Steel for wear-resistant parts with narrow hardenability and wide band and preparation method thereof

Abstract

The present invention relates to the technical field of steel making, and in particular to a steel for wear-resistant parts with narrow hardenability and a preparation method thereof, comprising the following mass percentage components: C: 0.32-0.35%, Si: 0.20-0.40%, Mn: 1.30-1.50%, Cr: 0.25-0.40%, Mo: ≤0.05%, Ni: ≤0.10%, P: ≤0.020%, S: ≤0.020%, Ti: 0.020-0.040%, B: 0.015-0.030%, Al: 0.020-0.040%, and the remainder is Fe and inevitable impurities. The present invention produces Φ50-80mm round steel through the process flow of "converter smelting → LF refining → vacuum treatment → continuous casting → hot rolling → finishing", which meets the requirements of material purity and hardenability, and the hardness bandwidth at J8 / J11mm is controlled within 4HRC, which meets the standard of track plate steel.

Description

Technical Field

[0001] The invention relates to the technical field of steel making, and in particular to a steel for wear-resistant parts with a narrow hardenability band and a preparation method thereof. Background Art

[0002] Track shoes are load-bearing parts of engineering machinery and equipment. They are consumable parts that need to withstand high gravity and work for a long time under various road conditions. They require high wear resistance, impact resistance and high fatigue performance. Therefore, it is of great significance to develop high wear-resistant track shoes.

[0003] Narrow hardenability refers to the ability of a material to achieve good hardness and toughness within a smaller temperature range under specific quenching conditions. This type of steel usually needs to contain specific alloying elements (such as chromium, manganese, nickel, etc.) to improve its hardenability and hardness distribution. The design of a narrow hardenability bandwidth can effectively control the depth of the hardened layer, so that the wear-resistant parts can maintain an appropriate balance between hardness and toughness during operation, reduce deformation of parts during heat treatment, reduce material processing losses, improve production efficiency and reduce production costs. Therefore, the development of track plates using narrow hardenability bandwidth wear-resistant steel can help improve the hardness and wear resistance of the track plates, maintain good toughness, effectively reduce wear in complex terrain and harsh environments, enable the track plates to withstand impacts and loads without breaking easily, adapt to high-intensity working conditions, and improve the overall strength and stability of the track plates, avoid local failures caused by uneven hardness, and thus extend the service life of the track plates.

[0004] Since narrow hardenability band wear-resistant parts have many advantages, the development of narrow hardenability steel has become one of the research hotspots in the steelmaking field. For example, the invention patent with application number CN201710170241.4 discloses a high-temperature carburized gear steel with fine grains and narrow hardenability band; the invention patent with application number CN202010840171.0 discloses a narrow hardenability gear steel and its preparation method; the invention patent with application number CN202110124348.1 discloses a narrow hardenability gear steel and its manufacturing method; the invention patent with application number CN202210150890.9 discloses a method for controlling the boron content of narrow hardenability gear steel; the invention patent with application number CN202210016139.X discloses a narrow hardenability band high-temperature carburized MnCr gear steel and its manufacturing method.

[0005] Based on the above, in order to enrich the models and types of narrow hardenability wide bandwidth steels and meet different steel needs, the present invention realizes the development of 4HRC narrow hardenability track plate steel by reasonably adjusting the amount of different components and optimizing the steelmaking process. Summary of the invention

[0006] In view of this, the purpose of the present invention is to propose a steel for wear-resistant parts with narrow hardenability and bandwidth and a preparation method thereof, the hardenability of the material is improved by increasing the Mn and Cr contents, while increasing the material strength and wear resistance, the deoxidation strength is guaranteed and the grains are refined by adding Al and Ti, the low-temperature impact toughness of the material is improved, a narrow range design is adopted in the composition, low superheat, electromagnetic stirring and secondary cooling water control are adopted in casting to reduce the segregation of the billet composition, a reasonable four-stage heating system is adopted in rolling to ensure uniform heating of the billet and reduce the influence of segregation, and slow cooling is adopted for round steel to ensure uniform organization, and finally, the development of 4HRC narrow hardenability track plate steel is realized.

[0007] Based on the above purpose, the present invention provides a steel for wear-resistant parts with narrow hardenability and wide band, comprising the following components in mass percentage: C: 0.32~0.35%, Si: 0.20~0.40%, Mn: 1.30~1.50%, Cr: 0.25~0.40%, Mo: ≤0.05%, Ni: ≤0.10%, P: ≤0.020%, S: ≤0.020%, Ti: 0.020~0.040%, B: 0.015~0.030%, Al: 0.030~0.040%, and the balance is Fe and unavoidable impurities.

[0008] Furthermore, the steel for narrow hardenability and wide wear-resistant parts comprises the following components in mass percentage: C: 0.33%, Si: 0.25%, Mn: 1.35%, Cr: 0.28%, Mo: 0.02%, Ni: 0.04%, P: 0.011%, S: 0.004%, Ti: 0.030%, B: 0.025%, Al: 0.035%, and the balance is Fe and unavoidable impurities.

[0009] Furthermore, the steel for narrow hardenability and wide wear-resistant parts comprises the following components in mass percentage: C: 0.34%, Si: 0.30%, Mn: 1.40%, Cr: 0.38%, Mo: 0.02%, Ni: 0.04%, P: 0.009%, S: 0.005%, Ti: 0.025%, B: 0.026%, Al: 0.035%, and the balance is Fe and unavoidable impurities.

[0010] Furthermore, the steel for narrow hardenability and wide wear-resistant parts comprises the following components in mass percentage: C: 0.34%, Si: 0.28%, Mn: 1.45%, Cr: 0.35%, Mo: 0.01%, Ni: 0.02%, P: 0.013%, S: 0.005%, Ti: 0.032%, B: 0.028%, Al: 0.030%, and the balance is Fe and unavoidable impurities.

[0011] The present invention further provides a method for preparing the narrow hardenability and wide band wear-resistant steel, comprising converter smelting, LF refining, vacuum treatment, continuous casting, hot rolling, slow cooling and finishing processes, specifically comprising the following steps: S1: Converter smelting: Add high-quality molten iron and pure scrap steel to the converter, use top blowing oxygen and carbon powder injection, stably control the end point carbon and end point temperature, maintain foam slag operation throughout the process to prevent overoxidation of molten steel and reduce the pressure of later deoxidation. Use the double-blocking mode of slag blocking balls and slide blocks to prevent slag from falling during steel tapping, control the steel tapping end point [C]: 0.12-20%, steel tapping [P] ≤ 0.010%, steel tapping temperature ≥ 1600℃, and the remaining residual elements are controlled below the standard requirements; and add 120kg of aluminum blocks during the steel tapping process for precipitation deoxidation, and add 750kg of lime, 350kg of cleaning agent, high carbon ferromanganese, and ferrosilicon alloy for preliminary alloying; S2: LF refining: After the ladle enters the station, the LF furnace is heated up, slag making and alloy fine-tuning operations are carried out, and diffusion deoxidation is used during the refining process; S3: RH vacuum treatment: The vacuum degree of the RH vacuum process is lower than 67Pa, and the holding time is ≥10min, so as to achieve effective dehydrogenation of molten steel. After breaking the air, aluminum wire is fed to adjust the [Al] content in the molten steel to 0.030~0.040%, and then titanium iron wire and boron wire are fed with this wire. Argon is blown from the bottom of the ladle double-permeable bricks, and the soft blowing time is ≥20min to ensure that non-metallic inclusions in the molten steel fully float up, avoid secondary pollution of the molten steel caused by wire feeding and nitrogen addition, and improve the purity of the molten steel; S4: Continuous casting: The continuous casting machine used is R10m arc-shaped with high static pressure, which is conducive to solidification and shrinkage compensation. To ensure the internal quality of the ingot, a low superheat of 18~28℃ is used for full-process protection casting, including argon protection of the long water nozzle, integral immersion long water nozzle, special covering agent for the tundish, etc., to achieve protection casting and prevent secondary oxidation of molten steel. At the same time, the casting process adopts two-stage electromagnetic stirring (M-EMS+F-EMS), which can adjust the solidification structure according to needs, effectively control the crystal structure of the ingot, effectively improve the looseness and segregation of the billet, improve the low density of the ingot, reduce the internal defects of the ingot, control the casting section to 240mm×240mm, and the pulling speed to 1.10~1.15m / min. Then, a light reduction process is used to further improve segregation and billet quality, and multi-point straightening is used to ensure the surface quality and size of the billet. The final finished billet is 220mm×240mm. S5: Hot rolling: The billet is heated by a four-stage heating method of "preheating section + heating section 1 + heating section 2 + soaking section" to prevent the billet from heating up too fast and causing stress cracks. The billet is then continuously rolled by a continuous rolling unit and then rolled by a kocks rolling mill to ensure the size accuracy of the round steel. S6: Slow cooling and finishing: In order to reduce the hardness of the finished round steel, the round steel is sheared at high temperature, quickly collected, and piled up to cool in the wind. It is placed in an enclosure surrounded by hot steel and finished after the temperature of the round steel cools down.

[0012] Furthermore, the mass ratio of the high-quality molten iron to the pure scrap steel is (85-90):(10-15).

[0013] Furthermore, the specific process of LF refining is as follows: After the ladle enters the station, the LF furnace is heated and protected by a water-cooled inert gas furnace cover to reduce secondary oxidation of the molten steel. In the early and middle stages of refining, calcium carbide, aluminum beans and silicon carbide are used as the main materials, and composite silicon carbide and ferrosilicon powder are used as auxiliary materials for diffusion deoxidation. The initial aluminum content reaches 0.020~0.035%; White slag is produced quickly after molten steel enters the station. In the middle and late stages of refining, diffusion deoxidizer is added in small quantities and batches to maintain a reducing atmosphere. The white slag retention time is ≥20 minutes, and the smelting time is ≥40 minutes. By producing foamy white slag, inclusions in the steel are effectively adsorbed to ensure the purity of the molten steel.

[0014] Furthermore, the four-stage heating method of "preheating stage + heating stage 1 + heating stage 2 + soaking stage" is: Preheating stage: <650℃, time ≥0.5h; Heating stage 1: 880~1100℃, rapid heating; Heating 2 stages 1100~1150℃; The soaking section is 1100~1150℃, and the soaking time is ≥0.5h; Total heating time ≥ 2h.

[0015] The present invention further provides application of the narrow hardenability belt width wear-resistant steel in the preparation of track shoes.

[0016] Beneficial effects of the present invention: The present invention produces Φ50~80mm narrow hardenability belt width round steel for wear-resistant parts through the process of "converter smelting → LF refining → vacuum treatment → continuous casting → hot rolling → finishing", which can meet the material purity and hardenability requirements, and the hardness bandwidth at J8 / J11mm is controlled within 4HRC, which meets the standard requirements for engineering machinery track plate steel. Specifically, product development is mainly achieved through the following methods: The hardenability of the material is improved by increasing the Mn and Cr content, while the strength and wear resistance of the material are increased. The deoxidation strength is guaranteed, the grains are refined, and the low-temperature impact toughness of the material is improved by adding Al and Ti. A narrow range design is adopted in the composition, and low superheat, electromagnetic stirring, and secondary cooling water control are used in casting to reduce the segregation of billet composition. A reasonable four-stage heating system is used in rolling to ensure uniform heating of the billet and reduce the influence of segregation. Slow cooling is used for round steel to ensure uniform structure. Finally, the development of 4HRC narrow hardenability track plate steel was realized.

[0017] On the one hand, the hardenability, material strength and wear resistance of the material are guaranteed by the content of Mn, Cr and B, and the deoxidation strength and effective B content are guaranteed by adding Al and Ti, and the grains are further refined to improve the low-temperature impact toughness of the material. On the other hand, narrow composition design, low superheat, electromagnetic stirring, light pressing and other measures are adopted to ensure the uniformity of the billet composition and the stability of the material properties, and to ensure small composition segregation and narrow hardenability bandwidth. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0019] The invention provides a steel for wear-resistant parts with narrow hardenability and wide band, comprising the following components in mass percentage: C: 0.32-0.35%, Si: 0.20-0.40%, Mn: 1.30-1.50%, Cr: 0.25-0.40%, Mo: ≤0.05%, Ni: ≤0.10%, P: ≤0.020%, S: ≤0.020%, Ti: 0.020-0.040%, B: 0.015-0.030%, Al: 0.030-0.040%, and the balance is Fe and inevitable impurities.

[0020] The preparation method of the steel for narrow hardenability and wide wear-resistant parts comprises converter smelting, LF refining, vacuum treatment, continuous casting, hot rolling, slow cooling and finishing processes, and specifically comprises the following steps: S1: Converter smelting: high-quality molten iron and pure scrap steel are added to the converter, and the mass ratio of high-quality molten iron and pure scrap steel is (85-90):(10-15). Top blowing oxygen and carbon powder injection are used to stably control the end point carbon and end point temperature. The foam slag operation is maintained throughout the process to prevent overoxidation of the molten steel and reduce the deoxidation pressure in the later stage. The double-blocking mode of slag blocking balls and slide plates is used to prevent slag from falling during steel tapping. The steel tapping end point [C] is controlled to 0.12-20%, steel tapping [P] ≤ 0.010%, steel tapping temperature ≥ 1600°C, and the content of other residual elements is controlled below the standard requirements; and 120kg of aluminum blocks are added during the steel tapping process for precipitation deoxidation, and 750kg of lime, 350kg of cleaning agent, high carbon ferromanganese and ferrosilicon alloy are added for preliminary alloying; S2: LF refining: After the ladle enters the station, the LF furnace is heated up, slag making and alloy fine-tuning operations are carried out, and diffusion deoxidation is used during the refining process; specifically: After the ladle enters the station, the LF furnace is heated and protected by a water-cooled inert gas furnace cover to reduce secondary oxidation of the molten steel. In the early and middle stages of refining, calcium carbide, aluminum beans and silicon carbide are used as the main materials, and composite silicon carbide and ferrosilicon powder are used as auxiliary materials for diffusion deoxidation. The initial aluminum content reaches 0.030~0.035%; After the molten steel enters the station, white slag is quickly produced. In the middle and late stages of refining, diffused deoxidizer is added in small quantities and batches to maintain a reducing atmosphere. The white slag retention time is ≥20 minutes, and the smelting time is ≥40 minutes. By producing foamy white slag, inclusions in the steel are effectively adsorbed to ensure the purity of the molten steel. S3: RH vacuum treatment: The vacuum degree of the RH vacuum process is lower than 67Pa, and the holding time is ≥10min, so as to achieve effective dehydrogenation of molten steel. After breaking the air, aluminum wire is fed to adjust the [Al] content in the molten steel to 0.030~0.040%, and then titanium iron wire and boron wire are fed with this wire. Argon is blown from the bottom of the ladle double-permeable bricks, and the soft blowing time is ≥20min to ensure that non-metallic inclusions in the molten steel fully float up, avoid secondary pollution of the molten steel caused by wire feeding and nitrogen addition, and improve the purity of the molten steel; S4: Continuous casting: The continuous casting machine used is R10m arc-shaped with high static pressure, which is conducive to solidification and shrinkage compensation. To ensure the internal quality of the ingot, a low superheat of 18~28℃ is used for full-process protection casting, including argon protection of the long water nozzle, integral immersion long water nozzle, special covering agent for the tundish, etc., to achieve protection casting and prevent secondary oxidation of molten steel. At the same time, the casting process adopts two-stage electromagnetic stirring (M-EMS+F-EMS), which can adjust the solidification structure according to needs, effectively control the crystal structure of the ingot, effectively improve the looseness and segregation of the billet, improve the low density of the ingot, reduce the internal defects of the ingot, control the casting section to 240mm×240mm, and the pulling speed to 1.10~1.15m / min. Then, a light reduction process is used to further improve segregation and billet quality, and multi-point straightening is used to ensure the surface quality and size of the billet. The final finished billet is 220mm×240mm. S5: Hot rolling: The billet is heated by a four-stage heating method of "preheating section + heating section 1 + heating section 2 + soaking section" to prevent the billet from heating up too fast and causing stress cracks. The billet is then continuously rolled by a continuous rolling unit and then rolled by a kocks rolling mill to ensure the size accuracy of the round steel. The four-stage heating method of "preheating stage + heating stage 1 + heating stage 2 + soaking stage" is: Preheating stage: <650℃, time ≥0.5h; Heating stage 1: 880~1100℃, rapid heating; Heating 2 stages 1100~1150℃; The soaking section is 1100~1150℃, and the soaking time is ≥0.5h; Total heating time ≥ 2h; S6: Slow cooling and finishing: In order to reduce the hardness of the finished round steel, the round steel is sheared at high temperature, quickly collected, and piled up to cool in the wind. It is placed in an enclosure surrounded by hot steel and finished after the temperature of the round steel cools down.

[0021] Examples 1 to 3: Steels for wear-resistant parts with narrow hardenability and wide bandwidth were prepared according to the above method. The specific chemical component parameters are shown in Table 1, and the specific preparation process parameters are shown in Table 2.

[0022] Table 1 Chemical composition of steel (wt%)

[0023] Table 2 Process parameters of the preparation process

[0024] The steel for wear-resistant parts with narrow hardenability and wide band produced in Examples 1 to 3 was sampled and tested for macrostructure, non-metallic inclusions, austenite grain size (austenitizing temperature 870°C), carbon segregation, and hardenability. The test results are shown in Tables 3 to 7.

[0025] Table 3 Macrostructure / Grade

[0026] Table 4 Non-metallic inclusions / grade

[0027] Table 5 Austenite grain size / grade

[0028] Table 6 Carbon segregation

[0029] Table 7 Hardenability

[0030] From Tables 3 to 7, it can be seen that the steels produced in Examples 1 to 3 have high purity, uniform composition, fine grains, and the hardenability of the steels meets the standard requirements. The hardness of J8 / J11 can be maintained within 4HRC, which meets the standard requirements for steel for engineering machinery track plates.

[0031] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0032] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, 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 steel for wear-resistant parts with narrow hardenability and wide band, characterized in that: It includes the following components in mass percentage: C: 0.32~0.35%, Si: 0.20~0.40%, Mn: 1.30~1.50%, Cr: 0.25~0.40%, Mo: ≤0.05%, Ni: ≤0.10%, P: ≤0.020%, S: ≤0.020%, Ti: 0.020~0.040%, B: 0.015~0.030%, Al: 0.030~0.040%, and the balance is Fe and unavoidable impurities; The preparation method of the narrow hardenability and wide band wear-resistant steel comprises converter smelting, LF refining, vacuum treatment, continuous casting, hot rolling, slow cooling and finishing steps. The following steps are involved: S1: Converter smelting: Add high-quality molten iron and pure scrap steel into the converter, use top blowing oxygen and carbon powder injection to stably control the end point carbon and end point temperature, maintain foam slag operation throughout the process, and use the double-blocking mode of slag blocking balls and slide blocks to control the steel tapping end point [C]: 0.12-20%, steel tapping [P] ≤ 0.010%, steel tapping temperature ≥ 1600℃, and the content of other residual elements is controlled below the standard requirements; and add 120kg of aluminum blocks during the steel tapping process for precipitation deoxidation, and add 750kg of lime, 350kg of cleaning agent, high carbon ferromanganese, and ferrosilicon alloy for preliminary alloying; S2: LF refining: After the ladle enters the station, the LF furnace is heated up, slag making and alloy fine-tuning operations are carried out, and diffusion deoxidation is used during the refining process; S3: RH vacuum treatment: The vacuum degree of the RH vacuum process is lower than 67Pa, and the holding time is ≥10min. After breaking the vacuum, aluminum wire is fed to adjust the [Al] content in the molten steel to 0.030~0.040%, and then titanium iron wire and boron wire are fed with it, and argon is blown from the bottom of the ladle double-permeable brick, and the soft blowing time is ≥20min; S4: Continuous casting: The continuous casting machine used is R10m arc-shaped, and 18~28℃ low superheat protection is adopted for the whole casting process. At the same time, two-stage electromagnetic stirring is adopted in the casting process, and the casting section is controlled to be 240mm×240mm, and the pulling speed is 1.10~1.15m / min. Then, a light pressure reduction process is adopted, and multi-point straightening is adopted. The final finished billet is 220mm×240mm; S5: Hot rolling: The billet is heated by a four-stage heating method of "preheating section + heating section 1 + heating section 2 + soaking section", and then continuously rolled by a continuous rolling unit, and then rolled by a kocks rolling mill; S6: Slow cooling and finishing: The round steel is sheared at high temperature, quickly collected, and piled up to avoid wind and placed in a fence surrounded by hot steel. Finishing inspection is carried out after the temperature of the round steel has cooled down; The four-stage heating method of "preheating stage + heating stage 1 + heating stage 2 + soaking stage" is: Preheating stage: <650℃, time ≥0.5h; Heating stage 1: 880~1100℃, rapid heating; Heating 2 stages 1100~1150℃; The soaking temperature is 1100~1150℃, and the soaking time is ≥0.5h; Total heating time ≥2h.

2. The steel for wear-resistant parts with narrow hardenability band according to claim 1, characterized in that: It includes the following components in mass percentage: C: 0.33%, Si: 0.25%, Mn: 1.35%, Cr: 0.28%, Mo: 0.02%, Ni: 0.04%, P: 0.011%, S: 0.004%, Ti: 0.030%, B: 0.025%, Al: 0.035%, and the balance is Fe and inevitable impurities.

3. The steel for wear-resistant parts with narrow hardenability band according to claim 1, characterized in that: It includes the following components in mass percentage: C: 0.34%, Si: 0.30%, Mn: 1.40%, Cr: 0.38%, Mo: 0.02%, Ni: 0.04%, P: 0.009%, S: 0.005%, Ti: 0.025%, B: 0.026%, Al: 0.035%, and the balance is Fe and inevitable impurities.

4. The steel for wear-resistant parts with narrow hardenability band according to claim 1, characterized in that: It includes the following components in mass percentage: C: 0.34%, Si: 0.28%, Mn: 1.45%, Cr: 0.35%, Mo: 0.01%, Ni: 0.02%, P: 0.013%, S: 0.005%, Ti: 0.032%, B: 0.028%, Al: 0.030%, and the balance is Fe and inevitable impurities.

5. A method for preparing steel for wear-resistant parts with narrow hardenability band according to any one of claims 1 to 4, characterized in that: It includes converter smelting, LF refining, vacuum treatment, continuous casting, hot rolling, slow cooling and finishing processes. The following steps are involved: S1: Converter smelting: Add high-quality molten iron and pure scrap steel into the converter, use top blowing oxygen and carbon powder injection to stably control the end point carbon and end point temperature, maintain foam slag operation throughout the process, and use the double-blocking mode of slag blocking balls and slide blocks to control the steel tapping end point [C]: 0.12-20%, steel tapping [P] ≤ 0.010%, steel tapping temperature ≥ 1600℃, and the content of other residual elements is controlled below the standard requirements; and add 120kg of aluminum blocks during the steel tapping process for precipitation deoxidation, and add 750kg of lime, 350kg of cleaning agent, high carbon ferromanganese, and ferrosilicon alloy for preliminary alloying; S2: LF refining: After the ladle enters the station, the LF furnace is heated up, slag making and alloy fine-tuning operations are carried out, and diffusion deoxidation is used during the refining process; S3: RH vacuum treatment: The vacuum degree of the RH vacuum process is lower than 67Pa, and the holding time is ≥10min. After breaking the vacuum, aluminum wire is fed to adjust the [Al] content in the molten steel to 0.030~0.040%, and then titanium iron wire and boron wire are fed with it, and argon is blown from the bottom of the ladle double-permeable brick, and the soft blowing time is ≥20min; S4: Continuous casting: The continuous casting machine used is R10m arc-shaped, and 18~28℃ low superheat protection is adopted for the whole casting process. At the same time, two-stage electromagnetic stirring is adopted in the casting process, and the casting section is controlled to be 240mm×240mm, and the pulling speed is 1.10~1.15m / min. Then, a light pressure reduction process is adopted, and multi-point straightening is adopted. The final finished billet is 220mm×240mm; S5: Hot rolling: The billet is heated by a four-stage heating method of "preheating section + heating section 1 + heating section 2 + soaking section", and then continuously rolled by a continuous rolling unit, and then rolled by a kocks rolling mill; S6: Slow cooling and finishing: The round steel is sheared at high temperature, quickly collected, and piled up to cool in the windproof manner. It is placed in an enclosure surrounded by hot steel and finished after the temperature of the round steel has cooled.

6. The method for preparing a steel for wear-resistant parts with narrow hardenability band according to claim 5, characterized in that: The mass ratio of the high-quality molten iron to the pure scrap steel is (85-90):(10-15).

7. The method for preparing a steel for wear-resistant parts with narrow hardenability band according to claim 5, characterized in that: The specific process of LF refining is: After the ladle enters the station, the LF furnace is heated and protected by a water-cooled inert gas furnace cover. In the early and middle stages of refining, calcium carbide, aluminum beans and silicon carbide are used as the main materials, and composite silicon carbide and ferrosilicon powder are used as the auxiliary materials for diffusion deoxidation. The initial aluminum content reaches 0.020~0.035%; White slag is produced quickly after molten steel enters the station. In the middle and late stages of refining, diffusion deoxidizer is added in small quantities and batches to maintain a reducing atmosphere. The white slag retention time is ≥20 minutes and the smelting time is ≥40 minutes.

8. Use of the steel for wear-resistant parts with narrow hardenability and bandwidth according to any one of claims 1 to 4 in the preparation of track shoes.

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