A method for manufacturing a thin gauge high carbon tool steel

Abstract

The application discloses a preparation method of thin-gauge high-carbon tool steel, and comprises the following steps: step 1, raw materials are added into molten steel according to a raw material ratio, smelted, and then cast into a casting blank after LF refining; step 2, the casting blank is preheated in a weak oxidizing atmosphere, then heated in a reducing atmosphere, and then hot continuous rolling is performed to obtain a semi-finished product; after the hot continuous rolling, laminar flow cooling is performed to 550-650 DEG C, and then hot coiling and air cooling are performed to room temperature; step 3, the oxide skin on the surface of the semi-finished product after cooling is removed, and then overall annealing treatment is performed; and step 4, the surface of the semi-finished product after the annealing treatment is finished to obtain a final product. Through the above method, the component stability within a product batch can be improved, the thickness of a decarburized layer on the surface of the product can be reduced, and the size precision and fatigue resistance of the steel strip when the steel strip is processed into a product can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for preparing thin-gauge high-carbon tool steel. Background Technology

[0002] Tool steel has a high carbon content, excellent mechanical strength, and good hardness and wear resistance. Therefore, it can be used to manufacture cutting tools, precision hardware tools, and forming tools widely used in the automotive, electronics, engineering machinery, and chemical industries. Currently, commonly used hot-rolled tool steel strips are mainly narrow strips and traditional hot continuous rolling. Due to the production process, the overall dimensions are poor, and the chemical composition is unstable, resulting in large fluctuations in overall performance, making it unsuitable for the production of high-end products. Summary of the Invention

[0003] The main technical problem solved by this invention is to provide a method for preparing high-carbon tool steel, which can produce high-carbon tool steel with stable performance and thin dimensions.

[0004] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a method for preparing thin-gauge high-carbon tool steel, the method comprising the following steps:

[0005] Step 1. According to the raw material ratio, add the raw materials to the molten steel for smelting, and after LF refining, continuously cast to obtain the billet.

[0006] The billet described in step 2 is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled to obtain a semi-finished product. After hot rolling, it is laminar cooled to between 550 and 650°C, hot-coiled, and air-cooled to room temperature.

[0007] Step 3: Remove the oxide scale from the surface of the cooled semi-finished product, and then perform overall annealing treatment.

[0008] Step 4 involves surface finishing of the annealed semi-finished product to obtain the final product.

[0009] In a preferred embodiment of the present invention, the mass fractions of each component of the thin-gauge high-carbon tool steel are as follows: C 0.55-0.7%, SI 0.40-0.60%, Ni 0.3-0.50%, Cr 0.02-0.05%, Mn 0.5-1%, Mo 0.10-0.30%, V 0.10-0.30%, S≤0.03%, P≤0.03%, with the remainder being iron, wherein the inclusions of types A, B, C, D, and DS do not exceed grade II.

[0010] In a preferred embodiment of the present invention, the continuous casting speed in step 1 is 3-5 m / min, and the thickness of the cast billet is 80-120 mm.

[0011] In a preferred embodiment of the present invention, during step 2, the preheating temperature of the billet entering the furnace is 600-800°C, the preheating temperature inside the furnace is 1150-1250°C, and the preheating time is 15-20 minutes. During homogenization, the furnace temperature is the same as the preheating temperature, and the time is 20-50 minutes.

[0012] In a preferred embodiment of the present invention, the exit temperature of the hot continuous rolling mill in step 2 is 850-900°C.

[0013] In a preferred embodiment of the present invention, the oxide scale removal step in step 3 includes three steps: water jet cleaning, acid washing, and high-pressure water washing.

[0014] In a preferred embodiment of the present invention, the annealing process in step 3 includes first placing the semi-finished product into an annealing furnace, heating it to between 750 and 780°C under a protective atmosphere, then holding it at that temperature for 20 to 30 hours, then cooling it in the furnace to 500 ± 20°C, and finally air-cooling it to room temperature using a cooling hood.

[0015] In a preferred embodiment of the present invention, the thickness of the finished product is 1.5 to 3 mm.

[0016] The beneficial effects of this invention are as follows: By further optimizing the production process of tool steel, this invention effectively improves the problem of batch performance instability caused by the instability of the actual composition of the product by precisely controlling the composition content of stainless steel during the LF refining process. On the other hand, by using the steps of preheating in a weak oxidizing atmosphere and homogenizing in a reducing atmosphere, a dense oxide scale is formed on the surface of the product, which reduces the penetration of the oxidation reaction into the interior of the steel strip during processing, reduces the thickness of the decarburized layer, effectively improves the fatigue resistance of the product, and has high overall dimensional accuracy, making it suitable as a raw material for the production of high-end hardware tools and knives. Detailed Implementation

[0017] The preferred embodiments of the present invention will be described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0018] The embodiments of the present invention include:

[0019] Example 1

[0020] A method for preparing thin-gauge high-carbon tool steel, characterized in that the method comprises the following steps:

[0021] Step 1. According to the raw material ratio, add the raw materials to the molten steel for smelting, and after LF refining, continuously cast to obtain the billet.

[0022] In step 2, the billet is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled. The exit temperature of the hot rolling is controlled between 850 and 900°C to obtain a semi-finished product with a thickness of 1.5 mm. Then, it is laminar cooled to between 550 and 650°C, hot-coiled, and air-cooled to room temperature.

[0023] Step 3: First, use a high-pressure water jet to cut the surface of the semi-finished product to remove loose oxide scale. Then, use acid pickling to further remove surface oxides. Next, use high-pressure water washing to remove residual chemicals. Finally, send it into an annealing furnace and heat it to between 750 and 780°C under a nitrogen protective atmosphere. Hold it at this temperature for 20 hours. After holding, cool it in the furnace to 500°C and then use a cooling hood to air cool it to room temperature before removing it from the furnace.

[0024] Step 4 involves unwinding the annealed semi-finished product and then performing surface finishing to make the steel strip surface smooth, thereby obtaining the final finished product, which is then coiled and stored in the warehouse.

[0025] In step 1, the composition of the refined molten steel is controlled as follows: C 0.7%, SI 0.40%, Ni 0.50%, Cr 0.05%, Mn 0.5%, Mo 0.30%, V 0.10%, S≤0.03%, P≤0.03%, with the remainder being iron. The inclusions of types A, B, C, D, and DS do not exceed grade II. The continuous casting speed is 4.7 m / min, the tundish superheating temperature is 19℃, and the thickness of the cast billet is 80 mm.

[0026] In step 2, the preheating atmosphere is nitrogen gas with an oxygen content between 1.5% and 3%. The billet temperature upon entering the furnace is 600°C, the furnace preheating temperature is 1150°C, and the preheating time is 20 minutes. During homogenization, the reducing atmosphere is nitrogen gas with an oxygen content below 0.5%, the furnace temperature is the same as the preheating temperature, and the homogenization time is 20 minutes. In this way, a dense oxide layer can be formed on the surface of the billet during preheating, thereby preventing further oxidation into the internal crystals of the steel plate during subsequent processing, thus improving the overall performance of the product.

[0027] Example 2

[0028] A method for preparing thin-gauge high-carbon tool steel, characterized in that the method comprises the following steps:

[0029] Step 1. According to the raw material ratio, add the raw materials to the molten steel for smelting, and after LF refining, continuously cast to obtain the billet.

[0030] In step 2, the billet is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled. The exit temperature of the hot rolling is controlled between 850 and 900°C to obtain a semi-finished product with a thickness of 2 mm. Then, it is laminar cooled to between 550 and 650°C, hot-coiled, and air-cooled to room temperature.

[0031] Step 3: First, use a high-pressure water jet to cut the surface of the semi-finished product to remove loose oxide scale. Then, use acid pickling to further remove surface oxides. Next, use high-pressure water washing to remove residual chemicals. Finally, send it into an annealing furnace and heat it to 750-780℃ under a nitrogen protective atmosphere. Hold it at this temperature for 24 hours. After holding, cool it in the furnace to 500±20℃ and then use a cooling hood to air cool it to room temperature before removing it from the furnace.

[0032] Step 4 involves unwinding the annealed semi-finished product and then performing surface finishing to make the steel strip surface smooth, thereby obtaining the final finished product, which is then coiled and stored in the warehouse.

[0033] In step 1, the composition of the refined molten steel is controlled as follows: C 0.65%, SI 0.60%, Ni 0.3-0.50%, Cr 0.04%, Mn 0.8%, Mo 0.10%, V 0.20%, S≤0.03%, P≤0.03%, with the remainder being iron. The inclusions of types A, B, C, D, and DS do not exceed grade II. The continuous casting speed is 3.5 m / min, the tundish superheating temperature is 15℃, and the billet thickness is 90 mm.

[0034] In step 2, the preheating atmosphere is nitrogen gas with an oxygen content between 1.5% and 3%. The billet temperature upon entering the furnace is 700°C, the furnace preheating temperature is 1200°C, and the preheating time is 15 minutes. During homogenization, the reducing atmosphere is nitrogen gas with an oxygen content below 0.5%, the furnace temperature is the same as the preheating temperature, and the homogenization time is 30 minutes. In this way, a dense oxide layer can be formed on the surface of the billet during preheating, thereby preventing further oxidation into the internal crystals of the steel plate during subsequent processing, thus improving the overall performance of the product.

[0035] Example 3

[0036] A method for preparing thin-gauge high-carbon tool steel, characterized in that the method comprises the following steps:

[0037] Step 1. According to the raw material ratio, add the raw materials to the molten steel for smelting, and after LF refining, continuously cast to obtain the billet.

[0038] In step 2, the billet is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled. The exit temperature of the hot rolling is controlled between 850 and 900°C to obtain a semi-finished product with a thickness of 2.5 mm. Then, it is laminar cooled to between 550 and 650°C, hot-coiled, and air-cooled to room temperature.

[0039] Step 3: First, use a high-pressure water jet to cut the surface of the semi-finished product to remove loose oxide scale. Then, use acid pickling to further remove surface oxides. Next, use high-pressure water washing to remove residual chemicals. Finally, send it into an annealing furnace and heat it to 750-780℃ under a nitrogen protective atmosphere. Hold it at this temperature for 24 hours. After holding, cool it in the furnace to 500±20℃ and then use a cooling hood to air cool it to room temperature before removing it from the furnace.

[0040] Step 4 involves unwinding the annealed semi-finished product and then performing surface finishing to make the steel strip surface smooth, thereby obtaining the final finished product, which is then coiled and stored in the warehouse.

[0041] In step 1, the composition of the refined molten steel is controlled as follows: C 0.60%, SI 0.500%, Ni 0.40%, Cr 0.05%, Mn 0.30%, Mo 0.30%, V 0.30%, S≤0.03%, P≤0.03%, with the remainder being iron. The inclusions of types A, B, C, D, and DS do not exceed grade II. The continuous casting speed is 5 m / min, the tundish superheating temperature is 17℃, and the billet thickness is 100 mm.

[0042] In step 2, the preheating atmosphere is nitrogen gas with an oxygen content between 1.5% and 3%. The billet temperature upon entering the furnace is 700°C, the furnace preheating temperature is 1200°C, and the preheating time is 15 minutes. During homogenization, the reducing atmosphere is nitrogen gas with an oxygen content below 0.5%, the furnace temperature is the same as the preheating temperature, and the homogenization time is 50 minutes. In this way, a dense oxide layer can be formed on the surface of the billet during preheating, thereby preventing further oxidation into the internal crystals of the steel plate during subsequent processing, thus improving the overall performance of the product.

[0043] Example 4

[0044] A method for preparing thin-gauge high-carbon tool steel, characterized in that the method comprises the following steps:

[0045] Step 1. According to the raw material ratio, add the raw materials to the molten steel for smelting, and after LF refining, continuously cast to obtain the billet.

[0046] In step 2, the billet is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled. The exit temperature of the hot rolling is controlled between 850 and 900°C to obtain a semi-finished product with a thickness of 3 mm. Then, it is laminar cooled to between 550 and 650°C, hot-coiled, and air-cooled to room temperature.

[0047] Step 3: First, use a high-pressure water jet to cut the surface of the semi-finished product to remove loose oxide scale. Then, use acid pickling to further remove surface oxides. Next, use high-pressure water washing to remove residual chemicals. Finally, send it into an annealing furnace and heat it to 750-780℃ under a nitrogen protective atmosphere. Hold it at that temperature for 30 hours. After holding, cool it in the furnace to 500±20℃ and then use a cooling hood to air cool it to room temperature before taking it out of the furnace.

[0048] Step 4 involves unwinding the annealed semi-finished product and then performing surface finishing to make the steel strip surface smooth, thereby obtaining the final finished product, which is then coiled and stored in the warehouse.

[0049] In step 1, the composition of the refined steel is controlled as follows: C 0.55%, SI 0.50%, Ni 0.40%, Cr 0.02%, Mn 1%, Mo 0.20%, V 0.30%, S≤0.03%, P≤0.03%, with the remainder being iron. The composition of inclusions of types A, B, C, D, and DS does not exceed grade II. The continuous casting speed is 3 m / min, the tundish superheating temperature is 20℃, and the thickness of the cast billet is 120 mm.

[0050] In step 2, the preheating atmosphere is nitrogen gas with an oxygen content between 1.5% and 3%. The billet temperature upon entering the furnace is 800°C, the furnace preheating temperature is 1250°C, and the preheating time is 20 minutes. During homogenization, the reducing atmosphere is nitrogen gas with an oxygen content below 0.5%, the furnace temperature is the same as the preheating temperature, and the homogenization time is 40 minutes. In this way, a dense oxide layer can be formed on the surface of the billet during preheating, thereby preventing further oxidation into the internal crystals of the steel plate during subsequent processing, thus improving the overall performance of the product.

[0051] The performance test results of the finished products obtained in Examples 1 to 4 above are as follows:

[0052]

[0053] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing thin-gauge high-carbon tool steel, characterized in that, The method for preparing the thin-gauge high-carbon tool steel includes the following steps: Step 1. According to the raw material ratio, the raw materials are added to molten steel for smelting and then continuously cast after LF refining to obtain a billet. The mass fraction of each component of the thin-gauge high-carbon tool steel is as follows: C 0.55~0.7%, Si 0.40~0.60%, Ni 0.3~0.50%, Cr 0.02~0.05%, Mn 0.5~1%, Mo 0.10~0.30%, V 0.10~0.30%, S≤0.03%, P≤0.03%, with the remainder being iron. The inclusions of types A, B, C, D, and DS do not exceed grade II. The billet drawing speed of the continuous casting is 3~5 m / min, and the thickness of the billet is 80~120 mm. Step 2. The billet is first preheated in a weak oxidizing atmosphere, then homogenized in a reducing atmosphere, and then hot-rolled to obtain a semi-finished product. After hot rolling, it is laminar cooled to 550~650℃, hot-coiled, and air-cooled to room temperature. During preheating, the billet temperature entering the furnace is 600~800℃, the furnace preheating temperature is 1150~1250℃, and the preheating time is 15~20min. During homogenization, the furnace temperature is the same as the preheating temperature, and the time is 20~50min. The exit temperature of the hot rolling mill is 850~900℃. Step 3. Remove the oxide scale from the surface of the cooled semi-finished product, and then perform overall annealing treatment; the oxide scale removal step includes three steps: water jet cleaning, pickling, and high-pressure water washing; the annealing treatment includes: first, putting the semi-finished product into an annealing furnace, heating it to between 750 and 780°C under a protective atmosphere, then holding it at that temperature for 20 to 30 hours, then cooling it in the furnace to 500±20°C, and finally air-cooling it to room temperature using a cooling hood; Step 4. Trim the surface of the annealed semi-finished product to obtain the final product.

2. The method for preparing thin-gauge high-carbon tool steel according to claim 1, characterized in that, The thickness of the finished product is 1.5~3mm.

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