Extremely low-cost low-alloy wear-resistant steel plate with Brinell hardness of 300HB and manufacturing method

Abstract

The invention discloses an extremely low-cost low-alloy wear-resistant steel plate with the Brinell hardness of 300 HB and a manufacturing method thereof, and belongs to the technical field of wear-resistant steel manufacturing, the steel plate comprises the following components in percentage by weight: 0.06%-0.20% of C, 0.20%-0.60% of Si, 0.8%-1.30% of Mn, less than or equal to 0.030% of P, less than or equal to 0.005% of S, 0.008%-0.020% of Ti, 0.20%-0.60% of Cr, 0.030%-0.070% of Al, 0.0008%-0.0050% of B, 0.0010%-0.0030% of Ca, less than or equal to 0.0060% of N and the balance of Fe and inevitable impurities, and the sum of the components is 100%. The manufacturing method is simple, short in process and low in cost, and the manufactured steel plate has good wear resistance and impact toughness, good forming performance and difficulty in cracking.

Description

Technical Field

[0001] The invention relates to a wear-resistant steel plate, in particular to an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB and a manufacturing method thereof, belonging to the technical field of wear-resistant steel manufacturing. Background Art

[0002] Low alloy wear-resistant steel is widely used in engineering machinery, mining, construction, agriculture, cement, ports, electricity, metallurgy and other industries due to its high strength and hardness, good weldability, good impact toughness and formability. It is mainly used to manufacture bulldozers, loaders, excavators, dump trucks, ball mills and various mining machinery. Such parts generally work in extremely harsh conditions of dry and wet environments, and are difficult to replace. The steel plate is required to have high strength, hardness, excellent wear resistance, and good welding performance to ensure a longer service life of the equipment.

[0003] Small excavators, loaders, lawn mowers and other equipment at home and abroad are widely used in relatively small scenes such as private farmland and gardens because of their favorable prices and flexible movements. The wear-resistant parts only need to have a certain wear resistance, but the price is required to be low. Conventional low-alloy wear-resistant steel NM360-NM600 has sufficient wear resistance and a high price. Therefore, a product with slightly lower wear resistance but affordable price has become a market demand. At present, there have been many patent reports on low-alloy wear-resistant steel, but there has been no report on the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB.

[0004] Patent CN108179350B discloses a low-cost, short-cycle preparation method for wear-resistant steel, which realizes the quenching + direct straightening process to produce wear-resistant steel NM400 steel plates, and does not require intermediate tempering treatment, thereby reducing the number of steps, reducing costs, and shortening the production cycle, thereby obtaining NM400 steel plates with lower residual stress values, which are equivalent to the residual stress values ​​of the steel plates after the quenching + tempering + straightening process, but have excess hardness, and require offline quenching + straightening, which has a longer process and high costs.

[0005] Patent CN114737128A discloses a NM300 grade wear-resistant steel and its production method, which improves the purity of the product and the surface quality of the ingot and steel plate. By optimizing the heat inspection and hot loading of the ingot and the heating temperature, the occurrence of cracks in the ingot is avoided. The secondary quenching technology is adopted to improve the sudden brittle fracture of the steel plate, ensure the quality and quantity of the steel plate production, and enhance the manufacturing advantage of the enterprise in the field of wear-resistant steel. It effectively improves the cracks, but the process is complicated and the cost is high, which cannot meet the requirements of medium wear resistance and low cost.

[0006] Therefore, developing an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB and a manufacturing method that can overcome the above defects has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0007] The technical problem to be solved by the present invention is to propose an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB and a manufacturing method thereof in view of the shortcomings of the above-mentioned prior art. The manufacturing method is simple, the process is short, and the cost is low. The manufactured steel plate has good wear resistance and impact toughness, good forming performance, and is not easy to crack.

[0008] The technical solution of the present invention to solve the above technical problems is: The invention discloses an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB. The steel plate comprises the following components by weight percentage: C: 0.06%-0.20%, Si: 0.20%-0.60%, Mn: 0.8%-1.30%, P≤0.030%, S≤0.005%, Ti: 0.008%-0.020%, Cr: 0.20%-0.60%, Al: 0.030%-0.070%, B: 0.0008%-0.0050%, Ca: 0.0010%-0.0030%, N≤0.0060%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0009] The technical solution further defined in the present invention is: Furthermore, in the aforementioned extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, the steel plate includes the following components by weight percentage: C: 0.15%, Si: 0.30%, Mn: 1.2%, P≤0.020%, S≤ 0.005%, Cr: 0.3%, Ti: 0.008~0.020%, Al: 0.050%, Ca: 0.0020%, B: 0.0008~0.0025%, N≤0.0060%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%. In the aforementioned extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, the steel plate includes the following components by weight percentage: C: 0.06%, Si: 0.20%, Mn: 0.8%, P≤0.030%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.20%, Al: 0.030%, B: 0.0008%~0.0010%, Ca: 0.0010%, N≤0.0060%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0010] In the aforementioned extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, the steel plate includes the following components by weight percentage: C: 0.20%, Si: 0.60%, Mn: 1.30%, P≤0.020%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.60%, Al: 0.070%, B: 0.0008%~0.0030%, Ca: 0.0030%, N≤0.0060%, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0011] In the aforementioned extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, the hardness of the steel plate is 250-350HBW, and the low-temperature impact toughness at -20°C is ≥15J.

[0012] The present invention also designs a method for manufacturing a low-alloy wear-resistant steel plate with an extreme low-cost Brinell hardness of 300HB, which includes the following processes: hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stacking - ingot heating - dephosphorization - rolling - controlled cooling - flaw detection - straightening - cutting - sampling - printing identification - inspection - warehousing, wherein: RH refining uses high vacuum treatment for 10 min; The continuous casting process adopts the secondary cooling single roller electromagnetic stirring process, current: 200-250A, frequency: 6HZ; The ingot stacking process lasts for more than 12 hours; The ingot is heated at 1180-1220℃ and then subjected to ordinary rolling, with the cumulative rolling reduction ratio ≥30%. It is then cooled online to 450-550℃ and after rolling is completed, it is cooled in a slow cooling pit for 24 hours for self-tempering effect without offline heat treatment.

[0013] The technical solution further defined in the present invention is: Furthermore, in the aforementioned method for manufacturing the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, the continuous casting is performed with any medium carbon steel, and the continuous casting speed is 0.2 m / min.

[0014] The beneficial effects of the present invention are: The RH refining of the present invention adopts high vacuum treatment for 10 minutes and ingot stacking treatment for more than 12 hours, with extremely short process time and low cost, and effectively reduces the risk of H delayed cracking of the steel plate.

[0015] The continuous casting process of the present invention adopts the secondary cooling single-roller electromagnetic stirring technology, which effectively improves the uniformity of the composition and structure of the casting blank.

[0016] The continuous casting production of the present invention can be continuously cast with any medium carbon steel, the number of continuous casting furnaces is unlimited, production scheduling is convenient, and the continuous casting speed is fast.

[0017] The present invention adopts reasonable composition design, medium-low carbon and alloying composition design, and through the interaction of alloy elements such as carbon, manganese, chromium and micro-alloy elements such as titanium, specifically: The requirements for the impurity content of P, S, and N in the ingredients are loose, the production process is short, the process requires short time, the production organization is convenient, and the production cost is extremely low; C is a traditional strengthening element with the advantages of low cost and good control sensitivity, but a high content also has the disadvantage of negatively affecting the welding performance, mechanical properties and hydrogen-induced cracking (HIC) resistance of steel. In addition, the strength matching relationship between carbon and steel is also particularly important, because the carbon content is proportional to the strength of the steel, but the impact toughness of the steel is significantly reduced, which cannot meet the requirements of high strength and high toughness of the steel. Carbon plays a key role in the strength of the steel, but it will reduce its plasticity and toughness. In order to ensure the toughness at ultra-low temperatures, its content needs to be controlled. In the present invention, low carbon ensures its toughness; The Ti content is controlled at 0.008-0.020%. Ti can produce strong precipitation strengthening and moderate grain refinement. Titanium has strong chemical activity and easily forms compounds with C, N, and S in steel. In order to reduce the content of solid-dissolved nitrogen in steel, micro-titanium treatment is usually used to fix the nitrogen in the steel. TiN can effectively prevent the growth of austenite grains during heating and play a direct strengthening role. Adding trace amounts of titanium to steel can improve the thermoplasticity of the steel and reduce the sensitivity to cracks.

[0018] P≤0.030%, S≤0.005%, high phosphorus composition design is adopted, which effectively improves the tapping temperature of converter smelting, improves the thermodynamic and kinetic conditions of molten steel, improves the alloying effect of molten steel through electromagnetic stirring after the converter, reduces the smelting pressure of LF, reduces the production of inclusions and the adverse effects of gas content, and is conducive to improving the cleanliness of molten steel and the quality of the core of molten steel; The wear-resistant steel with thickness of 10-40mm is produced by uncontrolled rolling process, online cooling and no offline heat treatment process to obtain the necessary hardness and low temperature toughness match.

[0019] After rolling, the product is cooled in a slow cooling pit for 24 hours for self-tempering effect. No offline heat treatment is required, which reduces the process flow and reduces the cost.

[0020] The structure obtained by the invention is mainly martensite + bainite structure, and sufficient wear resistance and impact toughness are obtained, and the low-temperature impact toughness of -20°C is ≥17J. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the microstructure diagram of 1 / 4 thickness of the steel plate in the embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0023] The present embodiment provides an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB. The steel plate includes the following components by weight percentage: C: 0.15%, Si: 0.30%, Mn: 1.2%, P≤0.020%, S≤0.005%, Cr: 0.3%, Al: 0.050%, Ca: 0.0020%, Ti: 0.008-0.020%, B: 0.0008-0.0025%, N≤0.0060%, does not contain precious metals, and the rest are Fe and unavoidable impurities. The sum of the above components is 100%. The manufacturing method of the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB comprises the following processes: hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stacking - ingot heating - dephosphorization - rolling - controlled cooling - flaw detection - straightening - cutting - sampling - printing mark - inspection - warehousing, wherein: RH refining uses high vacuum treatment for 10 min; The continuous casting process adopts the secondary cooling single roller electromagnetic stirring process, current: 250A, frequency: 6HZ; continuous casting is carried out with Q345 medium carbon steel, the number of continuous casting furnaces is 20, which is convenient for production scheduling, the section surface is 220*2270mm, and the continuous casting speed is 0.2m / min; The ingot stacking process lasts for more than 12 hours; The ingot is heated at 1180℃ and then subjected to ordinary rolling, with the cumulative rolling reduction ratio ≥30%. It is then cooled online to 520℃ without offline heat treatment. After rolling, it is cooled in a slow cooling pit for 24 hours and then subjected to self-tempering to relieve stress.

[0024] The thickness of the manufactured steel plate is 30mm, the hardness is 280HBW, and the low-temperature impact toughness of -20℃ is 28J. The structure of the manufactured steel plate 1 / 4 thickness is as follows Figure 1 As shown, martensite + bainite structure can be seen, the structure is fine and uniform, and a good match of sufficient strength and impact toughness is achieved. Example 2

[0025] The present embodiment provides an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, which comprises the following components by weight percentage: C: 0.06%, Si: 0.20%, Mn: 0.8%, P≤0.030%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.20%, Al: 0.030%, B: 0.0008%~0.0010%, Ca: 0.0010%, N≤0.0060%, does not contain precious metals, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0026] The manufacturing method of the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB comprises the following processes: hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stacking - ingot heating - dephosphorization - rolling - controlled cooling - flaw detection - straightening - cutting - sampling - printing mark - inspection - warehousing, wherein: RH refining uses high vacuum treatment for 10 min; The continuous casting process adopts the secondary cooling single roller electromagnetic stirring process, current: 200A, frequency: 6HZ; continuous casting production and Q345 medium carbon steel continuous casting, the number of continuous casting furnaces is 20 furnaces, which is convenient for production scheduling, the section surface is 220*2270mm, and the continuous casting speed is 0.2m / min; The ingot stacking process lasts for more than 12 hours; The ingot is heated at 1220℃ and then subjected to ordinary rolling, with the cumulative rolling reduction ratio ≥30%. It is then cooled online to 550℃ without offline heat treatment. After rolling, it is cooled in a slow cooling pit for 24 hours and then subjected to self-tempering to relieve stress.

[0027] The manufactured steel plate has a thickness of 40 mm, a hardness of 350 HBW, and a low-temperature impact toughness of 26 J at -20°C. Example 3

[0028] The present embodiment provides an extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, which comprises the following components by weight percentage: C: 0.20%, Si: 0.60%, Mn: 1.30%, P≤0.020%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.60%, Al: 0.070%, B: 0.0008%~0.0030%, Ca: 0.0030%, N≤0.0060%, does not contain precious metals, and the rest are Fe and unavoidable impurities, and the sum of the above components is 100%.

[0029] The manufacturing method of the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB comprises the following processes: hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - ingot stacking - ingot heating - dephosphorization - rolling - controlled cooling - flaw detection - straightening - cutting - sampling - printing mark - inspection - warehousing, wherein: RH refining uses high vacuum treatment for 10 min; The continuous casting process adopts the secondary cooling single roller electromagnetic stirring process, current: 220A, frequency: 6HZ; continuous casting production and Q345 medium carbon steel continuous casting, the number of continuous casting furnaces is 20 furnaces, which is convenient for production scheduling, the section surface is 220*2270mm, and the continuous casting speed is 0.2m / min; The ingot stacking process lasts for more than 12 hours; The ingot is heated at 1200℃ and then subjected to ordinary rolling, with the cumulative rolling reduction ratio ≥30%. It is then cooled online to 450℃ without offline heat treatment. After rolling, it is cooled in a slow cooling pit for 24 hours and then subjected to self-tempering to relieve stress.

[0030] The thickness of the manufactured steel plate is 20 mm, the hardness is 250 HBW, and the low-temperature impact toughness at -20°C is 24 J.

[0031] The extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB of the present invention is a low-level product of the wear-resistant steel series, has certain wear resistance and impact toughness, good forming performance, is not easy to crack, has an extremely simple production process, and has an extremely low manufacturing cost. It can be widely used in small excavators, loaders, lawn mowers and other parts, and can meet the use needs of customers. It has obvious price advantages and is widely used. It has greatly promoted the mass production and promotion of small machines, brought benefits to customers, and created a lot of economic benefits.

[0032] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. An extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300HB, characterized by: The steel plate comprises the following components by weight percentage: C: 0.06%~0.20%, Si: 0.20%~0.60%, Mn: 0.8%~1.30%, P≤0.030%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.20%~0.60%, Al: 0.030%~0.070%, B: 0.0008%~0.0050%, Ca: 0.0010%~0.0030%, N≤0.0060%, the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

2. The extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB according to claim 1 is characterized in that: The steel plate comprises the following components by weight percentage: C: 0.15%, Si: 0.30%, Mn: 1.2%, P≤0.020%, S≤0.005%, Cr: 0.3%, Ti: 0.008~0.020%, Al: 0.050%, B: 0.0008~0.0025%, Ca: 0.0020%, N≤0.0060%, the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

3. The extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB according to claim 1 is characterized in that: The steel plate comprises the following components by weight percentage: C: 0.06%, Si: 0.20%, Mn: 0.8%, P≤0.030%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.20%, Al: 0.030%, B: 0.0008%~0.0010%, Ca: 0.0010%, N≤0.0060%, the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

4. The extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB according to claim 1, characterized in that: The steel plate comprises the following components by weight percentage: C: 0.20%, Si: 0.60%, Mn: 1.30%, P≤0.020%, S≤0.005%, Ti: 0.008%~0.020%, Cr: 0.60%, Al: 0.070%, B: 0.0008%~0.0030%, Ca: 0.0030%, N≤0.0060%, the rest are Fe and unavoidable impurities. The sum of the above components is 100%.

5. The extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB according to any one of claims 1 to 4, characterized in that: The steel plate has a thickness of 10-40 mm, a hardness of 250-350 HBW, and a low-temperature impact toughness of -20°C ≥15J.

6. A method for manufacturing a low-alloy wear-resistant steel plate with an extreme low-cost Brinell hardness of 300HB, characterized in that: The manufacturing method includes the following steps: Hot metal desulfurization pretreatment - converter smelting - LF+RH refining - continuous casting - billet slow cooling pit stacking - billet heating - dephosphorization - rolling - controlled cooling - flaw detection - straightening - cutting - sampling - printing mark - inspection - storage, including: The RH refining adopts high vacuum treatment for 10 minutes; The continuous casting process adopts a secondary cooling single-roller electromagnetic stirring process, with a current of 200-250A and a frequency of 6HZ; The ingot stacking treatment takes more than 12 hours; The ingot is heated at 1180-1220°C and then subjected to ordinary rolling, with a cumulative rolling reduction ratio of ≥30%, and then cooled online to 450-550°C. After rolling, the ingot is subjected to slow cooling pit stack cooling for 24 hours for self-tempering to eliminate stress, without offline heat treatment.

7. The method for manufacturing the extremely low-cost low-alloy wear-resistant steel plate with a Brinell hardness of 300 HB according to claim 6, characterized in that: The continuous casting is performed with medium carbon steel, and the continuous casting speed is 0.2 m / min.

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