Steel for adjustment-free saw blade base body for mine and production method of steel

Abstract

The invention discloses adjustment-free steel for a saw blade base body for a mine and a production method of the adjustment-free steel. The technological process comprises the steps of converter smelting, refining, continuous casting, heating and rolling, performance inspection and inspection and warehousing. The steel comprises the following chemical components in percentage by mass: 0.27%-0.31% of C, 0.20%-0.30% of Si, 1.00%-1.15% of Mn, 0.018%-0.025% of Ti, 0.55%-0.65% of Cr, 0.025%-0.030% of Nb, 0.15%-0.20% of Mo, 0.0012%-0.0022% of B, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.02%-0.050% of Als and the balance of Fe and inevitable impurities. The tensile strength of the produced steel plate is larger than or equal to 900 MPa, the elongation A50 is larger than or equal to 12%, the surface hardness of the whole plate is 26-31 HRC, and the impact energy value at the temperature of 0 DEG C is larger than or equal to 100 J. The steel for the saw blade has the advantages of being low in alloy cost, easy to weld, free of quenching and tempering heat treatment, short in production period, capable of saving energy, environmentally friendly and high in toughness and plasticity, the service life can be greatly prolonged, and the production cost is reduced. The requirements of the steel for the high-strength saw blade base body for the mine are met.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and relates to a steel for the base of a mine-use, non-adjustable saw blade and its production method. Background Technology

[0002] Mining saw blades cut stone at high speeds, bearing significant radial and axial stresses. This necessitates high elastic limit, stiffness, fatigue strength, wear resistance, and impact toughness. Therefore, strict requirements are placed on the chemical composition, metallurgical quality, and mechanical properties of the saw blade steel. For example, high rigidity and toughness, low heat sensitivity, and hardenability are required. Currently, commonly used steel grades for manufacturing saw blades include medium carbon saw blade steel, medium carbon low-alloy saw blade steel, high carbon saw blade steel, and high carbon low-alloy saw blade steel. Representative grades include 45, 30CrMo, 50Mn2V, 65Mn, 75Cr1, T8A, and T10A. Common specifications are hot-rolled steel plates with thicknesses of 2.0–14.0 mm and widths of 900–3000 mm.

[0003] The commonly used saw blade steel grades mentioned above all present some problems during steel mill production or saw blade manufacturing processes: 1) Poor hardenability, resulting in low hardness after heat treatment, such as 45, 30CrMo, and 50Mn2V; 2) Insufficient hardenability, leading to low and uneven hardness after quenching, making it unsuitable for manufacturing thicker, larger-sized saw blades such as 45, 30CrMo, and 65Mn; 3) Difficulty in continuous casting and hot rolling of slabs, high sensitivity to slab defects, and chemical defects. Large elemental segregation easily leads to cracks and fractures, resulting in high strength of rolled steel plates, large residual stress, and poor plate shape, making it inconvenient for users to perform machining, cold working, and heat treatment, such as 50Mn2V, 65Mn, 75Cr1, T8A, and T10A; 4) Poor tempering stability, the hardness of saw blades will rapidly decrease when tempered at high temperatures after quenching, such as 45, 30CrMo, 50Mn2V, 65Mn, 75Cr1, T8A, and T10A.

[0004] Chinese patent CN104099520A discloses "a high-carbon low-alloy saw blade steel machine and its hot-rolled steel plate production method". The chemical composition is C=0.78~0.86%, Si=0.15~0.40%, Mn=0.40~0.70%, P≤0.025%, S≤0.015%, Al=0.005~0.050%, Ca=0~0.0050%, Cr=0.50~0.80%, V=0.15~0.25%, Ni≤0.25%, Cu≤0.20%. The high carbon content and the presence of Ni and relatively high levels of V result in high alloy costs and a tendency to exhibit defects such as segregation, which affects the service life.

[0005] Chinese patent CN102296243A discloses "a steel for the matrix of diamond saw blades and its production method". The chemical composition is C=0.67%~0.75%, Si=0.17%~0.37%, Mn=0.9%~1.20%, Cr=0.4%~0.7%, Ni≤0.25%, Cu≤0.2% heat-treated medium and thick plates. The high carbon content and the presence of Ni and relatively high Cr elements result in high alloy costs and a tendency to produce defects such as segregation, which affects the service life. At the same time, the presence of a certain amount of Cu is not conducive to the control of surface cracks in the cast billet.

[0006] Chinese patent CN 106319378 B discloses "a type of steel for the base of a large-diameter thin saw blade and its manufacturing method," with the following chemical composition: C=0.72%~0.95%, Si=0.06%~0.40%, Mn=0.5%~0.95%, Cr=0.10%~0.39%, V=0.03%~0.080%, Ni≤0.5%, H≤0.0002%, impurity elements P≤0.015%, S≤0.010%, and Al≤0.010% heat-treated steel plate. Its extremely high C and Mn content is unfavorable for welding the blade head. Furthermore, the high Ni content results in high alloy costs. Additionally, subsequent saw blade manufacturing requires oil quenching, which demands high-quality quenching media and pollutes the environment.

[0007] The existing steel grades mentioned above have some shortcomings and cannot meet the current development requirements of the mining saw blade industry. Therefore, there is an urgent need to develop a new type of saw blade base steel that is easy to weld, low in cost, and has high toughness and plasticity, which can significantly improve the service life of saw blades. Summary of the Invention

[0008] This invention aims to provide a steel for the base of mining saw blades that does not require tempering and a method for its production. The steel for the base of the saw blade produced has the characteristics of low alloy cost, easy welding, no need for tempering heat treatment, uniform microstructure and properties, good plate shape, low residual stress in the steel plate, short production cycle, energy saving and environmental protection, and high toughness and plasticity, which can significantly improve service life.

[0009] The technical solution of the present invention: A type of steel for the base of a mining saw blade, wherein the chemical composition by mass percentage is C=0.27%~0.31%, Si=0.20%~0.30%, Mn=1.00%~1.15%, Ti=0.018%~0.025%, Cr=0.55~0.65%, Nb=0.025~0.030%, Mo=0.15~0.20%, B=0.0012%~0.0022%, P≤0.015%, S≤0.003%, Als=0.02%~0.050%, with the balance being Fe and unavoidable impurities; the tensile strength of the steel plate is ≥900MPa; the steel plate is delivered in hot-rolled condition.

[0010] A method for producing steel for the base of mining saw blades that does not require adjustment, the process flow includes converter → LF furnace → VD furnace → continuous casting → rolling → performance testing → inspection and warehousing, characterized by the following key process steps: (1) Converter: The C content of the steel is controlled at 0.07%~0.10%, the P content is controlled at 0.015%, the steel tapping temperature is 1600~1630℃, ferrosilicon and manganese alloy are added during the steel tapping process for alloying, ferroaluminum is added for deoxidation, and appropriate amounts of lime and pre-melted slag are added for slag formation; the Al content of the molten steel leaving the station is 0.020%~0.050%; (2) LF furnace: When molten steel is smelted in the LF furnace, lime and pre-melted slag are added for slag formation, and SiC and Al particles are added for diffusion deoxidation. The Als in the molten steel is controlled at 0.02% to 0.05%, and the white slag is maintained for ≥20 min after adjusting the C, Si, Mn, S, Mo, Cr and Nb elements to the required range. Before leaving the station, ferrotitanium and ferroboron are added in sequence, and 150~200m of calcium wire is fed in and soft blowing is carried out for ≥5 min. (3) VD furnace: Argon gas is blown throughout the VD furnace, and the vacuum degree is maintained at <67Pa for more than 15 minutes; after breaking the vacuum, calcium wire ≥200m is fed in twice, and soft blowing ≥15 minutes is performed before leaving the station; (4) Continuous casting: The continuous casting process is protected by dynamic light reduction technology, and the superheat of the tundish is controlled at 6-16℃; the continuous casting protective slag is a special medium carbon protective slag. (5) Rolling: The slab temperature is controlled at 1230~1260℃, the roughing rolling start temperature is ≥1200℃, the finishing rolling start temperature is ≥1060℃, the rolling process adopts high temperature and high reduction rolling, and the roughing rolling final rolling stage ensures at least two passes with a reduction rate greater than 20%. After finishing rolling, no water is applied, and the slab is air-cooled to room temperature. Compared with existing technologies, this invention has the following advantages: it uses a C-Mn-Cr-Mo composition, adding Cr and Mo to improve the strength of the steel, ensuring strength without the need for tempering heat treatment, resulting in a short production cycle, low cost, and ensuring the purity of molten steel through appropriate steelmaking processes; it employs low superheat combined with dynamic light pressure to ensure the internal quality of the billet, resulting in low carbon equivalent, good plasticity and weldability of the steel, and a finished steel plate with a tensile strength Rm≥900MPa, elongation A50≥12%, surface hardness of 26~31HRC, and impact energy value at 0℃≥100J, fully meeting the requirements for high-strength saw blade base steel used in mining. According to feedback from saw blade manufacturers, saw blades made with steel matrix using this composition system have advantages such as good rigidity, small runout, faster cutting speed, and straight kerf. This can improve the yield of mining materials, increase mining output, save time and cutting heads, and improve overall efficiency by at least 20%. During use, the saw blades are less prone to quality problems such as deformation and cracking, have a high safety factor, and meet current safety, energy saving, and environmental protection requirements, making them very suitable for mining large-sized blocks. Attached Figure Description

[0011] Figure 1 The metallographic structure of the 11mm×4820mm steel plate shows that the structure is martensite + degenerate pearlite. Detailed Implementation

[0012] The present invention will be further described below with reference to embodiments. Example 1

[0013] A high-strength saw blade base steel for mining and its production method are disclosed. The steel produces 11mm × 4820mm saw blade steel. The chemical composition (mass percentage) of the steel is shown in Table 1, with the balance being Fe and unavoidable impurities. The process flow includes converter → LF furnace → VD furnace → continuous casting → rolling → performance testing. The key process steps are as follows: (1) Converter: The steel has a C content of 0.08% and a P content of 0.012% at the tapping temperature of 1608℃. Ferrosilicon and manganese alloy are added during the tapping process for alloying, ferroaluminum is added for deoxidation, and appropriate amounts of lime and pre-melted slag are added for slag formation. The Al content at the tapping station is 0.035%. (2) LF furnace: lime and pre-melted slag are added for slag formation, SiC and Al particles are added for diffusion deoxidation, and the Al content in the molten steel is 0.02% to 0.05%; after adjusting the C, Si, Mn, S, Mo, Cr and Nb elements to the required range, the white slag is maintained for 22 minutes, ferrotitanium and ferroboron are added before leaving the station, 200m of calcium wire is fed in, and soft blowing is carried out for 5 minutes; (3) VD furnace: Argon gas is blown throughout the VD process, and the vacuum degree is maintained at <67Pa for 18 minutes. After breaking the vacuum, 200m of calcium wire is fed in twice, and soft blowing is performed for 16 minutes before leaving the station. (4) Continuous casting: The continuous casting process is protected by dynamic light reduction technology, and the tundish superheat is 8~11℃; the continuous casting protective slag is a special medium carbon protective slag, and the water is supplied with weak cooling.

[0014] The rolling and heat treatment process parameters are shown in Table 2. The test results of the physical properties of the steel are shown in Table 3. Example 2

[0015] A high-strength saw blade base steel for mining and its production method are disclosed. The steel produces 11mm × 4820mm saw blades. The chemical composition percentages of the steel are shown in Table 1, with the balance being Fe and unavoidable impurities. The process flow includes converter → LF furnace → VD furnace → continuous casting → rolling → performance testing. The key process steps are as follows: (1) Converter: The steel has a C content of 0.07% and a P content of 0.010%, and a tapping temperature of 1618℃. During the tapping process, ferrosilicon and metallic manganese alloy are added for alloying, ferroaluminum is added for deoxidation, and appropriate amounts of lime and pre-melted slag are added for slag formation. The Al content at the tapping station is 0.029%. (2) LF furnace: Add lime and pre-melted slag for slag formation, add SiC and Al particles for diffusion deoxidation, and the Al content in the molten steel is 0.02% to 0.05%; after adjusting C, Si, Mn, S, Mo, Cr and Nb elements to the required range, the white slag is maintained for 25 minutes, ferrotitanium and ferroboron are added before leaving the station, 200m of calcium wire is fed in, and soft blowing is carried out for 6 minutes; (3) VD furnace: Argon gas is blown throughout the VD process, and the vacuum degree is maintained at <67Pa for 16 minutes. After breaking the vacuum, 200m of calcium wire is fed in twice, and soft blowing is performed for 17 minutes before leaving the station. (4) Continuous casting: The continuous casting process is protected by dynamic light reduction technology, and the tundish superheat is 9~14℃; the continuous casting protective slag is a special medium carbon steel protective slag, and the water is supplied with weak cooling. The rolling process parameters are shown in Table 2. The test results of the physical properties of the steel are shown in Table 3.

[0016] Table 1 Chemical composition (wt, %) of the steel in the examples .

[0017] Table 2 Rolling process parameters for 11mm×4820mm saw blade steel .

[0018] Table 3 Mechanical properties of 11mm×4820mm saw blade steel .

Claims

1. A type of steel for the base of a mining saw blade that requires no adjustment, characterized in that: The chemical composition of the steel, by mass percentage, is C=0.27%~0.31%, Si=0.20%~0.30%, Mn=1.00%~1.15%, Ti=0.018%~0.025%, Cr=0.55~0.65%, Nb=0.025~0.030%, Mo=0.15~0.20%, B=0.0012%~0.0022%, P≤0.015%, S≤0.003%, Als=0.02%~0.050%, with the balance being Fe and unavoidable impurities; The steel plate has a tensile strength ≥ 900 MPa; the steel plate is delivered in hot-rolled condition.

2. A method for producing steel for the base of mining saw blades that does not require adjustment, the process flow including converter → LF furnace → VD furnace → continuous casting → rolling → performance testing → inspection and warehousing, characterized in that... Key process steps include: (1) Converter: The C content of the steel is controlled at 0.07%~0.10%, the P content is controlled at 0.015%, the steel tapping temperature is 1600~1630℃, ferrosilicon and manganese alloy are added during the steel tapping process for alloying, ferroaluminum is added for deoxidation, and appropriate amounts of lime and pre-melted slag are added for slag formation; the Al content of the molten steel leaving the station is 0.020%~0.050%; (2) LF furnace: When molten steel is smelted in the LF furnace, lime and pre-melted slag are added for slag formation, and SiC and Al particles are added for diffusion deoxidation. The Als in the molten steel is controlled at 0.02% to 0.05%, and the white slag is maintained for ≥20 min after adjusting the C, Si, Mn, S, Mo, Cr and Nb elements to the required range. Before leaving the station, ferrotitanium and ferroboron are added in sequence, and 150~200m of calcium wire is fed in and soft blowing is carried out for ≥5 min. (3) VD furnace: Argon gas is blown throughout the VD furnace, and the vacuum degree is maintained at <67Pa for more than 15 minutes; after breaking the vacuum, calcium wire ≥200m is fed in twice, and soft blowing ≥15 minutes is performed before leaving the station; (4) Continuous casting: The continuous casting process is protected by dynamic light reduction technology, and the superheat of the tundish is controlled at 6-16℃; the continuous casting protective slag is a special medium carbon protective slag. (5) Rolling: The slab temperature is controlled at 1230~1260℃, the roughing rolling start temperature is ≥1200℃, the finishing rolling start temperature is ≥1060℃, the rolling process adopts high temperature and high reduction rolling, and the roughing and finishing rolling stages ensure at least two passes with a reduction rate greater than 20%. After finishing rolling, no water is applied, and the slab is air-cooled to room temperature.

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