Processing and manufacturing method and device of hot continuous rolling strip steel, processing and manufacturing method of hot forming steel and quality detection method of hot continuous rolling strip steel

Abstract

The invention relates to a processing and manufacturing method and device of hot continuous rolling strip steel, a processing and manufacturing method of hot forming steel and a quality detection method of the hot continuous rolling strip steel. The processing and manufacturing method of the hot continuous rolling strip steel comprises a heating procedure, a hot continuous rolling procedure, a laminar cooling procedure and a coiling procedure, the shape of the hot continuous rolling strip steel is controlled in the hot continuous rolling procedure, and the cooling speed is controlled in the laminar cooling procedure so as to avoid martensite phase transformation. The processing and manufacturing method of the hot-formed steel comprises the following steps: preparing the hot continuous rolling strip steel according to the processing and manufacturing method of the hot continuous rolling strip steel; and the hot continuous rolling strip steel is sequentially subjected to one or more working procedures of acid pickling, cold continuous rolling, annealing, plating and stamping thermal forming. The steel processing and manufacturing method provided by the invention can solve the problem of steel thickness fluctuation and improve the steel quality.

Description

Technical Field

[0001] The present application relates to the technical field of steel processing and manufacturing, and in particular to a processing and manufacturing method and device for hot-rolled strip steel, a processing and manufacturing method for hot-formed steel, and a quality inspection method for hot-rolled strip steel. Background Art

[0002] Energy conservation and emission reduction are the main driving forces for the development of lightweight automobiles. The application of 1000Mpa high-strength hot stamping steel (hot forming steel for short) in the body-in-white can reduce the weight of the body by more than 20%. The contribution of hot forming steel to the lightweight of automobiles has made it popular among users. However, the shape of hot forming steel is not easy to control, especially in the length direction of the strip, which is prone to drastic thickness fluctuations, thus affecting the quality, production efficiency and production cost of the steel.

[0003] The dramatic thickness fluctuation of the strip is directly related to the uniformity of the structure in the length direction of the strip. Under this steel composition system, when there is a large degree of undercooling ΔT, it is very easy to form a high-hardness and high-strength martensite structure, which has great differences in physical properties from the normal ferrite + pearlite mixed structure. This is the fundamental reason for the dramatic thickness fluctuation during the cold rolling process. Summary of the invention

[0004] Based on this, the present application provides a processing and manufacturing method and device for hot-rolled strip steel, a processing and manufacturing method for hot-formed steel, and a quality inspection method for hot-rolled strip steel, so as to reduce the thickness fluctuation problem in the processing and production process and improve the quality of hot-rolled strip steel and hot-formed steel.

[0005] In a first aspect of the present application, a method for processing and manufacturing hot-rolled strip steel is provided, comprising a heating process, a hot-rolling process, a laminar cooling process and a coiling process, wherein the shape of the hot-rolled strip steel is controlled in the hot-rolling process and the cooling rate is controlled in the laminar cooling process to avoid martensitic phase transformation.

[0006] The processing and manufacturing method of hot-rolled steel strip provided in the present application controls the shape of the hot-rolled steel strip in the hot-rolling process and controls the cooling rate in laminar cooling to avoid martensitic transformation of the steel locally due to the wave shape and excessive cooling rate. This effectively solves the problem of discontinuous hardness and strength mutations in the length direction of the hot-rolled steel strip due to martensitic transformation, thereby avoiding the problem of steel thickness fluctuation caused by the subsequent processing and manufacturing of the hot-rolled steel strip, thereby improving the quality of the hot-rolled steel strip and its processed products.

[0007] In some embodiments, controlling the hot rolled strip shape comprises the steps of:

[0008] Avoiding the middle wave of the hot rolled strip;

[0009] Avoiding rib waves of the hot rolled strip;

[0010] Control the edge waves of the hot rolled strip.

[0011] In some implementation methods, the amplitude of the edge wave is -25I to 150I.

[0012] In some embodiments, the cooling rate of the laminar cooling process is 50°C / s to 60°C / s.

[0013] In some embodiments, the final rolling temperature of the hot rolled strip is 800° C. to 950° C.; and / or,

[0014] The coiling temperature of the hot rolled strip is 500°C to 600°C.

[0015] In some of the embodiments, the laminar cooling process adopts a front-stage sparse cooling mode.

[0016] In some embodiments, the hot rolled steel strip is composed of the following chemical components in weight percentage:

[0017] C: 0.05%~0.09%; Cr: 0.04%~0.15%; Si: 0.3%~0.6%; Mn: 1.5%~1.8%; P≤0.02%; S≤0.005%; Alt: 0.03%~0.07%; N≤0.005%; Nb: 0.03%~0.08%; Ti: 0.012%~0.03%; B: 0.004~0.007%; the rest is Fe.

[0018] In a second aspect of the present application, a method for processing and manufacturing hot-formed steel is provided, comprising the following steps:

[0019] Prepare hot-rolled steel strip according to the processing and manufacturing method of hot-rolled steel strip described in the first aspect of the present application;

[0020] The hot rolled strip is sequentially subjected to one or more of the following processes: pickling, cold rolling, annealing, coating, and stamping and hot forming.

[0021] The processing and manufacturing method of hot-formed steel provided in the present application controls the strip shape in the hot rolling process and controls the cooling rate of the strip in laminar cooling at the same time to avoid local water accumulation and overcooling of the strip during laminar cooling (the wave shape factor causes local water accumulation) and / or excessive cooling rate causing local martensitic phase transformation, thereby reducing the drastic thickness fluctuation caused by discontinuous hardness and strength mutations in the length direction of the strip during subsequent cold rolling and acid rolling, thereby improving the quality of the hot-formed steel. The thickness fluctuation of the hot-formed steel prepared according to this method can be maintained within ±3% within the entire coil.

[0022] In a third aspect of the present application, there is provided a method for detecting the local martensitic phase transformation of the hot rolled strip steel prepared by the processing and manufacturing method according to the first aspect of the present application, comprising the following steps:

[0023] Prepare hot-rolled steel strip according to the processing and manufacturing method of hot-rolled steel strip described in the first aspect of the present application;

[0024] Observe whether there are local black spots on the surface of the hot-rolled strip after it leaves the laminar cooling section. If there are local black spots, the hot-rolled strip undergoes local martensitic phase transformation. If there are no local black spots, the hot-rolled strip does not undergo local martensitic phase transformation.

[0025] In a fourth aspect of the present application, a processing and manufacturing device for hot-rolled steel strip is provided, comprising a hot-rolled steel strip shape module for controlling the shape of the hot-rolled steel strip;

[0026] Among them, the hot-rolled strip shape module further includes a wave shape and amplitude automatic determination system and an alarm system. The wave shape and amplitude automatic determination system can automatically identify the wave shape and wave shape amplitude of the hot-rolled strip, and the alarm system can make an alarm reminder based on the wave shape and wave shape amplitude identified by the wave shape and wave shape amplitude automatic determination system. If the wave shape identified by the wave shape and amplitude automatic determination system is a middle wave and / or a rib wave, the alarm system will make an alarm reminder; if the wave shape identified by the wave shape and amplitude automatic determination system is an edge wave and the wave shape amplitude is outside the range of -25I to 150I, the alarm system will make an alarm reminder; no alarm reminder will be made in other cases. DETAILED DESCRIPTION

[0027] For ease of understanding of the present application, the present application will be described more fully below, and preferred embodiments of the present application are provided. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] In this application, "first aspect", "second aspect", "third aspect", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features.

[0030] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0031] In the present application, "one or more" refers to any one, any two, or any two or more of the listed items.

[0032] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0033] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0034] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0035] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0036] In the present application, the method steps that do not emphasize the temperature usually refer to the method steps performed at normal temperature or room temperature. In this article, normal temperature and room temperature are equivalent and interchangeable, and the specific temperature refers to 22°C to 25°C.

[0037] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0038] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0039] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0040] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0041] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0042] The conventional production method of hot-formed steel is generally to obtain hot-rolled steel coils through the main processes of smelting, continuous casting, hot rolling, and then to obtain the final product for stamping and hot forming through processes such as pickling, cold rolling, annealing, and coating. However, in the hot rolling production process, due to the good hardenability of the material, martensitic phase transformation is prone to occur during the water cooling process after rolling. The overall fast cooling speed and local wave shape lead to local martensitic transformation of the strip, and the hardness and strength increase sharply. In the subsequent cold rolling and acid rolling process, the discontinuous hardness and strength mutations in the length direction of the strip will cause drastic thickness fluctuations. This problem generally occurs at the end of the acid rolling, corresponding to the head of the hot-rolled steel coil. Therefore, how to avoid local martensitic phase transformation is the key to solving this problem.

[0043] In order to solve the above problems, the first aspect of the present application provides a method for processing and manufacturing hot rolled strip steel, comprising a heating process, a hot rolling process, a laminar cooling process and a coiling process. In the hot rolling process, the shape of the hot rolled strip steel is controlled, and in the laminar cooling process, the cooling rate is controlled to avoid martensitic phase transformation.

[0044] The above-mentioned hot-rolled strip processing and manufacturing method controls the shape of the hot-rolled strip in the hot-rolling process to avoid local water accumulation and overcooling of the strip during laminar cooling to cause martensitic transformation. At the same time, the cooling rate of the laminar cooling is controlled to avoid the martensitic transformation caused by excessive cooling. This effectively solves the problem of discontinuous hardness and strength mutations in the length direction of the hot-rolled strip due to martensitic transformation, thereby avoiding the problem of steel thickness fluctuation caused by subsequent hot-rolled strip processing and manufacturing, thereby improving the quality of the hot-rolled strip and its processed products.

[0045] In some embodiments, the hot rolling process includes a rough rolling process and a finish rolling process.

[0046] The "board shape" mentioned in this application is commonly known as the wave shape, that is, the flatness along the length direction of the medium and thick board. The specific wave shape includes middle wave, rib wave and side wave. The side wave can be single-sided wave or double-sided wave.

[0047] In some embodiments, controlling the hot rolled strip shape comprises the steps of:

[0048] Avoiding the middle wave of the hot rolled strip, specifically, by reducing the convexity of the intermediate billet produced by rough rolling, the bending roll of the finishing roll is biased towards the negative bending roll, and the negative shifting roll of the CVC rolling mill increases the thickness of the middle position in the width direction of the steel plate;

[0049] Avoid rib waves of the hot rolled strip. When rib waves occur, the rollers are severely worn and need to be replaced.

[0050] The edge waves of the hot rolled strip are controlled, specifically, by increasing the convexity of the intermediate billet output by rough rolling, the bending rolls of the finishing rolls are biased towards positive bending rolls, and the CVC rolling mill has positive roll shifting to reduce the thickness of the middle position in the width direction of the steel plate.

[0051] Control the shape of hot rolled strip to keep it without waves or with slight edge waves.

[0052] In some embodiments, the amplitude of the side wave is any value between -25I and 150I and the range therebetween. It can be understood that the amplitude of the side wave can be -25I, -20I, -15I, -10I, -5I, 0I, 5I, 10I, 20I, 30I, 40I, 50I, 60I, 70I, 80I, 90I, 100I, 110I, 120I, 130I, 140I, 150I and the range between any two values.

[0053] "I" has a well-known meaning in the art, and is a quantitative indicator that reflects the plate shape by measuring the longitudinal fiber extension difference ΔL / La distributed along the width of the plate. Among them, La is the post-rolling length of the reference point, and ΔL is the post-rolling length difference of other points relative to the reference point. The Ⅰ unit is defined as the change in plate shape caused by a strain difference of 0.001% in adjacent parts of the strip. The plate shape difference between the middle and the edge is called 1Ⅰ. The unit is represented by the symbol Ⅰ or ⅠU, which is the amplitude unit of the wave shape. The amplitude of the wave shape refers to the amplitude between the positive and negative peaks of the wave, which also has a well-known meaning in the art. It can be measured by conventional methods in the art. For example, the automatic flatness detector can easily measure the actual plate shape value of the strip, that is, the I value, based on the continuous scanning of the rays in the extension direction of the entire width of the strip.

[0054] In some embodiments, the cooling rate of the laminar cooling process is any value between 50°C / s and 60°C / s and the range therebetween. It can be understood that the cooling rate of the laminar cooling process can be 50°C / s, 51°C / s, 52°C / s, 53°C / s, 54°C / s, 55°C / s, 56°C / s, 57°C / s, 58°C / s, 59°C / s, 60°C / s and the range between any two values.

[0055] "Cooling rate in laminar cooling process" has a well-known meaning in the art, and specifically refers to the cooling rate of high-temperature strip steel rolled by the finishing mill when cooled by laminar cooling water. The unit is ℃ / s and can be measured by conventional methods in the art. For example, pyrometers are installed at both ends of the cooling water to measure the actual temperature before and after cooling. The cooling rate can be calculated relatively conveniently based on the length of the cooling section and the running speed of the strip steel, and the relevant calculated value can be given in the temperature automatic control model.

[0056] In some embodiments, the final rolling temperature of the hot-rolled strip is any value between 800°C and 950°C and ranges therebetween. It can be understood that the final rolling temperature of the hot-rolled strip can be 800°C, 850°C, 900°C, 950°C and a range between any two values.

[0057] In some embodiments, the coiling temperature of the hot-rolled strip is any value between 500°C and 600°C and ranges therebetween. It can be understood that the coiling temperature of the hot-rolled strip can be 500°C, 520°C, 540°C, 560°C, 580°C, 600°C and a range between any two values.

[0058] In some embodiments, the laminar cooling process adopts a sparse cooling mode in the front section. The sparse cooling mode can be that for every other row or multiple rows of laminar cooling water headers, so that the cooling rate of the laminar cooling process is 50°C / s to 60°C / s. The sparse cooling mode in the front section has the meaning well-known in the art and is a combination of the front section cooling and the sparse cooling mode. Understandably, the rear section area of the laminar cooling is air cooling.

[0059] In some embodiments, the hot rolled strip steel consists of the following chemical components by weight percentage:

[0060] C: 0.05% to 0.09%; Cr: 0.04% to 0.15%; Si: 0.3% to 0.6%; Mn: 1.5% to 1.8%; P ≤ 0.02%; S ≤ 0.005%; Alt: 0.03% to 0.07%; N ≤ 0.005%; Nb: 0.03% to 0.08%; Ti: 0.012% to 0.03%; B: 0.004 to 0.007%; the balance is Fe.

[0061] "P ≤ 0.02%" means 0 < P ≤ 0.02%. Similarly, "S ≤ 0.005%" means 0 < S ≤ 0.005%, and "N ≤ 0.005%" means 0 < N ≤ 0.005%.

[0062] A large supercooling degree ΔT is required to form martensite because a phase transformation driving force is needed to overcome the phase transformation resistance. The driving forces for martensite phase transformation include: (1) the free energy difference ΔGv between martensite and austenite. The larger the supercooling degree ΔT, the larger ΔG V is; (2) the energy ΔG D provided by the crystal defects of the parent phase austenite provides the driving force. The martensite phase transformation resistance includes interface energy, distortion energy, the energy increased due to the accompanying large amount of dislocations and twin crystal structures, and other phase transformation resistances. Only when the absolute value of the phase transformation driving force is greater than the resistance can the phase transformation proceed spontaneously. Since more energy is increased during martensite phase transformation, the resistance is larger, and the martensite transformation needs to be carried out at a larger supercooling degree. That is, a larger cooling rate is required to achieve a larger supercooling degree.

[0063] The martensite start point M S is the starting temperature of martensite phase transformation and is the temperature when the difference in the free energies of the two phases of austenite phase transformation and martensite phase transformation reaches the minimum driving force required for phase transformation. Representing the equilibrium temperature when the free energies of austenite and martensite are equal by T0, the larger the value of T0 - M S is, the larger the driving force of the phase transformation. The martensite start point in steel is closely related to the composition of the steel. As the content of C element decreases, the martensite start point increases. As the content of Al element increases, the martensite start point increases. The influence of Si element on the martensite start point is weak. The increase in the contents of Mn and Cr elements can lower the martensite start point. Among them, C has a greater influence.

[0064] The present application relates to a steel grade composition design that makes it easy to undergo martensitic phase transformation when there is a large degree of undercooling. Therefore, surface water accumulation caused by high cooling rate and large wave shape during production will lead to a large degree of undercooling ΔT in the strip steel, thereby forming a martensitic structure different from the normal structure at the local water accumulation location.

[0065] In a second aspect of the present application, a method for processing and manufacturing hot-formed steel is provided, comprising the following steps:

[0066] Prepare hot-rolled steel strip according to the processing and manufacturing method of hot-rolled steel strip described in the first aspect of the present application;

[0067] The hot rolled strip is sequentially subjected to one or more of the following processes: pickling, cold rolling, annealing, coating, and stamping and hot forming.

[0068] The above-mentioned processing and manufacturing method of hot-formed steel controls the strip shape in the hot rolling process and controls the cooling rate of the strip in laminar cooling at the same time to avoid local water accumulation and overcooling of the strip during laminar cooling (the wave shape factor causes local water accumulation) and / or excessive cooling rate causing local martensitic phase transformation, thereby reducing the drastic thickness fluctuation caused by discontinuous hardness and strength mutations in the length direction of the strip during subsequent cold rolling and acid rolling, thereby improving the quality of the hot-formed steel. The thickness fluctuation of the hot-formed steel prepared according to this method can be maintained within ±3% within the entire coil.

[0069] In a third aspect of the present application, there is provided a method for detecting the local martensitic transformation of a hot rolled strip steel prepared by the processing and manufacturing method of the first aspect of the present application, comprising the following steps:

[0070] Prepare hot rolled steel strip according to the processing and manufacturing method of hot rolled steel strip according to any embodiment of the first aspect of the present application;

[0071] Observe whether there are local black spots on the surface of the hot-rolled strip after it leaves the laminar cooling section. If there are local black spots, the hot-rolled strip undergoes local martensitic transformation. If there are no local black spots, the hot-rolled strip does not undergo local martensitic transformation.

[0072] In a fourth aspect of the present application, a processing and manufacturing device for hot-rolled strip steel is provided, comprising a hot-rolled strip steel shape module for controlling the shape of the hot-rolled strip steel.

[0073] The hot-rolled strip shape module further includes a wave shape and amplitude automatic determination system and an alarm system. The wave shape and amplitude automatic determination system can automatically identify the wave shape and wave shape amplitude of the hot-rolled strip. The alarm system can make an alarm reminder based on the wave shape and wave shape amplitude identified by the wave shape and amplitude automatic determination system.

[0074] If the wave shape and amplitude automatic determination system identifies the wave shape as a middle wave and / or a rib wave, the alarm system will issue an alarm reminder; if the wave shape and amplitude automatic determination system identifies the wave shape as a side wave and the wave shape amplitude is outside the range of -25I to 150I, the alarm system will issue an alarm reminder; in other cases, no alarm reminder will be issued.

[0075] Example

[0076] The following are specific embodiments. The purpose is to further explain the present application in detail to help the technical personnel and researchers in the field to further understand the present application. The relevant technical conditions do not constitute any limitation to the present application. Any form of modification made within the scope of the claims of the present application is within the scope of protection of the claims of the present application.

[0077] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods. Experimental methods without specific conditions specified in the examples are carried out according to conventional conditions, such as those described in literature or books or methods recommended by manufacturers.

[0078] The test method for thickness fluctuation of hot-formed steel cold-rolled acid continuous rolling in the following examples and comparative examples is as follows:

[0079] The thickness is measured using an X-ray thickness gauge, which can perform continuous high-precision measurements with a measurement accuracy of ±0.1% and a sampling time of 1ms. A continuous thickness measurement curve can be provided in real time.

[0080] Example 1

[0081] In this embodiment, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0082] Among them, the outlet temperature of the finishing rolling process is 888°C, the coiling temperature is 544°C, the strip shape in the finishing rolling process is controlled to have only symmetrical double-sided waves, and the amplitude of the wave shape is 50I, and the laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 54°C / S.

[0083] The remaining steps are all well-known to those skilled in the art.

[0084] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel in the whole coil of cold-rolled acid continuous rolling is within ±3%.

[0085] Example 2

[0086] In this embodiment, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0087] Among them, the outlet temperature of the finishing rolling process is 893°C, the coiling temperature is 541°C, the strip shape in the finishing rolling process is controlled to have only symmetrical double-sided waves, and the amplitude of the wave shape is 100I, and the laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 57°C / S.

[0088] The remaining steps are all well-known to those skilled in the art.

[0089] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel in the whole coil of cold-rolled acid continuous rolling is within ±3%.

[0090] Example 3

[0091] In this embodiment, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0092] Among them, the outlet temperature of the finishing rolling process is 891°C, the coiling temperature is 541°C, the strip shape in the finishing rolling process is controlled to have only symmetrical double-sided waves, and the amplitude of the wave shape is -15I, and the laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 54°C / S.

[0093] The remaining steps are all well-known to those skilled in the art.

[0094] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel in the whole coil of cold-rolled acid continuous rolling is within ±3%.

[0095] Comparative Example 1

[0096] In this comparative example, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0097] Among them, the outlet temperature of the finishing rolling process is 890℃, the coiling temperature is 538℃, the strip shape is controlled to have only symmetrical double-sided waves in the finishing rolling process, and the amplitude of the wave shape is -65I. The laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 96℃ / S.

[0098] The remaining steps are all well-known to those skilled in the art.

[0099] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel at the tail of the cold-rolled acid continuous rolling section exceeds ±3%.

[0100] Comparative Example 2

[0101] In this comparative example, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0102] Among them, the outlet temperature of the finishing rolling process is 893°C, the coiling temperature is 534°C, the strip shape is controlled to have only symmetrical double-sided waves in the finishing rolling process, and the amplitude of the wave shape is 25I. The laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 72°C / S.

[0103] The remaining steps are all well-known to those skilled in the art.

[0104] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel at the tail end of the cold-rolled acid continuous rolling process exceeds ±3%.

[0105] Comparative Example 3

[0106] In this comparative example, the hot-formed steel production process includes a heating process, a rough rolling process, a finishing rolling process, a laminar cooling process, a coiling process, a pickling process, a cold rolling process, an annealing process, a coating process and a stamping hot forming process.

[0107] Among them, the outlet temperature of the finishing rolling process is 890°C, the coiling temperature is 542°C, the strip shape is controlled to have only symmetrical double-sided waves in the finishing rolling process, and the amplitude of the wave shape is -165I, and the laminar cooling process adopts the front-stage sparse cooling mode with a cooling rate of 58°C / S.

[0108] The remaining steps are all well-known to those skilled in the art.

[0109] The thickness fluctuation test results show that the thickness fluctuation of the hot-formed steel at the tail of the cold-rolled acid continuous rolling section exceeds ±3%.

[0110] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A method for processing and manufacturing hot rolled strip steel, characterized in that: It includes heating process, hot rolling process, laminar cooling process and coiling process. Wherein, the shape of the hot rolled strip is controlled in the hot rolling process and the cooling rate is controlled in the laminar cooling process to avoid martensitic phase transformation.

2. The method for manufacturing hot rolled strip steel according to claim 1, characterized in that: The controlling of the hot rolled strip shape comprises the following steps: Avoiding the middle wave of the hot rolled strip; Avoiding rib waves of the hot rolled strip; Control the edge waves of the hot rolled strip.

3. The method for manufacturing hot rolled strip steel according to claim 2, characterized in that: The amplitude of the edge wave is -25I to 150I.

4. The method for manufacturing hot rolled strip steel according to claim 1, characterized in that: The cooling rate of the laminar cooling process is 50°C / s to 60°C / s.

5. The method for manufacturing hot rolled strip steel according to claim 4, characterized in that: The final rolling temperature of the hot rolled strip is 800° C. to 950° C.; and / or, The coiling temperature of the hot rolled strip is 500°C to 600°C.

6. The method for manufacturing hot rolled strip steel according to claim 5, characterized in that: The laminar cooling process adopts a front-stage sparse cooling mode.

7. The method for manufacturing hot rolled steel strip according to any one of claims 1 to 6, characterized in that: The hot rolled steel strip is composed of the following chemical components in weight percentage: C: 0.05%~0.09%; Cr: 0.04%~0.15%; Si: 0.3%~0.6%; Mn: 1.5%~1.8%; P≤0.02%; S≤0.005%; Alt: 0.03%~0.07%; N≤0.005%; Nb: 0.03%~0.08%; Ti: 0.012%~0.03%; B: 0.004~0.007%; the rest is Fe.

8. A method for processing and manufacturing hot-formed steel, characterized in that: The following steps are involved: The hot-rolled steel strip is prepared according to the processing and manufacturing method of the hot-rolled steel strip according to any one of claims 1 to 7; The hot rolled strip is sequentially subjected to one or more of the following processes: pickling, cold rolling, annealing, coating, and stamping and hot forming.

9. A method for detecting local martensitic transformation of hot rolled strip steel produced by the processing and manufacturing method according to any one of claims 1 to 7, characterized in that: The following steps are involved: The hot-rolled steel strip is prepared according to the processing and manufacturing method of the hot-rolled steel strip according to any one of claims 1 to 7; Observe whether there are local black spots on the surface of the hot-rolled strip after it leaves the laminar cooling section. If there are local black spots, the hot-rolled strip undergoes local martensitic phase transformation. If there are no local black spots, the hot-rolled strip does not undergo local martensitic phase transformation.

10. A hot rolled strip processing and manufacturing device, characterized in that: It includes a hot-rolled strip shape module, which is used to control the shape of the hot-rolled strip; Among them, the hot-rolled strip shape module further includes a wave shape and amplitude automatic determination system and an alarm system. The wave shape and amplitude automatic determination system can automatically identify the wave shape and wave shape amplitude of the hot-rolled strip, and the alarm system can make an alarm reminder based on the wave shape and wave shape amplitude identified by the wave shape and wave shape amplitude automatic determination system. If the wave shape identified by the wave shape and amplitude automatic determination system is a middle wave and / or a rib wave, the alarm system will make an alarm reminder; if the wave shape identified by the wave shape and amplitude automatic determination system is an edge wave and the wave shape amplitude is outside the range of -25I to 150I, the alarm system will make an alarm reminder; no alarm reminder will be made in other cases.