Production process of high-strength hot rolled steel coil

Abstract

The invention provides a production process of a high-strength hot rolled steel coil. The production process comprises the following steps that a steel strip of the high-strength hot rolled steel is curled at the target curling temperature, and a steel coil of the high-strength hot rolled steel is obtained. And the steel coil is subjected to stress relief annealing, and the stress relief annealed steel coil is obtained. In the stress relief annealing process, the temperature of the steel coil is increased to 200 DEG C; heating to 400 DEG C at the heating speed of 60-80 DEG C / h, and keeping the temperature for 4 hours; and heating to 500-660 DEG C at the speed of 60-80 DEG C / h, and keeping the temperature for 10-20 hours. And after the stress-relief annealed steel coil is subjected to acid pickling, spheroidizing annealing is conducted, and the high-strength hot rolled steel coil is obtained. According to the production process, low-temperature coiling, low-temperature stress relief annealing, acid pickling and high-temperature spheroidizing cover annealing are carried out, production is carried out in the form of wide coiled plates, the production efficiency is high, and the cost is low. The technology is used for producing high-end products such as acid-washed high-carbon tool steel and high-alloy tool steel, and remarkable economic benefits can be brought.

Description

Technical Field

[0001] The invention relates to the field of steel production, and in particular to a production process of a high-strength hot-rolled steel coil. Background Art

[0002] High-strength hot-rolled steel coil is a kind of high-strength and tough steel with high carbon content or high alloying element content, so it has a very high strength of more than 1400MPa. For example, high-strength hot-rolled steel coil includes hot-rolled high-carbon tool steel and hot-rolled high-alloy tool steel. Among them, the carbon content of hot-rolled high-carbon tool steel is ≥0.9%), and the alloy content of hot-rolled high-alloy tool steel is ≥8%.

[0003] High-strength hot-rolled steel coils are usually produced by direct pickling of hot-rolled coils or pickling after annealing and spheroidizing. However, due to the high carbon content or high alloy element content, the hot-rolled coil shape of this type of steel material is poor. At the same time, it has very high strength, resulting in problems such as difficulty in threading, easy breakage, and extremely low pickling efficiency when producing high-strength hot-rolled steel coils using the above method. Sometimes, physical methods are even required to remove oxides on the plate surface.

[0004] If such materials are coiled at high temperature, network cementite will be produced after hot rolling, which will increase brittleness and make the structure and performance unqualified. It will be difficult to obtain uniform spheroidized pearlite structure during the later spheroidizing annealing. If coiled at low temperature, the strength after hot rolling is extremely high, and the pickling operation is difficult, and it is difficult to unwind and thread the strip. That is, the qualified rate is low during the production process of high-strength hot-rolled steel coils. Summary of the invention

[0005] The main purpose of the present invention is to provide a production process for high-strength hot-rolled steel coils to solve the technical problem of low production qualification rate of high-strength hot-rolled steel coils.

[0006] To achieve the above object, the present application provides a production process of a high-strength hot-rolled steel coil, wherein the strength of the high-strength hot-rolled steel coil is ≥1400MPa, and the production process comprises the following steps:

[0007] The high-strength hot-rolled steel strip is coiled at a target coiling temperature to obtain a high-strength hot-rolled steel coil, wherein the lower limit of the feasible coiling temperature range of the high-strength hot-rolled steel is ≤ the target coiling temperature ≤ the lower limit of the feasible coiling temperature range + 20°C.

[0008] The steel coil is subjected to stress relief annealing to obtain a stress relief annealed steel coil. During the stress relief annealing, the steel coil is heated to 200°C. Then heated to 400°C at a heating rate of 60-80°C / h and kept at that temperature for 4 hours. Then heated to 500-660°C at a heating rate of 60-80°C / h and kept at that temperature for 10-20 hours.

[0009] After the stress relief annealing steel coil is pickled, spheroidizing annealing is performed to obtain a high-strength hot-rolled steel coil, and the maximum insulation temperature of the spheroidizing annealing is greater than the maximum insulation temperature of the stress relief annealing.

[0010] According to an embodiment of the present application, during the stress relief annealing, the steel coil is heated to 200°C, then heated to 400°C at a heating rate of 60-80°C / h and kept at that temperature for 4 hours, then heated to 500-660°C at a heating rate of 60-80°C / h and kept at that temperature for 10-20 hours.

[0011] According to the embodiment of the present application, in the cooling step of the stress relief annealing, after the heat preservation is completed, the steel is cooled to 400° C. by air, and then cooled to 100° C. by water before being taken out of the furnace.

[0012] According to an embodiment of the present application, the step of pickling the stress relief annealed steel coil comprises:

[0013] The stress relief annealed steel coil is sequentially subjected to acid washing, water rinsing and hot air drying at a moving speed of 60-120 m / min, wherein the concentration of hydrochloric acid in the acid is 12%-18%, the temperature of the acid is 70-85° C., the rinsing temperature is 60-80° C. and the hot air temperature is 120° C.

[0014] According to an embodiment of the present application, the step of spheroidizing annealing includes:

[0015] After pickling, the steel coil is heated freely from room temperature to 200℃. Then it is heated to 400℃ at a heating rate of 60-80℃ / h and kept at this temperature for 4 hours. Then it is heated to 700-800℃ at a heating rate of 60-80℃ / h and kept at this temperature for 10-30 hours.

[0016] According to the embodiment of the present application, the pickled steel coil is heated freely from room temperature to 200°C, then heated to 400°C at a heating rate of 60-80°C / h and kept at that temperature for 4 hours, then heated to 700-800°C at a heating rate of 60-80°C / h and kept at that temperature for 10-30 hours.

[0017] According to an embodiment of the present application, in the cooling step of the spheroidizing annealing, after the insulation is completed, the steel coil is naturally cooled to 640-660°C in a closed space, and then the steel coil is cooled to 380°C by air cooling, and then the steel coil is cooled to below 100°C by water cooling before being taken out from the closed space.

[0018] According to an embodiment of the present application, the target curling temperature is 580-680°C.

[0019] According to an embodiment of the present application, the method for determining the feasible curling temperature range includes:

[0020] According to the chemical composition or CCT curve of the high-strength hot-rolled steel coil, combined with the target performance index of the high-strength hot-rolled steel coil, a feasible coiling temperature range is determined.

[0021] The above-mentioned production process of high-strength hot-rolled steel coils includes low-temperature coiling, low-temperature stress relief annealing, pickling, high-temperature spheroidizing hood annealing and production in the form of wide-width coils. It has high production efficiency, low cost and high pass rate. Compared with the current traditional high-quality steel cold rolling enterprises at home and abroad, this technology is used to produce high-end products such as pickled high-carbon tool steel, high-alloy tool steel, etc., which can bring significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 is a physical surface diagram of an annealed finished coil according to an embodiment of the present application;

[0024] Figure 2 is a metallographic structure diagram of an annealed finished coil according to an embodiment of the present application;

[0025] Figure 3 is a metallographic structure diagram of a steel coil after low-temperature stress relief annealing according to an embodiment of the present application;

[0026] Figure 4 This is a metallographic structure diagram of a steel coil after low-temperature stress relief annealing according to a ratio of the present application;

[0027] Figure 5 This is a physical surface diagram of a steel coil after low-temperature stress relief annealing according to a ratio of the present application;

[0028] Figure 6 This is a physical surface diagram of the pickled coil of another comparative example of the present application.

[0029] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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 creative work are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0033] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0034] When the pickling process uses hot-rolled coils for direct pickling, the scale is relatively easy to remove. However, due to the high strength and poor plate shape of the steel coils, the unwinding is prone to strip breakage and scratches, pickling and threading are very difficult, and the pickling efficiency is low. Pickling after annealing and spheroidization can reduce the strength of the steel coils, but the surface scale is reduced to scale by hydrogen in the bell furnace. Pickling needs to be strictly controlled to low-speed pickling, with a pickling speed of 10-20m / min, and the efficiency is also extremely low. Moreover, it is difficult to remove the reduced scale covering the surface during pickling, and the residual oxide under the scale is easy to cause oxide pressure in the subsequent cold rolling. Even in an environment with high-temperature annealing under inert gas protection, the oxygen elements in the scale will diffuse into the matrix and react with the carbon in the matrix, causing the scale to be reduced to scale that is difficult to pickle. In addition, the migrated and diffused oxygen elements further oxidize the surface of the matrix, causing surface grain boundary oxidation. The pickling methods currently used in the industry all have disadvantages, so it is necessary to optimize the pickling process path for such steel grades.

[0035] The present application provides a production process for a high-strength hot-rolled steel coil, wherein the strength of the high-strength hot-rolled steel coil is ≥1400MPa, and the production process comprises the following steps:

[0036] S100: Curling the high-strength hot-rolled steel strip at a target curling temperature to obtain a high-strength hot-rolled steel coil, wherein the lower limit of a feasible curling temperature range of the high-strength hot-rolled steel is ≤ the target curling temperature ≤ the lower limit of the feasible curling temperature range + 20°C.

[0037] In this step, the applicable coiling temperature range of the high-strength hot-rolled steel (i.e., the feasible coiling temperature range) can be determined first, and then the target coiling temperature within the feasible coiling temperature range is taken as the actual coiling temperature. The method for determining the feasible coiling temperature range includes: determining the feasible coiling temperature range of the high-strength hot-rolled steel according to the chemical composition or CCT curve of the high-strength hot-rolled steel and the target performance index of the high-strength hot-rolled steel.

[0038] Since the actual coiling temperature is close to the lower limit of the feasible coiling temperature range, a lower coiling temperature is selected. The lower coiling temperature is conducive to making the pearlite in the high-strength hot-rolled steel thin and the carbides small and dispersed, and it can also prepare the organization for the subsequent spheroidizing annealing at a lower temperature and shorter time.

[0039] In this step, the steel coil is generally cooled to below 70°C to room temperature, and then stress relief annealing is performed. If the temperature is too high, the steel coil will be difficult to transport. In addition, high-temperature transportation will cause the steel coil to be exposed to rain and wind, which will cause the steel coil to cool rapidly, increase the strength of the steel coil, make the material brittle, and deteriorate the material properties.

[0040] S200: The steel coil is subjected to stress relief annealing to obtain a stress relief annealed steel coil. In the stress relief annealing, the steel coil is heated to 200°C. Then heated to 400°C at a heating rate of 60-80°C / h and kept at this temperature for 4 hours. Then heated to 500-660°C at a heating rate of 60-80°C / h and kept at this temperature for 10-20 hours.

[0041] In this step, the steel coil is subjected to stress relief annealing. The heat treatment of cold-deformed metal below the recrystallization temperature to remove internal stress but still retain the cold work hardening effect is called stress relief annealing.

[0042] The steel coil is usually annealed in a relatively closed space, such as an annealing furnace, specifically, a bell-type annealing furnace. Take a bell-type annealing furnace as an example.

[0043] Stress relief annealing includes multiple heating stages. The finished coils annealed in a bell furnace have good surface quality and the performance and structure meet the requirements of downstream cold rolling or forming processing.

[0044] In this step, 200℃ is used to remove aqueous solution residues, 400℃ is used to remove oil residues, and 500-660℃ is used to soften the steel coil material and reduce its strength.

[0045] S300: After pickling the stress relief annealing steel coil, spheroidizing annealing is performed to obtain a high-strength hot-rolled steel coil, and the maximum insulation temperature of the spheroidizing annealing is greater than the maximum insulation temperature of the stress relief annealing.

[0046] In this step, the pickling and spheroidizing annealing can adopt the pickling process parameters in the related art and the process parameters of the conventional spheroidizing annealing.

[0047] The hot rolled coils of high carbon tool steel and high alloy tool steel are first subjected to low temperature stress relief annealing in a bell furnace, then pickled in a pickling line, and then spheroidized annealing in a bell furnace. The surface quality of the finished coils annealed in a bell furnace is good, and the performance and structure meet the requirements of downstream cold rolling or forming processing.

[0048] Different from the existing high-carbon tool steel and high-alloy tool steel produced by direct pickling of hot-rolled coils or pickling after annealing and spheroidizing, which have complex process flow, low production efficiency, large material loss and high production cost, the present invention adopts a push-pull pickling line to produce high-quality pickled high-carbon tool steel, high-alloy tool steel and high-alloy tool steel, which has the characteristics of simple process flow, high production efficiency and low production cost.

[0049] Continuous pickling is a continuous pickling after welding, which is suitable for low-carbon steel coils with tensile strength less than 1000MPa. High-strength steel with strength greater than 1400MPa is difficult to weld due to its high strength and special material, and cannot be pickled continuously. The advantage of this process is that it also uses push-pull pickling. The pickling rate can be significantly increased by adopting this process path, and the belt threading is simple and the pickling effect is good.

[0050] The above-mentioned production process of high-strength hot-rolled steel coils includes low-temperature coiling, low-temperature stress relief annealing, pickling, high-temperature spheroidizing hood annealing and production in the form of wide-width coils. It has high production efficiency, low cost and high pass rate. Compared with the current traditional high-quality steel cold rolling enterprises at home and abroad, this technology is used to produce high-end products such as pickled high-carbon tool steel, high-alloy tool steel, etc., which can bring significant economic benefits.

[0051] According to an embodiment of the present application, during the stress relief annealing, the steel coil is heated to 200°C, then heated to 400°C at a heating rate of 60-80°C / h and kept at that temperature for 4 hours, then heated to 500-660°C at a heating rate of 60-80°C / h and kept at that temperature for 10-20 hours.

[0052] According to the embodiment of the present application, in the cooling step of the stress relief annealing, after the heat preservation is completed, the steel is cooled to 400° C. by air, and then cooled to 100° C. by water before being taken out of the furnace.

[0053] According to an embodiment of the present application, the step of pickling the stress relief annealed steel coil comprises:

[0054] The stress relief annealed steel coil is sequentially subjected to acid washing, water rinsing and hot air drying at a moving speed of 60-120 m / min, wherein the concentration of hydrochloric acid in the acid is 12%-18%, the temperature of the acid is 70-85° C., the rinsing temperature is 60-80° C. and the hot air temperature is 120° C.

[0055] According to an embodiment of the present application, the step of spheroidizing annealing includes:

[0056] After pickling, the steel coil is heated freely from room temperature to 200℃. Then it is heated to 400℃ at a heating rate of 60-80℃ / h and kept at this temperature for 4 hours. Then it is heated to 700-800℃ at a heating rate of 60-80℃ / h and kept at this temperature for 10-30 hours.

[0057] According to the embodiment of the present application, the pickled steel coil is heated freely from room temperature to 200°C, then heated to 400°C at a heating rate of 60-80°C / h and kept at that temperature for 4 hours, then heated to 700-800°C at a heating rate of 60-80°C / h and kept at that temperature for 10-30 hours.

[0058] According to an embodiment of the present application, in the cooling step of the spheroidizing annealing, after the insulation is completed, the steel coil is naturally cooled to 640-660°C in a closed space, and then the steel coil is cooled to 380°C by air cooling, and then the steel coil is cooled to below 100°C by water cooling before being taken out from the closed space.

[0059] According to an embodiment of the present application, the target curling temperature is 580-680°C.

[0060] According to an embodiment of the present application, the method for determining the feasible curling temperature range includes:

[0061] According to the chemical composition or CCT curve of the high-strength hot-rolled steel coil, combined with the target performance index of the high-strength hot-rolled steel coil, a feasible coiling temperature range is determined.

[0062] Example 1: Production of 9Cr2 pickled coil

[0063] The raw material is a hot-rolled steel coil of 9Cr2 steel, with a raw material specification of 3.2mm×1250mm and a tensile strength of 1450MPa. The chemical composition is C 0.93%, Si 0.35%, Mn 0.36%, Cr 1.65%, and the rest is Fe and indispensable residual or impurity elements.

[0064] The following process steps are used:

[0065] Hot rolling and low temperature coiling: The hot rolling coiling temperature of 9Cr2 is set to 610℃, the hot rolled coil is slowly cooled to room temperature off the line, and the coil weight is 22 tons.

[0066] The low temperature stress relief annealing process is: the steel coil is heated freely from room temperature to 200℃; then heated to 400℃ at a heating rate of 40℃ / h and kept at this temperature for 2 hours; then heated to 650℃ at 70℃ / h and kept at this temperature for 18 hours; after the end of the heat preservation, it is cooled to 400℃ by air; then cooled to 100℃ by water before being taken out of the furnace. The surface of the steel coil after low temperature stress relief annealing is sampled for metallographic testing, see Figure 3 The oxide on its surface is not reduced and is black-gray.

[0067] The pickling process is: hydrochloric acid pickling, acid concentration 16%, acid temperature 82°C. Water rinsing, rinsing temperature 70°C. The strip after rinsing is dried by hot air, the hot air temperature is 120°C. The pickling rate is 140m / min.

[0068] The high-temperature spheroidizing annealing process is as follows: the steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 40°C / h and kept warm for 4 hours; then heated to 780°C at 40°C / h and kept warm for 26 hours; after the end of the insulation, it is slowly cooled to about 640°C; cooled to 380°C with air; cooled to 100°C with water before being taken out of the furnace.

[0069] 9Cr2 pickled annealed finished coil produced after annealing, see Figure 1 and Figure 2 There is no oxide residue on the surface of the steel coil, and the structure is level 5 spheroidized pearlite structure.

[0070] Example 2: Production of T12 Pickled Coil

[0071] The raw material is a hot-rolled steel coil of T12 steel grade, with a raw material specification of 3.5mm×1250mm and a tensile strength of 1450MPa. The chemical composition is C1.21%, Si 0.32%, Mn 0.35%, and the rest is Fe and indispensable residual or impurity elements.

[0072] The following process steps are used:

[0073] Hot rolling and low temperature coiling: Set the hot rolling coiling temperature of T12 to 620℃, slowly cool the hot rolled coil to room temperature, and reduce the coil weight to 20 tons.

[0074] The low-temperature stress relief annealing process is as follows: the steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 70°C / h and kept warm for 2 hours; then heated to 660°C at 70°C / h and kept warm for 18 hours; after the insulation is completed, it is cooled to 400°C by air; then cooled to 100°C by water before being taken out of the furnace.

[0075] The pickling process is: hydrochloric acid pickling, acid concentration 15%, acid temperature 80°C. Water rinsing, rinsing temperature 71°C. The strip after rinsing is dried by hot air, the hot air temperature is 120°C. The pickling rate is 120m / min.

[0076] The high-temperature spheroidizing annealing process is as follows: the steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 70°C / h and kept warm for 4 hours; then heated to 760°C at 70°C / h and kept warm for 24 hours; after the end of the insulation, it is slowly cooled to about 640°C; cooled to 380°C with air; cooled to 100°C with water before being taken out of the furnace.

[0077] The T12 pickled annealed finished coil produced after annealing has no oxide residue on the surface of the steel coil, good surface quality, and a grade 5 spheroidized pearlite structure.

[0078] Example 3: Production of GCr15SiMn cold-rolled coil

[0079] The hot-rolled steel coil of GCr15SiMn is selected as the raw material, with the raw material specification of 3.0mm×1250mm and the tensile strength of 1550MPa. The chemical composition is C1.04%, Si 0.61%, Mn 1.17%, Cr 1.57%, Al0.017%, and the rest is Fe and indispensable residual or impurity elements.

[0080] The following process steps are used:

[0081] Hot rolling and low temperature coiling: The hot rolling coiling temperature of GCr15SiMn is set to 620℃, the hot rolled coil is slowly cooled to room temperature off the line, and the coil weight is 22 tons.

[0082] The low-temperature stress relief annealing process is as follows: the steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 70°C / h and kept warm for 2 hours; then heated to 660°C at 70°C / h and kept warm for 18 hours; after the insulation is completed, it is cooled to 400°C by air; then cooled to 100°C by water before being taken out of the furnace.

[0083] The pickling process is: hydrochloric acid pickling, acid concentration 16%, acid temperature 80°C. Water rinsing, rinsing temperature 70°C. The strip after rinsing is dried by hot air, the hot air temperature is 120°C. The pickling rate is 120m / min.

[0084] The high-temperature spheroidizing annealing process is as follows: the steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 70°C / h and kept warm for 4 hours; then heated to 780°C at 70°C / h and kept warm for 26 hours; after the end of the insulation, it is slowly cooled to about 660°C; cooled to 380°C with air; cooled to 100°C with water before being taken out of the furnace.

[0085] The GCr15SiMn pickled annealed finished coil produced after annealing has no oxide residue on the surface of the steel coil and has a grade 5 spheroidized pearlite structure.

[0086] Comparative Example 1:

[0087] The steel type is the same as that in Example 3, the hot rolling and low temperature coiling steps are the same, and the following process steps are subsequently adopted:

[0088] High temperature spheroidizing annealing → pickling, that is, omitting the low temperature stress relief annealing process, and the finished steel coil is obtained after pickling.

[0089] The high temperature spheroidizing annealing process is as follows: the steel coil is heated freely from room temperature to 200℃; then heated to 400℃ at a heating rate of 70℃ / h and kept at this temperature for 4 hours; then heated to 780℃ at 70℃ / h and kept at this temperature for 26 hours; after the end of the heat preservation, it is slowly cooled to about 610℃; then cooled to 400℃ by air; then cooled to 100℃ by water before being taken out of the furnace. The surface of the steel coil after high temperature spheroidizing annealing is sampled for metallographic testing, see Figure 4 , the oxide on its surface is reduced and appears white.

[0090] The pickling process is: hydrochloric acid pickling, acid concentration 16%, acid temperature 80℃. Water rinsing, rinsing temperature 70℃. The strip after rinsing is dried by hot air, the hot air temperature is 120℃. Pickling speed 20m / min. Figure 5 The pickled coils produced by this process have reduced oxides on the surface of the steel coils and cannot be cleaned by pickling.

[0091] Comparative Example 2:

[0092] Steel grade 9SICR material is selected, the hot rolling and low-temperature coiling steps are the same, and then it is directly pickled.

[0093] The pickling process is: hydrochloric acid pickling, acid concentration 16%, acid temperature 80°C. Water rinsing, rinsing temperature 70°C. The strip after rinsing is dried by hot air, the hot air temperature is 120°C. The pickling rate is 10m / min.

[0094] See also Figure 5 This process produces pickled coils, the steel coils have poor shape, are difficult to thread, and some parts break directly.

[0095] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A production process for high-strength hot-rolled steel coil, characterized in that: The strength of the high-strength hot-rolled steel coil is ≥1400MPa, and the production process comprises the following steps: The steel strip of the high-strength hot-rolled steel is coiled at a target coiling temperature to obtain a steel coil of the high-strength hot-rolled steel, wherein the lower limit of the feasible coiling temperature range of the high-strength hot-rolled steel is ≤ the target coiling temperature ≤ the lower limit of the feasible coiling temperature range + 20°C; The steel coil is subjected to stress relief annealing to obtain a stress relief annealed steel coil; during the stress relief annealing, the steel coil is heated to 200° C.; then heated to 400° C. at a heating rate of 60 to 80° C. / h and kept at that temperature for 4 hours; then heated to 500 to 660° C. at a heating rate of 60 to 80° C. / h and kept at that temperature for 10 to 20 hours; After the stress relief annealing steel coil is pickled, spheroidizing annealing is performed to obtain a high-strength hot-rolled steel coil, and the maximum insulation temperature of the spheroidizing annealing is greater than the maximum insulation temperature of the stress relief annealing.

2. The production process according to claim 1, characterized in that: In the stress relief annealing, the steel coil is heated to 200°C; then heated to 400°C at a heating rate of 60-80°C / h and kept warm for 4 hours; then heated to 500-660°C at a heating rate of 60-80°C / h and kept warm for 10-20 hours.

3. The production process according to claim 1, characterized in that: In the cooling step of the stress relief annealing, after the heat preservation is completed, the steel is cooled to 400° C. by air; and then cooled to 100° C. by water before being taken out of the furnace.

4. The production process according to claim 1, characterized in that: The step of pickling the stress relief annealed steel coil comprises: The stress relief annealed steel coil is sequentially subjected to acid washing, water rinsing and hot air drying at a moving speed of 60 to 120 m / min, wherein the concentration of hydrochloric acid in the acid is 12% to 18%, the temperature of the acid is 70 to 85°C; the rinsing temperature is 60 to 80°C; and the hot air temperature is 120°C.

5. The production process according to claim 1, characterized in that: The spheroidizing annealing step comprises: The pickled steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 60-80°C / h and kept warm for 4 hours; then heated to 700-800°C at a heating rate of 60-80°C / h and kept warm for 10-30 hours.

6. The production process according to claim 5, characterized in that: The pickled steel coil is heated freely from room temperature to 200°C; then heated to 400°C at a heating rate of 60-80°C / h and kept warm for 4 hours; then heated to 700-800°C at a heating rate of 60-80°C / h and kept warm for 10-30 hours.

7. The production process according to claim 5, characterized in that: In the cooling step of the spheroidizing annealing, the steel coil is naturally cooled to 640-660° C. in a closed space, then cooled to 380° C. by air cooling, and then cooled to below 100° C. by water cooling before being taken out of the closed space.

8. The production process according to claim 1, characterized in that: The target curling temperature is 580-680°C.

9. The production process according to any one of claims 1 to 8, characterized in that: The method for determining the feasible curling temperature range includes: According to the chemical composition or CCT curve of the high-strength hot-rolled steel coil, combined with the target performance index of the high-strength hot-rolled steel coil, a feasible coiling temperature range is determined.

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