Q890f high-strength quenched and tempered steel plate and method for producing the same

Abstract

The application discloses a Q890F high-strength and high-quality steel plate and a production method thereof, and a heat treatment process of variable-temperature quenching + variable-temperature tempering is used to obtain the 100-150mm-thick Q890F high-strength and high-quality steel plate, and the steel plate is detected to meet GB / T 6402 level 1; in terms of performance, the yield strength is greater than or equal to 890MPa, the tensile strength is 949-1000MPa, the elongation is greater than or equal to 19%, the impact performance at-60 DEG C is greater than or equal to 150J, the surface-40 DEG C transverse 5% strain aging impact value is greater than or equal to 120J, the core-60 DEG C transverse impact value is greater than or equal to 150J, and the steel plate layer tearing resistance reaches Z55, so that the needs of high-head pumped storage power station, coal mine machinery, large hoisting machinery and other equipment core components can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of super-thick plate production, in particular to a Q890F high-strength and high-quality steel plate and a production method thereof. BACKGROUND

[0002] With the continuous development of various types of mechanical equipment towards large-scale and lightweight, high-strength steel plates have been applied to some extent. Q890-grade high-strength steel plates are often used in hydraulic supports and pull rods of coal mine machinery, waterway diversion branch pipes of pumped storage power stations, and jibs of large-scale hoisting machinery, etc. According to the application environment, the most basic performance requirements are high strength and high toughness, etc. When the thickness is more than 100 mm, due to the influence of billet compression ratio and thickening effect, it is difficult to guarantee the full-thickness performance of the steel plate, especially the low-temperature impact toughness.

[0003] Chinese patent application CN202111409028.7, entitled "Manufacturing method of yield strength 890MPa grade high-strength steel plate", optimizes the alloy composition design without adding Ni and Mo, shortens the process flow and reduces the heat treatment cost through online DQ + offline tempering process, and realizes the ultra-low cost production of 890MPa grade high-strength steel plate. The disadvantage is that it is only suitable for producing 890MPa grade high-strength steel plates with a thickness of 10-30 mm from 150-300 mm thick cast billets. Due to insufficient compression ratio and increased thickness, for super-thick 890MPa grade high-strength steel plates with a thickness of 100 mm or more, only air-cooled controlled rolling and online DQ can not guarantee the quenched strength, and even with offline tempering process, the strength and toughness performance cannot be guaranteed.

[0004] Chinese patent application CN201310559862.3 "Production method of quenched and tempered high-strength Q890D super-thick steel plate", discloses that 300mm thick clean steel continuous casting billets are used to change the center deformation conditions of the rolled piece by high-temperature heating and large temperature gradient reduction, increase the intense deformation of the center of the steel plate, and use online quenching and forced cooling as a preliminary heat treatment to retain the refined structure of the steel plate after controlled rolling, and the steel plate is subjected to offline quenching and tempering treatment to produce quenched and tempered high-strength Q890D super-thick steel plates with a thickness of 100-150 mm.

[0005] Chinese patent application CN201310560834.3 "Production method of quenched and tempered high-strength Q890E super-thick steel plate", discloses that 300mm thick clean steel continuous casting billets are used to change the center deformation conditions of the rolled piece by high-temperature heating and large temperature gradient reduction, increase the intense deformation of the center of the steel plate, and use online quenching and forced cooling as a preliminary heat treatment to retain the refined structure of the steel plate after controlled rolling, and the steel plate is subjected to offline quenching and tempering treatment to produce quenched and tempered high-strength Q890E super-thick steel plates with a thickness of 100-150 mm.

[0006] The above two patents aim to provide thick plates using continuous casting billets and low compression ratio rolling, while ensuring performance and flaw detection quality. The shortcomings are: first, in order to ensure that large reduction can be achieved in the rough rolling stage, the heating temperature needs to reach 1280-1300℃, and the rough rolling opening temperature exceeds 1200℃. Such high heating and rolling temperature is easy to coarsen the austenite grain structure, which is not conducive to performance. In industrialization promotion, it is easy to lead to unstable qualified rate; second, in order to realize the surface temperature far lower than the core temperature, so as to facilitate the penetration of rolling force to the core and realize differential temperature rolling, it is necessary to use high-pressure water for continuous multiple times to reduce the surface temperature, and at the same time, fast and temperature-stealing rolling is needed to prevent the core temperature from quickly returning to red to the surface. The risks brought by this are: it is easy to cause uneven cooling of the upper and lower surfaces by high-pressure water cooling, and at the same time, high-speed steel feeding rolling is adopted, which leads to plate warping, even rolling waste and equipment accidents.

[0007] The Q890F high-strength steel plate with a thickness of 100-150 mm is still a blank in the national standard, and the core components of a large domestic high-water head pumped storage power station use Q890 grade high-strength quenched and tempered steel plates with a thickness of 100-150 mm, which require yield strength ≥ 870 MPa, tensile strength 920-1100 MPa, elongation ≥ 16%, transverse impact value ≥ 100 J. In addition to these conventional performance requirements, the steel plate surface transverse 5% strain aging impact value is ≥ 60 J, the steel plate core transverse impact value is ≥ 80 J, the steel plate lamination tear resistance reaches Z35, and the steel plate flaw detection needs to reach GB / T6402 level 1. At present, there is no related report that can use continuous casting or mold casting to ensure this requirement through rolling and heat treatment.

[0008] Therefore, the present application is proposed. SUMMARY

[0009] The purpose of the present application is to provide a Q890F high-strength quenched and tempered steel plate and a production method thereof, which overcomes the problem that the performance of high-strength quenched and tempered steel plates with a thickness of more than 100 mm is difficult to guarantee due to the influence of billet compression ratio and thickening effect, especially the poor low-temperature impact toughness.

[0010] The present application is implemented in the following manner:

[0011] In a first aspect, the present application provides a production method of a Q890F high-strength quenched and tempered steel plate, which comprises heat treatment, and the heat treatment comprises:

[0012] Quenching stage: the billet is heated to 900±10℃ at a speed of ≥ 60℃ / h and then kept for 0.5 hours, and then placed in a temperature zone of 880±10℃ for h1min, and then kept in a temperature zone of 900±10℃ for 0.5 hours, and then cooled to room temperature by water quenching after the end of the keeping; wherein h1min=thickness×(2.2-2.5)min / mm;

[0013] tempering stage: heating the billet to 630±10℃ at a rate of ≤50℃ / h and holding for 0.5h, then holding at 600±10℃, the overall holding time of the tempering stage being h2min, after the holding, air cooling to 300-400℃, and then air cooling to room temperature; wherein h2min=thickness x (1.5-2.5) min / mm, to obtain a Q890F high-strength quenched and tempered steel plate with a thickness of 100-150mm.

[0014] To improve the comprehensive performance of the core of the steel plate, variable holding measures are taken for heat treatment before and after quenching. In the quenching stage, the preset target holding temperature in the heating process is 900±10℃, which is higher than the normal holding temperature of 880±10℃, and its significant advantage is that it is beneficial to the rapid heat transfer in the thickness direction of the steel plate, reduces the in-furnace time of the steel plate, and is beneficial to the rapid austenitization of the steel plate and prevents coarsening; within 0.5h before tapping, the holding temperature is raised to 900±10℃ again to increase the surface temperature of the steel plate, and the purpose is to offset the surface heat loss during the tapping process of the steel plate by increasing the surface temperature of the steel plate, which is beneficial to increasing the undercooling degree and the quenching cooling speed, so as to obtain fine martensite structure and create a good structure basis for tempering. In the tempering process, the preset target holding temperature in the heating process is 630±10℃, which is higher than the normal holding temperature of 600±10℃, and its significant advantage is that it softens the hardened layer on the surface of the steel plate, making the strength uniform in the thickness direction. At the same time, it is beneficial to the rapid heat transfer in the thickness direction of the steel plate, and the core of the steel plate quickly enters the holding stage, which is beneficial to the good matching of the low-temperature impact performance and the strength of the core of the steel plate. The mechanical properties obtained by the steel plate not only meet the requirements of the user, but also are significantly higher than the requirements of the user, especially the impact performance.

[0015] In an optional embodiment, the heat treatment step further comprises sequentially performing water-cooled mold casting of the ingot, heating of the ingot, rolling, and cooling.

[0016] In an optional embodiment, the water-cooled mold casting step comprises: using a water-cooled mold with an inner cavity thickness of ≥500mm to cast, ensuring that the rolling reduction ratio is ≥5, the mold casting temperature is 1560±5℃, the casting time is 20±5min, and after casting, a heating agent is added for riser holding, and the time from the completion of casting to demolding is 8±2h.

[0017] And / or, the heating rate of the ingot heating step is ≤50℃ / h, the holding temperature is 1220±20℃, and the holding time is h3min, h3min=ingot body thickness x (5-10) min / cm.

[0018] And / or, two-stage air-cooling rolling is adopted, the open rolling temperature is greater than or equal to 950 DEG C, the rough rolling pass reduction is 5-10%, the air-cooling thickness is equal to the thickness of the finished steel plate + (80-100) mm; the open rolling temperature of the finish rolling is greater than or equal to 900 DEG C, the finish rolling pass reduction is 5-15 mm, and the final rolling temperature is greater than or equal to 800 DEG C; no high-pressure water cooling is used in the rolling process, and temperature rising rolling is adopted;

[0019] And / or, the cooling times of the cooling step are greater than or equal to 2, the single cooling speed is greater than or equal to 5 DEG C / S, and the final cooling re-red temperature is 500-550 DEG C.

[0020] By using the internal quality advantage of the water-cooled ingot, the steel plate with a flaw detection quality level reaching the level of a forged piece is obtained through large reduction rolling, the thickness reaches 150 mm, compared with the rolling of a billet or a conventional cast iron mold cast ingot, the quality advantage is more; compared with forging, the low cost advantage is more.

[0021] In the second aspect, the application provides a Q890F high-strength and high-quality steel plate produced by the production method in any one of the preceding embodiments.

[0022] In an optional embodiment, the chemical components include the following mass fractions: C≤0.10wt%, Si≤0.10wt%, Mn 1.60-1.90wt%, P≤0.010wt%, S≤0.005wt%, Als 0.020-0.050wt%, Nb 0.015-0.030wt%, Cr 0.70-0.86wt%, Mo 0.10-0.30wt%, Ni 0.20-0.50wt%, V 0.050-0.080wt% and B 0.0010-0.0015wt%, and the rest is Fe and residual elements; wherein: the carbon equivalent CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15≤0.65%.

[0023] In an optional embodiment, the Q890F high-strength and high-quality steel plate has a yield strength greater than or equal to 890 MPa, a tensile strength of 949-1000 MPa, an elongation greater than or equal to 19%, a-60 DEG C impact performance greater than or equal to 150 J, a surface-40 DEG C transverse 5% strain aging impact value greater than or equal to 120 J, a steel plate core-60 DEG C transverse impact value greater than or equal to 150 J, a steel plate resistance to lamellar tearing performance reaching Z55, and a flaw detection conforming to GB / T6402 level 1.

[0024] The application has the following beneficial effects:

[0025] The application adopts the heat treatment process of quenching at variable temperature + tempering at variable temperature to obtain 100-150mm thick Q890F high-strength quenched and tempered steel plate, and after detection, the flaw detection conforms to GB / T 6402 level 1; in terms of performance: yield strength ≥ 890MPa, tensile strength 949-1000MPa, elongation ≥ 19%, -60℃ impact performance ≥ 150J, surface -40℃ transverse 5% strain aging impact value ≥ 120J, core -60℃ transverse impact value ≥ 150J, and the steel plate lamination tear resistance reaches Z55.

[0026] The quality of the 100-150mm thick Q890F high-strength quenched and tempered steel plate in the application meets the use needs of core components of high-head pumped storage power stations, coal mine machinery, large hoisting machinery and the like. The physical quality reaches the level of forgings, and compared with the forging process, the process is simple and batch production is easier to realize. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 The figure is the quenching and tempering heat treatment curve of the steel plate;

[0029] Figure 2 The figure is the macroscopic photo of the welding joint of the steel plate obtained in the embodiment 3 of the application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the application more clear, the technical solutions in the embodiments of the application will be clearly and completely described below. The specific conditions in the embodiments are not specified, and are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased in the market.

[0031] The application provides a production method of 100-150mm thick Q890F high-strength and high-quality steel plate, which contains the following chemical components in mass fraction (unit, wt%): C: ≤0.10, Si: ≤0.10, Mn: 1.60-1.90, P: ≤0.010, S: ≤0.005, Als: 0.020-0.050, Nb: 0.015-0.030, Cr: 0.70-0.85, Mo: 0.10-0.30, Ni: 0.20-0.50, V: 0.050-0.080, B: 0.0010-0.0015, and the rest is Fe and residual elements; wherein: carbon equivalent CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 ≤ 0.65%;

[0032] The heat treatment method comprises the following steps: quenching + tempering process, the heating speed of the quenching process is greater than or equal to 60 ℃ / h, the furnace temperature is controlled at 900 ± 10 ℃ for 0.5 hours before the heat preservation stage and 0.5 hours before the steel tapping, the furnace temperature is kept at 880 ± 10 ℃ for the rest of the time, the heat preservation time is equal to the thickness multiplied by (2.2-2.5) min / mm, and the water quenching is used to cool to room temperature after the heat preservation is completed, and then the tempering is carried out in the furnace; in the tempering process, the temperature is increased to 630 ± 10 ℃ at a speed of less than or equal to 50 ℃ / h and is kept for 0.5 hours, then the temperature is kept at 600 ± 10 ℃, the overall heat preservation time is equal to the thickness multiplied by (1.5-2.5) min / mm, after the steel is taken out of the furnace, the air cooling is used to cool to 300-400 ℃, and then the air cooling is used to cool to room temperature;

[0033] The water-cooled mold ingot, the steel ingot heating, the rolling and the cooling are further included and are specifically as follows:

[0034] a. Water-cooled mold ingot: the water-cooled mold with an inner cavity thickness greater than or equal to 500 mm is used for casting, the rolling reduction ratio is ensured to be greater than or equal to 5, the mold casting temperature is 1560 ± 5 ℃, the casting time is 20 ± 5 minutes, the heating agent is added for the riser heat preservation after the casting, and the time from the completion of the casting to the demolding is 8 ± 2 hours;

[0035] b. Steel ingot heating: the heating speed is less than or equal to 50 ℃ / h, the heat preservation temperature is 1220 ± 20 ℃, and the heat preservation time is equal to the thickness of the steel ingot body multiplied by (5-10) min / cm;

[0036] c. Rolling: two-stage air-cooled rolling is used, the open rolling temperature is greater than or equal to 950 ℃, the rough rolling pass reduction rate is 5-10%, high-pressure water is not used in the rolling process, the temperature is rolled, the air-cooled thickness is equal to the thickness of the steel plate plus (80-100) mm, the open rolling temperature of the finish rolling is greater than or equal to 900 ℃, the finish rolling pass reduction amount is 5-15 mm, and the final rolling temperature is greater than or equal to 800 ℃;

[0037] d. Cooling: the high-density cooling equipment is used for fast cooling after rolling, the cooling frequency is greater than or equal to 2 times, the single cooling speed is greater than or equal to 5 ℃ / S, and the final cooling red temperature is 500-550 ℃;

[0038] The steel plate has yield strength ≥ 890 MPa, tensile strength 949-1000 MPa, elongation ≥ 19%, impact property at -60℃ ≥ 150 J, surface impact value at -40℃ and 5% transverse strain aging ≥ 120 J, core impact value at -60℃ ≥ 150 J, and steel plate resistance to lamellar tearing property reaches Z55, and the flaw detection conforms to GB / T 6402 level 1.

[0039] The features and properties of the present application are further described in detail below in combination with examples.

[0040] Example 1

[0041] The present example provides a processing method of a Q890F high-strength and high-quality steel plate with a rolling plate thickness of 100 mm.

[0042] Through hot metal pretreatment, converter smelting and secondary refining, a molten steel with the following mass fractions (unit, wt%) is obtained: C: 0.09; Si: 0.08; Mn: 1.68; P: 0.008; S: 0.001; Als: 0.045; Nb: 0.027; Cr: 0.73; Mo: 0.15; Ni: 0.21; V: 0.053; B: 0.0014; and the rest is Fe and residual elements. Among them: carbon equivalent CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 = 0.57%. The molten steel is sequentially subjected to water-cooled mold ingot casting, ingot heating, rolling, cooling and heat treatment to obtain a Q890F high-strength and high-quality steel plate, wherein:

[0043] a. Water-cooled mold ingot casting: casting is performed using a water-cooled mold with an inner cavity thickness of 650 mm, and the rolling reduction ratio is 6.5. The mold casting temperature is 1557-1563℃, the casting time is 18 minutes, and after casting, a heating agent is added for riser heat preservation, and the time from casting completion to demolding is 6 hours.

[0044] b. Heating: the heating rate is 33-40℃ / h, the holding temperature is 1206-1225℃, and the holding time is 455 minutes. After the ingot is discharged, the whole is red and the color is uniform.

[0045] c. Rolling: two-stage air-cooled rolling is adopted, the rough rolling temperature is 1070℃, the rough rolling pass reduction is 50-55 mm, high-pressure water is not used during rolling, temperature is rolled, air-cooled thickness is 180 mm, rough rolling temperature is 910℃, and the rough rolling pass reduction is 5-10 mm. Small reduction rolling is adopted to maintain the plate shape, and the finish rolling temperature is 850℃.

[0046] d. Post-rolling cooling: high-density cooling equipment is used for fast cooling after rolling, the cooling frequency is 3 times, the single cooling rate is 6.3℃ / S, and the final cooling red temperature is 516℃.

[0047] e. Heat treatment: quenching + tempering process is adopted, the heating speed in quenching process is 75-90 ℃ / h, the furnace temperature is kept at 900±10 ℃ for 0.5 hours before the heat preservation stage and 0.5 hours before tapping, the rest time is kept at 880±10 ℃, the heat preservation time is 220 minutes, and the water quenching is adopted to cool to room temperature, and then the furnace is charged for tempering. In the tempering process, the temperature is raised to 630±10 ℃ at a speed of 30-40 ℃ / h and kept for 0.5 hours, the rest time is kept at 600±10 ℃, and the heat preservation time is 200 minutes. After tapping, air cooling is adopted to 350 ℃, and then air cooling is adopted to room temperature.

[0048] The Q890F high-strength quenched and tempered steel plate with a thickness of 100 mm produced by the above method has the following properties: ultrasonic wave conforms to GB / T 6402 level 1; yield strength surplus (compared with the requirement of a core component of a certain large high-water-head pumped storage power station in China) is 27-56 MPa, tensile strength surplus is 47-70 MPa, elongation surplus is 3-7%, -60 ℃ impact value surplus is 84-94 J, surface -40 ℃ transverse 5% strain aging impact value surplus is 90 J, core -60 ℃ transverse impact value surplus is 110 J, and steel plate resistance to lamellar tearing performance surplus is 27%. The specific performance data are shown in Table 1.

[0049] Table 1 Performance test of 100 mm Q890F high-strength quenched and tempered steel plate

[0050]

[0051] Example 2

[0052] The embodiment provides a processing method of a Q890F high-strength quenched and tempered steel plate with a rolling plate thickness of 120 mm.

[0053] Through molten iron pretreatment, converter smelting and secondary refining, a molten steel with the following mass fractions (unit, wt%) is obtained: C: 0.09; Si: 0.06; Mn: 1.62; P: 0.006; S: 0.001; Als: 0.025; Nb: 0.021; Cr: 0.80; Mo: 0.20; Ni: 0.27; V: 0.061; B: 0.0014; and the rest is Fe and residual elements. Among them: carbon equivalent CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 = 0.59%. The molten steel is sequentially subjected to water-cooled mold ingot casting, ingot heating, rolling, cooling and heat treatment to obtain a Q890F high-strength quenched and tempered steel plate, wherein:

[0054] a. Water-cooled mold ingot casting: casting is performed by using a water-cooled mold with an inner cavity thickness of 650 mm, and the rolling reduction ratio is 5.4. The mold casting temperature is 1558-1561 ℃, the casting time is 19 minutes, and after casting, a heating agent is added for riser heat preservation, and the time from casting completion to demolding is 6.5 hours.

[0055] b. Heating: the temperature rising speed is 40-45°C / h, the holding temperature is 1220-1230°C, the holding time is 450 minutes, after the steel ingot is discharged, the whole is red and the color is uniform, and there is no overburning problem.

[0056] c. Rolling: two-stage air-cooling rolling is adopted, the rough rolling temperature is 1010°C, the rough rolling pass reduction is 50-55mm, high-pressure water is not used in the rolling process, temperature is rolled, air-cooling thickness = 180mm, the finish rolling rough rolling temperature is 930°C, the finish rolling pass reduction is 10-15mm, and the finish rolling temperature is 860°C.

[0057] d. Post-rolling cooling: high-density cooling equipment is used for fast cooling after rolling, the cooling times is 4 times, the single cooling speed is 6.2°C / s, and the final cooling red temperature is 537°C.

[0058] e. Heat treatment: quenching + tempering process is adopted, the temperature rising speed in the quenching process is 65-70°C / h, the furnace temperature is kept at 900±10°C for 0.5 hours before the holding stage and 0.5 hours before the steel discharging, the furnace temperature is kept at 880±10°C for the rest of time, and the holding time is 290 minutes. After water quenching to room temperature, the steel is charged into the furnace for tempering. In the tempering process, the temperature is raised to 630±10°C at a speed of 35-40°C / h and kept for 0.5 hours, the temperature is kept at 600±10°C for the rest of time, and the holding time is 240 minutes. After discharging, air cooling is used to 350°C, and air cooling is used to room temperature.

[0059] The 120mm Q890F high-strength quenched and tempered steel plate produced by the above method: the ultrasonic wave meets GB / T 6402 level 1; the yield strength surplus is 23-35MPa, the tensile strength surplus is 42-45MPa, the elongation surplus is 4-6%, the-60°C impact value surplus is 71-87J, the surface-40°C transverse 5% strain aging impact value surplus is 75J, the steel plate core-60°C transverse impact value surplus is 91J, and the steel plate anti-lamellar tearing performance surplus is 21%. The specific performance data is shown in Table 2.

[0060] Table 2 Performance test of 120mm Q890F high-strength quenched and tempered steel plate

[0061]

[0062] Example 3:

[0063] The embodiment provides a processing method of a Q890F high-strength quenched and tempered steel plate with a rolled plate thickness of 150mm.

[0064] The molten steel containing the following mass fraction (unit, wt%) of chemical components is obtained through hot metal pretreatment, converter smelting and secondary refining: C: 0.08; Si: 0.09; Mn: 1.88; P: 0.09; S: 0.001; Als: 0.038; Nb: 0.017; Cr: 0.86; Mo: 0.18; Ni: 0.25; V: 0.075; B: 0.0012; and the rest is Fe and residual elements. Among them: carbon equivalent CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 = 0.63%. The molten steel is sequentially subjected to water-cooled mold ingot casting, ingot heating, rolling, cooling and heat treatment to obtain a Q890F high-strength quenched and tempered steel plate, wherein:

[0065] a. Water-cooled mold ingot casting: casting is performed using a water-cooled mold with an inner cavity thickness of 800 mm, and the rolling reduction ratio is 5.3. The mold casting temperature is 1559-1563℃, the casting time is 20 minutes, and after casting, a heat generating agent is added for riser insulation. The time from casting completion to demolding is 8 hours.

[0066] b. Heating: the heating rate is 40-45℃ / h, the holding temperature is 1220-1230℃, and the holding time is 800 minutes. After the ingot is discharged, the whole is red and the color is uniform.

[0067] c. Rolling: two-stage open-air steel rolling is adopted, the open rolling temperature is 1050℃, the rough rolling pass reduction is 50-55mm, high-pressure water is not used during rolling, temperature is rolled, the open-air steel thickness is 200mm, the open rolling temperature of finish rolling is 925℃, the finish rolling pass reduction is 5-10mm, and the finish rolling temperature is 840℃.

[0068] d. Post-rolling cooling: high-density cooling equipment is used for fast cooling after rolling, the cooling frequency is 5 times, the single cooling rate is 5.7℃ / s, and the final cooling red temperature is 525℃.

[0069] e. Heat treatment: quenching + tempering process is adopted, the heating rate during quenching is 65-70℃ / h, the furnace temperature is maintained at 900±10℃ for 0.5 hours before the holding stage and 0.5 hours before discharging, the rest of the time is maintained at 880±10℃, and the holding time is 350 minutes. After water quenching to room temperature, the ingot is reheated. During the tempering process, the temperature is raised to 630±10℃ at a rate of 45-50℃ / h and maintained for 0.5 hours, and the rest of the time is maintained at 600±10℃, and the holding time is 350 minutes. After discharging, air cooling is used to 350℃, and air cooling is used to room temperature.

[0070] The 150mm thick Q890F high-strength tempered steel plate produced by the above method has the following properties: ultrasonic testing conforms to GB / T 6402 Grade 1; yield strength is greater than 20-29MPa, tensile strength is greater than 29-38MPa, elongation is greater than 4-7%, impact value at -60℃ is greater than 75-86J, surface impact value at -40℃ with 5% strain aging is greater than 74J, core impact value at -60℃ is greater than 77J, and the steel plate has a resistance to lamellar tearing exceeding 16%. Specific performance data are shown in Table 3.

[0071] Table 3 Performance Tests of 150mm Q890F High-Strength Tempered Steel Plate

[0072]

[0073] The steel plate obtained in Example 3 was commissioned to a domestic welding research institute to conduct tensile tests, impact tests, and bending tests on the welded joints. Macroscopic photographs of the welded joints are shown below. Figure 2 As shown in Table 4, the specific test results are as follows: Tensile tests were conducted on the welded state, and the tensile strength was sufficient (21 MPa), the cold bending performance was qualified, the average longitudinal impact at -40℃ was 78 J, the average longitudinal impact at -40℃ at the weld center was 116 J, the average longitudinal impact at -40℃ 2 mm from the fusion line was 125 J, the average longitudinal impact at -40℃ 3 mm from the fusion line was 143 J, and the average longitudinal impact at -40℃ 20 mm from the fusion line was 161 J, indicating excellent performance in the weld area.

[0074] Table 4. Weld performance test of 150mm Q890F high-strength and high-quality steel plate

[0075]

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of producing a Q890F high-strength steel plate, characterized by, The heat treatment comprises: quenching stage: heating the billet to 900±10℃ at a speed of ≥60℃ / h, holding for 0.5h, then holding at 880±10℃ for h1min, then entering the temperature zone of 900±10℃ for 0.5h, and then cooling to room temperature by water quenching after the holding; wherein h1min = thickness × (2.2-2.5) min / mm; tempering stage: heating the billet to 630±10℃ at a speed of ≤50℃ / h, holding for 0.5h, then holding at 600±10℃, the overall holding time of the tempering stage being h2min, and then cooling to 300-400℃ by air cooling, and then cooling to room temperature by air cooling; wherein h2min = thickness × (1.5-2.5) min / mm, to obtain a Q890F high-strength quenched and tempered steel plate with a thickness of 100-150mm; The water-cooled mold casting step comprises: using a water-cooled mold with an inner cavity thickness of ≥500mm to cast, ensuring that the rolling reduction ratio is ≥5, the mold casting temperature is 1560±5℃, the casting time is 20±5min, and a heating agent is added for riser insulation after casting, and the time from casting completion to demolding is 8±2h; two-stage air-cooled rolling is used, the opening rolling temperature is ≥950℃, the rough rolling pass reduction rate is 5-10%, the air-cooled thickness is the finished steel plate thickness + (80-100) mm, the opening rolling temperature of the finishing rolling is ≥900℃, the finishing rolling pass reduction amount is 5-15mm, and the final rolling temperature is ≥800℃; high-pressure water cooling is not used during rolling, and temperature is raised for rolling; the cooling frequency of the cooling step is ≥2 times, the single cooling speed is ≥5℃ / s, and the final cooling red temperature is 500-550℃; The Q890F high-strength quenched and tempered steel plate comprises the following chemical components in mass fraction: C ≤0.10wt%, Si ≤0.10wt%, Mn 1.60-1.90wt%, P ≤0.010wt%, S ≤0.005wt%, Als 0.020-0.050wt%, Nb 0.015-0.030wt%, Cr 0.70-0.86wt%, Mo 0.10-0.30wt%, Ni 0.20-0.50wt%, V 0.050-0.080wt%, and B 0.0010-0.0015wt%, and the rest is Fe and residual elements; wherein: carbon equivalent CEV = C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15 ≤0.65%.

2. The method of producing a Q890F high-strength quenched and tempered steel plate according to claim 1, characterized in that, The heating speed of the ingot heating step is ≤50℃ / h, the holding temperature is 1220±20℃, and the holding time is h3min, h3min = ingot body thickness × (5-10) min / cm.

3. A Q890F high-strength quenched and tempered steel plate produced by the production method of claim 1 or 2.

4. The Q890F high-strength quenched and tempered steel plate according to claim 3, characterized by, The Q890F high-strength and high-quality steel plate has yield strength greater than or equal to 890 MPa, tensile strength of 949-1000 MPa, elongation greater than or equal to 19%, impact performance at-60 DEG C greater than or equal to 150 J, surface impact value at-40 DEG C and 5% transverse strain greater than or equal to 120 J, core impact value at-60 DEG C and transverse greater than or equal to 150 J, steel plate resistance to lamellar tearing performance reaches Z55, and flaw detection conforms to GB / T 6402 level 1.

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