035%.

[0011] The present invention also provides a method for hot-rolling round steel of high-carbon, high-chromium, high-density grinding balls containing Ti: The method includes the following steps: Electric furnace steelmaking → LF refining → VD vacuum treatment → continuous casting (φ500) → hot charging → heating → rolling, pit cooling → finishing, inspection, warehousing; For the production method of the grinding ball steel, the steelmaking raw materials are successively subjected to electric furnace steelmaking, LF refining, VD vacuum treatment, and continuous casting processes to obtain continuous casting round billets, and then the continuous casting round billets are subjected to hot rolling and pit cooling processes to obtain hot-rolled round steel.

[0012] The process requirements are as follows: (1) The specific process requirements for the electric furnace steelmaking stage are: Process requirements: ① End point C: 0.23~0.70%; Si: 0.10~0.25%; Mn: 0.12~0.25%; Cr: 0.05~0.17%; ② Target P≤0.015%; ③Target temperature ≥1620℃; ④ Turn on the bottom blowing of argon before tapping, and blow argon throughout the tapping process (100 t of steel from an electric furnace). It is strictly forbidden to slag during tapping, and the steel should be hoisted to the LF station in time after tapping.

[0013] ⑤ Steelmaking: Add 400±30 kg of lime, 400±30 kg of cleaning agent and 100 kg of aluminum / furnace to every 100-105 t of molten steel; preliminary alloying and sufficient deoxidation are carried out in the early stage.

[0014] (2) The production method of the grinding ball steel, the process requirements of the LF refining stage: ① Feed aluminum wire according to LF refining, the target is 0.030~0.050%; ② White slag time ≥ 20min, smelting time ≥ 40min; In the early stage of refining, 0-1 kg of lime is added to each ton of molten steel for slag adjustment according to the slag condition; Fe-Si powder and Si-C slag surface diffusion deoxidation are used throughout the refining process, with an amount of 1.2-2.5 kg added per ton of molten steel, and the mass ratio of the two is 1:1; ③Introduce argon during the LF refining process to keep the argon flow unobstructed; In the early stage of refining, the argon stirring is increased and the flow rate is set to 200-400NL / min to promote deoxidation and alloying; in the middle stage of refining and alloying, the argon strength is maintained at a medium level and the flow rate is set to 120-250NL / min; in the late stage of refining, the molten steel is prevented from tumbling and oxidation, and the flow rate is set to 60-150NL / min.

[0015] (3) The production method of grinding ball steel, the VD vacuum treatment stage process requirements: ① Vacuum treatment, the highest vacuum degree is ≤67pa, the high vacuum holding time is ≥12min, and the soft blowing time is ≥15min to ensure that the inclusions float fully; ② Use bottom blowing nitrogen to increase nitrogen; after breaking the air, feed in the order of aluminum wire → titanium iron wire → silicon calcium wire, and feed the aluminum wire at one time.

[0016] ③ Feeding amount of silicon-calcium wire: 80-100 meters for the first furnace and 50-60 meters for the continuous casting furnace.

[0017] (4)Process requirements for the continuous casting stage: Control the precipitation morphology of TiN. Since Ti and N are enriched at the solidification front of the molten steel, the formation reaction of TiN inclusions can proceed. Therefore, to reduce or even eliminate the precipitation of TiN inclusions, while controlling the Ti and N contents in the steel, the molten steel must be rapidly solidified, shortening the time for the molten steel to cool from the liquidus temperature to the solidus temperature, reducing the enrichment of Ti and N at the solidification front, and minimizing the precipitation of TiN so that it precipitates in a fine and dispersed form.

[0018] The described continuous casting process (using two-stage water cooling in combination with mold electromagnetic stirring, strand stirring, and final electromagnetic stirring): ① Pour with a low superheat degree, where the superheat degree is between 18 - 30°C, and both stages of water cooling are fully opened; The flow rate parameters for the two-stage water cooling are as follows: The flow rate of the first cooling water is 4000 L / min, the flow rate in the first zone of the second cooling water is 80 L / min, the flow rate in the 2a zone of the second cooling water is 55 L / min, and the flow rate in the 2b zone of the second cooling water is 40 L / min. Increase the degree of undercooling, weaken the fractional crystallization, and reduce the enrichment of Ti and N at the solidification front; ② The current of the mold electromagnetic stirring is 300 A, the frequency is 2 Hz, the current of the strand stirring is 180 A, the frequency is 8 Hz, the current of the final electromagnetic stirring is 1100 A, the frequency is 8 Hz, and the casting speed is 0.40 m / min; Effectively control the macrostructure quality and center segregation; Control the carbon segregation index of the round steel to be less than 1.15, making the performance of the grinding balls more uniform.

[0019] (5)The described grinding ball rolling process: During the heating described, the heating temperature and heating time are as follows: The round billet is directly hot-fed into the heating furnace without slow cooling, which can prevent the round billet from being supercooled and cracking during the heating process.

[0020] The temperature in the preheating section is < 900°C, and the time is > 1 h; The temperature in the first heating section is 900 - 1100°C, and the time is ≥ 1 h; The temperature in the second heating section is 1150 - 1250°C, the soaking section temperature is 1200 - 1260°C, the time for the second heating section and the soaking section is 4.5 - 6 h, and the total heating time is > 6.5 h.

[0021] Preferably, the target temperature in the preheating section is 850°C, the target temperature in the first heating section is 950°C, the target temperature in the second heating section is 1230°C, the target temperature in the soaking section is 1240°C, and the total heating time is 7 - 13 h.

[0022] The present invention appropriately increases the time of the second heating stage and the soaking stage. On the one hand, it improves component segregation, and on the other hand, it makes the heating of the round billet more uniform. For round steel with high carbon and high chromium and poor core quality, the flaw detection level of the rolled round steel can be guaranteed. Using a φ500mm continuous casting round billet to roll φ92mm round steel, the rolling ratio reaches an astonishing 29.5, obtaining dense round steel. The flaw detection adopts the EN10308 standard to meet the level of a flat-bottomed hole smaller than φ1.6mm.

[0023] In the rolling process described above, the rolling process is as follows: The φ500 round billet becomes an intermediate billet of 175mm*200mm after passing through the blooming mill, and the head and tail are sheared hydraulically. It is rolled by a 9-stand continuous rolling mill with controlled rolling temperature, and the starting rolling temperature is 1000 - 1100°C.

[0024] Finally, the collection temperature of the first furnace is increased to ≥550°C and sent to the slow cooling pit to prevent the appearance of white spot defects due to high H in the first furnace. The temperature of other heats is reduced, and the temperature entering the slow cooling pit is 400 - 450°C; the slow cooling time is ≥24h, and the temperature leaving the pit is ≤200°C. Beneficial effects:

[0025] 1. Through component optimization, by adding components Ti and Al, the present invention effectively inhibits the growth of austenite grain size, promotes grain refinement, and improves the comprehensive performance of the material. At the same time, hard particles such as TiN, TiC, and AlN precipitated in a dispersed manner maximize the reduction of the fatigue tendency of the grinding balls while improving the wear resistance of the grinding balls, effectively extending the service life of the grinding balls.

[0026] 2. In the continuous casting stage of the present invention, the precipitation morphology of TiN is controlled; due to the enrichment of Ti and N at the solidification front of the molten steel, the formation reaction of TiN inclusions can proceed. Therefore, to reduce or even eliminate the precipitation of TiN inclusions, while controlling the content of Ti and N in the steel, the molten steel must be rapidly solidified, shortening the time for the molten steel to cool from the liquidus temperature to the solidus temperature, reducing the enrichment of Ti and N at the solidification front, and reducing the precipitation of TiN to make it precipitate in a fine and dispersed form. The present invention adopts secondary cooling and electromagnetic stirring of the mold, and controls the casting speed to effectively control the macrostructure quality and center segregation; controls the carbon segregation index of the round steel to be less than 1.15, making the performance of the grinding balls more uniform.

[0027] 3. The present invention appropriately increases the time of the second heating stage and the soaking stage. On the one hand, it improves component segregation, and on the other hand, it makes the heating of the round billet more uniform. For round steel with high carbon and high chromium and poor core quality, the flaw detection level of the rolled round steel can be guaranteed. Using a φ500mm continuous casting round billet to roll φ92mm round steel, the rolling ratio reaches an astonishing 29.5, obtaining dense round steel. The flaw detection adopts the EN10308 standard to meet the level of a flat-bottomed hole smaller than φ1.6mm.

[0028] 4. Through the effective combination of composition and process control, specifically by setting the parameters of the electric furnace, LF refining, VD, and continuous casting, a complete production process of hot-rolled round steel for high-carbon, high-chromium, high-density grinding balls containing Ti is formed, obtaining a steel with excellent properties such as wear resistance and impact toughness, with a hardness ≥ 62 HRC and an impact performance ≥ 8 AK / J; and it can effectively control non-metallic inclusions, carbon segregation, and the precipitation of TiN, where the precipitation size of TiN is within 10 μm; at the same time, the inclusions of the products in the examples are rated, and the results show that the sulfide inclusions of this steel grade meet the standard requirements of ≤ 0.5 grade, indicating that through the implementation of the process of the present invention, the inclusion level is effectively controlled, the risk of fatigue cracking of the grinding balls is reduced, and the service life of the grinding balls is extended. Description of the Drawings

[0029] Figure 1 It is a scanning electron microscope image of the steel prepared in Example 1.

[0030] Figure 2 For Figure 1 The energy spectrum diagram at the corresponding position of Spectrum 23 in

[0031] Figure 3 For Figure 1 The energy spectrum diagram at the corresponding position of Spectrum 24 in Detailed Description of the Invention

[0032] The present invention is described in detail below with reference to examples, but the present invention is not limited to these examples. Example 1:

[0033] The round steel contains the following chemical components in mass percentage (unit, wt%): C: 1.07%, Si: 0.25%, Mn: 0.28%, P: 0.009%, S: 0.003%, Cr: 2.05%, Ni: 0.11%, Cu: 0.019%, Mo: 0.018%, V: 0.01%, Nb: 0.0038%, Ti: 0.015%, Al: 0.020%, H: 1.2 ppm, O: 8.9 ppm, N: 0.0067 ppm, and the balance is Fe and unavoidable impurities.

[0034] The production process includes the following steps: electric furnace steelmaking → LF refining → VD vacuum treatment → continuous casting (φ500) → hot charging → heating → rolling → pit cooling → finishing, inspection, and warehousing to obtain φ92 mm round steel.

[0035] The specific process requirements are as follows: (1) The specific process requirements in the electric furnace steelmaking stage are: ① Endpoint C: 0.30%; Si: 0.20%; Mn: 0.22%; Cr: 0.11%; ② P ≤ 0.005%; ③The target temperature is 1620℃; ④ Turn on the bottom blowing of argon before tapping, and blow argon throughout the tapping process; the electric furnace taps 100t of steel, and slag is strictly prohibited during tapping. After tapping, it is hoisted to the LF station in time.

[0036] ⑤ Steelmaking: Add 400±30kg of lime, 400±30kg of cleaning agent and 100kg / furnace of aluminum for steelmaking to every 100-105t of molten steel; preliminary alloying and sufficient deoxidation are carried out in the early stage.

[0037] (2) Process requirements for LF refining stage: ① Feed aluminum wire according to LF refining, the target is 0.030~0.050%; ② In the early stage of refining, according to the slag condition, 0.5kg lime is added per ton of molten steel for slag adjustment, and Fe-Si powder and Si-C slag surface diffusion deoxidation are used. The amount used per ton of molten steel is 2.2kg, and the ratio of the two is 1:1. The white slag time is ≥20min, and the smelting time is ≥40min; ③ During the LF refining process, keep the argon flow unobstructed, increase the argon stirring in the early stage, set the flow rate to 300NL / min, promote deoxidation and alloying, maintain medium argon strength in the middle alloying stage, set the flow rate to 180NL / min, and avoid tumbling and oxidation of molten steel in the later stage of refining, and set the flow rate to 110NL / min.

[0038] (3) VD vacuum treatment process requirements: ① Vacuum treatment, the highest vacuum degree is 32pa, the high vacuum holding time is 15min, and the soft blowing time is 20min to ensure that the inclusions float fully; ② Use bottom blowing nitrogen to increase nitrogen; after breaking the air, feed in the order of aluminum wire → titanium iron wire → silicon calcium wire, and feed the aluminum wire at one time.

[0039] ③ Feeding amount of silicon-calcium wire: 90 meters for the first furnace and 55 meters for the continuous casting furnace.

[0040] (4) Process requirements in the continuous casting stage: Control the precipitation morphology of TiN. Due to the enrichment of Ti and N at the solidification front of the molten steel, the formation reaction of TiN inclusions can proceed. Therefore, to reduce or even eliminate the precipitation of TiN inclusions, it is necessary to control the Ti and N content in the steel while making the molten steel solidify quickly, shorten the time for the molten steel to drop from the liquidus temperature to the solidus temperature, reduce the enrichment of Ti and N at the solidification front, and reduce the precipitation of TiN so that it precipitates in a fine and dispersed form.

[0041] Continuous casting process: ①The pouring has a low superheat degree, with the superheat degree between 18 - 30°C. Both sections of water cooling are fully opened. The flow rate of the first cooling water is 4000 L / min, the flow rate in the first area of the second water cooling is 80 L / min, the flow rate in area 2a is 55 L / min, and the flow rate in area 2b is 40 L / min. Increase the undercooling degree, weaken the fractional crystallization, and reduce the enrichment of Ti and N at the solidification front. ②The current of the mold electromagnetic stirring is 300 A and the frequency is 2 Hz. The current of the casting stream stirring is 180 A and the frequency is 8 Hz. The current of the final electromagnetic stirring is 1100 A and the frequency is 8 Hz. The casting speed is 0.40 m / min, effectively controlling the macrostructure quality and central segregation; control the carbon segregation index of the round steel to be less than 1.15, making the performance of the grinding balls more uniform.

[0042] (5)The grinding ball rolling process (φ92mm): During the heating, the heating temperature and heating time are as follows: The round billet is directly hot - sent to the heating furnace without slow cooling, which can prevent the round billet from being super - cooled and cracking during the heating process.

[0043] The temperature in the pre - heating section is < 900°C, with a target of 850°C and a time > 1 h; the temperature in heating section I is 900 - 1100°C, with a target temperature of 950°C and a time ≥ 1 h; the temperature in heating section II is 1150 - 1250°C, with a target temperature of 1230°C, and the temperature in the soaking section is 1200 - 1260°C, with a target temperature of 1240°C. The time in heating section II and the soaking section is 4.5 - 6 h, and the total heating time is 7 - 13 h.

[0044] During the rolling, the rolling process is as follows: The round billet of φ500 specification becomes an intermediate billet of 175mm * 200mm after passing through the blooming mill. The head and tail are cut by hydraulic shearing, and it is rolled by a 9 - stand continuous rolling mill with controlled - rolling temperature. The starting rolling temperature is 1000 - 1100°C.

[0045] For the first furnace, increase the collection temperature ≥ 550°C and put it into the slow - cooling pit to prevent the appearance of white - point defects due to high H in the first furnace. For other furnace charges, appropriately reduce the temperature, with a target temperature of 400°C, a slow - cooling time ≥ 24 h, and the temperature out of the pit ≤ 200°C.

[0046] Figure 1 It is the scanning electron microscope image of the steel prepared in Example 1; among them Figure 2 is Figure 1 the energy - dispersive spectroscopy diagram at the corresponding position of spectrum 23 in Figure 3 is Figure 1 the energy - dispersive spectroscopy diagram at the corresponding position of spectrum 24 in (sampling and observing at the R / 2 radius position of the round steel).

[0047] Through scanning electron microscope observation and measurement, it can be known that the TiN precipitation size of the round steel product is within 10 μm. Example 2:

[0048] The φ92mm round steel is obtained through electric furnace steelmaking, LF refining, VD vacuum treatment, continuous casting, slow cooling, and rolling. It contains the following chemical components in mass percentage (unit: wt%): C: 1.05%, Si: 0.23%, Mn: 0.26%, P: 0.010%, S: 0.004%, Cr: 2.1%, Ni: 0.10%, Cu: 0.018%, Mo: 0.018%, V: 0.01%, Nb: 0.0038%, Ti: 0.016%, Al: 0.022%, H: 1.2 ppm, O: 8.9 ppm, N: 75 ppm, and the balance is Fe and unavoidable impurities.

[0049] The specific operation process of Example 2 is the same as that of Example 1. Example 3:

[0050] The φ92mm round steel is obtained through electric furnace steelmaking, LF refining, VD vacuum treatment, continuous casting, slow cooling, and rolling. It contains the following chemical components in mass percentage (unit: wt%): C: 1.03%, Si: 0.26%, Mn: 0.27%, P: 0.009%, S: 0.003%, Cr: 2.09%, Ni: 0.11%, Cu: 0.018%, Mo: 0.018%, V: 0.01%, Nb: 0.0038%, Ti: 0.015%, Al: 0.021%, H: 1.2 ppm, O: 8.9 ppm, N: 65 ppm, and the balance is Fe and unavoidable impurities.

[0051] The specific operation process of Example 3 is the same as that of Example 1.

[0052] During the implementation of the present invention, the time of the second heating section and the soaking section is appropriately increased. On the one hand, it improves the composition segregation, and on the other hand, it makes the heating of the round billet more uniform, which can ensure the flaw detection level of the rolled round steel for the round steel with poor core quality of high carbon and high chromium. Examples 1-3 use a φ500mm continuous casting round billet to roll a φ92mm round steel, and the rolling ratio reaches an amazing 29.5, obtaining a dense round steel. The flaw detection adopts the EN10308 standard to meet the level of less than φ1.6mm flat bottom hole.

[0053] The composition is detected according to the GB / T 4336 standard, and the impact test (at room temperature) is carried out in accordance with the metal material Charpy pendulum impact test process GB / T 229 standard.

[0054] The products of Examples 1 to 3 are respectively subjected to hardness test and impact performance test after being made into grinding balls. The test results are shown in Table 1: Table 1 Hardness and impact performance

[0055] The products of Examples 1 to 3 were respectively subjected to inclusion rating according to ASTM E45. The test results are shown in Table 2: Table 2 Inclusion Rating

[0056] The standard requirement for sulfide inclusions in this steel grade is ≤3.0 grade. Through the implementation of this process, the inclusion level was effectively controlled, reducing the risk of grinding ball fatigue cracking.

[0057] The carbon segregation C0 / C80 of the products of Examples 1 to 3 was respectively detected, and the results are shown in Table 3: Table 3 Carbon Segregation C0 / C80

[0058] The carbon segregation C0 / C80 values of the products of Examples 1 to 3 are between 0.8 and 0.91, indicating the stable performance and quality of the steel.

[0059] By controlling the addition of components Ti and Al in the present invention, the growth of austenite grain size is effectively inhibited, promoting grain refinement and improving the comprehensive properties of the material; while the wear resistance of the grinding ball is improved by the dispersion-precipitated hard particles such as TiN, TiC, and AlN, the fatigue tendency of the grinding ball is minimized, effectively prolonging the service life of the grinding ball, and obtaining a steel with excellent properties such as wear resistance and impact toughness.

[0060] Note: The above examples are only used to illustrate the present invention and do not limit the technical solutions described in the present invention; therefore, although the present specification has described the present invention in detail with reference to the above-mentioned various examples, those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced; and all technical solutions and their improvements that do not depart from the spirit and scope of the present invention shall be covered within the scope of the claims of the present invention.

Claims

1. A Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel, characterized in that: The invention is composed of the following components in mass percentage: C: 1.0-1.10%, Si: 0.15-0.40%, Mn: 0.20-0.40%, P ≤0.020%, S: ≤0.030%, Cr: 2.0-2.20%, Cu: 0.015-0.020%, Mo: 0.015-0.020%, Nb: 0.0020-0.004%, V: ≤0.030%, Al: 0.015-0.035%, Ni: ≤0.25%, Ti: 0.010-0.025%, H: ≤1.5ppm, O: ≤25ppm, N: 0.005-0.010%, and the balance is Fe and unavoidable impurities; The hardness of the round steel is ≥62 HRC, the impact resistance is ≥8 J, the TiN precipitation size is within 10 μm, and the sulfide inclusion standard requirement is ≤0.5 level.

2. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 1, characterized in that: The following steps are involved: The steelmaking raw materials are sequentially subjected to electric furnace steelmaking, LF refining, VD vacuum treatment, and continuous casting processes to obtain continuous casting round billets, and then the continuous casting round billets are subjected to heating rolling and pit cooling processes to obtain hot-rolled round steel; In the electric furnace steelmaking process: C: 0.23-0.70%; Si: 0.10-0.25%; Mn: 0.12-0.25%; Cr: 0.05-0.17%; target P ≤ 0.015%; target temperature ≥ 1620°C; In the LF refining process: feed aluminum wire, target 0.030~0.050%; white slag time ≥20min, smelting time ≥40min; In the VD vacuum treatment process: the highest vacuum degree is ≤67pa, the high vacuum holding time is ≥12min, and the soft blowing time is ≥15min; nitrogen is added by bottom blowing; after breaking the air, the aluminum wire is fed in the order of aluminum wire → titanium iron wire → silicon calcium wire, and the aluminum wire is fed at one time; In the continuous casting process: the superheat is between 18-30℃, two-stage water cooling is used with electromagnetic stirring of the crystallizer, strand stirring and end electromagnetic stirring, and the casting speed is limited to control the carbon segregation index of round steel to be less than 1.15; In the heating rolling process: the preheating section temperature is less than 900°C, and the time is greater than 1h; the heating section I temperature is 900-1100°C, and the time is ≥1h; the heating section II temperature is 1150-1250°C, the soaking section temperature is 1200-1260°C, the heating section II and soaking section time are 4.5-6h, and the total heating time is greater than 6.5h; the rolling is carried out using a 9-stand continuous rolling mill, temperature-controlled rolling, and the starting rolling temperature is 1000-1100°C; Pit cooling process: slow cooling time ≥ 24h, pit exit temperature ≤ 200℃.

3. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: In the electric furnace steelmaking process: the bottom blowing of argon is turned on before steel is tapped, and argon is blown throughout the steel tapping process; 400±30kg of lime and 400±30kg of cleaning agent are added to every 100-105t of molten steel, and 100kg of aluminum is added per furnace.

4. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: In the LF refining process, 0-1 kg of lime is added to each ton of molten steel for slag adjustment according to the slag condition in the early stage of refining, and Fe-Si powder and Si-C slag surface diffusion deoxidation are used throughout the refining process, with an amount of 1.2-2.5 kg added per ton of molten steel, and the mass ratio of the two is 1:1; argon is introduced during the LF refining process, and the flow rate is set to 200-400 NL / min in the early stage of refining, the argon flow rate is maintained at 120-250 NL / min in the alloying stage in the middle stage of refining, and the flow rate is set to 60-150 NL / min in the late stage of refining.

5. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: In the VD vacuum treatment process: the feeding amount of broken silicon calcium wire is: 80 to 100 meters for the first furnace and 50 to 60 meters for the continuous casting furnace.

6. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: In the continuous casting process, the flow parameters of the two-stage water cooling are: the flow rate of the first cooling water is 4000L / min; the flow rate of the second cooling water zone 1 is 80L / min, the flow rate of the second cooling water zone 2a is 55L / min, and the flow rate of the second cooling water zone 2b is 40L / min; The current of the crystallizer electromagnetic stirring is 300A and the frequency is 2Hz, the current of the strand stirring is 180A and the frequency is 8Hz, the current of the end electromagnetic stirring is 1100A and the frequency is 8Hz; the pulling speed is 0.40m / min.

7. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: In the heating rolling process: the target temperature of the preheating section is 850°C, the target temperature of the heating section I is 950°C, the target temperature of the heating section II is 1230°C, the target temperature of the soaking section is 1240°C, and the total heating time is 7-13h.

8. The production process of a Ti-containing high-carbon, high-chromium, high-density grinding ball hot-rolled round steel according to claim 2, characterized in that: The temperature of the first furnace entering the slow cooling pit is ≥550℃, and the temperature of other furnaces entering the slow cooling pit is 400-450℃.

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