A HB450 grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact and its preparation method

Abstract

The present invention relates to the technical field of metal material manufacturing, and more specifically to an HB450-grade online water-cooled wear-resistant steel plate resistant to low-temperature impacts of -40°C and a preparation method thereof. The chemical composition of the steel plate includes C: 0.20% to 0.26%, Si: 0.10% to 0.20%, Mn: 0.60% to 1.10%, P ≤ 0.010%, S ≤ 0.003%, Ni: 0.30% to 0.80%, Cr: 0.70% to 1.00%, Mo: 0.10% to 0.40%, Ti: 0.015% to 0.030%, Al: 0.030% to 0.070%, B: 0.0008% to 0.0035%, O ≤ 0.0025%, N ≤ 0.0030%, H ≤ 0.00018%, and the remainder is Fe and unavoidable impurities. The steel plate of the present invention has the characteristics of a short production process, good low-temperature impact toughness, and high surface hardness.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material manufacturing, and in particular to a HB450-grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact and a preparation method thereof. Background Art

[0002] Wear-resistant steel plates are key materials for manufacturing engineering equipment such as coal mining machinery, port machinery, engineering machinery, mining equipment, and dump trucks. In recent years, the large-scale and heavy-duty characteristics of equipment have become increasingly prominent, and multi-scenario application environments have put forward higher requirements on the performance of wear-resistant steel plates. At present, for the production of high-level wear-resistant steel, the offline quenching heat treatment method is generally adopted, and the tempering temperature is relatively high. This production method has a long process flow and high heat treatment costs, which is not conducive to improving efficiency and energy conservation and environmental protection. In addition, impact toughness has a great influence on wear resistance under complex wear conditions, but at this stage, there is little research on the low-temperature (-40°C) impact toughness of wear-resistant steel. Therefore, shortening the production process of high-level wear-resistant steel and developing wear-resistant steel products that can withstand low-temperature impacts of -40°C are one of the important directions for the development of wear-resistant steel.

[0003] Chinese patent application CN201710899388.7 discloses a high-strength wear-resistant steel plate for mining machinery, which is designed with high C (0.7% to 0.9%) and high Mn (1.6% to 1.8%) components. The high C and Mn contents make it easy for the continuous casting billet to produce center segregation, and the steel plate is prone to cracking, while the welding performance is poor. In addition, offline quenching is adopted, and the quenching temperature is Ac3+0 to 100°C. The process flow is long, and the heat treatment cost is increased, which is not conducive to energy saving. No research on low-temperature impact performance is involved.

[0004] Chinese patent application CN202010949264.7 discloses a martensitic high-temperature wear-resistant steel and a production method thereof, which adopts an offline quenching process with a quenching temperature of Ac3+30~50°C. The process flow is long, while increasing the heat treatment cost, which is not conducive to energy conservation; and does not involve research on low-temperature impact performance.

[0005] Chinese patent application CN201010200002.7 discloses a high-strength and high-toughness low-alloy wear-resistant steel and a method for manufacturing the same. The steel adopts a high Mn (1.2% to 1.6%) composition design. The high Mn content makes it easy for the continuous casting billet to produce center segregation, and the steel plate to produce cracks, and the welding performance is poor. Off-line quenching is adopted, which has a long process flow and increases the heat treatment cost, which is not conducive to energy conservation. In addition, it only mentions that the impact absorption energy at -20°C is above 60J, and does not involve the impact absorption energy at -40°C.

[0006] Chinese patent application CN201810398720.6 discloses a low-cost, high-hardenability HB450 grade medium and thick wear-resistant steel plate and a manufacturing method, which adds excessive Si (1.4% to 1.6%) and Mn (3.7% to 4%). Excessive Si content can easily cause the welding performance of the steel plate to decline and the sensitivity of welding cracks to increase. High Mn content can easily cause central segregation of the continuous casting billet; in addition, a relatively high V (0.15% to 0.25%) is also added, which increases the alloy cost; this invention does not undergo LF furnace refining during the steelmaking process, and cannot effectively control the inclusion content in the molten steel, which will eventually affect the impact performance of the steel plate; high-temperature tempering is used, which increases energy consumption and heat treatment costs; and no research on low-temperature impact performance is involved.

[0007] It can be seen that there are few cases in the existing technology where both the short-process production process of high-grade wear-resistant steel and -40°C low-temperature impact toughness are studied. Therefore, it is of great practical significance to develop a HB450 grade wear-resistant steel plate resistant to -40°C low-temperature impact and a manufacturing method thereof. Summary of the Invention

[0008] In view of the problem that the existing technology lacks simultaneous research on the short-process production process and -40℃ low-temperature impact toughness of high-grade wear-resistant steel, the present invention provides a HB450-grade online water-cooled wear-resistant steel plate resistant to -40℃ low-temperature impact and a preparation method thereof. With the goals of saving costs, improving production efficiency and low-temperature impact toughness, the steel plate produced through clean smelting, continuous casting, rolling, water cooling and heat treatment processes has a yield strength of ≥1150MPa, a tensile strength of ≥1250MPa, an elongation after fracture of ≥8%, an impact absorption energy of ≥40J at -40℃, and a surface Brinell hardness of 440-470HBW. It has the characteristics of a short production process, good low-temperature impact toughness and high surface hardness.

[0009] In a first aspect, the present invention provides a method for preparing a HB450-grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact, wherein the chemical composition of the HB450-grade online water-cooled wear-resistant steel plate, measured by weight percentage, includes C: 0.20% to 0.26%, Si: 0.10% to 0.20%, Mn: 0.60% to 1.10%, P≤0.010%, S≤0.003%, Ni: 0.30% to 0.80%, Cr: 0.70% to 1.00%, Mo: 0.10% to 0.40%, Ti: 0.015% to 0.030%, Al: 0.030% to 0.070%, B: 0.0008% to 0.0035%, O≤0.0025%, N≤0.0030%, H≤0.00018%, and the remainder is Fe and unavoidable impurities;

[0010] The preparation method of HB450 grade online water-cooled wear-resistant steel plate includes smelting, continuous casting, heating, rolling, online water cooling and heat treatment.

[0011] Furthermore, the smelting process adopts converter smelting + double refining (LF+RH) technology to strictly control harmful elements and inclusions such as P, S, O, N, and H.

[0012] Furthermore, the superheat of the tundish in the continuous casting process is controlled at 10-20°C, the casting is protected throughout the process, the casting machine speed fluctuation is controlled at the target value ±0.1m / min, the thickness of the ingot is 200-300mm, and the ingot is stacked in a slow cooling pit for slow cooling for more than 60 hours.

[0013] Furthermore, the target casting speed of the casting machine is 0.9 to 1.3 m / min.

[0014] Furthermore, the heating time of the casting in the heating process is 3.0 to 6.0 hours, and the furnace temperature is controlled at 1230 to 1260°C.

[0015] Furthermore, after the ingot is taken out of the furnace, high-pressure water descaling is carried out, and the descaling water pressure is ≥24MPa to ensure clean descaling.

[0016] Furthermore, the specific steps of the rolling process are:

[0017] The rough rolling + finishing rolling mode is adopted, the rough rolling start temperature is 1130-1170℃, the high reduction mode is adopted in the rough rolling stage, the rolling reduction rate of the first and last passes in the rough rolling stage is ≥20%, and the rolling reduction of the intermediate passes is ≥25mm; the thickness of the intermediate billet is at least 2.3 times the thickness of the finished steel plate;

[0018] The intermediate billet is kept warm before finishing rolling. For steel plates with a finished thickness of [10,20] mm, the starting temperature of finishing rolling is 1020-1060°C, and the finishing temperature of finishing rolling is 920-960°C. For steel plates with a finished thickness of (20,50] mm, the starting temperature of finishing rolling is 940-980°C, and the finishing temperature of finishing rolling is 880-920°C.

[0019] Furthermore, the starting cooling temperature of the online water cooling process is ≥850°C, the final cooling temperature is 350-400°C, and the cooling rate is ≥30°C / ≥.

[0020] Furthermore, the heat treatment process adopts tempering treatment, the tempering heating temperature is ≤200℃, the holding time is 35-120min, and the steel is air-cooled after being taken out of the furnace to obtain HB450 grade online water-cooled wear-resistant steel plate.

[0021] In a second aspect, the present invention provides a HB450 grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact produced by the above-mentioned preparation method.

[0022] Furthermore, the thickness of the HB450 grade online water-cooled wear-resistant steel plate is 10 to 50 mm.

[0023] Furthermore, the yield strength of the HB450 grade online water-cooled wear-resistant steel plate is ≥1150MPa, the tensile strength is ≥1250MPa, the elongation after fracture is ≥8%, the impact absorption energy at -40°C is ≥40J, and the surface Brinell hardness is 440-470HBW.

[0024] The beneficial effects of the present invention are:

[0025] (1) Through reasonable composition design, the austenite zone is expanded, the A3 temperature is lowered, and the martensite start transformation temperature (M≥) is increased, which better guarantees the realization of the start cooling temperature and the transformation of the martensite structure, and achieves a lower start cooling temperature and a higher final cooling temperature. The process is simple and efficient; (2) There is no need for offline quenching, and the online water cooling + low-temperature tempering process is adopted, which greatly shortens the process flow, reduces the heat treatment cost, and reduces energy consumption.

[0026] The preparation method of the present invention realizes the production of HB450 grade online water-cooled wear-resistant steel plate resistant to low-temperature impact at -40°C. The steel has a yield strength of 1170-1260 MPa, a tensile strength of ≥1350 MPa, an elongation after fracture of 9%-17%, an impact absorption energy at -40°C of 40-86 J, a surface Brinell hardness of 440-470 HBW, an appropriate performance margin, good low-temperature impact toughness, and stable quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 This is a typical scanning electron microscope micrograph of the HB450 grade online water-cooled wear-resistant steel plate produced in Example 1 of the present invention.

[0029] Figure 2 This is a typical scanning electron microscope micrograph of the HB450 grade online water-cooled wear-resistant steel plate produced in Example 2 of the present invention.

[0030] Figure 3 This is a typical scanning electron microscope micrograph of the HB450 grade online water-cooled wear-resistant steel plate produced in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0032] Example 1

[0033] A HB450 grade online water-cooled wear-resistant steel plate resistant to low-temperature impact at -40°C has a thickness of 10 mm and a chemical composition, by weight percentage, comprising C: 0.22%, Si: 0.15%, Mn: 0.75%, P: 0.007%, S: 0.001%, Ni: 0.42%, Cr: 0.75%, Mo: 0.21%, Ti: 0.023%, Al≥: 0.048%, B: 0.0014%, O: 0.0016%, N: 0.0022%, H: 0.00012%, and the remainder being Fe and unavoidable impurities.

[0034] The HB450 grade online water-cooled wear-resistant steel plate is produced according to the following preparation method:

[0035] (1) Smelting: According to the steel plate composition, the converter smelting + double refining (LF+RH) process is adopted, and harmful elements and inclusions such as P, S, O, N, and H are strictly controlled.

[0036] (2) Continuous casting: The superheat of the tundish is controlled at 10-20°C, and the casting is protected throughout the process. The casting speed fluctuation of the casting machine is controlled at 1.2±0.1m / min; the thickness of the ingot is 200mm, and the ingot is stacked in a slow cooling pit for slow cooling for 65h.

[0037] (3) Heating: The heating time of the ingot is 3.2 h, and the furnace temperature is controlled at 1253 °C.

[0038] (4) Rolling: After the billet is removed from the furnace, high-pressure water descaling is carried out, and the descaling water pressure is ≥24MPa to ensure that the descaling is clean;

[0039] The rolling mode of roughing + finishing rolling is adopted; the starting temperature of roughing rolling is 1170℃, and the large reduction mode is adopted in the roughing stage. The rolling reduction rates of the first and last passes in the roughing stage are 23% and 21% respectively, and the rolling reduction of the intermediate passes is ≥25mm; the thickness of the intermediate billet is 45mm; the intermediate billet is warmed before the start of finishing rolling, the starting temperature of finishing rolling is 1050℃, and the final temperature of finishing rolling is 932℃.

[0040] (5) Online water cooling: The rolled steel plate is water cooled online, with the starting cooling temperature at 859°C, the final cooling temperature at 388°C, and the cooling rate at 30°C / ≥.

[0041] (6) Tempering: The tempering heating temperature is 160℃, the holding time is 35min, and the steel is air-cooled after being taken out of the furnace to obtain HB450 grade online water-cooled wear-resistant steel plate.

[0042] The mechanical properties of the HB450 grade online water-cooled wear-resistant steel plate were tested, and the results are shown in Table 1 below.

[0043] Table 1 Mechanical properties of the steel plate of Example 1

[0044]

[0045] Example 2

[0046] A HB450 grade online water-cooled wear-resistant steel plate resistant to low-temperature impact at -40°C has a thickness of 30 mm and a chemical composition, by weight percentage, comprising C: 0.24%, Si: 0.17%, Mn: 0.86%, P: 0.007%, S: 0.001%, Ni: 0.61%, Cr: 0.86%, Mo: 0.29%, Ti: 0.021%, Al≥: 0.055%, B: 0.0018%, O: 0.0021%, N: 0.0026%, H: 0.00016%, and the remainder being Fe and unavoidable impurities.

[0047] The HB450 grade online water-cooled wear-resistant steel plate is produced according to the following preparation method:

[0048] (1) Smelting: According to the steel plate composition, the converter smelting + double refining (LF+RH) process is adopted, and harmful elements and inclusions such as P, S, O, N, and H are strictly controlled.

[0049] (2) Continuous casting: The superheat of the tundish is controlled at 10-20°C, and the casting is protected throughout the process. The casting speed fluctuation of the casting machine is controlled at 1.0±0.1m / min; the thickness of the billet is 300mm, and the billets are stacked in a slow cooling pit for slow cooling for 70h.

[0050] (3) Heating: The heating time of the ingot is 5.0 h, and the furnace temperature is controlled at 1245 °C.

[0051] (4) Rolling: After the billet is removed from the furnace, high-pressure water descaling is carried out, and the descaling water pressure is ≥24MPa to ensure that the descaling is clean;

[0052] The rolling mode of roughing + finishing rolling is adopted; the starting temperature of roughing rolling is 1162℃, and the large reduction mode is adopted in the roughing stage. The rolling reduction rates of the first and last passes in the roughing stage are 22% and 21% respectively, and the rolling reduction of the intermediate passes is ≥25mm; the thickness of the intermediate billet is 90mm; the intermediate billet is warmed before the start of finishing rolling, the starting temperature of finishing rolling is 972℃, and the final rolling temperature of finishing rolling is 916℃.

[0053] (5) Online water cooling: The rolled steel plate is water cooled online, with the starting cooling temperature at 874°C, the final cooling temperature at 380°C, and the cooling rate at 31°C / ≥.

[0054] (6) Tempering: The tempering heating temperature is 180℃, the holding time is 65min, and the steel is air-cooled after being taken out of the furnace to obtain HB450 grade online water-cooled wear-resistant steel plate.

[0055] The mechanical properties of the HB450 grade online water-cooled wear-resistant steel plate were tested, and the results are shown in Table 2 below.

[0056] Table 2 Mechanical properties of the steel plate of Example 2

[0057]

[0058] Example 3

[0059] A HB450 grade online water-cooled wear-resistant steel plate resistant to low-temperature impact of -40°C has a thickness of 50 mm and a chemical composition, by weight percentage, comprising C: 0.25%, Si: 0.14%, Mn: 1.00%, P: 0.006%, S: 0.001%, Ni: 0.74%, Cr: 0.92%, Mo: 0.36%, Ti: 0.025%, Al≥: 0.053%, B: 0.0015%, O: 0.0019%, N: 0.0023%, H: 0.00012%, and the remainder being Fe and unavoidable impurities.

[0060] The HB450 grade online water-cooled wear-resistant steel plate is produced according to the following preparation method:

[0061] (1) Smelting: According to the steel plate composition, the converter smelting + double refining (LF+RH) process is adopted, and harmful elements and inclusions such as P, S, O, N, and H are strictly controlled.

[0062] (2) Continuous casting: The superheat of the tundish is controlled at 10-20°C, and the casting is protected throughout the process. The casting speed fluctuation of the casting machine is controlled at 0.95±0.1m / min; the thickness of the ingot is 300mm, and the ingot is stacked in a slow cooling pit for slow cooling for 72h.

[0063] (3) Heating: The heating time of the ingot is 5.3 h, and the furnace temperature is controlled at 1240 °C.

[0064] (4) Rolling: After the billet is removed from the furnace, high-pressure water descaling is carried out, and the descaling water pressure is ≥24MPa to ensure that the descaling is clean;

[0065] The rolling mode of roughing + finishing rolling is adopted; the starting temperature of roughing rolling is 1159℃, and the large reduction mode is adopted in the roughing stage. The rolling reduction rates of the first and last passes in the roughing stage are 20% and 22% respectively, and the rolling reduction of the intermediate passes is ≥25mm; the thickness of the intermediate billet is 115mm; the intermediate billet is warmed before the start of finishing rolling, the starting temperature of finishing rolling is 951℃, and the finishing temperature is 902℃.

[0066] (5) Online water cooling: The rolled steel plate is water cooled online, with the starting cooling temperature at 884°C, the final cooling temperature at 352°C, and the cooling rate at 32°C / ≥.

[0067] (6) Tempering: The tempering heating temperature is 200℃, the holding time is 120min, and the steel is air-cooled after being taken out of the furnace to obtain HB450 grade online water-cooled wear-resistant steel plate.

[0068] The mechanical properties of the HB450 grade online water-cooled wear-resistant steel plate were tested, and the results are shown in Table 3 below.

[0069] Table 3 Mechanical properties of the steel plate of Example 3

[0070]

[0071] Although the present invention has been described in detail with reference to the accompanying drawings and in conjunction with preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any changes or substitutions that can be easily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall be within the scope of protection of the present invention.

Claims

1. A method for preparing a HB450 grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact, characterized in that: The chemical composition of HB450 grade online water-cooled wear-resistant steel plate is calculated by weight percentage, including C: 0.20%~0.26%, Si: 0.10%~0.20%, Mn: 0.60%~1.10%, P≤0.010%, S≤0.003%, Ni: 0.30%~0.80%, Cr: 0.70%~1.00%, Mo: 0.10%~0.40%, Ti: 0.015%~0.030%, Al: 0.030%~0.070%, B: 0.0008%~0.0035%, O≤0.0025%, N≤0.0030%, H≤0.00018%, and the rest is Fe and unavoidable impurities; The preparation method of HB450 grade online water-cooled wear-resistant steel plate includes smelting, continuous casting, heating, rolling, online water cooling and heat treatment; The specific steps of the rolling process are: The rough rolling + finishing rolling mode is adopted, the rough rolling start temperature is 1130~1170℃, the high reduction mode is adopted in the rough rolling stage, the rolling reduction rate of the first and last passes in the rough rolling stage is ≥20%, and the rolling reduction of the intermediate passes is ≥25mm; the thickness of the intermediate billet is at least 2.3 times the thickness of the finished steel plate; The intermediate billet is kept warm before finishing rolling. For finished steel plates with a thickness of [10,20] mm, the start temperature of finishing rolling is 1020~1060℃, and the finishing temperature is 920~960℃. For finished steel plates with a thickness of (20,50] mm, the start temperature of finishing rolling is 940~980℃, and the finishing temperature is 880~920℃. The starting temperature of the online water cooling process is ≥850℃, the final cooling temperature is 350~400℃, and the cooling rate is ≥30℃ / s; The heat treatment process adopts tempering treatment, the tempering heating temperature is ≤200℃, the holding time is 35~120min, and the furnace is air-cooled to obtain HB450 grade online water-cooled wear-resistant steel plate; The yield strength of HB450 grade online water-cooled wear-resistant steel plate is ≥1150MPa, the tensile strength is ≥1250MPa, the elongation after fracture is ≥8%, the impact absorption energy at -40℃ is ≥40J, and the surface Brinell hardness is 440~470HBW.

2. The preparation method according to claim 1, wherein The superheat of the tundish in the continuous casting process is controlled at 10~20℃, the casting is protected throughout the process, the casting machine speed fluctuation is controlled at the target value ±0.1m / min, the thickness of the ingot is 200~300mm, and the ingot is stacked in a slow cooling pit for slow cooling for more than 60 hours.

3. The preparation method according to claim 2, wherein The target casting speed of the casting machine is 0.9~1.3m / min.

4. The preparation method according to claim 1, wherein The heating time of the casting in the heating process is 3.0~6.0h, and the furnace temperature is controlled at 1230~1260℃.

5. An HB450 grade online water-cooled wear-resistant steel plate resistant to -40°C low-temperature impact produced by the preparation method according to any one of claims 1 to 4.

6. The HB450 grade online water-cooled wear-resistant steel plate according to claim 5, characterized in that: The thickness of HB450 grade online water-cooled wear-resistant steel plate is 10~50mm.

Images