Low-alloy high-toughness martensite wear-resistant steel as well as preparation method and application thereof

Abstract

The invention relates to low-alloy high-toughness martensite wear-resistant steel, which is characterized by comprising the following chemical components in percentage by mass: 0.1 to 0.3 percent of C, 0.1 to 0.3 percent of Si, 1.0 to 1.5 percent of Mn, 0 to 0.02 percent of P, 0 to 0.002 percent of S, 0.05 to 0.25 percent of Cr, 0.0001 to 0.01 percent of La, 0.0001 to 0.01 percent of Ce and the balance of Fe and inevitable impurities. The wear-resistant steel is low in production cost, good in plasticity, high in hardness, good in wear resistance, good in toughness, particularly excellent in low-temperature toughness and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy wear-resistant steel materials, in particular to a low-alloy high-toughness martensitic wear-resistant steel and a preparation method and application thereof. Background Art

[0002] Alloy steel refers to an iron-carbon alloy formed by adding appropriate amounts of one or more alloying elements to ordinary carbon steel. Depending on the added elements and appropriate processing techniques, special properties such as high strength, high toughness, wear resistance, corrosion resistance, low and high temperature resistance, and non-magnetic properties can be achieved.

[0003] Wear is one of the main forms of material failure, and more than one million tons of steel are consumed each year due to abrasive wear. Wear-resistant steel is a type of steel material widely used in various wear conditions, such as excavators, bulldozers, mining machinery, roadbed equipment, and dump trucks. The function of wear-resistant steel is to slow down the wear and tear of mechanical parts, increase the life of the product, and extend the time before mechanical products fail due to wear. It is required to have a high hardness value to ensure friction and wear resistance under harsh working conditions. Low-alloy wear-resistant steel is usually alloyed with elements such as Mn, Cr, Ni, and Mo, and then a martensitic structure with higher hardness is obtained through quenching and low-temperature tempering heat treatment. However, the prices of alloys such as Ni and Mo are relatively high, which significantly increases the production cost of wear-resistant steel.

[0004] Traditional tough wear-resistant materials mainly include high manganese steel, low alloy cast iron, and low alloy steel. After water toughening treatment, the surface hardness of high manganese steel is greatly improved under high impact conditions; under low impact conditions, due to the insignificant work hardening effect, good results cannot be achieved. Low alloy cast iron mostly uses carbides to enhance hardness, that is, wear resistance is enhanced through high hardness, but the large difference in hardness between carbides and the matrix can cause cracks to form and reduce the plastic toughness of the steel. Low alloy steel produces a wear-resistant hard phase by adding a small amount of alloying elements. The resulting steel has better wear resistance, but the difference in hardness between the hard phase and the matrix can cause cracks to form and expand, reducing the plastic toughness of the steel.

[0005] Furthermore, with the advancement of industrial development, various types of machinery and equipment are becoming increasingly complex, larger, and lighter. This places higher demands on the toughness, wear resistance, and weldability of materials used in construction machinery components, particularly in mining equipment. This has also driven the development and production of steel for construction machinery to continuously strive for superior overall mechanical properties. Therefore, the development of a low-alloy, high-toughness, wear-resistant steel with excellent overall performance and low cost is of great significance to the development of construction machinery. Summary of the Invention

[0006] Based on this, the present invention provides a low-alloy high-toughness martensitic wear-resistant steel with low production cost, good plasticity, good toughness, high hardness and good wear resistance, and also provides a preparation method and application of the wear-resistant steel.

[0007] The technical solution is as follows:

[0008] Disclosed is a low-alloy high-toughness martensitic wear-resistant steel, the chemical composition of which, by mass percentage, comprises: C: 0.1%-0.3%, Si: 0.1%-0.3%, Mn: 1.0%-1.5%, P: 0-0.02%, S: 0-0.002%, Cr: 0.05%-0.25%, La: 0.0001%-0.01%, Ce: 0.0001%-0.01%, and the balance is Fe and unavoidable impurities.

[0009] In one embodiment, the carbon content of the low alloy high toughness martensitic wear-resistant steel is 0.12% to 0.25% by mass.

[0010] In one embodiment, the Si content of the low alloy high toughness martensitic wear-resistant steel is 0.1% to 0.2% by mass.

[0011] In one embodiment, the Mn content of the low alloy high toughness martensitic wear-resistant steel is 1.0% to 1.3% by mass.

[0012] In one embodiment, the S content of the low alloy high toughness martensitic wear-resistant steel is 0-0.001% by mass.

[0013] In one embodiment, the Cr content of the low alloy high toughness martensitic wear-resistant steel is 0.05% to 0.2% by mass.

[0014] In one embodiment, the La content of the low alloy high toughness martensitic wear-resistant steel is 0.006% to 0.009% by mass.

[0015] In one embodiment, the Ce content of the low alloy high toughness martensitic wear-resistant steel is 0.006% to 0.009% by mass.

[0016] In one embodiment, the yield strength of the low-alloy high-toughness martensitic wear-resistant steel is ≥1000 MPa.

[0017] In one embodiment, the tensile strength of the low-alloy high-toughness martensitic wear-resistant steel is ≥1000 MPa.

[0018] In one embodiment, the elongation of the low-alloy high-toughness martensitic wear-resistant steel is ≥10%.

[0019] In one embodiment, the hardness of the low-alloy high-toughness martensitic wear-resistant steel is ≥350 HBW.

[0020] In one embodiment, the low-alloy high-toughness martensitic wear-resistant steel has a low-temperature impact energy of ≥120J at -20°C.

[0021] In one embodiment, the low-alloy high-toughness martensitic wear-resistant steel has a low-temperature impact energy of ≥60J at -60°C.

[0022] The present invention also provides a method for preparing the low-alloy high-toughness martensitic wear-resistant steel as described above, comprising the steps of steelmaking, steel rolling and heat treatment.

[0023] In one embodiment, the steelmaking comprises the steps of: hot metal KR desulfurization, converter steelmaking, LR refining, RH vacuum refining, adding rare earth in a tundish, and continuous casting;

[0024] Among them, the refining temperature is ≥1530℃, the refining time is ≥45min, the superheat range of the tundish is 10℃~25℃, the rare earth alloy added to the tundish is ≥70kg, the continuous casting drawing speed is 0.9m / min~1.2m / min, and the slab thickness is 200mm~250mm.

[0025] In one embodiment, the steel rolling comprises the steps of: slab heating, rough rolling, finish rolling, coiling and coil stacking;

[0026] Among them, the set temperature of the soaking section of the heating furnace is 1200℃~1230℃, the total time of the steel plate in the furnace is 150min~200min, 5~7 rough rolling passes are adopted, the surface temperature of the slab after rough rolling is 1100℃~1150℃, the surface temperature of the slab after finish rolling is 880℃~940℃, and the coiling temperature is set to 550℃~620℃.

[0027] In one embodiment, the heat treatment includes the steps of: cross-cutting the steel coil, quenching the single plate, tempering the single plate, and stacking and packaging;

[0028] Among them, the quenching heating temperature of the steel plate is 860℃~920℃, and the quenching holding time is 20min~40min; the tempering heating temperature of the steel plate is 160℃~240℃, and the tempering holding time is 35min~70min.

[0029] The present invention also provides an application of the low-alloy high-toughness martensitic wear-resistant steel as described above, and the technical solution is as follows:

[0030] The low alloy high toughness martensitic wear resistant steel as described above is used in cutlery and knives, steel parts for engineering machinery, aerospace parts, medical equipment, oil and gas industry parts, automobile parts or power generation equipment.

[0031] The present invention has at least the following beneficial effects:

[0032] The present invention regulates the chemical composition of the wear-resistant steel, in particular the types and content percentages of the elements, to provide a wear-resistant steel having high yield strength, high tensile strength, good toughness (especially low-temperature toughness), high hardness, and good wear resistance. Furthermore, since the chemical composition of the wear-resistant steel of the present invention does not contain precious metals such as Ni and Nb, and the Mn content is relatively low, the alloy cost is significantly reduced. That is, the present invention ensures that the steel has good mechanical properties, wear resistance, and processability while also having lower costs, facilitating large-scale industrial production and the promotion and application of the wear-resistant steel market.

[0033] The preparation method of the wear-resistant steel of the present invention has the advantages of simple operation, high efficiency, good repeatability, green environmental protection, low energy consumption, low production cost, etc., and is suitable for industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Comparison of the impact energy of ordinary wear-resistant steel NM400 and low-alloy high-toughness martensitic high-wear-resistant steel NM400plus prepared in Example 1 of the present invention at different temperatures;

[0035] Figure 2 This is the metallographic structure diagram of the finished product of low-alloy, high-toughness, martensitic, and high-wear-resistant steel NM400plus prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the present disclosure.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Where “including,” “having,” and “comprising” are used herein, it is intended to cover a non-exclusive inclusion, and another component may also be added unless a clear limiting term such as “only,” “consisting of,” etc. is used.

[0039] The words "preferably", "more preferably", "preferably", "better", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the statement of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention. That is, in the present invention, "preferably", "more preferably", "preferably", "better", etc. are only used to describe implementation methods or examples with better effects, but do not constitute a limitation on the scope of protection of the present invention.

[0040] In the present invention, “further”, “further”, “particularly”, etc. are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of the present invention.

[0041] In the present invention, "at least one" means more than one, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layer" means at least two layers, such as two, three, etc., unless otherwise specifically defined. In the description of the present invention, "several" means at least one, such as one, two, etc., unless otherwise specifically defined.

[0042] When a numerical range is disclosed in the present invention, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein. And only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value itself can be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0043] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0044] Unless mentioned otherwise, terms in the singular may include plural forms and should not be construed as having one number.

[0045] The temperature parameters in the present invention, unless otherwise specified, allow for either constant temperature treatment or treatment within a certain temperature range. The constant temperature treatment allows for temperature fluctuations within the precision range controlled by the instrument.

[0046] The weights of the relevant components mentioned in the examples of the present invention may not only refer to the specific content of each component, but also represent the weight ratios between the components. Therefore, as long as the content of the relevant components is proportionally increased or decreased according to the examples of the present invention, it is within the scope disclosed in the examples of the present invention. Specifically, the weights described in the examples of the present invention may be mass units known in the chemical industry, such as μg, mg, g, and kg.

[0047] In the present invention, when referring to a data range, if the unit is only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 800-850nm means that the units of the left endpoint "800" and the right endpoint "850" are both nm (nanometers).

[0048] In the present invention, “above” or “below” both include the number itself, for example, “below 1” means less than or equal to 1 (≤1), and “above 1” means greater than or equal to 1 (≥1).

[0049] In the present invention, "A and B are independently selected from x, y or z" means that A and B are independent events, and event A does not affect the occurrence of event B. Therefore, when A is selected from x, B can be selected from any one of x, y or z; when A is selected from y, B can be selected from any one of x, y or z; when A is selected from z, B can be selected from any one of x, y or z.

[0050] Unless mentioned otherwise, terms in the singular may include plural forms and should not be construed as having one number.

[0051] The present invention provides a low-alloy high-toughness martensitic wear-resistant steel with low production cost, good plasticity, good toughness, high hardness and good wear resistance, and also provides a preparation method and application of the wear-resistant steel.

[0052] The technical solution is as follows:

[0053] Disclosed is a low-alloy high-toughness martensitic wear-resistant steel, the chemical composition of which, by mass percentage, comprises: C: 0.1%-0.3%, Si: 0.1%-0.3%, Mn: 1.0%-1.5%, P: 0-0.02%, S: 0-0.002%, Cr: 0.05%-0.25%, La: 0.0001%-0.01%, Ce: 0.0001%-0.01%, and the balance is Fe and unavoidable impurities.

[0054] Carbon (C): C is an effective economic element for increasing steel strength. However, excessive C content can result in a brittle structure, reducing the low-temperature impact toughness of the alloy steel, and worsening its weldability and corrosion resistance. Taking all factors into consideration, the present invention controls the carbon content in the steel to 0.1% to 0.3%. This range can be, but is not limited to, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. Furthermore, the carbon content of the low-alloy, high-toughness martensitic wear-resistant steel is, by mass percentage, 0.12% to 0.25%.

[0055] Silicon (Si): Si is dissolved in alloy steel, which can improve the strength of the alloy steel and reduce the corrosion rate of the alloy steel. However, too high a Si content will deteriorate the weldability of the steel and reduce the toughness of the material. Taking all factors into consideration, the present invention controls the Si content in the wear-resistant steel to be 0.1% to 0.3%. It can be understood that it includes but is not limited to 0.1%, 0.15%, 0.2%, 0.25% or 0.3%. Furthermore, the Si content of the low-alloy high-toughness martensitic wear-resistant steel is 0.1% to 0.2% by mass.

[0056] Manganese (Mn): Mn has a strong solid solution strengthening effect and a significant grain refining effect, improving both the strength and toughness of alloy steel. However, excessive Mn content can easily lead to core component segregation, affecting processability and increasing alloy cost. Therefore, to ensure good toughness of the steel plate, avoid core component segregation, and reduce alloy steel cost, the present invention controls the Mn content in the wear-resistant steel to 1.0% to 1.5%. This includes, but is not limited to, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%. Furthermore, the wear-resistant steel contains 1.0% to 1.3% Mn by mass.

[0057] Phosphorus (P): P can increase the corrosion resistance of alloy steel, but will deteriorate the toughness of alloy steel. Taking all factors into consideration, the present invention controls the P content in the wear-resistant steel to be 0-0.02%, which can be understood to include but not limited to 0, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.012%, 0.014%, 0.015%, 0.018% or 0.02%. Furthermore, the P content of the wear-resistant steel is 0-0.01% by mass.

[0058] Sulfur (S): Sulfur deteriorates the corrosion resistance, ductility, and toughness of alloy steels, primarily due to the poor plasticity of iron sulfide formed by the combination of sulfur and iron. Taking all factors into consideration, the present invention controls the S content in the wear-resistant steel to ≤ 0.002%. This includes, but is not limited to, 0, 0.0001%, 0.0002%, 0.0005%, 0.0008%, 0.001%, or 0.002%. Furthermore, the wear-resistant steel contains S in an amount of 0 to 0.001% by mass.

[0059] Chromium (Cr): Cr is a strong carbide-forming element that can reduce the activity of carbon in alloy steel, improve the oxidation resistance of alloy steel, and form a dense passivation film on the surface of the steel, thereby improving the corrosion resistance of the alloy steel. Cr can significantly increase the strength and hardness of the alloy steel, as well as the hardenability, but it can also increase the temper brittleness tendency of the alloy steel. That is, an appropriate amount of Cr can improve the mechanical properties, but excessive Cr will lead to a deterioration in the toughness of the alloy steel. Taking all factors into consideration, in the present invention, the Cr content in the wear-resistant steel is controlled to be 0.05% to 0.25%, which can be understood to include but not limited to 0.05%, 0.1%, 0.15%, 0.2% or 0.25%. Furthermore, the Cr content of the wear-resistant steel is 0.05% to 0.2% by mass.

[0060] Lanthanum (La): La is a rare earth element. In alloy steel, its main function is to enhance mechanical properties (such as strength and toughness), improve heat resistance and corrosion resistance. However, excessive La can reduce the mechanical properties of alloy steel. Taking all factors into consideration, the present invention controls the La content of weathering steel to 0.0001% to 0.01%, including but not limited to 0.0001%, 0.0002%, 0.0003%, 0.0004%, 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.0015%, 0.002%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009% or 0.01%. Furthermore, the La content of the low-alloy high-toughness martensitic wear-resistant steel is 0.006% to 0.009% by mass.

[0061] Cerium (Ce): The role of Ce in alloy steel is mainly reflected in grain refinement, improving mechanical properties and corrosion resistance, but the elongation and impact energy will decrease. Taking all factors into consideration, the present invention controls the Ce content of weathering steel to 0.0001% to 0.01%, including but not limited to 0.0001%, 0.0002%, 0.0003%, 0.0004%, 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.0015%, 0.002%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009% or 0.01%. Furthermore, the Ce content of the low-alloy high-toughness martensitic wear-resistant steel is 0.006% to 0.009% by mass.

[0062] The present invention provides a wear-resistant steel with high yield strength, high tensile strength, good low-temperature toughness, high hardness, and good wear resistance by regulating the chemical composition of the wear-resistant steel, especially regulating the types of elements and the percentage of their content. The matrix structure of the wear-resistant steel is nano-martensite, and nano-precipitates and high-density dislocation clusters are distributed within the martensite laths. The equivalent diameter of the nano-precipitates is less than 60nm. At the same time, because the chemical composition of the wear-resistant steel of the present invention does not contain precious metals such as Ni and Nb, and the Mn content is relatively low, the alloy cost is greatly reduced. That is, the present invention ensures that the steel has good mechanical properties, wear resistance, and processability while also having lower costs, which facilitates large-scale industrial production and the promotion and application of the wear-resistant steel market.

[0063] In one embodiment, the yield strength of the low-alloy high-toughness martensitic wear-resistant steel is ≥1000 MPa. Furthermore, the yield strength of the low-alloy high-toughness martensitic wear-resistant steel is 1000 MPa to 1350 MPa.

[0064] In one embodiment, the tensile strength of the low-alloy high-toughness martensitic wear-resistant steel is ≥1000 MPa. Furthermore, the tensile strength of the low-alloy high-toughness martensitic wear-resistant steel is 1150 MPa to 1550 MPa.

[0065] In one embodiment, the elongation of the low-alloy high-toughness martensitic wear-resistant steel is ≥10%. Furthermore, the elongation of the low-alloy high-toughness martensitic wear-resistant steel is 12% to 30%.

[0066] In one embodiment, the hardness of the low alloy high toughness martensitic wear-resistant steel is ≥350 HBW. Furthermore, the hardness of the low alloy high toughness martensitic wear-resistant steel is 370 HBW to 430 HBW.

[0067] In one embodiment, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -20°C is ≥120 J. Furthermore, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -20°C is 120 J to 160 J.

[0068] In one embodiment, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -40°C is ≥80 J. Furthermore, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -40°C is 90 J to 120 J.

[0069] In one embodiment, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -60°C is ≥ 60 J. Furthermore, the low-temperature impact energy of the low-alloy high-toughness martensitic wear-resistant steel at -60°C is 70 J to 90 J.

[0070] The present invention also provides a method for preparing the low-alloy high-toughness martensitic wear-resistant steel as described above, comprising the steps of steelmaking, steel rolling and heat treatment.

[0071] In one embodiment, the steelmaking comprises the steps of: hot metal KR desulfurization, converter steelmaking, LR refining, RH vacuum refining, adding rare earth in a tundish, and continuous casting;

[0072] Among them, the refining temperature is ≥1530℃, the refining time is ≥45min, the superheat range of the tundish is 10℃~25℃, the rare earth alloy added to the tundish is ≥70kg, the continuous casting drawing speed is 0.9m / min~1.2m / min, and the slab thickness is 200mm~250mm.

[0073] In one embodiment, the steel rolling comprises the steps of: slab heating, rough rolling, finish rolling, coiling and coil stacking;

[0074] Among them, the set temperature of the soaking section of the heating furnace is 1200℃~1230℃, the total time of the steel plate in the furnace is 150min~200min, 5~7 rough rolling passes are adopted, the surface temperature of the slab after rough rolling is 1100℃~1150℃, the surface temperature of the slab after finish rolling is 880℃~940℃, and the coiling temperature is set to 550℃~620℃.

[0075] In one embodiment, the heat treatment includes the steps of: cross-cutting the steel coil, quenching the single plate, tempering the single plate, and stacking and packaging;

[0076] Among them, the quenching heating temperature of the steel plate is 860℃~920℃, and the quenching holding time is 20min~40min; the tempering heating temperature of the steel plate is 160℃~240℃, and the tempering holding time is 35min~70min.

[0077] As a preferred embodiment of the present invention, the method for preparing the low-alloy high-toughness martensitic wear-resistant steel comprises the following steps:

[0078] S1: Composition design, the weight percentage of its chemical composition is: C: 0.1%~0.3%, Si: 0.1%~0.3%, Mn: 1.0%~1.5%, P: 0~0.02%, S: 0~0.002%, Cr: 0.05%~0.25%, La: 0.0001%~0.01%, Ce: 0.0001%~0.01%, and the balance is Fe and unavoidable impurities.

[0079] S2: Steel plate preparation, including steelmaking and rolling, wherein the above alloy components are subjected to molten iron KR desulfurization, converter steelmaking, LR refining, RH vacuum refining, rare earth addition in tundish, continuous casting and drawing, slab heating, rough rolling, finish rolling, and then slowly cooled to room temperature before cutting into steel plates to be heat treated. The process conditions are the same as those described above.

[0080] The addition of rare earths to the tundish can reduce sulfides and other substances in the molten steel, thereby improving the cleanliness of the molten steel. Furthermore, in step S2, 100 kg of rare earth alloy is added to the tundish.

[0081] S3: Heat treatment: the steel coil is cut flat across the steel plate or coil, and the steel plate or coil is quenched and tempered.

[0082] The steel coil needs to be cut horizontally into single steel plates, which are then subjected to quenching and tempering treatment.

[0083] The quenching conditions are as follows: the steel plate quenching heating temperature is 860℃~920℃ (preferably 900±10℃), and the quenching holding time is 20min~40min. After the furnace time is reached, the steel plate is immediately water quenched at 25±10℃ until the steel plate temperature reaches the same temperature as the water.

[0084] The tempering conditions are as follows: heat the tempering furnace to 160℃~240℃, and after the furnace temperature stabilizes, immediately place the quenched steel plate in the tempering furnace. The tempering time in the furnace is 35min~70min. After the tempering time is up, the steel plate is taken out of the furnace and air-cooled.

[0085] In the preparation method of the present invention, the steel plate production method is simple and can be achieved using existing equipment. After hot rolling, the steel plate is directly quenched and then tempered. The quenching is used to form a martensitic matrix, and the tempering is used to promote the VC and M 2.5Nano-scale carbides of C and M3C (M represents Fe, Mn, and Cr) precipitate, creating a precipitation strengthening effect. The addition of rare earth alloys to the tundish effectively removes harmful impurities such as sulfur and oxygen from the steel, reducing the number of inclusions by forming stable sulfides and oxides. This process not only improves the purity of the steel but also optimizes its internal structure, thereby enhancing the overall performance of the material. Furthermore, the use of rare earth elements promotes the formation of crystal nuclei in the steel, slowing grain growth and ultimately refining the grains, thereby enhancing the strength and toughness of the steel.

[0086] The present invention also provides an application of the low-alloy high-toughness martensitic wear-resistant steel as described above, and the technical solution is as follows:

[0087] The low-alloy, high-toughness martensitic wear-resistant steel described above is used in cutlery and knives, steel parts for engineering machinery (such as excavators, bulldozers, mining machinery, roadbed equipment and dump trucks), aerospace components (such as turbine blades, aircraft fasteners and landing gear components), medical devices (such as surgical instruments and orthopedic implants), oil and gas industry components (such as valves, pumps and drilling equipment), automotive parts (such as springs, brake parts and exhaust systems) or power generation equipment (such as gas turbines, steam turbines).

[0088] The present invention will be further described below with reference to examples.

[0089] (1) Steel wear resistance index I = 26.01Cu + 3.88Ni + 1.2Cr + 1.49Si + 17.28P - 7.29CuNi - 9.1NiP - 33.39CuCu = 8.09 (without adding Ni element, Ni value is 0 in the formula calculation).

[0090] (2) The mechanical properties of steel were tested by tensile test according to GB / T 228.1-2010 and by bending test according to GB / T 232-2010.

[0091] Example 1

[0092] The production line of Liangang's 210 converter plant, 2250 hot-rolled plate plant, and heat treatment plant produces a low-alloy, high-toughness, wear-resistant steel NM400plus product. Requirements for the NM400plus product include a yield strength of 1000MPa to 1350MPa, a tensile strength of 1150MPa to 1550MPa, a steel plate hardness of 370HBW to 430HBW, an elongation of 12% to 30%, and an impact energy of 120J to 160J at -20°C, ≥80J at -40°C, and ≥60J at -60°C. The specific requirements are as follows:

[0093] (1) A pilot NM400plus furnace was produced at the 210 converter plant, producing 200 tons of molten steel and eight slabs. The argon station temperature during converter steelmaking was 1537°C, the molten steel was refined in the LF furnace for 50 minutes, the tundish superheat was 15°C, 100 kg of rare earth alloy was added to the tundish, the continuous casting speed was 1.1 m / min, the thickness of the cast slab was 230 mm, and the width was 2000 mm. The slab compositions are shown in Table 1.

[0094] Table 1 Composition (wt%) of NM400plus product in Example 1, the balance being Fe and unavoidable impurities

[0095] C Si Mn P S Cr La Ce 0.1706 0.1235 1.1285 0.0099 0.0009 0.1681 0.006 0.0076

[0096] (2) After receiving the 2250 hot-rolled slab, the slab is slowly cooled in the finished product warehouse for 16 hours before being loaded into the furnace. The temperature of the soaking section of the heating furnace is set at 1200°C, and the total time the steel plate is in the furnace is 210 minutes. After 7 rough rolling passes, the slab surface temperature is measured to be 1125°C. The slab is finished at the F7 speed of 6.8m / s. The surface temperature of the strip after finishing is 920°C. The layer cooling process is used for cooling, and the average coiling temperature is 580°C. The steel coil is sent to the finished product warehouse for packaging, printed, and slowly cooled to room temperature in the slow cooling box.

[0097] (3) After the heat treatment plant's cross-cutting line receives the steel coils that have cooled to room temperature, the steel plates are flattened according to customer requirements. The flattened plate specifications are customized to the customer's order. Each NM400plus steel plate undergoes a quenching and tempering process, with a quenching temperature of 900°C and a holding time of 30 minutes; the tempering temperature is 220°C and a holding time of 40 minutes. After tempering, the steel plates are slowly cooled on a cooling bed. After cooling to room temperature, they are packaged and printed.

[0098] The mechanical properties of the NM400plus product produced in Example 1 were tested, and the results are shown in Table 2.

[0099] Table 2 Mechanical properties data of NM400plus product in Example 1

[0100]

[0101] As can be seen from Table 2, the performance of the low-alloy high-toughness wear-resistant steel sample of Example 1 fully meets the product requirements.

[0102] Figure 1 The impact energy comparison results of ordinary wear-resistant steel NM400 and high toughness wear-resistant steel NM400plus at different temperatures are shown in Figure 2. Figure 1As can be seen, at -20°C, the average impact energy of NM400plus is 141J, while that of ordinary NM400 wear-resistant steel remains at only 89J. At -40°C, the impact energy is 109J and 65J, respectively, and at -60°C, the impact energy is 71J and 27J, respectively. This analysis shows that NM400plus maintains high impact toughness even in low-temperature environments, demonstrating superior impact resistance and wear resistance.

[0103] Figure 2 This is the metallographic structure of the finished product of low alloy high toughness martensitic high wear resistant steel NM400plus prepared in Example 1 of the present invention, Figure 2 It can be seen that the matrix structure of the wear-resistant steel is nano-scale martensite, and nano-scale precipitates and high-density dislocation clusters are distributed in the martensite laths.

[0104] Examples 2 to 5 and Comparative Example 1

[0105] Referring to the operating steps of Example 1, Examples 2 to 5 and Comparative Example 1 were used to produce different wear-resistant steels by changing the chemical composition of the steel billets, and performance tests were performed. The chemical composition of the steel billets is shown in Table 3, and the performance test results are shown in Table 4.

[0106] Table 3 Chemical composition of the steel billets used in Examples 2 to 5 and Comparative Example 1

[0107] chemical composition C Si Mn P S Cr La Ce Example 2 0.1846 0.1825 1.1585 0.0105 0.0004 0.178 0.007 0.0086 Example 3 0.1789 0.1248 1.2264 0.0049 0.0005 0.196 0.008 0.0075 Example 4 0.1746 0.1238 1.1280 0.0099 0.0011 0.1684 0.005 0.005 Example 5 0.1695 0.1235 1.1255 0.0109 0.0008 0.1686 0.0005 0.0005 Comparative Example 1 0.1721 0.1264 1.1265 0.0095 0.0005 0.5002 0.006 0.0076

[0108] Table 4 Mechanical properties data of wear-resistant steel products of Examples 2 to 5 and Comparative Example 1

[0109]

[0110] As can be seen from Table 5, the present invention provides a wear-resistant steel with high yield strength, high tensile strength, good low-temperature toughness, high hardness and good wear resistance by regulating the chemical composition of the wear-resistant steel, especially regulating the type and content percentage of the elements.

[0111] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0112] The embodiments described above only express several implementation methods of the present invention, which are convenient for understanding the technical solutions of the present invention in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several variations and improvements can be made, which all fall within the scope of protection of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the scope of protection of the claims attached to the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the content of the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A low alloy high toughness martensitic wear-resistant steel, characterized in that: Calculated by mass percentage, its chemical composition includes: C: 0.1% to 0.3%, Si: 0.1% to 0.3%, Mn: 1.0% to 1.5%, P: 0 to 0.02%, S: 0 to 0.002%, Cr: 0.05% to 0.25%, La: 0.0001% to 0.01%, Ce: 0.0001% to 0.01%, and the balance is Fe and unavoidable impurities.

2. The low alloy high toughness martensitic wear-resistant steel according to claim 1, characterized in that: Calculated by mass percentage, the Cr content of the wear-resistant steel is 0.05% to 0.2%.

3. The low alloy high toughness martensitic wear-resistant steel according to claim 1, characterized in that: Calculated by mass percentage, the La content of the wear-resistant steel is 0.006% to 0.009%.

4. The low alloy high toughness martensitic wear-resistant steel according to claim 1, characterized in that: Calculated by mass percentage, the Ce content of the wear-resistant steel is 0.006% to 0.009%.

5. The low alloy high toughness martensitic wear-resistant steel according to any one of claims 1 to 4, characterized in that: Calculated by mass percentage, satisfy one or more of the following (1) to (4): (1) The wear-resistant steel has a carbon content of 0.12% to 0.25%; (2) The Si content of the wear-resistant steel is 0.1% to 0.2%; (3) The wear-resistant steel has a Mn content of 1.0% to 1.3%; (4) The S content of the wear-resistant steel is 0 to 0.001%.

6. The low alloy high toughness martensitic wear-resistant steel according to any one of claims 1 to 4, characterized in that: Satisfy one or more of the following (1) to (6): (1) The yield strength of the wear-resistant steel is ≥1000 MPa; (2) The tensile strength of the wear-resistant steel is ≥1000 MPa; (3) The elongation of the wear-resistant steel is ≥10%; (4) The hardness of the wear-resistant steel is ≥350 HBW; (5) The low-temperature impact energy of the wear-resistant steel at -20°C is ≥120J; (6) The low-temperature impact energy of the wear-resistant steel at -60°C is ≥60J.

7. A method for preparing the low alloy high toughness martensitic wear-resistant steel according to any one of claims 1 to 6, characterized in that: include: the steps of steelmaking, rolling, and heat treating; The steelmaking process includes: hot metal KR desulfurization, converter steelmaking, LR refining, RH vacuum refining, adding rare earth in a tundish, and continuous casting. Among them, the refining temperature is ≥1530℃, the refining time is ≥45min, the superheat range of the tundish is 10℃~25℃, the rare earth alloy added to the tundish is ≥70kg, the continuous casting drawing speed is 0.9m / min~1.2m / min, and the slab thickness is 200mm~250mm.

8. The method for preparing low alloy high toughness martensitic wear-resistant steel according to claim 7, characterized in that: The steel rolling comprises the steps of: slab heating, rough rolling, finish rolling, coiling and coil stacking; Among them, the set temperature of the soaking section of the heating furnace is 1200℃~1230℃, the total time of the steel plate in the furnace is 150min~200min, 5~7 rough rolling passes are adopted, the surface temperature of the slab after rough rolling is 1100℃~1150℃, the surface temperature of the slab after finish rolling is 880℃~940℃, and the coiling temperature is set to 550℃~620℃.

9. The method for preparing low alloy high toughness martensitic wear-resistant steel according to any one of claims 7 to 8, characterized in that: The heat treatment includes the steps of: cross-cutting the steel coil, quenching the single plate, tempering the single plate, and stacking and packaging; Among them, the quenching heating temperature of the steel plate is 860℃~920℃, and the quenching holding time is 20min~40min; the tempering heating temperature of the steel plate is 160℃~240℃, and the tempering holding time is 35min~70min.

10. Use of the low-alloy high-toughness martensitic wear-resistant steel according to any one of claims 1 to 6 in tableware and knives, steel parts for engineering machinery, aerospace parts, medical equipment, oil and gas industry parts, automotive parts or power generation equipment.

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