Thin-gauge high-yield-ratio high-titanium tempered plate and preparation method thereof

Abstract

The invention provides a thin-gauge high-yield-ratio high-titanium tempered plate and a preparation method thereof. The thin-gauge high-yield-ratio high-titanium tempered plate is prepared from, by mass, 0.04%-0.10% of C, 0.15%-0.40% of Si, 1.05%-1.25% of Mn, 0.15%-0.30% of Ti, 0.08%-0.19% of Mo, smaller than or equal to 0.008% of P, smaller than or equal to 0.003% of S, smaller than or equal to 0.004% of N, smaller than or equal to 0.004% of O and the balance Fe and microelements. The thickness of the thin-specification high-yield-ratio high-titanium tempered plate ranges from 1 mm to 3 mm. According to the steel plate, a high-titanium component system is adopted, the thin-specification tempered plate with the yield strength larger than or equal to 960 MPa, the tensile strength larger than or equal to 1000 MPa, the ductility larger than or equal to 10% and the yield ratio larger than or equal to 0.96 is prepared through the after-rolling gradient tempering technology, and the performance is excellent.

Description

Technical Field

[0001] The present application belongs to the technical field of steel production, and specifically relates to a thin-gauge high-yield-to-strength ratio high-titanium tempered plate and a preparation method thereof. Background Art

[0002] High-strength steel with a yield strength of 960MPa is widely used in many civil and military fields such as engineering machinery, rail transportation and bridge engineering. The traditional hot rolling and heat treatment processes of this steel are mostly TMCP and quenching + tempering processes, and finally a tempered martensite structure with excellent toughness is obtained. With the upgrading of the automation level of equipment, the quenching-tempering process has gradually been upgraded from the initial offline quenching-tempering to online quenching-tempering. However, due to the large internal stress generated by quenching, the plate shape of high-strength steel with a yield strength of 960MPa is difficult to control, so its thickness specification is always maintained in the medium and thick plate range (thickness above 3mm).

[0003] In order to improve the hardenability of high-strength steel, traditional high-strength steel with a yield strength of 960MPa often adds a large amount of precious alloy elements, resulting in high alloy costs. Therefore, high-strength steel with a yield strength of 960MPa is difficult to meet the requirements of ultra-high-strength steel alloy reduction, thickness reduction and process optimization due to the complex quenching-tempering process and large thickness specifications. Summary of the invention

[0004] The present application provides a thin-gauge high-yield ratio high-titanium tempered plate based on a CSP production line and a preparation method thereof, which can obtain a tempered plate with a thickness of 1 mm to 3 mm, a yield strength ≥960 MPa, a tensile strength ≥1000 MPa, an elongation ≥10%, and a yield ratio ≥0.96.

[0005] The first aspect of the present application provides a thin-gauge high-yield-strength-high-titanium tempered plate, comprising the following components by mass fraction: C: 0.04% to 0.10%, Si: 0.15% to 0.40%, Mn: 1.05% to 1.25%, Ti: 0.15% to 0.30%, Mo: 0.08% to 0.19%, P: ≤0.008%, S: ≤0.003%, N: ≤0.004%, O: ≤0.004%, and the rest are Fe and trace elements; the thickness of the thin-gauge high-yield-strength-high-titanium tempered plate is 1 mm to 3 mm.

[0006] In some embodiments, the mass fraction of Ti is 0.22% to 0.30%.

[0007] In some embodiments, the thin gauge high yield ratio high titanium tempered plate has a thickness of 2.2 mm to 2.9 mm.

[0008] The second aspect of the present application provides a method for preparing the thin-gauge high-yield ratio high-titanium tempered plate provided in the first aspect of the present application, comprising the following steps:

[0009] The molten steel after smelting and refining in a converter is obtained for casting to obtain a casting billet;

[0010] The ingot is heated, dephosphorized, and rolled to obtain a steel strip; the steel strip is cooled and coiled to obtain a steel coil; the steel coil is subjected to gradient tempering to obtain a thin gauge high yield ratio high titanium tempered plate;

[0011] Gradient tempering includes first stage tempering and second stage tempering; the temperature of the first stage tempering process is 165℃~245℃, and the insulation time is 11min~17min; the temperature of the second stage tempering is 550℃~650℃, and the insulation time is 18min~39min.

[0012] In some embodiments, the temperature of the first stage tempering is 180°C to 225°C; the temperature of the second stage tempering is 585°C to 615°C.

[0013] In some embodiments, the coiling temperature is 455°C to 535°C.

[0014] In some embodiments, the rolling includes rough rolling and finish rolling, the starting rolling temperature of the rough rolling is 1060°C to 1165°C, and the final rolling temperature of the finish rolling is 800°C to 860°C.

[0015] In some embodiments, the rolling includes 7 passes of finish rolling, the reduction rate of the first pass is 30% to 40%, the reduction rate of the second pass is 35% to 55%, and the reduction rate of the other passes other than the first and second passes is 15% to 25%.

[0016] In some embodiments, the temperature of heating the ingot is 1250° C. to 1350° C., and the holding time is 80 min to 160 min.

[0017] In some embodiments, in the step of obtaining molten steel after smelting and refining in a converter for casting to obtain a cast billet, the casting speed is 1.1 m / min to 1.3 m / min, and the thickness of the cast billet is 55 mm to 75 mm.

[0018] In some embodiments, the pressure of water for phosphorus removal is 45 MPa to 60 MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the metallographic structure diagram of the thin gauge high yield ratio high titanium tempered plate of Example 1 of the present application. DETAILED DESCRIPTION

[0020] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0021] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0022] In the description herein, when a composition is described as containing, comprising or including specific components, or when a process is described as containing, comprising or including specific process steps, it is expected that the composition of the present application also consists essentially of or consists of the components, and the process of the present application also consists essentially of or consists of the process steps.

[0023] The use of the terms "including," "comprising," "containing," and "having" should generally be interpreted as open ended and non-limiting unless expressly stated otherwise.

[0024] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.

[0025] The above-mentioned summary of the invention of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0026] In order to ensure the hardenability of high-strength steel, traditional high-strength steel with a yield strength of 960MPa often adds a large amount of precious alloy elements. For example, a certain steel adds more Mo and Mn elements, which has a high alloy cost and is prone to segregation. For example, a certain steel adds the precious alloy element Ni to ensure strength and toughness, which also increases the alloy cost to a certain extent.

[0027] In view of this, the present application provides a thin-gauge high-yield-to-strength ratio high-titanium tempered plate based on a CSP production line that does not require a quenching step, has a small amount of alloy addition, is low in cost, has a thin tempered plate thickness, and still meets the future development of high-strength steel with a yield strength of 960MPa.

[0028] The present application provides a thin-gauge high-yield ratio high-titanium tempered plate based on a CSP production line and a preparation method thereof, which can obtain a tempered plate with a thickness of 1 mm to 3 mm, a yield strength ≥960 MPa, a tensile strength ≥1000 MPa, an elongation ≥10%, and a yield ratio ≥0.96.

[0029] The first aspect of the present application provides a thin-gauge high-yield-strength-high-titanium tempered plate, comprising the following components by mass fraction: C: 0.04% to 0.10%, Si: 0.15% to 0.40%, Mn: 1.05% to 1.25%, Ti: 0.15% to 0.30%, Mo: 0.08% to 0.19%, P: ≤0.008%, S: ≤0.003%, N: ≤0.004%, O: ≤0.004%, and the rest are Fe and trace elements (or unavoidable impurities); the thickness of the thin-gauge high-yield-strength-high-titanium tempered plate is 1 mm to 3 mm.

[0030] The metallographic structure of the thin-gauge high-yield-to-strength ratio high-titanium tempered plate of the present application is ferrite+bainite, and (Ti, Mo)C second phase precipitation particles are dispersed in the matrix.

[0031] The elements and functions of the thin-gauge high-yield-to-strength ratio high-titanium tempered plate of this application are as follows:

[0032] Carbon: Carbon is an important strengthening element in this application. It can increase the hardness of the bainite hard phase and affect the distribution of the second phase precipitated particles. According to the application scope of the forming processing of this steel type, the material is required to have good weldability while meeting the strength requirements. If the carbon content is less than 0.04%, the hardness of the bainite hard phase will be reduced, and the volume fraction of bainite will be reduced. Under certain component conditions, the yield strength of the material will not meet the standard requirements; if the carbon content is greater than 0.10%, the good weldability of the material cannot be met. Therefore, the limited range of carbon element is 0.04% to 0.10%, and 0.04%<C<0.10% can be selected.

[0033] Silicon: Silicon is one of the important strengthening elements in this application. A part of the solid solution silicon element can improve the solid solution strength of the steel, and the other part of the silicon can control the precipitation of the second phase particles and improve the precipitation strength. According to the application scope of the forming processing of this type of steel, the material is required to have good product surface quality while meeting the strength requirements. If the silicon content is less than 0.15%, the solid solution strength of the matrix phase will be reduced, and the yield strength of the material will not meet the standard requirements; if the silicon content is greater than 0.40%, it will bring difficulties to descaling during rolling, resulting in surface quality defects and seriously reducing the welding performance of the steel. Therefore, the limited range of silicon element is 0.15% to 0.40%, and 0.15% < Si < 0.40% can be selected.

[0034] Manganese: Manganese is one of the important strengthening elements in this application. It can improve the hardenability of steel and is beneficial to obtain bainite structure after coiling. According to the application scope of the forming processing of this type of steel, the material is required to have obvious advantages of thin specifications while meeting the strength requirements. If the manganese content is less than 1.05%, the hardenability of the steel will be reduced, and the yield strength of the material will not meet the standard requirements; if the manganese content is greater than 1.25%, the continuous casting process is prone to cracks in the ingot and lead to ingot defects, and the welding performance of the steel will also be reduced. Therefore, the limited range of manganese elements is 1.05% to 1.25%, and 1.05% <Mn <1.25% can be selected.

[0035] Titanium: Titanium is one of the important strong carbonitride forming elements in this application. Adding a certain amount of Ti to the steel can have a precipitation strengthening effect to improve the strength of the steel. According to the application scope of this steel type forming processing, the material is required to have the advantage of high strength after rolling and tempering while being thin in size. Comprehensively considering the solid solubility product of Ti and related elements in steel and the content of elements such as N and C in steel, and combining the ideal chemical ratio of related compounds, the reasonable addition range of Ti content in the thin-gauge high-yield ratio high-Ti tempered plate of this application is determined to be 0.15-0.30%. If the titanium content is less than 0.15%, in the absence of micro-alloying elements such as Nb and V, the second phase precipitation strengthening effect during tempering is not obvious, and the strength of the material does not meet the standard requirements; if the titanium content is greater than 0.30%, it will cause alloy waste and increase production costs. Secondly, if the titanium content is too high, it is easy to precipitate large TiN particles at the solid-liquid front, and the liquid precipitation TiN significantly deteriorates the low-temperature toughness of the steel. Therefore, the limited range of titanium element is 0.15% to 0.30%, and 0.15%<Ti<0.30% can be selected.

[0036] Molybdenum: Molybdenum is one of the important strong carbonitride forming elements in this application. It can be combined with Ti element to form complex second phase precipitation particles during tempering. Such particles have stronger precipitation strengthening effect. In addition, molybdenum element can also promote the formation of precipitation phase and refine the size of precipitation particles, which is conducive to effectively improving strength and toughness. In addition, Mo element combines controlled rolling and controlled cooling technology to obtain granular bainite + ferrite structure, which improves the strength of steel to a certain extent and maintains a certain plasticity. According to the application scope of this steel type forming processing, the material is required to have the advantages of high strength after rolling and tempering while being thin in specification. Comprehensively considering the solid solubility product of Mo and related elements in steel and the content of elements such as Ti, N, and C in steel, and combining the ideal chemical ratio of related compounds, the reasonable addition range of Mo content in the thin specification high yield strength ratio high Ti tempered plate of this application is determined to be 0.08-0.19%. If the molybdenum content is less than 0.08%, the second phase precipitation strengthening effect in the tempering process is not significant, and the strength of the material does not meet the standard requirements; if the molybdenum content is greater than 0.19%, it will cause alloy waste and increase production costs. Therefore, the content of molybdenum is limited to 0.08% to 0.19%, 0.08%<Mo<0.19% may be selected, and 0.09% to 0.12% may be further selected.

[0037] Phosphorus: Phosphorus is one of the main harmful elements in steel. Phosphorus has strong solid solution strengthening and cold work hardening effects in steel. Adding it to low-alloy structural steel as an alloying element can improve its strength and atmospheric corrosion resistance, but reduce its cold stamping performance. Phosphorus also increases temper brittleness, significantly increases the plasticity and toughness of steel, and makes steel prone to brittle cracking during cold working, which is the so-called "cold brittle" phenomenon. Phosphorus also has an adverse effect on weldability. According to the application scope of this steel type forming processing, the material is required to have the advantages of high strength after rolling and tempering while being thin in size. Therefore, the limited range of phosphorus is below 0.008%.

[0038] Sulfur: Sulfur is one of the main harmful elements in steel. Sulfur segregates seriously in steel, which deteriorates the quality of steel. It exists in the form of FeS with a low melting point. When steel is rolled at 1100-1200℃, FeS on the grain boundary will melt, greatly weakening the bonding force between the grains, resulting in hot brittleness of the steel. In addition, MnS inclusions produced by excessive sulfur content will cause significant differences in the longitudinal and transverse properties of the steel, deteriorating low-temperature toughness. Therefore, the limited range of sulfur element is below 0.003%.

[0039] Nitrogen: Nitrogen is one of the main harmful elements in steel. It can combine with Ti, Nb, V and other elements in steel at high temperature to form corresponding compounds. Such compounds will coarsen and grow at high temperature, seriously damaging the plasticity and toughness of steel. In addition, such coarse carbonitride particles formed at high temperature contribute little to precipitation strengthening and will consume the effective Ti, Nb and V content in steel. Therefore, the limited range of nitrogen is below 0.004%.

[0040] Oxygen: Oxygen is one of the main harmful elements in steel. Although manganese, silicon, iron and aluminum are added for deoxidation at the end of steelmaking, it is impossible to remove it completely. Oxygen in steel will form a large number of bubbles in the casting, reduce the density of the steel, and damage the toughness and plasticity of the steel. Oxygen will increase the iron loss in silicon steel, weaken the magnetic permeability and magnetic induction, and intensify the magnetic aging effect. Therefore, the limit range of oxygen element is below 0.004%.

[0041] The steel plate of the present application adopts a high titanium component system, and is prepared through a post-rolling gradient tempering process to obtain a thin-gauge tempered plate with a yield strength ≥ 960MPa, a tensile strength ≥ 1000MPa, an elongation ≥ 10%, and a yield strength ratio ≥ 0.96, with excellent performance. In addition, the composition of the steel plate of the present application is relatively pure, for example, on the basis of a high titanium content, a low manganese and molybdenum content, other alloy components are low in content or even do not contain precious alloy components, which reduces the cost of the steel plate and effectively shortens the process flow.

[0042] In some embodiments, the mass fraction of Ti is 0.22% to 0.30%.

[0043] In some embodiments, the thin gauge high yield ratio high titanium tempered plate has a thickness of 2.2 mm to 2.9 mm.

[0044] In steel production, the thinner the tempered steel plate is, the more difficult it is to meet the strength standard and control the plate shape. This application uses a gradient tempering process, combined with a rolling process, a heating process and the selection of a coiling temperature, to obtain a tempered plate with a thickness of 2.2 mm to 2.9 mm and high yield strength and tensile strength.

[0045] The second aspect of the present application provides a method for preparing the thin-gauge high-yield ratio high-titanium tempered plate provided in the first aspect of the present application, comprising the following steps:

[0046] The molten steel after smelting and refining in a converter is obtained for casting to obtain a casting billet;

[0047] The ingot is heated, dephosphorized, and rolled to obtain a steel strip; the steel strip is cooled and coiled to obtain a steel coil; the steel coil is subjected to gradient tempering to obtain a thin gauge high yield ratio high titanium tempered plate;

[0048] Gradient tempering includes first stage tempering and second stage tempering; the temperature of the first stage tempering process is 165℃~245℃, and the insulation time is 11min~17min; the temperature of the second stage tempering is 550℃~650℃, and the insulation time is 18min~39min.

[0049] The thin-gauge high-titanium tempered plate of this application does not require a quenching process during the preparation process based on the CSP production line. After rolling and cooling, tempering is performed. The gradient tempering method is used to control the first-stage tempering temperature to 165-245°C. The first-stage low-temperature tempering can effectively promote the nucleation of nano-scale precipitation particles without growth. The second-stage tempering temperature is 550-650°C. Through the second-stage high-temperature tempering, the fine dispersed nano-scale (Ti, Mo) C is fully precipitated, and finally a large number of dispersed nano-scale second-phase precipitation particles are formed, which plays the best tempering strengthening role, and obtains a high-titanium tempered plate with a thickness of 1mm to 3mm, low alloy cost and high strength. At the same time, the two-stage tempering can effectively release the internal stress and significantly improve the plate shape of the thin plate. The obtained thin plate has a smooth surface, neat edges, and no deformation and warping problems.

[0050] If a single-stage high-temperature tempering process is used, although the second phase particles are fully precipitated, the proportion of mature particles is difficult to control, which can easily cause performance fluctuations and is not conducive to the precise improvement of strength and toughness; if a single-stage low-temperature tempering process is used, the second phase particles are difficult to fully precipitate, and the internal stress accumulation is too large, which is not conducive to improving strength and toughness.

[0051] In some embodiments, the temperature of the first stage tempering is 180°C to 225°C, and may be 210°C to 220°C; the temperature of the second stage tempering is 585°C to 615°C, and may be 600°C to 615°C.

[0052] In some embodiments, the coiling temperature is 455°C to 535°C.

[0053] The reason why the coiling temperature is controlled at 455-535°C in the present application, and the coiling temperature is optionally at 490-520°C; and naturally cooled to room temperature after coiling is completed; is because a higher coiling temperature will promote the precipitation of second-phase particles, and coiling at this temperature can fully inhibit the precipitation of second-phase particles, avoid the precipitation of more second-phase particles before tempering, and avoid ripening during the subsequent tempering process, which deteriorates the precipitation strengthening effect. Inhibiting the precipitation of second-phase particles in the coiling stage and retaining the second-phase precipitated particles until precipitation in the tempering stage can significantly improve the strength and toughness of thin-gauge tempered plates. In addition, when the coiling temperature is low, the strength of the steel plate is low. Coiling in this temperature range can effectively reduce the residual stress of the steel plate and control the excellent plate shape.

[0054] In some embodiments, the rolling includes rough rolling and finish rolling, the starting rolling temperature of the rough rolling is 1060°C to 1165°C, and the final rolling temperature of the finish rolling is 800°C to 860°C.

[0055] In some embodiments, the rolling includes 7 passes of finish rolling, the reduction rate of the first pass is 30% to 40%, the reduction rate of the second pass is 35% to 55%, and the reduction rate of the other passes other than the first and second passes is 15% to 25%.

[0056] The reason why the reduction rate of the first pass of finishing rolling is controlled at 30-40% in this application is that the reduction rate is slightly less than the maximum reduction rate allowed by the equipment, taking into account the possible fluctuation of the strip thickness and the possible difficulty in biting, etc. In addition, the tension after the first pass of the rolling mill is too small, and the plate shape and thickness deviation of the hot-rolled coil are uneven, and even present a wave-shaped, scoop-shaped, sickle-shaped or wedge-shaped section, which makes it difficult to ensure the centering of the rolled piece, bringing certain difficulties to rolling, so the reduction rate of the first pass cannot be too large.

[0057] The reason why the second pass reduction rate is controlled at 35% to 55% in this application is to make full use of the equipment capacity and give as much reduction as possible to obtain thin strip steel. In addition, in order to avoid the segregation problem caused by high Mn content as much as possible, the second pass reduction rate can be appropriately increased.

[0058] In some embodiments, the temperature of heating the ingot is 1250° C. to 1350° C., and the holding time is 80 min to 160 min.

[0059] The reason why the present application controls the heating temperature to be 1250-1350°C, and optionally the heating temperature to be 1270-1310°C; and keeps the temperature at this temperature for 80-160 minutes; is because at this temperature, it can fully ensure that the second phase precipitated particles are completely dissolved in the matrix, avoiding the precipitation of more second phase particles before tempering, and ripening during the subsequent tempering process, which deteriorates the precipitation strengthening effect. The higher heating temperature causes most of the precipitated particles to melt back, which is convenient for the precipitation of small dispersed second phase particles during the subsequent tempering process, significantly improving the strength and toughness of the tempered plate. In addition, the higher heating temperature can increase the atomic diffusion activity, which is beneficial to improve the segregation phenomenon caused by the Mn element. Finally, the higher heating temperature will promote uniform and sufficient austenitization and uniform element distribution. In the subsequent hot rolling cooling process, it is easy to obtain a bainite structure with uniform composition and no significant difference in morphology, which is ultimately conducive to obtaining a thin-gauge tempered plate with small performance fluctuations.

[0060] In some embodiments, in the step of obtaining molten steel after smelting and refining in a converter for casting to obtain a cast billet, the casting speed is 1.1 m / min to 1.3 m / min, and the thickness of the cast billet is 55 mm to 75 mm.

[0061] In some embodiments, the pressure of water for phosphorus removal is 45 MPa to 60 MPa.

[0062] Example

[0063] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0064] Example 1

[0065] A method for preparing a thin-gauge high-yield-to-strength ratio high-titanium tempered plate based on a CSP production line comprises the following steps:

[0066] The molten steel after smelting and refining in the converter is obtained for casting, and the casting speed is 1.25 m / min to obtain a casting with a thickness of 58 mm;

[0067] The above-mentioned ingot is heated; the heating temperature is controlled at 1300°C, and the total holding time is controlled at 122 minutes, and high-pressure water is used for descaling, and the water pressure is controlled at 55MPa;

[0068] Two-stage rolling is performed to the product thickness: the rough rolling start temperature is controlled at 1130°C, and the finishing rolling temperature is controlled at 850°C; there are 7 passes of finishing rolling: the first pass reduction rate is controlled at 35%, the second pass reduction rate is controlled at 51%, and the remaining passes reduction rate is controlled at 19%, and the strip thickness is 2.54mm;

[0069] The strip is cooled in a laminar flow manner in the rear cooling mode, cooled to a coiling temperature of 498° C., and then coiled to obtain a steel coil;

[0070] The steel coil is subjected to gradient tempering, the first stage tempering temperature is 189°C, and it is kept at this temperature for 14 minutes; the second stage tempering temperature is 610°C, and it is kept at this temperature for 18 minutes to obtain the thin-gauge high-yield-strength ratio high-titanium tempered plate, and the thickness of the steel plate is 2.54 mm.

[0071] The chemical composition of the thin gauge high yield ratio high titanium tempered plate of this embodiment is shown in Table 1. The chemical components not shown in the table are Fe and unavoidable impurities.

[0072] Embodiments 2 to 5

[0073] Compared with Example 1, the changed parameters in the preparation process are shown in Tables 1-2.

[0074] Comparative Examples 1 to 5

[0075] Compared with Example 1, the changed parameters in the preparation process of each comparative example are shown in Tables 1-2.

[0076] Table 1 Chemical composition values ​​of various embodiments and comparative examples of this application (wt%)

[0077] Serial number C Si Mn Ti Mo P S N O Example 1 0.048 0.25 1.24 0.27 0.17 0.008 0.003 0.004 0.003 Example 2 0.079 0.39 1.13 0.26 0.11 0.008 0.003 0.004 0.003 Example 3 0.096 0.19 1.16 0.17 0.14 0.008 0.002 0.004 0.003 Example 4 0.057 0.32 1.19 0.22 0.09 0.007 0.003 0.004 0.003 Example 5 0.066 0.28 1.22 0.28 0.16 0.008 0.003 0.008 0.003 Comparative Example 1 0.123 0.14 0.87 0.12 0.22 0.008 0.003 0.004 0.004 Comparative Example 2 0.089 0.39 1.33 0.19 0.19 0.009 0.003 0.004 0.003 Comparative Example 3 0.111 0.46 1.16 0.22 0.07 0.008 0.004 0.007 0.004 Comparative Example 4 0.038 0.48 1.29 0.36 0.16 0.007 0.003 0.004 0.003 Comparative Example 5 0.032 0.22 0.94 0.39 0.08 0.009 0.003 0.004 0.003

[0078] Table 2 Variation of process parameters of various embodiments and comparative examples of the present application

[0079]

[0080] Table 3 Mechanical properties of various embodiments and comparative examples of this application

[0081]

[0082] It can be seen from Tables 1 to 3 that the thin-gauge high-titanium tempered plate in the embodiment of the present application has excellent mechanical properties, with a yield strength ratio of ≥0.96 and a thickness specification of 1.0mm to 3.0mm. It can be seen that the combination of the chemical composition ratio of the molten steel and the CSP+ gradient tempering preparation process provided by the present application can effectively make the obtained thin-gauge high-titanium tempered plate still have good mechanical properties under the low alloy component system and short process preparation process. And its preparation method is simple, the process is short, and it is easy to operate and control, which is conducive to industrial production. Figure 1 It can be seen that the structure of the thin-gauge high-titanium tempered plate of Example 1 is a bainite and ferrite multiphase structure, and a large number of fine dispersed carbides are distributed in the matrix.

[0083] The above embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A thin gauge high yield ratio high titanium tempered plate, characterized in that: The invention comprises the following components in mass fraction: C: 0.04% to 0.10%, Si: 0.15% to 0.40%, Mn: 1.05% to 1.25%, Ti: 0.15% to 0.30%, Mo: 0.08% to 0.19%, P: ≤0.008%, S: ≤0.003%, N: ≤0.004%, O: ≤0.004%, and the rest are Fe and trace elements; the thickness of the thin-gauge high-yield-strength ratio high-titanium tempered plate is 1mm to 3mm.

2. The thin gauge high yield ratio high titanium tempered plate according to claim 1, characterized in that: The mass fraction of Ti is 0.22% to 0.30%.

3. The thin gauge high yield ratio high titanium tempered plate according to claim 1 or 2, characterized in that: The thickness of the thin-gauge high-yield-to-strength ratio high-titanium tempered plate is 2.2 mm to 2.9 mm.

4. A method for preparing a thin gauge high yield ratio high titanium tempered plate as claimed in any one of claims 1 to 3, characterized in that: The steps include: The molten steel after smelting and refining in a converter is obtained for casting to obtain a casting billet; The ingot is heated, dephosphorized, and rolled to obtain a steel strip; the steel strip is cooled, coiled, and a steel coil is obtained; the steel coil is subjected to gradient tempering to obtain the thin-gauge high-yield-to-strength ratio high-titanium tempered plate; The gradient tempering includes first-stage tempering and second-stage tempering; the temperature of the first-stage tempering process is 165°C to 245°C, and the insulation time is 11min to 17min; the temperature of the second-stage tempering process is 550°C to 650°C, and the insulation time is 18min to 39min.

5. The method for preparing a thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: The temperature of the first stage tempering is 180°C to 225°C; the temperature of the second stage tempering is 585°C to 615°C.

6. The method for preparing thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: The coiling temperature is 455°C to 535°C.

7. The method for preparing a thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: The rolling includes rough rolling and finish rolling. The starting rolling temperature of the rough rolling is 1060°C to 1165°C, and the final rolling temperature of the finish rolling is 800°C to 860°C.

8. The method for preparing thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: The rolling includes 7 passes of finishing rolling, the reduction rate of the first pass is 30% to 40%, the reduction rate of the second pass is 35% to 55%, and the reduction rate of other passes except the first and second passes is 15% to 25%.

9. The method for preparing thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: The heating temperature of the casting is 1250° C. to 1350° C., and the insulation time is 80 min to 160 min.

10. The method for preparing thin gauge high yield ratio high titanium tempered plate according to claim 4, characterized in that: In the step of obtaining the molten steel after smelting and refining in a converter for casting to obtain a cast billet, the casting speed is 1.1 m / min to 1.3 m / min, and the thickness of the cast billet is 55 mm to 75 mm.

11. The method for preparing a thin gauge high yield ratio high titanium tempered plate according to any one of claims 4 to 10, characterized in that: The pressure of the water for dephosphorization is 45MPa to 60MPa.

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