Production method of non-tempering process HB450 grade wear-resistant steel plate

Abstract

The application discloses a production method of a non-tempering process HB450-grade wear-resistant steel plate, and mainly has the following process parameters: 1) smelting and casting; after continuous casting billet cutting is completed, stacking and slow cooling are carried out; 2) heating and rolling; the slab discharge temperature is controlled to be 1185-1210 DEG C; the rough rolling opening rolling temperature is above 1100 DEG C, the finish rolling temperature is required to be 840+ / -20 DEG C, and stacking and slow cooling are carried out; 3) heat treatment, without tempering treatment; the chemical components are as follows: C: 0.19-0.21%, Si: 0.31-0.45%, Mn: 1.25-1.35%, P: <=0.012%, S: <=0.010%, Nb: 0.015-0.025%, Cr: 0.70-0.85%, Mo: 0.20-0.35%, and B: 0.0010-0.0020%. Through reasonable component design and appropriate process, the application produces the wear-resistant steel with excellent performance.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant steel technology, and in particular to a method for producing HB450 grade wear-resistant steel plates without tempering. Background Technology

[0002] Steel plates, characterized by high wear resistance, long service life, and good impact resistance, have become a product urgently needed for upgrading in industries such as coal mining, mining transportation, and warehousing. Steel is a special plate product used under abrasive conditions. Wear-resistant steel plates offer high wear resistance, long service life, and certain impact resistance, making them very cost-effective. Furthermore, with the development of lightweighting, slag dump trucks, while using high-strength wear-resistant steel, have increased strength, effectively reducing material thickness, lightening vehicle weight, improving wear resistance, and extending service life.

[0003] Currently, the country's green, environmental protection, and low-carbon development has become an urgent need and direction. The production of wear-resistant steel requires heat treatment, which consumes a lot of energy. Therefore, how to reduce consumption and emissions has become an important direction in the production of wear-resistant steel.

[0004] Application publication number CN 106244920 A discloses a Brinell hardness grade 450 wear-resistant steel and its manufacturing method. The chemical composition of the steel, by weight percentage, is: C 0.17-0.22%, Si 0.40-0.60%, Mn 1.2-1.45%, P≤0.01%, S≤0.005%, Cr 0.6-0.85%, Ni≤0.1%, Mo≤0.1%, Al 0.02-0.05%, Ti≤0.015%, V≤0.02%, B≤0.004%, with the remainder being iron and unavoidable impurities. The invention also provides a method for manufacturing the Brinell hardness grade 450 wear-resistant steel. This invention differs from the aforementioned invention in its composition design and production process; it does not require tempering heat treatment. The low-temperature impact toughness of this invention is significantly better than that of the aforementioned inventions.

[0005] The invention disclosed in CN 108315652 B, a low-cost, high-hardenability HB450 grade medium-thick wear-resistant steel plate and its manufacturing method, has the following chemical element composition and weight percentages: C: 0.24-0.29%, Si: 1.4-1.6%, Mn: 3.7-4%, Ni: 0.38-0.42%, Mo: 0.20-0.35%, V: 0.15-0.25%, P≤0.010%, S≤0.005%, satisfying 0.4%≤V+Mo≤0.56%, with the remainder being Fe and unavoidable inclusions. The thickness of the steel plate is 20-70mm. This wear-resistant steel plate exhibits good hardenability, uniform microstructure, and low residual stress, avoiding microcrack initiation that may result from repeated high-temperature heating of wear-resistant steel. The risk of cracking during application is significantly reduced, with a tensile strength exceeding 1250MPa and a Brinell hardness exceeding 420. The composition design of this invention differs significantly from that of the aforementioned inventions. The manufacturing process of this invention also differs significantly from that of the aforementioned inventions; this invention does not require tempering heat treatment. The hardness index of this invention is higher than that of the aforementioned inventions. The microstructure of this invention differs significantly from that of the aforementioned inventions.

[0006] The invention disclosed in CN 109609839 B is a low-alloy high-strength wear-resistant steel NM450 with high elongation performance and its production method. The NM450 has the following chemical composition by weight percentage: C: 0.17-0.23, Si: 0.10-0.50, Mn: 0.8-1.50, P≤0.020, S≤0.015, Al2S: 0.030-0.055, Nb: 0.015-0.050, Ti: 0.010-0.030, Cr: 0.30-0.50%; Mo: 0.15-0.35; B: 0.0005-0.0018%; the remainder being Fe and unavoidable impurities. The production method of this wear-resistant steel includes a two-pass controlled rolling process for cast billets. The first pass of this process includes widening rolling and elongation rolling. Widening rolling consists of 1-5 passes with a single-pass reduction rate not exceeding 8% to avoid edge folding defects. Elongation rolling employs a large reduction regime, consisting of 4-10 passes with a single-pass reduction rate ranging from 15-25%. The second pass involves 3-8 passes of elongation rolling, with a single-pass reduction rate ranging from 8-15%. The NM450 wear-resistant steel produced using this invention has a tensile strength ≥1250MPa, an elongation ≥13.5%, and wear resistance 1.2-1.4 times that of wear-resistant steel produced by ordinary processes. The difference between this invention and the aforementioned inventions lies in the different composition design and manufacturing processes. The aforementioned inventions use online quenching followed by low-temperature tempering, while this invention uses furnace quenching, eliminating the need for tempering. The steel plate of this invention has significantly better performance in terms of strength, elongation, and low-temperature impact toughness. Summary of the Invention

[0007] To reduce production consumption, lower production costs, improve production efficiency, and shorten delivery cycles in the production of wear-resistant steel, this invention aims to provide a method for producing HB450 grade wear-resistant steel plates without tempering. Through rational composition design and appropriate rolling and quenching heat treatment processes, high-performance HB450 grade wear-resistant steel is produced. This invention increases the production efficiency of wear-resistant steel, shortens the turnaround time, reduces production costs for manufacturers, improves efficiency, and also saves social resources.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This invention discloses a method for producing HB450 grade wear-resistant steel plates without tempering. The main process parameters are as follows:

[0010] 1) Smelting and casting

[0011] The molten iron undergoes desulfurization pretreatment, high-quality scrap steel is added, and LF refining and heating and alloying treatment are carried out to ensure that the composition and temperature of the molten steel meet the requirements of subsequent processes; RH vacuum treatment is performed for 15-25 minutes; after vacuum treatment, soft blowing is carried out. During soft blowing, the surface of the ladle slag should be kept calm and the molten steel should not be exposed to air.

[0012] After the continuously cast billets are cut, they are stacked and cooled slowly.

[0013] 2) Heating and rolling

[0014] The slab exit temperature is controlled at 1185-1210℃; the hot rolling stage adopts two-stage rolling, in which the initial rolling temperature of roughing rolling is above 1100℃, and the final rolling temperature of finishing rolling is required to be 840±20℃, and then the slab is stacked for slow cooling.

[0015] 3) Heat treatment

[0016] The quenching temperature is 910-930℃, the holding time is 40-50min, the quenching cooling rate is 23-29℃ / s, and the surface temperature of the steel plate after quenching should be less than or equal to 50℃. After that, it is placed in a slow cooling pit for slow cooling and no tempering treatment is required.

[0017] The chemical composition of the steel plate, by weight percentage, is: C: 0.19-0.21%, Si: 0.31-0.45%, Mn: 1.25-1.35%, P: ≤0.012%, S: ≤0.010%, Nb: 0.015-0.025%, Cr: 0.70-0.85%, Mo: 0.20-0.35%, B: 0.0010-0.0020%, with the balance being Fe and unavoidable impurities.

[0018] Furthermore, the vacuum treatment time is 20 minutes.

[0019] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.207%, Si: 0.34%, Mn: 1.26%, P: 0.0103%, S: 0.004%, Nb: 0.020%, Cr: 0.78%, Mo: 0.27%, B: 0.0012%, with the balance being Fe and unavoidable impurities.

[0020] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.201%, Si: 0.37%, Mn: 1.29%, P: 0.0103%, S: 0.007%, Nb: 0.016%, Cr: 0.74%, Mo: 0.32%, B: 0.0016%, with the balance being Fe and unavoidable impurities.

[0021] Furthermore, the chemical composition of the steel plate by weight percentage is C: 0.191%, Si: 0.43%, Mn: 1.34%, P: 0.0113%, S: 0.005%, Nb: 0.023%, Cr: 0.82%, Mo: 0.23%, B: 0.0013%, with the balance being Fe and unavoidable impurities.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] This invention produces high-performance HB450 grade wear-resistant steel through rational composition design and appropriate rolling and quenching heat treatment processes. This invention increases the production efficiency of wear-resistant steel, shortens the turnaround time, reduces production costs for manufacturers, improves efficiency, and also saves social resources.

[0024] The key feature of this invention lies in its heat treatment process, which eliminates the need for tempering. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 The metallographic structure is shown in Example 1 of this invention;

[0027] Figure 2 The metallographic structure is shown in Example 2 of this invention;

[0028] Figure 3 The metallographic structure is shown in Example 3 of this invention. Detailed Implementation

[0029] A temper-free high and low temperature toughness HB450 grade wear-resistant steel plate and its production method are disclosed. Through optimization of the heat treatment process, the tempering heat treatment process can be eliminated, reducing the production consumption of wear-resistant steel, reducing production costs, improving production efficiency, and shortening the delivery cycle.

[0030] The production method specifically includes the following steps:

[0031] 1) Smelting

[0032] The molten iron undergoes desulfurization pretreatment, and high-quality scrap steel is added. It is then refined and heated using LF refining and alloying processes to ensure the steel's composition and temperature meet the requirements of subsequent processes. RH vacuum treatment is then performed for 20 minutes. After vacuum treatment, soft blowing is carried out. During soft blowing, the slag surface in the ladle should be kept calm, and the molten steel must not be exposed to air.

[0033] 2) Continuous casting

[0034] The continuous casting process employs protective pouring, while electromagnetic stirring and light pressure are used to ensure the quality of the steel billet.

[0035] 3) Rolling

[0036] The slab exit temperature is controlled at 1185-1210℃. The hot rolling stage adopts a two-stage rolling process, in which the initial rolling temperature of roughing rolling is above 1100℃, and the final rolling temperature of finishing rolling is required to be 840±20℃. Then, the slabs are stacked and slowly cooled without tempering.

[0037] 4) Heat treatment process

[0038] The quenching temperature is 910-930℃, the holding time is 40-50min, the quenching cooling rate is 23-29℃, and the surface temperature of the steel plate after quenching should be less than or equal to 50℃. After that, it is placed in a slow cooling pit for slow cooling.

[0039] Example 1

[0040] The chemical composition (weight percentage) of the steel plate is shown in Table 1 below. The furnace exit temperature of the slab is 1189℃. Two-stage rolling is adopted: roughing rolling start temperature is 1140℃, and finishing rolling finish temperature is 824℃. Quenching process: quenching holding temperature is 915℃, holding temperature is 40 min, quenching cooling rate is 24℃ / s, and after quenching, it is slowly cooled in a slow cooling pit. The steel plate is then obtained. The mechanical properties of the steel plate are shown in Table 2. The microstructure of the steel plate is martensite; the microstructure details are shown in [Table 2]. Figure 1 .

[0041] Example 2

[0042] The chemical composition (weight percentage) of the steel plate is shown in Table 1 below. The furnace exit temperature of the slab was 1197℃, and a two-stage rolling process was adopted. The roughing rolling start temperature was 1147℃, and the finishing rolling finish temperature was 830℃. The quenching process was as follows: quenching holding temperature was 925℃, holding temperature was 43 min, quenching cooling rate was 25℃ / s, and after quenching, the plate was slowly cooled in a slow cooling pit. The steel plate was then obtained. The mechanical properties of the steel plate are shown in Table 2. The microstructure of the steel plate is martensite, and the microstructure details are shown in [Table 2]. Figure 2 .

[0043] Example 3

[0044] The chemical composition (weight percentage) of the steel plate is shown in Table 1 below. The furnace exit temperature of the slab was 1209℃, and a two-stage rolling process was adopted. The roughing rolling start temperature was 1156℃, and the finishing rolling finish temperature was 854℃. Quenching process: quenching holding temperature was 925℃, held for 46 minutes, followed by quenching at a quenching cooling rate of 28℃ / s. After quenching, the slab was placed in a slow cooling pit for slow cooling. The steel plate is then obtained. The mechanical properties of the steel plate are shown in Table 2. The microstructure of the steel plate is martensite, and the microstructure details are shown in Table 2. Figure 3 .

[0045] Table 1: Chemical composition of steel plates (wt%)

[0046]

[0047] Table 2: Steel Plate Properties

[0048]

[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for producing HB450 grade wear-resistant steel plate without tempering, characterized in that: The main process parameters are as follows: 1) Smelting and casting The molten iron undergoes desulfurization pretreatment, high-quality scrap steel is added, and LF refining and heating and alloying treatment are carried out to ensure that the composition and temperature of the molten steel meet the requirements of subsequent processes; RH vacuum treatment is performed for 15-25 minutes; after vacuum treatment, soft blowing is carried out. During soft blowing, the surface of the ladle slag should be kept calm and the molten steel should not be exposed to air. After the continuously cast billets are cut, they are stacked and cooled slowly. 2) Heating and rolling The slab exit temperature is controlled at 1185-1210℃; the hot rolling stage adopts two-stage rolling, in which the initial rolling temperature of roughing rolling is above 1100℃, and the final rolling temperature of finishing rolling is required to be 840±20℃, and then the slab is stacked for slow cooling. 3) Heat treatment The quenching temperature is 910-930℃, the holding time is 40-50min, the quenching cooling rate is 23-29℃ / s, and the surface temperature of the steel plate after quenching should be less than or equal to 50℃. After that, it is placed in a slow cooling pit for slow cooling and no tempering treatment is required. The chemical composition of the steel plate, by weight percentage, is: C: 0.19-0.21%, Si: 0.31-0.45%, Mn: 1.25-1.35%, P: ≤0.012%, S: ≤0.010%, Nb: 0.015-0.025%, Cr: 0.70-0.85%, Mo: 0.20-0.35%, B: 0.0010-0.0020%, with the balance being Fe and unavoidable impurities.

2. The production method of HB450 grade wear-resistant steel plate without tempering process according to claim 1, characterized in that: Vacuum treatment time: 20 minutes.

3. The method for producing HB450 grade wear-resistant steel plate without tempering process according to claim 1, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.207%, Si: 0.34%, Mn: 1.26%, P: 0.0103%, S: 0.004%, Nb: 0.020%, Cr: 0.78%, Mo: 0.27%, B: 0.0012%, with the balance being Fe and unavoidable impurities.

4. The production method of HB450 grade wear-resistant steel plate without tempering process according to claim 1, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.201%, Si: 0.37%, Mn: 1.29%, P: 0.0103%, S: 0.007%, Nb: 0.016%, Cr: 0.74%, Mo: 0.32%, B: 0.0016%, with the balance being Fe and unavoidable impurities.

5. The method for producing HB450 grade wear-resistant steel plate without tempering process according to claim 1, characterized in that: The chemical composition of the steel plate by weight percentage is C: 0.191%, Si: 0.43%, Mn: 1.34%, P: 0.0113%, S: 0.005%, Nb: 0.023%, Cr: 0.82%, Mo: 0.23%, B: 0.0013%, with the balance being Fe and unavoidable impurities.

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