A novel abrasion-resistant steel and a method for manufacturing the same

Abstract

This invention discloses a novel wear-resistant steel and its manufacturing method. It is prepared from the following raw materials by mass percentage: C: 0.12–0.18%, Si: 1.10–1.30%, Mn: 1.60–1.90%, S≤0.005%, P≤0.015%, Ti: 0.10–0.15%, Al: 0.30–0.50%, N≤0.0050%, with the remainder being Fe and unavoidable impurity elements. This invention provides a novel wear-resistant steel and its manufacturing method that changes the existing online rolling method for strengthening wear-resistant steel by relying on hard-phase martensite. By introducing economical, high-hardness TiC particles into the microstructure, the wear resistance of the steel plate is enhanced, and the strength is appropriately reduced. This results in lower stress in the steel plate and easier control of the plate shape. The novel wear-resistant steel produced by this invention and its method has a tensile strength Rm≥950MPa, a yield strength 550MPa≤Rel≤850MPa, HBW≥270HB, and elongation A. 50 With a purity of ≥12%, excellent wear resistance, and simple production process, it is mainly used in the bodies of special-purpose vehicles and has great promotional value.

Description

Technical Field

[0001] This invention belongs to the field of steel materials technology, specifically a new type of wear-resistant steel and its manufacturing method. Background Technology

[0002] In recent years, the demand for thin-gauge wear-resistant steel has been increasing in the professional vehicle industry.

[0003] Patent publication number CN 108411203 A discloses a high-silicon, high-alumina NM300 wear-resistant steel for concrete mixer trucks and its production method. Its chemical composition is: C: 0.10–0.16%, Si: 1.00–1.50%, Mn: 1.50–2.00%, S: ≤0.005%, P ≤0.015%, Nb: 0.010–0.060%, Ti: ≤0.030%, Al: 0.40–0.60%. The method employs segmented cooling to 100–300°C, with the initial cooling rate after finishing rolling being 100–300°C / s, ultimately yielding a wear-resistant steel with a microstructure of ferrite + martensite and a small amount of retained austenite. However, the aforementioned invention suffers from an excessively high initial cooling rate after finishing rolling, making plate shape difficult to control and placing high demands on laminar flow equipment.

[0004] Therefore, we propose a new type of wear-resistant steel and its manufacturing method. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a new type of wear-resistant steel and its manufacturing method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A new type of wear-resistant steel is prepared from the following raw materials by mass percentage: C: 0.12-0.18%, Si: 1.10-1.30%, Mn: 1.60-1.90%, S≤0.005%, P≤0.015%, Ti: 0.10-0.15%, Al: 0.30-0.50%, N≤0.0050%, with the remainder being Fe and unavoidable impurity elements.

[0008] The principle and chemical element dosage control mechanism of this invention are as follows:

[0009] C: In steel, C increases the hardness of the material through solid solution strengthening and has a significant impact on the phase transformation process. High C content tends to result in poor ductility, toughness, and weldability of the steel plate, which is detrimental to subsequent processing and use. Low C content tends to generate a large amount of ferrite, resulting in lower performance. Considering the comprehensive influence of C on material properties, the C control range is set at 0.12–0.18%.

[0010] Mn: Mn mainly plays a role in solid solution strengthening in steel. It can also refine grains, improve strength, and increase wear resistance and toughness. Mn is also a good deoxidizer and desulfurizer. However, the Mn content should not be too high, as excessive Mn content is detrimental to center segregation in the billet and banded structure in the steel plate. Considering the comprehensive influence of Mn on material properties, the Mn content is set within the range of 1.60–1.90%.

[0011] Si (Si): Si dissolves in steel, promoting ferrite precipitation and increasing its hardness. Si can also inhibit cementite formation in austenite, increase carbon activity in austenite, and increase austenite instability. During bainite or martensite transformation, it enriches the carbon in the untransformed retained austenite between laths, ultimately retaining the austenite in a thin film form. This thin film-like retained austenite helps improve the toughness of the steel. However, excessive Si content affects the surface quality of the steel. Considering the overall impact of Si on material properties, the Si content is controlled within the range of 1.10–1.30%.

[0012] Al: Al is a common deoxidizing element in steel. It can also combine with nitrogen to form AlN, which inhibits austenite growth during heating and thus refines the grain size. In steel, aluminum promotes the graphitization of carbon, hinders carbide precipitation, and improves the surface quality of hot-rolled plates. Considering the overall influence of Al on material properties, the Al content is set within the range of 0.30–0.50%.

[0013] Ti: In steel, Ti combines with N to form TiN, which can prevent austenite grain growth and refine the grain size during the billet heating process. In this steel grade, Ti mainly combines with C to form TiC during the billet cooling process. Undissolved TiC during subsequent heating increases the wear resistance of the steel. Considering the overall influence of Ti on material properties, the Ti content is controlled within the range of 0.10–0.15%.

[0014] Preferably, the wear-resistant steel has a thickness of 2.5–6.0 mm, Rm ≥ 950 MPa, 550 MPa ≤ Rel ≤ 850 MPa, HBW ≥ 270 HB, and elongation A. 50 ≥12%.

[0015] Preferably, the manufacturing method of the novel wear-resistant steel includes the following specific steps:

[0016] (S1) Hot metal pretreatment:

[0017] Desulfurization pretreatment is carried out on blast furnace molten iron;

[0018] (S2) Converter smelting:

[0019] The pretreated molten iron is then smelted in a converter.

[0020] (S3), Refining:

[0021] The molten steel after smelting is refined in an LF furnace and then in a RH vacuum furnace.

[0022] (S4), Continuous casting:

[0023] The refined molten steel is then continuously cast to form a billet.

[0024] (S5) Heating;

[0025] Heat treatment is applied to the cast billet;

[0026] (S6), Continuous rolling:

[0027] The heat-treated billet is subjected to rough rolling and finish rolling;

[0028] (S7) Laminar flow cooling:

[0029] After continuous rolling, the strip steel is cooled by laminar flow and then rolled into a coil.

[0030] (S8) Slow cooling

[0031] The coiled steel coil is placed in a slow cooling chamber for slow cooling.

[0032] Preferably, in step (S1), the S content of the molten iron after pretreatment is ≤0.002%, in step (S2), the S content of the molten steel tapped from the converter is ≤0.02%, and in step (S3), the LF refining furnace controls aluminum and nitrogen throughout the process, and the N content of the molten steel after treatment in the RH vacuum refining furnace is ≤0.005%.

[0033] Preferably, in the (S4) continuous casting process, the continuous casting process adopts full-process protective casting, the billet adopts direct charging or hot charging process, and the billet charging temperature is ≥400℃.

[0034] During continuous casting, as the temperature of the billet decreases, a large number of supersaturated TiC particles precipitate from the microstructure.

[0035] Preferably, in the (S5) heating process, the billet is heated to 1200℃~1280℃ in a heating furnace and held for 130~200min.

[0036] At this temperature and holding time, a large number of undissolved TiC particles exist in the steel, which can enhance the wear resistance of the steel plate.

[0037] Preferably, in step (S6), the roughing temperature is 1050-1100℃, 5 passes are used, and the reduction rate is 80-85%; the finishing rolling is 7 passes, the reduction rate is 80-92%, and the finishing rolling exit temperature is 830-920℃.

[0038] Preferably, in the laminar flow cooling (S7), front-end centralized cooling is adopted, with a cooling rate of 15-35℃ / S, cooling to 400℃-450℃, and the curling temperature is 400℃-450℃.

[0039] At this temperature, the coiling process yields a ferrite + bainite + retained austenite microstructure.

[0040] Preferably, the coiled steel coil (S8) is immediately placed in a slow cooling chamber for slow cooling for more than 48 hours.

[0041] Slow cooling serves two purposes: firstly, it releases the internal stress of the steel itself; secondly, it increases the cooling rate of the steel coil after uniform coiling, thereby improving the stability of the coil's continuous winding performance.

[0042] Compared with the prior art, the novel wear-resistant steel and its manufacturing method according to the present invention have the following beneficial effects:

[0043] 1. The novel wear-resistant steel and its manufacturing method provided by this invention change the existing online rolling wear-resistant steel strengthening method that relies on hard phase martensite. By introducing economical high-hardness TiC particles into the microstructure, the wear resistance of the steel plate is enhanced, and the strength is appropriately reduced. It has the characteristics of low cost, low stress in the steel plate, and easy control of plate shape.

[0044] 2. The new wear-resistant steel changes the current situation where online rolling of wear-resistant steel relies on advanced 2250mm hot continuous rolling mills and dense laminar flow systems for production. The production process is simple, and it is mainly used in special vehicle bodies, which has great promotional value. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1 The following describes a specific embodiment of the novel wear-resistant steel and its manufacturing method according to the present invention. The novel wear-resistant steel and its manufacturing method according to the present invention are not limited to the descriptions in the following embodiments.

[0047] Example 1:

[0048] In this embodiment, a wear-resistant steel with ferrite + bainite and a small amount of retained austenite can be obtained, and the specifications of the new wear-resistant steel are 3.50*1500mm.

[0049] A novel wear-resistant steel is prepared from the following raw materials by mass percentage: C: 0.16%, Si: 1.15%, Mn: 1.70%, S: 0.003%, P: 0.010%, Ti: 0.11%, Al: 0.35%, N: 0.0042%, O: 0.0015%, with the remainder being Fe and unavoidable impurity elements.

[0050] The manufacturing method of the novel wear-resistant steel comprises the following specific steps:

[0051] (S1) Hot metal pretreatment:

[0052] The blast furnace molten iron was pretreated for desulfurization, and the sulfur content of the molten iron after pretreatment was 0.001%.

[0053] (S2) Converter smelting:

[0054] The pretreated molten iron was smelted in a converter, and the sulfur content of the molten steel tapped from the converter was 0.008%.

[0055] (S3), Refining:

[0056] The molten iron after smelting is refined in an LF furnace and then in a RH vacuum furnace. The LF refining furnace controls aluminum and nitrogen throughout the process, and the N content of the molten steel after being treated in the RH vacuum furnace is 0.035%.

[0057] (S4), Continuous casting:

[0058] The refined molten steel is then continuously cast to form a billet. The continuous casting process adopts full-process protective casting, and the billet adopts a hot charging process with a billet charging temperature of 490℃.

[0059] (S5) Heating;

[0060] The billet is heated in a heating furnace to 1200℃~1280℃ and held for 130~200min.

[0061] (S6), Continuous rolling:

[0062] The heat-treated billet is subjected to rough rolling and finish rolling. The rough rolling temperature is 1050-1100℃, with 5 passes and a reduction rate of 80-85%. The finish rolling is carried out in 7 passes with a reduction rate of 80-92% and an exit temperature of 830-920℃.

[0063] (S7) Laminar flow cooling;

[0064] After continuous rolling, the billet is cooled by laminar flow and then rolled into a steel coil and processed into a steel plate. The laminar flow cooling adopts front-end centralized cooling at a cooling rate of 25℃ / s, cooling to 400℃~450℃. The rolling temperature is 400℃~450℃. The rolled steel coil is immediately placed in a slow cooling chamber for slow cooling for 50 hours.

[0065] The purpose of this invention is to provide a new type of wear-resistant steel that can be used in the body of special-purpose vehicles to achieve lightweighting.

[0066] Another objective of this invention is to provide a novel method for manufacturing wear-resistant steel, which yields wear-resistant steel with performance indicators such as Rm≥950MPa, 550MPa≤Rel≤850MPa, HBW≥270HB, elongation A50≥10%, and longitudinal impact energy ≥20J at -20℃.

[0067] Table 1 shows the rolling process for the 3.50*1500mm millimeter ...

[0068]

[0069] Table 2 shows the performance of the new wear-resistant steel of Example 3.50*1500mm.

[0070]

[0071] As shown in Table 2, the new 3.50*1500mm wear-resistant steel produced in this embodiment meets the requirements of high strength and high wear resistance, while also achieving an elongation of A. 50 ≥12%.

[0072] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A wear-resistant steel, characterized in that: It is prepared from the following raw materials according to the mass percentage: C: 0.12~0.18%, Si: 1.10~1.30%, Mn: 1.60~1.90%, S≤0.005%, P≤0.015%, Ti: 0.10~0.15%, Al: 0.30~0.50%, N≤0.0050%, with the remainder being Fe and unavoidable impurity elements; The method for manufacturing the wear-resistant steel is characterized by including the following steps: hot metal pretreatment, converter smelting, LF refining, RH refining, continuous casting, heating, continuous rolling, laminar flow cooling and slow cooling; In the laminar flow cooling: front-end centralized cooling is adopted, with a cooling rate of 15-35℃ / s, cooling to 400℃-450℃, and the winding temperature is 400℃-450℃.

2. The wear-resistant steel as described in claim 1, characterized in that, The wear-resistant steel has a thickness of 2.5–6.0 mm, Rm ≥ 950 MPa, 550 MPa ≤ Rel ≤ 850 MPa, HBW ≥ 270 HB, and elongation A50 ≥ 12%.

3. The wear-resistant steel as described in claim 1, characterized in that, In the hot metal pretreatment, converter smelting, LF refining, and RH refining processes: the sulfur content in the hot metal pretreatment is controlled to be ≤0.002%, the sulfur content in the molten steel from the converter is ≤0.02%, the aluminum and nitrogen content in the LF refining furnace is controlled throughout the process, and the nitrogen content in the molten steel after treatment in the RH vacuum refining furnace is ≤0.005%.

4. The wear-resistant steel as described in claim 1, characterized in that, In the continuous casting process: protective casting is used throughout the entire continuous casting process, and the billet is charged using direct charging or hot charging processes, with the billet charging temperature ≥400℃.

5. The wear-resistant steel as described in claim 1, characterized in that, During the heating process: the billet is heated to 1200℃~1280℃ in a heating furnace and held for 130~200min.

6. The wear-resistant steel as described in claim 1, characterized in that, In the continuous rolling process: the roughing temperature is 1050-1100℃, with 5 passes and a reduction rate of 80-85%; the finishing rolling process uses 7 passes with a reduction rate of 80-92%, and the finishing rolling exit temperature is 830-920℃.

7. The wear-resistant steel as described in claim 1, characterized in that, During the slow cooling process: the coiled steel coil is immediately placed in a slow cooling chamber for slow cooling, and the slow cooling time is greater than 48 hours.

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