High carbon alloy tool steel for chain saw tools and method of making same

Abstract

The application discloses a high-carbon alloy tool steel for chain saw tools and a preparation method thereof, and belongs to the technical field of steel production. The hot-rolled plate of the high-carbon alloy tool steel for chain saw tools has the following mechanical properties in the hot-rolled state: the yield strength is 710-1650 MPa, the tensile strength is 860-1950 MPa, the elongation is greater than or equal to 5%, the Brinell hardness is 258-550, and the single-side decarburization layer depth is less than or equal to 0.01 mm. The pure steel is obtained by adopting the following technologies: LF deep desulfurization, RH vacuum degassing, Ca treatment spheroidization inclusion technology, temperature control at each node in the smelting process, oxygen and nitrogen control in the whole process, reasonable application of light pressing and electromagnetic stirring technology, and secondary cooling water model optimization, so that the occurrence of corner cracks and longitudinal cracks is effectively prevented.

Description

Technical Field

[0001] This invention belongs to the field of steel production technology, specifically relating to a high-carbon alloy tool steel for chainsaw tools and its preparation method. Background Technology

[0002] The development of the chainsaw is the result of both technological advancements and market demand. Its continuously evolving technology and functions have enabled it to play a vital role in forestry, landscaping, and other fields. From the late 19th to the early 20th century, the global forestry industry experienced rapid growth. Traditional manual logging was inefficient and labor-intensive. To improve logging efficiency, people began exploring mechanized logging tools. In 1905, drawing inspiration from the manual chainsaw invented by 19th-century surgeons for medical procedures, American Samuel Burns invented the first chain-driven chainsaw. The portable chainsaw appeared in 1918, laying the foundation for the development of the oil chainsaw.

[0003] Electric chainsaws are becoming increasingly popular in home maintenance and small-scale operations due to their advantages such as environmental friendliness, low noise, and ease of operation. This will put some pressure on the market share of hydraulic chainsaws. With technological advancements and stricter environmental requirements, hydraulic chainsaws will evolve towards higher efficiency, environmental friendliness, and intelligent operation. They will remain irreplaceable in specific fields (such as large-scale forestry operations and emergency rescue). Therefore, developing a high-carbon alloy tool steel for chainsaw tools and its preparation method is of great significance for meeting the needs of emerging fields such as outdoor sports and emergency rescue in my country, and for improving product quality. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, this invention provides a high-carbon alloy tool steel for chainsaw tools and a method for preparing the same.

[0005] In a first aspect of the invention, a high-carbon alloy tool steel for chainsaw tools is provided, the chemical composition of which is controlled by mass percentage as follows: 0.70%≤C≤0.79%, 0.40%≤Si≤0.60%, 0.80%≤Mn≤1.15%, 0.015%≤Al≤0.060%, P≤0.010%, S≤0.005%, 0.60%≤Cr≤0.85%, 0.30%≤Ni≤0.68%, 0.10%≤Mo≤0.30%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.050%, Cu≤0.070%, with the balance being Fe and unavoidable impurities.

[0006] Furthermore, the chemical composition of the high-carbon alloy tool steel used in the chainsaw tools is controlled by mass percentage as follows: 0.71%≤C≤0.76%, 0.41%≤Si≤0.56%, 0.82%≤Mn≤1.10%, P≤0.010%, S≤0.005%, 0.020%≤Al≤0.050%, 0.62%≤Cr≤0.79%, 0.35%≤Ni≤0.62%, 0.12%≤Mo≤0.25%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.047%, Cu≤0.070%, with the balance being Fe and unavoidable impurities.

[0007] Furthermore, the hot-rolled mechanical properties of the high-carbon alloy tool steel hot-rolled coils used for chainsaw tools are as follows: yield strength of 710-1650MPa, tensile strength of 860-1950MPa, elongation ≥5%, Brinell hardness of 258-550, and single-sided decarburized layer depth ≤0.01mm.

[0008] Furthermore, the mechanical properties of the hot-rolled coil of high-carbon alloy tool steel used for chainsaw tools in the heat-treated annealed state are as follows: yield strength of 345-885 MPa, tensile strength of 555-1250 MPa, elongation ≥25%, Brinell hardness of 163-370, single-sided decarburization layer depth ≤0.02 mm, the Brinell hardness fluctuation of the hot-rolled coil of high-carbon alloy tool steel after quenching and tempering is less than 1.5%, the yield strength after quenching and tempering is not less than 1100 MPa, and the tensile strength is not less than 1500 MPa.

[0009] In a second aspect of the invention, the method for preparing high-carbon alloy tool steel for chainsaw tools includes the following steps: (1) Hot metal pretreatment: Desulfurization pretreatment is carried out on the blast furnace hot metal, and slag is removed so that the mass percentage of sulfur in the hot metal after pretreatment does not exceed 0.003%; (2) Converter smelting and alloying: The pretreated molten iron and scrap steel with a sulfur content not exceeding 0.03% by mass are added to the converter for smelting. When the steel is tapped from the converter, alloy materials are added to alloy the composition. Then, argon blowing is performed to obtain molten steel. (3) LF furnace refining and desulfurization: The molten steel is sent into the LF furnace for desulfurization treatment until the mass percentage of sulfur in the molten steel does not exceed 0.005%. Then the alloy element composition is finely adjusted and bottom blowing argon weak stirring is performed until the composition is uniform, and refined molten steel is obtained. (4) RH vacuum refining and inclusion modification: The refined molten steel is fed into an RH furnace and circulated for more than 10 minutes under a vacuum pressure of no more than 10 mbar. After the vacuum is broken, the molten steel is subjected to inclusion modification treatment under bottom blowing argon weak stirring. (5) Continuous casting: The molten steel processed in step (4) is continuously cast to obtain a continuously cast slab; (6) Hot rolling and heat treatment after coiling: The continuously cast slab is subjected to slab heating, rough rolling descaling, rough rolling, fine rolling descaling, fine rolling, cooling after rolling, coiling, and heat treatment after coiling in sequence to obtain hot-rolled coil of high carbon alloy tool steel.

[0010] Furthermore, in the above-mentioned method for preparing high-carbon alloy tool steel for chainsaw tools, in step (2), the mass percentage of the pretreated molten iron to scrap steel is 80%~95%:5%~20%, and the alloy materials include carbon powder, aluminum ferromanganese, high-carbon ferromanganese, silicon-manganese alloy and ferrochrome.

[0011] Furthermore, in the above-mentioned method for preparing high-carbon alloy tool steel for chainsaw tools, in step (3), the argon flow rate for bottom-blown argon weak stirring is 20~200NL / min, and the stirring time is not less than 5 minutes.

[0012] Furthermore, in the above-mentioned method for preparing high-carbon alloy tool steel for chainsaw tools, in step (4), the bottom-blowing argon weak stirring time after vacuum breaking is not less than 8 minutes, and the inclusion modification treatment is to feed calcium-silicon wire into the molten steel.

[0013] Furthermore, in the above-mentioned method for preparing high-carbon alloy tool steel for chainsaw tools, during the continuous casting process in step (5), the pouring temperature is 1455~1565℃, the casting speed is 0.85~1.65m / min, the superheat of molten steel is 15℃~50℃, the light reduction of the billet is 0~5mm, and the frequency of electromagnetic stirring is 2.5~5.0Hz.

[0014] Furthermore, in the above-mentioned method for preparing high-carbon alloy tool steel for chainsaw tools, in step (6), before heating the slab, the continuously cast slab is first hot-charged and hot-loaded or heat-treated, then ground and coated. The hot-charged and hot-loaded temperature is not lower than 200℃, and the heat treatment temperature is 550~850℃. The slab heating temperature is 1150℃~1300℃, the roughing and finishing rolling temperature is 1000℃~1200℃, the finishing rolling temperature is 800℃~930℃, the coiling temperature is 580℃~800℃, and the heat treatment temperature after coiling is 550~850℃.

[0015] The high-carbon alloy tool steel for chainsaw tools and its preparation method of the present invention have the following advantages and beneficial effects: (1) The present invention provides a method for preparing hot-rolled coils of high-carbon alloy tool steel. Pure steel is obtained by using ladle refining: LF deep desulfurization + RH vacuum degassing, Ca treatment of spheroidized inclusions, temperature control at each node of the smelting process and oxygen and nitrogen control throughout the process, reasonable application of light pressing and electromagnetic stirring technology, and optimization of secondary cooling water model. This effectively prevents the occurrence of corner cracks and longitudinal cracks. (2) The present invention provides a method for preparing hot-rolled coil of high-carbon alloy tool steel. Through specific hot charging and loading processes, heat treatment processes, slab grinding and coating processes, the slab crack defects that may occur in the connection process between hot rolling and steelmaking are effectively controlled, and a hot-rolled coil of high-carbon alloy tool steel with pure steel quality and excellent quality is obtained. (3) The hot-rolled coil of high-carbon alloy tool steel of the present invention has good comprehensive performance; it has excellent hardness uniformity, high strength and toughness, and high wear resistance. Its hot-rolled mechanical properties are: its yield strength is 710-1650MPa, its tensile strength is 860-1950MPa, its elongation is ≥5%, its Brinell hardness is 258-550, and its single-sided decarburization layer depth is ≤0.01mm; its heat-treated annealed mechanical properties are: its yield strength is 345-885MPa, its tensile strength is 555-1250MPa, its elongation is ≥25%, its Brinell hardness is 163-370, and its single-sided decarburization layer depth is ≤0.02mm; the Brinell hardness fluctuation of the hot-rolled coil of high-carbon alloy tool steel after quenching and tempering is less than 1.5%, its yield strength after quenching and tempering is not less than 1100MPa, and its tensile strength is not less than 1500MPa. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of this application and constitute a part of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 The annealed microstructure of the high-carbon alloy tool steel for chainsaw tools prepared for embodiments of this application is shown. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] In a first aspect of the invention, a high-carbon alloy tool steel for chainsaw tools is provided. The high-carbon alloy tool steel for chainsaw tools of the present invention has good comprehensive performance, and features excellent hardness uniformity, high strength and toughness, and high wear resistance.

[0019] Specifically, the chemical composition of the high-carbon alloy tool steel for chainsaw tools of the present invention is controlled by mass percentage as follows: 0.70%≤C≤0.79%, 0.40%≤Si≤0.60%, 0.80%≤Mn≤1.15%, 0.015%≤Al≤0.060%, P≤0.010%, S≤0.005%, 0.60%≤Cr≤0.85%, 0.30%≤Ni≤0.68%, 0.10%≤Mo≤0.30%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.050%, Cu≤0.070%, with the balance being Fe and unavoidable impurities.

[0020] Preferably, the chemical composition of the high-carbon alloy tool steel for chainsaw tools of the present invention is controlled by mass percentage as follows: 0.71%≤C≤0.76%, 0.41%≤Si≤0.56%, 0.82%≤Mn≤1.10%, P≤0.010%, S≤0.005%, 0.020%≤Al≤0.050%, 0.62%≤Cr≤0.79%, 0.35%≤Ni≤0.62%, 0.12%≤Mo≤0.25%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.047%, Cu≤0.07%, with the balance being Fe and unavoidable impurities.

[0021] Specifically, the hot-rolled mechanical properties of the high-carbon alloy tool steel hot-rolled coil for chainsaw tools of the present invention are as follows: yield strength of 710-1650MPa, tensile strength of 860-1950MPa, elongation ≥5%, Brinell hardness of 258-550, and single-sided decarburization layer depth ≤0.01mm.

[0022] Specifically, the hot-rolled coil of high-carbon alloy tool steel for chainsaw tools of the present invention has the following mechanical properties in the heat-treated annealed state: yield strength of 345-885 MPa, tensile strength of 555-1250 MPa, elongation ≥25%, Brinell hardness of 163-370, single-sided decarburization layer depth ≤0.02 mm, the Brinell hardness fluctuation of the hot-rolled coil of high-carbon alloy tool steel after quenching and tempering is less than 1.5%, the yield strength after quenching and tempering is not less than 1100 MPa, and the tensile strength is not less than 1500 MPa.

[0023] The function of the required elements and content control ranges of the high-carbon alloy tool steel for chainsaw tools in this invention is described below: Carbon: It is the most economical and basic strengthening element in steel. In this invention, the C content is controlled within the range of 0.70%-0.79%, preferably 0.70%-0.78%.

[0024] Silicon: Silicon can significantly improve the elastic limit, yield point, and tensile strength of steel. When combined with Mo and Cr, it enhances corrosion resistance and oxidation resistance. In this invention, the Si content is controlled at 0.40-0.60%, preferably 0.40%-0.58%.

[0025] Manganese: Manganese can strengthen steel, improving its strength, hardness, and wear resistance. It can also reduce the critical cooling rate of steel, improve its hardenability, and refine pearlite, thus increasing the strength of pearlitic steel. In this invention, the Mn content is controlled at 0.80-1.15%, preferably 0.80%-1.13%.

[0026] Aluminum: Aluminum is a major deoxidizing element and nitrogen-fixing element in steel. Adding a small amount of aluminum to steel can refine the grains, improve impact toughness, and especially lower the brittle transition temperature of steel. However, excessive aluminum during deoxidation will promote the graphitization tendency of steel. When the aluminum content is high, its high-temperature strength and toughness are low. Aluminum also has antioxidant and corrosion-resistant properties. This invention controls the Al content at 0.015%-0.060%, which can improve the toughness of steel at low temperatures, lower the brittle transition temperature of steel, and avoid the graphitization tendency of steel; preferably, the aluminum content is 0.015%-0.058%.

[0027] Phosphorus: Generally, phosphorus is a harmful element in steel, with its greatest harm being severe segregation, increased temper brittleness, significantly reduced toughness and brittleness, and increased cold brittleness. This invention controls the P content to ≤0.010%.

[0028] Sulfur: Under normal circumstances, sulfur is also a harmful element, causing hot brittleness in steel, reducing its ductility and toughness, and decreasing its corrosion resistance. This invention controls the S content to ≤0.005%.

[0029] Chromium: Chromium can improve the strength, hardness, high-temperature mechanical properties, hardenability, and wear resistance of steel, giving it good corrosion resistance, oxidation resistance, tempering stability, and toughness. It also helps prevent graphitization. This invention controls the Cr content at 0.60%-0.85%, which effectively improves the various properties of the steel. Preferably, the Cr content is controlled at 0.60%-0.82%.

[0030] Nickel: Nickel is a solid solution strengthening agent in steel and also a good hardenability additive. By lowering the critical transformation temperature, it reduces the diffusion rate of various elements in steel, thereby improving hardenability; it can improve the fatigue performance of steel and reduce its sensitivity to notches; nickel can increase the pearlite content in the normalized state and refine the grains. Nickel-chromium or nickel-chromium-molybdenum steel used in mechanical manufacturing can achieve a good balance of strength and toughness after heat treatment. In this invention, the Ni content is controlled at 0.30%-0.68%, preferably 0.30%-0.65%.

[0031] Molybdenum: Molybdenum is a good carbide-forming element; as an alloying element in steel, molybdenum can improve the strength of steel, especially its high-temperature strength and toughness; it can also improve the wear resistance, hardenability, weldability, and heat resistance of steel. In this invention, the molybdenum content is controlled at 0.10%-0.30%; preferably 0.10%-0.28%.

[0032] Vanadium is a strong carbide-forming element, producing dense steel with good deoxidation and dehydrogenation properties. It can also refine grains, reduce overheating sensitivity, and improve the strength, toughness, and fatigue performance of steel. Vanadium carbides are among the hardest and most wear-resistant of all metallic carbides; dispersed V4C3 will improve the hardness and wear resistance of steel. In this invention, the V content is controlled at 0.05%-0.10%.

[0033] Niobium: In the steel industry, niobium is mainly used to manufacture various alloy steels, heat-resistant alloys, niobium-based alloys, and niobium carbide. Niobium is one of the main alloying elements in steel, possessing excellent properties such as improving the mechanical and weldability of steel, enhancing its heat resistance and corrosion resistance, and reducing its brittleness. In this invention, the Nb content is controlled at 0.040%-0.050%, preferably 0.040%-0.049%.

[0034] Copper: To address the impact of residual Cu on intergranular cracks in continuously cast billets, it is generally required that the Cu content in medium and high carbon steel be <0.3%, while also necessitating low secondary cooling intensity and high continuous casting speed. In this invention, the Cu content is controlled at ≤0.070%.

[0035] Through the synergistic effect of various elements, the hot-rolled coil of high-carbon alloy tool steel for chainsaw tools has excellent hardness uniformity, high strength, and high wear resistance.

[0036] In a second aspect of the invention, a method for preparing high-carbon alloy tool steel for chainsaw tools is provided, comprising the following steps: (1) Hot metal pretreatment: Desulfurization pretreatment is carried out on the blast furnace hot metal, and slag is removed so that the mass percentage of sulfur in the hot metal after pretreatment does not exceed 0.003%; (2) Converter smelting and alloying: The pretreated molten iron and scrap steel with a sulfur content not exceeding 0.03% by mass are added to the converter for smelting. When the steel is tapped from the converter, alloy materials are added to alloy the composition. Then, argon blowing is performed to obtain molten steel. (3) LF furnace refining and desulfurization: The molten steel is sent into the LF furnace for desulfurization treatment until the mass percentage of sulfur in the molten steel does not exceed 0.005%. Then the alloy element composition is finely adjusted and bottom blowing argon weak stirring is performed until the composition is uniform, and refined molten steel is obtained. (4) RH vacuum refining and inclusion modification: The refined molten steel is fed into an RH furnace and circulated for more than 10 minutes under a vacuum pressure of no more than 10 mbar. After the vacuum is broken, the molten steel is subjected to inclusion modification treatment under bottom blowing argon weak stirring. (5) Continuous casting: The molten steel processed in step (4) is continuously cast to obtain a continuously cast slab; (6) Hot rolling and heat treatment after coiling: The continuously cast slab is subjected to slab heating, rough rolling descaling, rough rolling, fine rolling descaling, fine rolling, cooling after rolling, coiling, and heat treatment after coiling in sequence to obtain hot-rolled coil of high carbon alloy tool steel.

[0037] Preferably, in the preparation method of high carbon alloy tool steel for chainsaw tools of the present invention, in step (2), the mass percentage of the pretreated molten iron to scrap steel is 80%~95%:5%~20%, and the alloy material includes carbon powder, aluminum ferromanganese, high carbon ferromanganese, silicon-manganese alloy and ferrochrome.

[0038] Preferably, in the preparation method of high carbon alloy tool steel for chainsaw tools of the present invention, in step (3), the argon flow rate of the bottom-blown argon weak stirring is 20~200NL / min, and the stirring time is not less than 5 minutes.

[0039] Preferably, in the preparation method of high carbon alloy tool steel for chainsaw tools of the present invention, in step (4), the bottom blowing argon weak stirring time after vacuum breaking is not less than 8 minutes, and the inclusion modification treatment is to feed calcium silicon wire into the molten steel.

[0040] Preferably, in the preparation method of high carbon alloy tool steel for chainsaw tools of the present invention, during the continuous casting process of step (5), the pouring temperature is 1455~1565℃, the casting speed is 0.85~1.65m / min, the superheat of molten steel is 15℃~50℃, the light reduction of the billet is 0~5mm, and the frequency of electromagnetic stirring is 2.5~5.0Hz.

[0041] Preferably, in the preparation method of high carbon alloy tool steel for chainsaw tools of the present invention, in step (6), before heating the slab, the continuously cast slab is first hot-charged and hot-loaded or heat-treated, then ground and coated, wherein the hot-charged and hot-loaded temperature is not lower than 200°C, the heat treatment temperature is 550~850°C; the slab heating temperature is 1150°C~1300°C, the roughing and finishing rolling temperature is 1000°C~1200°C, the finishing rolling temperature is 800°C~930°C, the coiling temperature is 580°C~800°C, and the heat treatment temperature after coiling is 550~850°C.

[0042] The high-carbon alloy tool steel for chainsaw tools and its preparation method of the present invention are described in detail below with reference to embodiments.

[0043] The methods for measuring performance parameters in the following embodiments are as follows: Yield strength: GB / T 228 Metallic materials - Tensile testing at room temperature; Tensile strength: GB / T 228 Metallic materials - Tensile testing at room temperature; Elongation: GB / T 228 Metallic materials - Tensile testing at room temperature; Brinell hardness: GB / T 231.1 Metallic materials - Brinell hardness test; Decarburized layer thickness: GB / T 224 Determination of decarburized layer depth in steel; Inclusions: GB / T10561 Microscopic evaluation method for non-metallic inclusions.

[0044] Table 1: Composition (wt.%) of the high-carbon alloy tool steel used in chainsaw tools in Examples 1-5

[0045] Table 2: Process parameters and test performance of high-carbon alloy tool steels used in chainsaw tools in Examples 1-5

[0046] Example 1 The chemical composition of the high-carbon alloy tool steel for chainsaw tools in Example 1, by mass percentage, is as follows: C: 0.71%; Si: 0.42%; Mn: 0.90%; Al: 0.035%; P: 0.010%; S: 0.004%; Cr: 0.62%; Ni: 0.50%; Mo: 0.16%; V: 0.08%; Nb: 0.040%; Cu: 0.06%, with the balance being Fe and unavoidable impurity elements.

[0047] The specific process of preparing high-carbon alloy tool steel for chainsaw tools in Example 1 includes: This embodiment is prepared in an 80-ton top-and-bottom blowing converter and a 1549mm hot strip mill. The preparation process includes the following steps in sequence: (1) Hot metal pretreatment The blast furnace molten iron is desulfurized and pretreated by removing slag, so that the mass percentage of sulfur in the molten iron after pretreatment is reduced to 0.003%.

[0048] (2) Converter smelting and alloying 70 tons of pretreated molten iron and 15 tons of scrap steel with a sulfur content not exceeding 0.03% by mass are added to a converter for smelting. Alloy materials are added during tapping to alloy the composition. After tapping, argon blowing is performed to obtain molten steel.

[0049] (3) LF furnace refining and desulfurization The obtained molten steel is sent to an LF furnace for desulfurization treatment, reducing the sulfur content in the molten steel to 0.004%. After desulfurization, the alloy element composition is finely adjusted, and bottom blowing argon is performed to weakly stir until the composition is uniform, thus obtaining refined molten steel.

[0050] (4) RH vacuum refining and inclusion denaturation The refined molten steel was fed into an RH furnace and circulated for 20 minutes under a vacuum pressure of 5 mbar. After the vacuum was broken, 150 m of Ca-Si wire was fed in under bottom-blown argon weak stirring to modify the inclusions. Then, weak stirring was continued for 15 minutes with an argon flow rate of 125 NL / min.

[0051] (5) Continuous casting The treated molten steel is then continuously cast: the molten steel in the ladle is poured into the tundish and continuously cast into slabs through a crystallizer. Continuous casting process parameters: casting speed 1.40 m / min, pouring temperature 1520℃, slab reduction 2.6 mm, electromagnetic stirring frequency 3.5 Hz; a special protective slag is used, with a melting point of 1050±30℃, a viscosity of 0.5±0.05 poise at 1300℃, a basicity of 1.0±0.05, and a melting rate of 25±10 seconds.

[0052] The specifications of the obtained continuously cast slab are: thickness 220mm, width 1260mm, and length 6890mm.

[0053] The slab can be pre-treated by hot conveying and hot charging or by grinding and coating after heat treatment: hot conveying and hot charging temperature of 350℃; heat treatment temperature of 660℃.

[0054] (6) Hot rolling and heat treatment after coiling The continuously cast slab is subjected to the following processes in sequence: slab heating, rough rolling descaling, rough rolling, finish rolling descaling, finish rolling, post-rolling cooling, coiling, and post-coiling heat treatment to obtain hot-rolled coils of high-carbon alloy tool steel. The specific parameters for each process are as follows: ① Slab heating: The slab is heated in a walking beam furnace at a temperature of 1230℃; ② Rough rolling descaling: The heated slab is descaled by high-pressure water during rough rolling to remove the iron oxide scale generated on the surface of the steel billet; ③ Rough rolling: The slab is rolled back and forth 5 times on a four-roll reversible rough rolling mill to form an intermediate strip with a thickness of 40mm, a width of 1260mm and a length of 37913mm. The final rough rolling temperature is 1080℃. ④ Finish rolling descaling: Before finish rolling, the secondary iron oxide scale on the surface of the intermediate billet is removed by a high-pressure water descaling box during finish rolling. ⑤ Finishing rolling: The intermediate strip is rolled into a steel strip with a thickness of 5.0 mm, a width of 1250 mm, and a length of 305.7 m on a 7-stand finishing mill. The finishing rolling temperature is 850℃. ⑥ Post-rolling cooling: Cooling the finished steel strip after rolling; ⑦ Winding: A fully hydraulic mobile winding machine with 3 sets of winding rollers is used to wind steel coils at a temperature of 730℃; ⑧ Heat treatment after coiling: The hot-rolled coil is heat-treated at a temperature of 660℃.

[0055] The test results of this embodiment, based on quality and performance testing, are as follows: Hot-rolled condition: yield strength 860MPa, tensile strength 1170MPa, elongation 13%, Brinell hardness (HBW) 350, single-sided decarburization layer depth 0.01mm; Heat-treated annealed state: yield strength 510MPa, tensile strength 800MPa, elongation 25%, Brinell hardness (HBW) 240, single-sided decarburized layer depth 0.01mm, total inclusions 0.5.

[0056] Example 2 The chemical composition of the high-carbon alloy tool steel for chainsaw tools in Example 2, by mass percentage, is as follows: C: 0.74%; Si: 0.52%; Mn: 0.82%; Al: 0.020%; P: 0.008%; S: 0.003%; Cr: 0.79%; Ni: 0.62%; Mo: 0.20%; V: 0.07%; Nb: 0.041%; Cu: 0.07%, with the balance being Fe and unavoidable impurity elements.

[0057] The specific process of preparing high-carbon alloy tool steel for chainsaw tools in Example 2 includes: This embodiment is prepared in an 80-ton top-and-bottom blowing converter and a 1549mm hot strip mill. The preparation process includes the following steps in sequence: (1) Hot metal pretreatment The blast furnace molten iron is desulfurized and pretreated by removing slag, so that the mass percentage of sulfur in the molten iron after pretreatment is reduced to 0.003%.

[0058] (2) Converter smelting and alloying 70 tons of pretreated molten iron and 15 tons of scrap steel with a sulfur content not exceeding 0.03% by mass are added to a converter for smelting. Alloy materials are added during tapping to alloy the composition. After tapping, argon blowing is performed to obtain molten steel.

[0059] (3) LF furnace refining and desulfurization The obtained molten steel is sent to an LF furnace for desulfurization treatment, reducing the sulfur content in the molten steel to 0.003%. After desulfurization, the alloy element composition is finely adjusted, and bottom blowing argon is performed to weakly stir until the composition is uniform, thus obtaining refined molten steel.

[0060] (4) RH vacuum refining and inclusion denaturation The refined molten steel was fed into an RH furnace and circulated for 20 minutes under a vacuum pressure of 5 mbar. After the vacuum was broken, 150 m of Ca-Si wire was fed in under bottom-blown argon weak stirring to modify the inclusions. Then, weak stirring was continued for 15 minutes with an argon flow rate of 125 NL / min.

[0061] (5) Continuous casting The treated molten steel is then continuously cast: the molten steel in the ladle is poured into the tundish and continuously cast into slabs through a crystallizer. Continuous casting process parameters: casting speed 1.40 m / min, pouring temperature 1520℃, slab reduction 2.6 mm, electromagnetic stirring frequency 3.5 Hz; a special protective slag is used, with a melting point of 1050±30℃, a viscosity of 0.5±0.05 poise at 1300℃, a basicity of 1.0±0.05, and a melting rate of 25±10 seconds.

[0062] The specifications of the obtained continuously cast slab are: thickness 220mm, width 1260mm, and length 6890mm.

[0063] The slab can be pre-treated by hot conveying and hot charging or by grinding and coating after heat treatment: hot conveying and hot charging temperature of 350℃; heat treatment temperature of 660℃.

[0064] (6) Hot rolling and heat treatment after coiling The continuously cast slab is subjected to the following processes in sequence: slab heating, rough rolling descaling, rough rolling, finish rolling descaling, finish rolling, post-rolling cooling, coiling, and post-coiling heat treatment to obtain hot-rolled coils of high-carbon alloy tool steel. The specific parameters for each process are as follows: ① Slab heating: The slab is heated in a walking beam furnace at a temperature of 1270℃; ② Rough rolling descaling: The heated slab is descaled by high-pressure water during rough rolling to remove the iron oxide scale generated on the surface of the steel billet; ③ Rough rolling: The slab is rolled back and forth 5 times on a four-roll reversible rough rolling mill to form an intermediate strip with a thickness of 40mm and a width of 1260mm. The final rough rolling temperature is 1140℃. ④ Finish rolling descaling: Before finish rolling, the secondary iron oxide scale on the surface of the intermediate billet is removed by a high-pressure water descaling box during finish rolling. ⑤ Finishing rolling: The intermediate strip is rolled into a steel strip with a thickness of 5.0 mm and a width of 1250 mm on a 7-stand finishing mill. The finishing rolling temperature is 920℃. ⑥ Post-rolling cooling: Cooling the finished steel strip after rolling; ⑦ Winding: A fully hydraulic mobile winding machine with 3 sets of winding rollers is used to wind steel coils at a temperature of 630℃; ⑧ Heat treatment after coiling: The hot-rolled coil is heat-treated at a temperature of 660℃.

[0065] The hot-rolled state test results of this embodiment, based on quality and performance testing, are as follows: Yield strength 1370MPa, tensile strength 1620MPa, elongation 7%, Brinell hardness (HBW) 445, single-sided decarburized layer depth 0.00mm, total inclusions 0.5.

[0066] The product in this embodiment meets the performance requirements of hot-rolled coils of high-carbon alloy tool steel for chainsaw tools.

[0067] Example 3 The chemical composition of the high-carbon alloy tool steel for chainsaw tools in Example 3, by mass percentage, is as follows: C: 0.75%; Si: 0.45%; Mn: 0.95%; Al: 0.050%; P: 0.009%; S: 0.005%; Cr: 0.72%; Ni: 0.38%; Mo: 0.25%; V: 0.10%; Nb: 0.047%; Cu: 0.05%, with the balance being Fe and unavoidable impurity elements.

[0068] The specific process of preparing high-carbon alloy tool steel for chainsaw tools in Example 3 includes: This embodiment is prepared in an 80-ton top-and-bottom blowing converter and a 1549mm hot strip mill. The preparation process includes the following steps in sequence: (1) Hot metal pretreatment The blast furnace molten iron is desulfurized and pretreated by removing slag, so that the mass percentage of sulfur in the molten iron after pretreatment is reduced to 0.003%.

[0069] (2) Converter smelting and alloying 70 tons of pretreated molten iron and 15 tons of scrap steel with a sulfur content not exceeding 0.03% by mass are added to a converter for smelting. Alloy materials are added during tapping to alloy the composition. After tapping, argon blowing is performed to obtain molten steel.

[0070] (3) LF furnace refining and desulfurization The obtained molten steel is sent to an LF furnace for desulfurization treatment, reducing the sulfur content in the molten steel to 0.005%. After desulfurization, the alloy element composition is finely adjusted, and bottom blowing argon is performed to weakly stir until the composition is uniform, thus obtaining refined molten steel.

[0071] (4) RH vacuum refining and inclusion denaturation The refined molten steel was fed into an RH furnace and circulated for 20 minutes under a vacuum pressure of 5 mbar. After the vacuum was broken, 150 m of Ca-Si wire was fed in under bottom-blown argon weak stirring to modify the inclusions. Then, weak stirring was continued for 15 minutes with an argon flow rate of 125 NL / min.

[0072] (5) Continuous casting The treated molten steel is then continuously cast: the molten steel in the ladle is poured into the tundish and continuously cast into slabs through a crystallizer. Continuous casting process parameters: casting speed 1.40 m / min, pouring temperature 1520℃, slab reduction 2.6 mm, electromagnetic stirring frequency 3.5 Hz; a special protective slag is used, with a melting point of 1050±30℃, a viscosity of 0.5±0.05 poise at 1300℃, a basicity of 1.0±0.05, and a melting rate of 25±10 seconds.

[0073] The specifications of the obtained continuously cast slab are: thickness 220mm, width 1260mm, and length 6890mm.

[0074] The slab can be pre-treated by hot conveying and hot charging or by grinding and coating after heat treatment: hot conveying and hot charging temperature of 350℃; heat treatment temperature of 660℃.

[0075] (6) Hot rolling and heat treatment after coiling The continuously cast slab is subjected to the following processes in sequence: slab heating, rough rolling descaling, rough rolling, finish rolling descaling, finish rolling, post-rolling cooling, coiling, and post-coiling heat treatment to obtain hot-rolled coils of high-carbon alloy tool steel. The specific parameters for each process are as follows: ① Slab heating: The slab is heated in a walking beam furnace at a temperature of 1220℃; ② Rough rolling descaling: The heated slab is descaled by high-pressure water during rough rolling to remove the iron oxide scale generated on the surface of the steel billet; ③ Rough rolling: The slab is rolled back and forth 5 times on a four-roll reversible rough rolling mill to form an intermediate strip with a thickness of 40mm and a width of 1260mm. The final rough rolling temperature is 1080℃. ④ Finish rolling descaling: Before finish rolling, the secondary iron oxide scale on the surface of the intermediate billet is removed by a high-pressure water descaling box during finish rolling. ⑤ Finishing rolling: The intermediate strip is rolled into a steel strip with a thickness of 5.0 mm and a width of 1250 mm on a 7-stand finishing mill. The finishing rolling temperature is 870℃. ⑥ Post-rolling cooling: Cooling the finished steel strip after rolling; ⑦ Winding: A fully hydraulic mobile winding machine with 3 sets of winding rollers is used to wind steel coils at a temperature of 750℃; ⑧ Heat treatment after coiling: The hot-rolled coil is heat-treated at a temperature of 660℃.

[0076] The hot-rolled state test results of this embodiment, based on quality and performance testing, are as follows: Yield strength 960MPa, tensile strength 1290MPa, elongation 9%, Brinell hardness (HBW) 379, single-sided decarburized layer depth 0.00mm, total inclusions 0.5.

[0077] Example 4 The chemical composition of the high-carbon alloy tool steel for chainsaw tools in Example 4, by mass percentage, is as follows: C: 0.76%; Si: 0.56%; Mn: 0.89%; Al: 0.035%; P: 0.006%; S: 0.003%; Cr: 0.65%; Ni: 0.46%; Mo: 0.15%; V: 0.06%; Nb: 0.044%; Cu: 0.03%; with the balance being Fe and unavoidable impurity elements.

[0078] The specific process of preparing high-carbon alloy tool steel for chainsaw tools in Example 4 includes: This embodiment is prepared in an 80-ton top-and-bottom blowing converter and a 1549mm hot strip mill. The preparation process includes the following steps in sequence: (1) Hot metal pretreatment The blast furnace molten iron is desulfurized and pretreated by removing slag, so that the mass percentage of sulfur in the molten iron after pretreatment is reduced to 0.003%.

[0079] (2) Converter smelting and alloying 70 tons of pretreated molten iron and 15 tons of scrap steel with a sulfur content not exceeding 0.03% by mass are added to a converter for smelting. Alloy materials are added during tapping to alloy the composition. After tapping, argon blowing is performed to obtain molten steel.

[0080] (3) LF furnace refining and desulfurization The obtained molten steel is sent to an LF furnace for desulfurization treatment, reducing the sulfur content in the molten steel to 0.003%. After desulfurization, the alloy element composition is finely adjusted, and bottom blowing argon is performed to weakly stir until the composition is uniform, thus obtaining refined molten steel.

[0081] (4) RH vacuum refining and inclusion denaturation The refined molten steel was fed into an RH furnace and circulated for 20 minutes under a vacuum pressure of 5 mbar. After the vacuum was broken, 150 m of Ca-Si wire was fed in under bottom-blown argon weak stirring to modify the inclusions. Then, weak stirring was continued for 15 minutes with an argon flow rate of 125 NL / min.

[0082] (5) Continuous casting The treated molten steel is then continuously cast: the molten steel in the ladle is poured into the tundish and continuously cast into slabs through a crystallizer. Continuous casting process parameters: casting speed 1.40 m / min, pouring temperature 1520℃, slab reduction 2.6 mm, electromagnetic stirring frequency 3.5 Hz; a special protective slag is used, with a melting point of 1050±30℃, a viscosity of 0.5±0.05 poise at 1300℃, a basicity of 1.0±0.05, and a melting rate of 25±10 seconds.

[0083] The specifications of the obtained continuously cast slab are: thickness 220mm, width 1260mm, and length 6890mm.

[0084] The slab can be pre-treated by hot conveying and hot charging or by grinding and coating after heat treatment: hot conveying and hot charging temperature of 350℃; heat treatment temperature of 660℃.

[0085] (6) Hot rolling and heat treatment after coiling The continuously cast slab is subjected to the following processes in sequence: slab heating, rough rolling descaling, rough rolling, finish rolling descaling, finish rolling, post-rolling cooling, coiling, and post-coiling heat treatment to obtain hot-rolled coils of high-carbon alloy tool steel. The specific parameters for each process are as follows: ① Slab heating: The slab is heated in a walking beam furnace at a temperature of 1250℃; ② Rough rolling descaling: The heated slab is descaled by high-pressure water during rough rolling to remove the iron oxide scale generated on the surface of the steel billet; ③ Rough rolling: The slab is rolled back and forth 5 times on a four-roll reversible rough rolling mill to form an intermediate strip with a thickness of 40mm and a width of 1260mm. The final rough rolling temperature is 1090℃. ④ Finish rolling descaling: Before finish rolling, the secondary iron oxide scale on the surface of the intermediate billet is removed by a high-pressure water descaling box during finish rolling. ⑤ Finishing rolling: The intermediate strip is rolled into a steel strip with a thickness of 5.0 mm and a width of 1250 mm on a 7-stand finishing mill. The finishing rolling temperature is 900℃. ⑥ Post-rolling cooling: Cooling the finished steel strip after rolling; ⑦ Winding: A fully hydraulic mobile winding machine with 3 sets of winding rollers is used to wind steel coils at a temperature of 700℃; ⑧ Heat treatment after coiling: The hot-rolled coil is heat-treated at a temperature of 660℃.

[0086] The hot-rolled state test results of this embodiment, based on quality and performance testing, are as follows: Yield strength 930MPa, tensile strength 1250MPa, elongation 10%, Brinell hardness (HBW) 368, single-sided decarburized layer depth 0.01mm, total inclusions 0.5.

[0087] Example 5 The chemical composition of the high-carbon alloy tool steel for chainsaw tools in Example 5, by mass percentage, is as follows: C: 0.72%; Si: 0.41%; Mn: 1.10%; Al: 0.042%; P: 0.010%; S: 0.002%; Cr: 0.75%; Ni: 0.35%; Mo: 0.12%; V: 0.05%; Nb: 0.042%; Cu: 0.03%, with the balance being Fe and unavoidable impurity elements.

[0088] The specific process of preparing high-carbon alloy tool steel for chainsaw tools in Example 5 includes: This embodiment is prepared in an 80-ton top-and-bottom blowing converter and a 1549mm hot strip mill. The preparation process includes the following steps in sequence: (1) Hot metal pretreatment The blast furnace molten iron is desulfurized and pretreated by removing slag, so that the mass percentage of sulfur in the molten iron after pretreatment is reduced to 0.003%.

[0089] (2) Converter smelting and alloying 70 tons of pretreated molten iron and 15 tons of scrap steel with a sulfur content not exceeding 0.03% by mass are added to a converter for smelting. Alloy materials are added during tapping to alloy the composition. After tapping, argon blowing is performed to obtain molten steel.

[0090] (3) LF furnace refining and desulfurization The obtained molten steel is sent to an LF furnace for desulfurization treatment, reducing the sulfur content in the molten steel to 0.002%. After desulfurization, the alloy element composition is finely adjusted, and bottom blowing argon is performed to weakly stir until the composition is uniform, thus obtaining refined molten steel.

[0091] (4) RH vacuum refining and inclusion denaturation The refined molten steel was fed into an RH furnace and circulated for 20 minutes under a vacuum pressure of 5 mbar. After the vacuum was broken, 150 m of Ca-Si wire was fed in under bottom-blown argon weak stirring to modify the inclusions. Then, weak stirring was continued for 15 minutes with an argon flow rate of 125 NL / min.

[0092] (5) Continuous casting The treated molten steel is then continuously cast: the molten steel in the ladle is poured into the tundish and continuously cast into slabs through a crystallizer. Continuous casting process parameters: casting speed 1.40 m / min, pouring temperature 1520℃, slab reduction 2.6 mm, electromagnetic stirring frequency 3.5 Hz; a special protective slag is used, with a melting point of 1050±30℃, a viscosity of 0.5±0.05 poise at 1300℃, a basicity of 1.0±0.05, and a melting rate of 25±10 seconds.

[0093] The specifications of the obtained continuously cast slab are: thickness 220mm, width 1260mm, and length 6890mm.

[0094] The slab can be pre-treated by hot conveying and hot charging or by grinding and coating after heat treatment: hot conveying and hot charging temperature of 350℃; heat treatment temperature of 660℃.

[0095] (6) Hot rolling and heat treatment after coiling The continuously cast slab is subjected to the following processes in sequence: slab heating, rough rolling descaling, rough rolling, finish rolling descaling, finish rolling, post-rolling cooling, coiling, and post-coiling heat treatment to obtain hot-rolled coils of high-carbon alloy tool steel. The specific parameters for each process are as follows: ① Slab heating: The slab is heated in a walking beam furnace at a temperature of 1170℃; ② Rough rolling descaling: The heated slab is descaled by high-pressure water during rough rolling to remove the iron oxide scale generated on the surface of the steel billet; ③ Rough rolling: The slab is rolled back and forth 5 times on a four-roll reversible rough rolling mill to form an intermediate strip with a thickness of 40mm and a width of 1260mm. The final rough rolling temperature is 1020℃. ④ Finish rolling descaling: Before finish rolling, the secondary iron oxide scale on the surface of the intermediate billet is removed by a high-pressure water descaling box during finish rolling. ⑤ Finishing rolling: The intermediate strip is rolled into a steel strip with a thickness of 5.0 mm and a width of 1250 mm on a 7-stand finishing mill. The finishing rolling temperature is 830℃. ⑥ Post-rolling cooling: Cooling the finished steel strip after rolling; ⑦ Winding: A fully hydraulic mobile winding machine with 3 sets of winding rollers is used to wind steel coils at a temperature of 650℃; ⑧ Heat treatment after coiling: The hot-rolled coil is heat-treated at a temperature of 660℃.

[0096] The hot-rolled state test results of this embodiment, based on quality and performance testing, are as follows: Yield strength 1330MPa, tensile strength 1575MPa, elongation 8%, Brinell hardness (HBW) 442, single-sided decarburized layer depth 0.00mm, total inclusions 0.5.

[0097] In summary, compared with the prior art, the high-carbon alloy tool steel for chainsaw tools and its preparation method of the present invention have the following advantages and positive effects: (1) The present invention provides a method for preparing hot-rolled coils of high-carbon alloy tool steel. Pure steel is obtained by using ladle refining: LF deep desulfurization + RH vacuum degassing, Ca treatment of spheroidized inclusions, temperature control at each node of the smelting process and oxygen and nitrogen control throughout the process, reasonable application of light pressing and electromagnetic stirring technology, and optimization of secondary cooling water model. This effectively prevents the occurrence of corner cracks and longitudinal cracks. (2) The present invention provides a method for preparing hot-rolled coil of high-carbon alloy tool steel. Through specific hot charging and loading processes, heat treatment processes, slab grinding and coating processes, the slab crack defects that may occur in the connection process between hot rolling and steelmaking are effectively controlled, and a hot-rolled coil of high-carbon alloy tool steel with pure steel quality and excellent quality is obtained. (3) The hot-rolled coil of high-carbon alloy tool steel of the present invention has good comprehensive performance; it has excellent hardness uniformity, high strength and toughness, and high wear resistance. Its hot-rolled mechanical properties are: its yield strength is 710-1650MPa, its tensile strength is 860-1950MPa, its elongation is ≥5%, its Brinell hardness is 258-550, and its single-sided decarburization layer depth is ≤0.01mm; its heat-treated annealed mechanical properties are: its yield strength is 345-885MPa, its tensile strength is 555-1250MPa, its elongation is ≥25%, its Brinell hardness is 163-370, and its single-sided decarburization layer depth is ≤0.02mm; the Brinell hardness fluctuation of the hot-rolled coil of high-carbon alloy tool steel after quenching and tempering is less than 1.5%, its yield strength after quenching and tempering is not less than 1100MPa, and its tensile strength is not less than 1500MPa.

[0098] In the description of this specification, the term "embodiment" means a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. The illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment. Furthermore, those skilled in the art can combine or combine the different embodiments and features described in this specification without creating contradiction.

[0099] It should be noted that, unless otherwise specified, the terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, when a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum. Further, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Moreover, when multiple ranges are provided to describe features, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0100] It should also be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A high-carbon alloy tool steel for chainsaw tools, characterized in that, The chemical composition of the high-carbon alloy tool steel used for chainsaw tools is controlled by mass percentage as follows: 0.70%≤C≤0.79%, 0.40%≤Si≤0.60%, 0.80%≤Mn≤1.15%, 0.015%≤Al≤0.060%, P≤0.010%, S≤0.005%, 0.60%≤Cr≤0.85%, 0.30%≤Ni≤0.68%, 0.10%≤Mo≤0.30%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.050%, Cu≤0.070%, with the balance being Fe and unavoidable impurities.

2. The high-carbon alloy tool steel for chainsaw tools according to claim 1, characterized in that, The chemical composition of the high-carbon alloy tool steel used for chainsaw tools is controlled by mass percentage as follows: 0.71%≤C≤0.76%, 0.41%≤Si≤0.56%, 0.82%≤Mn≤1.10%, P≤0.010%, S≤0.005%, 0.020%≤Al≤0.050%, 0.62%≤Cr≤0.79%, 0.35%≤Ni≤0.62%, 0.12%≤Mo≤0.25%, 0.05%≤V≤0.10%, 0.040%≤Nb≤0.047%, Cu≤0.070%, with the balance being Fe and unavoidable impurities.

3. The high-carbon alloy tool steel for chainsaw tools according to claim 1, characterized in that, The hot-rolled mechanical properties of the high-carbon alloy tool steel hot-rolled coils used for chainsaw tools are as follows: yield strength of 710-1650MPa, tensile strength of 860-1950MPa, elongation ≥5%, Brinell hardness of 258-550, and single-sided decarburization layer depth ≤0.01mm.

4. The high-carbon alloy tool steel for chainsaw tools according to claim 1, characterized in that, The hot-rolled coil of high-carbon alloy tool steel used for chainsaw tools has the following mechanical properties in the heat-treated annealed state: yield strength of 345-885 MPa, tensile strength of 555-1250 MPa, elongation ≥25%, Brinell hardness of 163-370, single-sided decarburization layer depth ≤0.02 mm, Brinell hardness fluctuation of the hot-rolled coil of high-carbon alloy tool steel after quenching and tempering is less than 1.5%, yield strength of not less than 1100 MPa and tensile strength of not less than 1500 MPa after quenching and tempering.

5. A method for preparing high-carbon alloy tool steel for chainsaw tools, characterized in that, Includes the following steps: (1) Hot metal pretreatment: Desulfurization pretreatment is carried out on the blast furnace hot metal, and slag is removed so that the mass percentage of sulfur in the hot metal after pretreatment does not exceed 0.003%; (2) Converter smelting and alloying: The pretreated molten iron and scrap steel with a sulfur content not exceeding 0.03% by mass are added to the converter for smelting. When the steel is tapped from the converter, alloy materials are added to alloy the composition. Then, argon blowing is performed to obtain molten steel. (3) LF furnace refining and desulfurization: The molten steel is sent into the LF furnace for desulfurization treatment until the mass percentage of sulfur in the molten steel does not exceed 0.005%. Then the alloy element composition is finely adjusted and bottom blowing argon weak stirring is performed until the composition is uniform, and refined molten steel is obtained. (4) RH vacuum refining and inclusion modification: The refined molten steel is fed into an RH furnace and circulated for more than 10 minutes under a vacuum pressure of no more than 10 mbar. After the vacuum is broken, the molten steel is subjected to inclusion modification treatment under bottom blowing argon weak stirring. (5) Continuous casting: The molten steel processed in step (4) is continuously cast to obtain a continuously cast slab; (6) Hot rolling and heat treatment after coiling: The continuously cast slab is subjected to slab heating, rough rolling descaling, rough rolling, fine rolling descaling, fine rolling, cooling after rolling, coiling, and heat treatment after coiling in sequence to obtain hot-rolled coil of high carbon alloy tool steel.

6. The method for preparing high-carbon alloy tool steel for chainsaw tools according to claim 5, characterized in that, In step (2), the mass percentage of the pretreated molten iron to scrap steel is 80%~95%:5%~20%, and the alloy materials include carbon powder, aluminum ferromanganese, high carbon ferromanganese, silicon-manganese alloy and ferrochrome.

7. The method for preparing high-carbon alloy tool steel for chainsaw tools according to claim 5, characterized in that, In step (3), the argon flow rate for bottom blowing argon weak stirring is 20~200NL / min, and the stirring time is not less than 5 minutes.

8. The method for preparing high-carbon alloy tool steel for chainsaw tools according to claim 5, characterized in that, In step (4), the bottom blowing argon weak stirring time after vacuum breaking is not less than 8 minutes, and the inclusion modification treatment is to feed calcium silicon wire into the molten steel.

9. The method for preparing high-carbon alloy tool steel for chainsaw tools according to claim 5, characterized in that, In the continuous casting process of step (5), the pouring temperature is 1455~1565℃, the casting speed is 0.85~1.65m / min, the superheat of molten steel is 15℃~50℃, the light reduction of the billet is 0~5mm, and the frequency of electromagnetic stirring is 2.5~5.0Hz.

10. The method for preparing high-carbon alloy tool steel for chainsaw tools according to claim 5, characterized in that, In step (6), before heating the slab, the continuously cast slab is first hot-charged or heat-treated, then ground and coated. The hot-charge temperature is not lower than 200℃, and the heat treatment temperature is 550~850℃. The slab heating temperature is 1150℃~1300℃, the roughing and finishing rolling temperature is 1000℃~1200℃, the finishing rolling temperature is 800℃~930℃, the coiling temperature is 580℃~800℃, and the heat treatment temperature after coiling is 550~850℃.

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