High toughness and high wear resistance saw blade steel and manufacturing method thereof

Abstract

The present application belongs to the field of ferrous materials, and particularly relates to a high-strength and high-toughness high-wear-resistance saw blade steel and a manufacturing method thereof. The chemical components of the steel are as follows in terms of percentage by weight: C: 0.30-0.40%, Si: 0.8-1.0%, Mn: 0.9-1.1%, P≤0.025%, S≤0.010%, B: 0.0020-0.0040%, TiB2: 0.50-0.60%, and B / TiB2: 0.003-0.006, with the balance being Fe and inevitable impurities. The yield strength of the saw blade steel is ≥1185 MPa, the tensile strength is ≥1406 MPa, the elongation is ≥19%, the room temperature impact energy AKV is ≥90 J, the hardness is 42-48 HRC, the tooth tip quenching hardness satisfies ≥58 HRC, and the 24h abrasion loss is <15 mg.

Description

Technical Field

[0001] This invention belongs to the field of ferrous metal materials, and particularly relates to a high-strength, high-toughness, and high-wear-resistant saw blade steel and its manufacturing method. Background Technology

[0002] Stone saws are primary tools in modern mining, used to cut various types of hard rock. They endure immense wear during operation, making wear resistance the primary factor affecting their lifespan. Simultaneously, a good balance of strength and ductility is required to maintain good resistance to impact cracking. Furthermore, in actual saw blade production, the hardness of the saw teeth is generally achieved through induction hardening; therefore, it is also essential to ensure that the saw blade steel possesses sufficient hardness at the tooth tips after quenching.

[0003] Patent document CN113528943B discloses a high-strength and high-toughness steel for metallurgical saw blades and its preparation method. The composition, by mass percentage, is: C 0.35–0.42%, Si 1.1–1.4%, Mn 0.08–1.4%, Cr 0.3–0.7%, P ≤0.009%, S ≤0.002%, V 0.08–1.4%, Al 0.005–0.040%, with the balance being Fe and unavoidable impurities. The saw blade steel manufactured using this technology achieves a room temperature toughness of 20–24 J and a hardness of 268–283 HBW.

[0004] Patent document CN116121644A discloses a high-toughness mining circular saw blade steel plate and its manufacturing method. The composition, by mass percentage, includes: C 0.47–0.52%, Si 0.4–0.6%, Mn 1.30–1.50%, V 0.08–0.12%, Al 0.03–0.06%, Cr 0.10–0.30%, P ≤ 0.012%, S ≤ 0.002%, Ca 0.0010–0.0030%, with the balance being Fe and unavoidable impurities. The steel plate of this invention has a thickness ≤ 12 mm, a width up to 4000 mm, an impact strength (Akv ≥ 27 J) at 20℃, and a hardness of 30–40 HRC.

[0005] The saw blade steel produced by the above two technologies has low strength, hardness and toughness, which cannot meet the high hardness and high toughness requirements of diamond saw blade matrix steel for stone, and the wear resistance of the saw blade steel is not taken into consideration.

[0006] Patent document CN104532150B discloses an economical, ultra-wide saw blade steel and its manufacturing method. The composition, by mass percentage, includes: C 0.35–0.45%, Si 0.10–0.50%, Mn 0.60–1.20%, P ≤0.030%, S ≤0.010%, B 0.0010–0.0040%, Al 0.010–0.080%, Ti ≤0.060%, Ca 0.0010–0.0040%. The saw blade contains one or more of the following components: 0.0080%, N≤0.0080%, O≤0.0080%, H≤0.0004%, and Nb 0.001~0.050%, Cr 0.01~0.50%, Mo 0.01~0.50%, Ni 0.01~0.50%, and V 0.01~0.15%, with the condition that 0.15%≤(Cr / 5+Mn / 6+50B)≤0.45%, and the remainder being Fe and unavoidable impurities. This technology can produce steel plates with a thickness of 6~16mm and saw blade diameters of 1700~4500mm. Through online water cooling and tempering, the saw blade steel has a yield strength greater than 850MPa, a tensile strength of 1000~1400MPa, an elongation greater than 10%, and a Charpy V-shaped longitudinal impact energy of 50~90J. The hardness of the saw blade steel in the invention is less than 49 HRC in the quenched state, which cannot meet the requirement of ≥58 HRC hardness for the tooth tip quenching, and the wear resistance of the saw blade steel is not taken into consideration.

[0007] Therefore, existing technologies have not solved the performance requirements of stone saws for the high strength, toughness, and wear resistance of the saw blade matrix. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a high-strength, high-toughness, and high-wear-resistant saw blade steel and its manufacturing method. By appropriately reducing the carbon content and adding the highly hardenable element boron (B), the steel's ductility and toughness are improved while maintaining its strength and hardness. The addition of reinforcing phase particles TiB2 refines the grain size and increases strength. Simultaneously, the growth morphology and distribution of TiB2 are regulated by B, resulting in long rod-shaped TiB2 particles (≥10µm in length) distributed within the grains, serving as wear-resistant reinforcing particles and improving the steel's wear resistance under hot cutting conditions. Through smelting process design, uniform distribution of TiB2 particles is promoted, resulting in good billet quality. Through rolling heat treatment process design, the uniformity of the microstructure is improved and the grain size is refined, obtaining a tempered troostite microstructure with a reasonable balance of strength, toughness, and wear resistance, thus achieving the production of high-strength, high-toughness, and high-wear-resistant saw blade steel.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] A high-strength, high-toughness, and high-wear-resistant saw blade steel, wherein the chemical composition of the steel by weight percentage is: C: 0.30%–0.40%, Si: 0.8%–1.0%, Mn: 0.9%–1.1%, P≤0.025%, S≤0.010%, B: 0.0020%–0.0040%, TiB2: 0.50%–0.60%, and the B / TiB2 ratio is 0.003–0.006, with the balance being Fe and unavoidable impurities.

[0011] The reasons for using the above-mentioned components are as follows:

[0012] C: C is an important element for ensuring the strength and wear resistance of saw blade steel, but an increase in C content will significantly reduce the plasticity and toughness of the steel. Therefore, this invention controls the C content in the steel within the range of 0.30% to 0.40%.

[0013] Si: Si is a good deoxidizer that can improve the strength and wear resistance of steel, but an increase in Si content will reduce the plasticity and toughness of steel. Therefore, the Si content in this invention is controlled at 0.8% to 1.0%.

[0014] Mn: Mn is an important deoxidizer and desulfurizer in steel. Excessive Mn content can lead to increased thermal stress and a high risk of cracking in steel. Therefore, the Mn content in this invention is controlled at 0.9% to 1.1%.

[0015] P: P is a harmful element in steel, easily causing cold brittleness. However, strict control of P content increases production costs. Therefore, this invention controls the P content in steel to ≤0.025%.

[0016] S: S is a harmful element in steel, causing hot brittleness and reducing its ductility and toughness. Therefore, this invention requires that the S content in the steel be ≤0.010%.

[0017] B: B can significantly improve the hardenability of steel and is an important strengthening element in steel, but excessive B content will lead to a decrease in the toughness of steel. Therefore, in this invention, the B content is controlled at 0.0020% to 0.0040%.

[0018] TiB2: TiB2 has excellent high-temperature resistance and high hardness, but excessive TiB2 is detrimental to the plasticity of steel. Therefore, the TiB2 content in this invention is controlled at 0.50% to 0.60%.

[0019] This invention controls the B / TiB2 ratio to be 0.003–0.006. B has a significant impact on the growth morphology and distribution of TiB2 particles in steel. With the relative change of B content, the TiB2 particle size is distributed along grain boundaries or within grains in the form of long rods or granules. This invention, by controlling the addition ratio of the two, makes the TiB2 particles distributed in the grains in the form of long rods (length ≥10µm), serving as wear-resistant reinforcing particles and improving the wear resistance of steel under hot cutting conditions.

[0020] The thickness of the saw blade steel is 6-12 mm.

[0021] The saw blade steel has a yield strength ≥1185MPa, tensile strength ≥1406MPa, elongation ≥19%, room temperature impact energy AKV ≥90J, hardness 42~48HRC, tooth tip quenching hardness ≥58HRC, and 24h wear amount <15mg.

[0022] A method for manufacturing high-strength, high-toughness, and high-wear-resistant saw blade steel, the specific method including:

[0023] 1) Use converter slag-blocking for steel tapping, and control the slag layer thickness to 40-55mm to improve the recovery rate of alloying elements and reduce the content of inclusions; control the quenching time of the ladle before it is put on the machine to 15-25min to ensure that the composition of the molten steel is uniform.

[0024] 2) TiB2 is produced using a KBF4-K2TiF6 mixed salt powder system, with a Ti / B atomic ratio of 1:2 to 2.5. The mixed salt powder is wrapped in a thin steel strip to form a cored wire, which is fed into the ladle through a wire feeder during the ladle refining process. The target superheat of the tundish is controlled at 20 to 25°C to ensure the quality of the billet and production efficiency. The entire casting process is protected and electromagnetic stirring is carried out in the crystallizer to promote the uniform distribution of TiB2 particles, with a current intensity of 500 to 600 A. To eliminate defects such as cracks, segregation, porosity, and shrinkage cavities in the billet, dynamic light reduction is applied at the end of solidification. The reduction range is at the position of 0.6 to 1.0 in the central solid fraction, with a reduction of 8 to 9 mm and a reduction rate of 1.2 to 1.6 mm / min. The secondary cooling water volume is controlled at 0.40 to 0.48 L / kg. The continuous casting process adopts a constant casting speed of 0.8 to 1.0 m / min.

[0025] 3) The temperature of the second heating section of the slab is 1160~1220℃, the temperature of the soaking section is 1170~1200℃, and the total time in the furnace is 0.8~1.2min / mm to allow the alloying elements to diffuse fully; the initial rolling temperature is not less than 1100℃, the reduction rate of the first three passes is ≥30% to allow the rolling force to penetrate into the core of the slab and improve the uniformity of the structure, the reduction rate of the last two passes is 6%~9% to improve the slab shape, and the final rolling temperature is 820~850℃ to refine the grains and improve the plasticity of the steel.

[0026] 4) The heat treatment adopts the quenching (oil) + tempering process. The quenching (oil) temperature is 800-820℃ and the holding time is 8-12min. The tempering temperature is 400-450℃ and the holding time is 4-6h. The steel structure is tempered martensite.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1) By appropriately reducing the C content and adding the highly hardenable element B, the ductility and toughness of the steel can be improved while ensuring its strength and hardness. The addition of reinforcing phase particles TiB2 can refine the grains and improve the strength. At the same time, by controlling the growth morphology and distribution of TiB2 through B, the TiB2 particles are distributed in the grains in the form of long rods (length ≥10µm), which serve as wear-resistant reinforcing particles and improve the wear resistance of the steel under hot cutting conditions.

[0029] 2) Through smelting process design, promote the uniform distribution of TiB2 particles and reduce defects in the billet to obtain good billet quality; through rolling process design, improve the uniformity of the structure and refine the grains, laying the structural foundation for obtaining good strength and plasticity; through heat treatment process design, obtain tempered troostite structure with a reasonable match between strength, toughness and wear resistance.

[0030] 3) The saw blade steel of this invention has a thickness of 6-12mm, yield strength ≥1185MPa, tensile strength ≥1406MPa, elongation ≥19%, room temperature impact energy AKV ≥90J, hardness 42-48HRC, tooth tip quenching hardness ≥58HRC, and 24h wear amount <15mg. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the specific implementation methods of this invention will be further described below in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of this invention. These embodiments are only general descriptions of the content of this invention and do not limit the content of this invention.

[0032] The specific implementation method of a high-strength, high-toughness, and high-wear-resistant saw blade steel and its manufacturing method is as follows:

[0033] The alloy element ratios in Table 1 are used for converter smelting, VD refining, continuous casting, slab heating, controlled rolling, and controlled cooling. The main process parameters for smelting, heating, controlled rolling, and controlled cooling in each embodiment are shown in Tables 2 to 6, and the mechanical properties are shown in Table 7.

[0034] Table 1. Chemical composition (%) of steel smelting in each embodiment

[0035]

[0036] Table 2 Steelmaking process parameters for each embodiment

[0037]

[0038] Table 3 Steelmaking process parameters for each embodiment

[0039]

[0040] Table 4 Steelmaking process parameters for each embodiment

[0041]

[0042] Table 5 Steelmaking process parameters for each embodiment

[0043]

[0044] Table 6. Steel heat treatment process parameters for each embodiment.

[0045]

[0046] Table 7 Mechanical properties of each embodiment

[0047]

[0048] *Test conditions: M-2000 testing machine, dry friction, test force 20N, speed 120 rpm, ambient temperature 26℃.

[0049] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-strength, high-toughness, and high-wear-resistant saw blade steel, characterized in that, The chemical composition of the steel, by weight percentage, is as follows: C: 0.30%~0.40%, Si: 0.8%~1.0%, Mn: 0.9%~1.1%, P≤0.025%, S≤0.010%, B: 0.0020%~0.0040%, TiB2: 0.50%~0.60%, and the B / TiB2 ratio is 0.003~0.006, with the balance being Fe and unavoidable impurities; The saw blade steel has a yield strength ≥1185MPa, tensile strength ≥1406MPa, elongation ≥19%, room temperature impact energy AKV ≥90J, hardness 42~48HRC, tooth tip quenching hardness ≥58HRC, and 24h wear amount <15mg.

2. The high-strength, high-toughness, and high-wear-resistant saw blade steel according to claim 1, characterized in that, The thickness of the saw blade steel is 6-12 mm.

3. The high-strength, high-toughness, and high-wear-resistant saw blade steel according to claim 1, characterized in that, The microstructure of saw blade steel is tempered martensite.

4. The high-strength, high-toughness, and high-wear-resistant saw blade steel according to claim 1, characterized in that, In steel, TiB2 particles are distributed in the form of long rods within the crystals, with a length ≥10µm.

5. A method for manufacturing high-strength, high-toughness, and high-wear-resistant saw blade steel as described in any one of claims 1-4, characterized in that, Specific methods include: 1) Use converter slag-blocking tapping, control the slag layer thickness to 40-55mm, and control the quenching time of the ladle before it is loaded onto the machine to 15-25min; 2) The target superheat of the tundish is controlled at 20-25℃. The entire process is protected during casting and the crystallizer is used for electromagnetic stirring with a current intensity of 500-600A. The reduction zone is located at the center solids content of 0.6-1.0, with a reduction of 8-9mm and a reduction rate of 1.2-1.6mm / min. The secondary cooling water volume is controlled at 0.40-0.48L / kg. The continuous casting process adopts a constant casting speed of 0.8-1.0m / min. 3) The temperature of the second heating section of the slab is 1160~1220℃, the temperature of the soaking section is 1170~1200℃, the total time in the furnace is 0.8~1.2min / mm, the initial rolling temperature is not less than 1100℃, the reduction rate of the first three passes is ≥30%, the reduction rate of the last two passes is 6%~9%, and the final rolling temperature is 820~850℃. 4) The heat treatment adopts the quenching + tempering process. The quenching temperature is 800~820℃ and the holding time is 8~12min. The tempering temperature is 400~450℃ and the holding time is 4~6h.

Images