CN107597845B - Endless continuous casting and rolling ultra-deep drawing ultra-low carbon steel coil ferrite rolling method and device - Google Patents

Abstract

The invention provides a ferrite rolling method and device for ultra-low carbon steel coils for ultra-deep drawing of endless continuous casting and rolling, and belongs to the field of metallurgical steel rolling. The process of the invention comprises continuous casting and blank forming, high-pressure water descaling, rough rolling by a rough rolling unit, quick cooling (phase change control), high-pressure water descaling, ferrite rolling by a finishing rolling unit (purging water between frames), cooling by a layer cooling device, high-speed flying shear coil separation and coiling by a coiling machine. The invention solves the problems of high heating temperature of a heating furnace before rough rolling in the conventional hot rolling process, long cooling time to be heated between rough rolling in an austenite region and finish rolling in a ferrite region, and the problems of difficult stable control of finish rolling temperature, steel coil surface quality and forming performance in the thin slab continuous casting and rolling process represented by CSP, and the like, has the advantages of compact arrangement, less investment, high production efficiency, safety, reliability, energy conservation, environmental protection, cost reduction and the like, and realizes the production of ultra-low carbon steel coil for ultra-deep drawing by endless continuous casting and continuous rolling and ferrite rolling.

Description

Ferrite rolling method and device for ultra-low carbon steel coils for endless continuous casting and rolling for ultra-deep drawing

technical field

The invention belongs to the technical field of metallurgical steel rolling, and in particular provides a ferrite rolling method and device for producing ultra-low carbon steel coils for ultra-deep drawing by endless continuous casting and rolling.

Background technique

Thin slab continuous casting and rolling technology is a new technology that appeared in the late 1980s. Mainly include the CSP process of German SMS company, which adopts roller hearth furnace for heating, soaking and heat preservation, and the CPR process cooperated with German Thyssen factory can realize semi-endless rolling; the ISP process of German MDS company, the intermediate billet is heated by induction and hot coil box-type soaking, which can realize semi-endless rolling; the FTSR process of Italian Danieli company has liquid core reduction technology, which is heated and kept in a roller hearth tunnel furnace and then rough rolled. There are thermal insulation roller tables; Japan’s Sumitomo Metal’s QSP process, the continuous casting slab is heated by a roller hearth furnace; VAI’s CONROLL process has an induction edge heater and a roller hearth soaking furnace; Italy’s Arvedi company’s ESP process , Continuous casting includes liquid core reduction, soft reduction, etc., and induction heating is used between finishing and rough rolling. It is the world's first thin slab endless continuous casting and rolling production line. "A strip steel production process—ESP" (Lv Kunyong, Chinese patent, 200510057404.5) proposes a new ESP process: continuous casting machine (liquid core pressing)→swing shearing and splitting→heating furnace→descaler→rough rolling mill→ Descaling→finishing rolling unit→laminar cooling→coiler. The BCT process of SMS company in Germany is directly rolled after continuous casting, and can continuously cast 15mm thick non-finished steel strips, but this technology is not mature, and is currently used for HSD steels with high manganese, silicon and aluminum content. The conventional semi-continuous hot rolling process uses a single slab to be rolled, and the slab is heated, soaked and kept warm in a roller hearth furnace, and a hot coil box is required for the production of thin-gauge products. At present, continuous casting and rolling of thin slabs is the main production method to obtain thin and ultra-thin hot-rolled sheets, but the difficulty in controlling the shape and surface quality is the main factor restricting its development to thinner and higher quality requirements.

Endless rolling and semi-endless rolling technologies are new steel plate rolling technologies that have emerged in recent years that can reduce energy consumption, improve efficiency, and reduce costs. Endless rolling is mainly used in the production of hot-rolled strip steel and rods and wires, and semi-endless rolling is mainly used in the production of thin slab continuous casting and rolling. The first full continuous endless rolling hot strip rolling machine was put into use in Chiba Works of JFE Company in Japan in 1996. The induction heating connection method adopted for the intermediate billet can increase the yield compared with conventional hot rolling. 1%-2%, the roll consumption is reduced by 1%-2%. Subsequently, Japan's Nippon Steel and South Korea's Posco carried out endless rolling transformations for their hot continuous rolling. At present, the existing connecting methods for the intermediate billet after rough rolling mainly include the overlapping rolling connection method, thermite welding connection method, direct energization connection method, induction heating connection method, laser heating connection method, mechanical shearing + pressing connection method, etc. . "Connection method of hot-rolled strip endless rolling intermediate billet" (Kang Yonglin, Chinese patent, 201010289783.1) proposes a connection method of intermediate billet through cutting head and tail-pressing teeth-lapping-pressing. Alvedi built the world's first endless continuous casting and rolling production line ESP in 2009. Compared with conventional hot rolling, the energy consumption can be increased by 40%-75%, and the production efficiency can be increased by 25%-30%. At present, there are no relevant reports on the ferrite rolling method and device for endless continuous casting and rolling in the world.

The ferrite rolling process (also known as warm rolling, Warm Rolling) was developed by the Belgian Iron and Steel Research Center in the late 1980s, with the aim of producing a cheap, soft steel that can be used directly or for subsequent cold rolling production. , Non-aging hot-rolled sheet, which has attracted widespread attention and research from scholars from all over the world. Due to the large range of ferrite zone and high temperature of ultra-low carbon steel (carbon content <0.01%), the current ferrite rolling process is mainly used in the production of IF steel. "Method and device for producing ferritic rolled steel strip" (Andre Bodin, Chinese patent, 98811974.9) proposes a process suitable for low carbon steel and IF steel: continuous casting→tunnel furnace heating→shearing Cutting into slab sections→rough rolling by rough rolling unit→forced cooling by forced cooling device→storage in uncoil box→shearing→descaling→finish rolling→cooling/heating→shearing→coiling. "Production equipment for hot-rolled strip in ferrite zone and production process for ferrite strip" (W Rode, German patent, 19531538.3; Chinese patent, 96112270.6) proposes a process suitable for low-carbon steel: continuous casting →heating→rough rolling→finish rolling→cooling→(coil)→thin strip mill→coil. "Ferritic rolling method of interstitial-free steel on traditional hot rolling mill" (Mu Hailing, Chinese patent, 200810122770.8) proposes a rolling method of IF steel: heating furnace → descaling → rough rolling → descaling Scaling → reversible rough rolling → hot coil box → descaling → finishing rolling → laminar cooling → coiler. "A heating method for ferritic rolling of IF steel" (Gao Yue, Chinese patent, 201611036820.1) proposes a method for improving the quality of finished products of ferritic rolling IF steel through segmental temperature control of the heating furnace. "Ferrite zone rolling temperature control system" (Xu Rongchang, Chinese patent, 201010548338.2) proposes to realize ferrite zone rolling on conventional hot rolling production line by adding temperature sensor and billet rolling temperature control system. "Thin slab continuous casting and rolling ferritic rolling process" (Chen Yuguang, Chinese patent, 201310723913.1) proposes a rolling temperature control method for ≤2mm thin plates, the heating temperature is 1100°C-1300°C, and the finish rolling temperature is 600°C-700°C ℃. "A method for producing low-carbon steel using ferrite rolling process in CSP production line" (Du Xiufeng, Chinese patent, 201610759108.8) proposes a process suitable for low-carbon steel: continuous casting → heating → descaling → rolling →Laminar flow cooling→coiling, the billet exit temperature is 1020°C-1080°C, and the thickness of the finished product is 2mm-6mm. "A method for rolling IF ferrite on a semi-continuous rolling production line" (Wang Jiangong, Chinese patent, 201611044089.7) proposes a method of placing steel before the last pass of rough rolling R2 or before entering the finish rolling line. Reduce the slab temperature to ensure that the finish rolling temperature is controlled to the ferrite temperature range. "Finish rolling control method and device for a ferritic rolling process" (Wang Jiangong, Chinese patent, 201611059348.3) proposed a method of controlling the deviation of rolling parameters through model self-learning to ensure the quality of ferritic steel. The document "Research on Ferritic Rolling Low Carbon Steel Plate Process of FTSR Production Line" (Li Yiwei, Proceedings of the Tenth Annual Conference of China Association for Science and Technology (4): 1172-1176; Proceedings of 2008 National Steel Rolling Production Technology Conference: 111-114) proposed The process route is: continuous casting→soaking furnace→1880mm rolling mill (rough rolling→quick cooling→finish rolling)→laminar cooling→coiling→cold rolling→recrystallization annealing, and the coiling temperature is ≥700℃. "Ultra-deep drawing interstitial-free steel and its production method" (Qiu Musheng, Chinese patent, 201610077093.7) proposed P, Ti, B-treated ultra-deep drawing interstitial-free steel and its method. The process is slab heating→rough rolling→finishing Rolling → coiling → pickling → cold rolling → continuous annealing → skin pass. "A production method for hot continuous rolling pickling steel strip for ultra-deep drawing" (Wang Chuangwei, Chinese patent, 201610979358.2) proposed the use of low C+low Cr+micro-Ti alloying treatment technology, coupled with low-temperature coiling control technology, production The method of hot continuous rolling pickled steel strip for ultra-deep drawing with high surface quality can solve the problem of cross-bending. "An ultra-deep drawn steel plate" (Hua Zhaohong, Chinese patent, 201210436021.9) proposes an ultra-deep drawn steel plate with a carbon content of 0.03%-0.05%. "Technology and related production lines for manufacturing pressed or deep-drawn finished products directly from continuous cast and rolled ultra-thin hot-rolled strips" (Giovini Arvedi, Chinese patent, 99811611.4) proposed a new process of hot rolling + pickling + cold rolling and production line. The literature "Practice of rolling IF steel in the ferritic zone" (Gao Honggang, Physical and Chemical Testing-Physical Volume, 2017, Vol. 53, No. 8: 577-579) carried out ferritic zone rolling in the thin slab continuous casting and rolling production line. Rolling trial production, it is considered that the iron oxide scale defect caused by poor descaling of hot rolling is the main problem restricting its mass production.

The above various ferrite rolling methods and thin slab continuous casting and rolling technologies have their own characteristics, but because they are restricted by the existing conventional hot rolling production line and thin slab continuous casting and rolling production line, they also have their own shortcomings. , especially before rough rolling, heating in the heating furnace, storage of hot coil box before finishing rolling or swinging of steel before finishing rolling, induction heating before finishing rolling, cold rolling, finishing or annealing after hot rolling, and hot coil surface Difficult to control the quality. At the same time, the single-block or semi-endless rolling technology is basically adopted. Even if it is transformed into endless rolling by adding intermediate billet connecting devices, there are still difficulties in controlling the process temperature, low production efficiency, and energy consumption required for heating. High, large investment and other issues. In order to reduce production costs and achieve stable, continuous and reliable industrial production, scholars, researchers and industries from various countries are still working hard and exploring, trying to find new ferrite rolling technology and devices. At the same time, judging from the current pressure of China's environmental protection and steel production capacity release, it is still necessary to propose a new thin slab ferrite rolling method and device to simplify the process, reduce costs, improve efficiency, etc., and promote endless continuous casting and rolling. Industrial application of ferritic rolling.

In addition, there is a large market demand for thin-gauge ultra-low carbon steel for ultra-deep drawing grades, which require lower strength, higher elongation, and small aging. At the same time, high The surface quality of the thin-gauge finishing plate, so IF cold-rolled plate is basically used at present. Studies have shown that conventional hot-rolled thin specifications can cover about 13%-25% of current cold-rolled sheets, and the annual demand for "replacing cold with heat" in my country is about 10-15 million tons. With the advancement of process technology, the use of hot rolling process to replace the traditional hot rolling + cold rolling process to produce ultra-deep drawing steel, to realize "cooling with hot zone" has become a new development direction for ultra-low carbon steel product development and process development; at the same time, the hot coil It can also be used as a high-quality cold rolling base material, which can reduce the number of cold rolling and improve the formability of the steel strip after cold rolling, and meet the requirements of ultra-ultra-deep drawing and ultra-deep drawing cold-rolled sheets.

Contents of the invention

The purpose of the present invention is to solve the existing problems of complex technological process, low production efficiency, high energy consumption, high cost, low yield and difficult control of performance stability in the existing production method and device for ultra-low carbon steel coils for ultra-deep drawing. Provided are a ferrite rolling method and device for producing ultra-low carbon steel coils for ultra-deep drawing by endless continuous casting and rolling. This device innovates the traditional continuous casting and rolling technology, and adopts the endless continuous casting and rolling process, which reduces the slab division process of conventional continuous casting flame cutting into slab segments, the slab heating process during conventional rolling, and the heating process before finishing rolling. Coiling box process or pendulum steel process, at the same time, only one head and tail cutting is carried out in the whole pouring time, which saves the cutting loss of continuous casting, the oxidation burning loss of heating furnace, the fuel and energy consumption of heating furnace, etc., and significantly reduces the cutting head and the loss of cutting tail, which improves the output and yield; adopts thin slab technology and continuous casting high casting speed technology, and at the same time compensates for the output change caused by thickness reduction through the increase of casting speed, and reduces the thickness of the slab through thinning. The rolling pass improves the production efficiency and output; the ferrite rolling technology is adopted, and the rough rolling is controlled in the austenite temperature zone of 1150°C-1050°C where the rolling stress is low, so that coarse austenite can be obtained. The ferrite grains and internal quality are improved, and the finishing rolling is controlled in the ferrite region of 880°C-730°C where the rolling stress is low, which can avoid the mixed crystal phenomenon that may be caused by rolling in the two-phase region. Harmful effects; the phase transformation is controlled by the rapid cooling device, and the transformation from austenite to ferrite is realized, and at the same time, the finishing temperature is ensured to achieve ferrite rolling, and water cooling or vapor mist cooling can be used; cooling by layer cooling device It is to ensure that the coiling temperature hits and the stability of product quality is ensured; coiling adopts a lower temperature of 730°C-600°C to obtain AlN and cementite of appropriate size, which is beneficial to obtain more {111} textures and improve n value and r value, to meet the ultra-deep drawing performance, to realize the omission of subsequent cold rolling and other processes, or to provide high-quality cold rolling base material. The purpose of high-speed flying shear is to obtain the required single roll weight. The purpose of descaling with high-pressure water before rough rolling and finishing rolling is to obtain good surface quality of hot coils. At the same time, the use of purge water between finishing stands can eliminate the influence of scale and residual water on the surface quality of hot coils; in addition, the finishing rolling unit Lubricated rolling can also reduce rolling pressure and improve the surface quality of hot coils. Nitrogen and oxygen control ultra-low carbon steel alloyed with Nb, Ti, Al, etc. is used to reduce the content of solid solution C and N as much as possible, reduce the aging phenomenon, and facilitate the realization of hot coils for thin gauge ultra-deep drawing that are cooled by hot strips. Mass production or high-quality base materials for ultra-ultra-deep drawing and ultra-deep drawing cold-rolled sheets.

The chemical composition and mass percentage of the ultra-low carbon steel provided by the present invention are: C≤0.007%, Si≤0.05%, Mn≤0.25%, Nb≤0.050%, Ti≤0.070%, Als: 0.010-0.060%, P ≤0.015%, S≤0.010%, N≤0.005%, O≤0.0035%, and the rest are Fe and unavoidable impurities.

The role and mechanism of the main alloying elements:

C: It will increase the strength and hardness of the steel and reduce the plasticity. For ultra-deep drawing steel, low yield strength and high elongation are required. With the increase of solid solution carbon content in the steel, the {111} texture density decreases, and the product aging problem is obvious, so the smaller the carbon content is required The better, but at the same time it will increase the cost of steelmaking; carbon seriously affects the deep drawing performance of Ti-IF steel, and must be removed as much as possible. For the residual C in the steel, it is fixed by adding Ti and Nb.

Nb: Partially dissolves into solid solution, plays a role of solid solution strengthening, and significantly improves the hardenability of steel when dissolved into austenite. However, when it exists in the form of carbide and oxide particles, it has a strong fine-grain strengthening effect and reduces the hardenability of steel, which can improve the impact toughness of steel and reduce its brittle transition temperature; trace niobium can be used without affecting the plasticity or In the case of toughness, the strength of steel is improved. When the content is more than 8 times that of carbon, almost all the carbon in the steel can be fixed, so that the steel has good ultra-deep drawing performance.

Ti: Titanium has a very strong affinity with nitrogen, oxygen, and carbon, and its affinity with sulfur is stronger than that of iron. It is a good deoxidizing and degassing agent and an effective element for fixing nitrogen and carbon, which can eliminate the aging phenomenon of steel and make it Steel has good deep drawing performance; titanium is also a strong ferrite forming element, which strongly increases the A1 and A3 temperature of steel, increases the ferrite rolling temperature, and is beneficial to the control of rolling temperature.

Al: The main function of aluminum in steel is to refine grains, fix nitrogen in steel, and act as a strong deoxidizer, thereby significantly improving the impact toughness of steel and reducing the tendency of cold embrittlement and aging. The AlN precipitation size has a great influence on the ultra-deep drawing performance.

N: With the increase of nitrogen content, the strength of the steel can be significantly improved, and the plasticity, especially the toughness, will also be significantly reduced; at the same time, the aging tendency, cold brittleness and hot brittleness will be increased, and the welding performance, deep drawing performance and cold bending performance of the steel will be damaged. Therefore, the nitrogen content in steel should be minimized and limited.

O: It is a harmful element in steel and needs to be strictly controlled. During the solidification of molten steel, oxygen and carbon in the solution react to form carbon monoxide, which forms air bubbles and causes cold-rolled voids. Oxygen mainly exists in the form of FeO, MnO, SiO2, Al2O3 and other inclusions in steel, which reduces the strength and plasticity of steel, especially has a serious impact on fatigue strength, impact toughness and deep drawing performance. Therefore, the oxygen content in steel should be minimized and limited.

The technological process of the production line provided by the present invention is: continuous casting into billets→high-pressure water descaling→rough rolling in the roughing mill unit→rapid cooling (control phase transformation)→high-pressure water descaling→ferrite rolling in the finishing mill mill (between stands Purge water) → layer cooling device cooling → high-speed flying shear splitting → coiler coiling.

The invention provides an ultra-low carbon steel coil ferrite rolling device for endless continuous casting and rolling ultra-deep drawing, which mainly consists of a slab continuous casting machine 1, a high-pressure water descaling device 2, a rough rolling unit 3, and a rapid cooling Device 4, rolling shear 5, high-pressure water descaling device 2 6, finishing mill 7 (supporting purge water device 8), interlayer cooling device 9, high-speed flying shear 10, coiler 11, and each component is arranged in order .

Its specific process steps:

1) According to the chemical composition and mass percentage of ultra-low carbon steel: C≤0.007%, Si≤0.05%, Mn≤0.25%, Nb≤0.050%, Ti≤0.070%, Als: 0.010—0.060%, P≤ 0.015%, S≤0.010%, N≤0.005%, O≤0.0035%, the rest is Fe and unavoidable impurities for smelting.

2) Cast billets in the continuous casting machine, the temperature target of the continuous casting ladle is 1570°C, rapid solidification prevents grain growth and center segregation, improves density and homogenization; continuous casting casting speed 4m/min-7m/min , The thickness of the slab is 70mm-130mm.

3) Send directly to the rough rolling unit for rough rolling. The rough rolling temperature is controlled in the austenite temperature zone of 1150°C-1050°C. The rough rolling unit preferably has 2 stands, and the thickness of the intermediate billet after rough rolling is 6mm-25mm.

4) The phase transformation of the intermediate billet is controlled by a rapid cooling device, the cooling rate is 7°C/s-40°C/s, and strong cooling methods such as water cooling or steam mist cooling can be used; at the same time, the finishing rolling temperature can be ensured to achieve rolling in the ferrite zone. And reduce the rolling pressure to avoid the mixed crystal phenomenon that may be caused by rolling in the two-phase region.

5) Rolling shearing head, using rolling shears to cut the first billet of the pouring time, except for the division of the slab in emergency situations, the cutting operation will not be performed until the end of the entire pouring time, to achieve seamless head rolling.

6) High-pressure water descaling, in order to ensure the descaling effect, the descaling water pressure is ≥ 26MPa to ensure that the surface of the intermediate billet is clean before finishing rolling. quality.

7) Finish rolling in the finishing rolling unit, the finishing rolling temperature is controlled in the ferrite zone of 880°C-730°C, the rolling force is reduced, and the structure and performance are optimized. After the end, the thickness of the finished product is 0.6mm-4mm.

8) Cooling by the layer cooling device, the cooling rate is ≤40°C/s, and the front section, back section and subsection cooling mode can be used to ensure that the coiling temperature hits, which is conducive to the formation of precipitates of appropriate size.

9) High-speed flying shears are divided into coils. In order to ensure the belt threading effect of the layer cooling section, the high-speed flying shears are installed after the layer cooling and before coiling; due to the use of endless rolling technology, the coils are cut according to the coil weight requirements.

10) Coiling by the coiler to realize the recovery and growth of ferrite by using the waste heat after rolling, and obtain AlN and cementite of appropriate size. The coiling temperature is controlled at 730°C-600°C, and then natural cooling or Slow cooling to room temperature is beneficial to improve formability.

11) The performance of the produced ultra-low carbon steel coil meets the requirements of ultra-deep drawing, the tensile strength is 270MPa-380MPa, the elongation is ≥40%, the n value is 0.20-0.25, and the r value is 2.0-3.3.

The effect and mechanism of main technique among the present invention:

Adopting thin slab continuous casting and rolling technology, rolling directly after continuous casting, compact structure, short production line and low investment; adopting endless rolling technology, reducing head and tail cutting losses, improving production efficiency and output, and reducing production costs Cost: Ferrite rolling technology is adopted to effectively reduce the rolling pressure of the rolling mill, improve the structure and formability, save energy and reduce production costs.

Compared with the prior art, the present invention has the following advantages:

1) The nitrogen-controlled oxygen-controlled ultra-low carbon steel alloyed with Nb, Ti, Al, etc. is used to improve the structure, reduce the aging phenomenon of hot coils, and meet the performance requirements of ultra-deep drawing.

2) No roller hearth heating furnace or induction heating furnace is used to heat the slab before rough rolling, which reduces oxidation burning loss, heating furnace fuel and energy consumption, and equipment investment, and improves metal yield and finished product rate, reducing energy consumption and investment.

3) Through the endless rolling technology, the burning loss of continuous casting flame cutting is omitted, the head cutting rate and tail cutting rate are reduced, the rolling process is more stable, and the uniformity of temperature and structure is improved; the continuous casting and rolling technology is adopted, Increase the casting speed, reduce the number of rolling passes and descaling, reduce the number of sampling and inspection, and significantly improve the yield, production efficiency and output.

4) Rough rolling adopts austenitic rolling technology, and finishing rolling adopts ferrite zone rolling technology, which reduces rolling pressure, improves microstructure, and improves formability; and adopts rapid cooling device to control phase transformation and combine with Layer cooling ensures the accuracy of the temperature control of finishing rolling and coiling, reduces the processing time of pendulum steel or hot coil box process, and improves the efficiency.

5) Coiling adopts a higher temperature of 730°C-600°C, which can eliminate the adverse effect of deformation on texture orientation, improve the n value and r value, and meet the performance requirements of ultra-deep drawing; at the same time, subsequent annealing, cold rolling, etc. Processing, to achieve industrial production with hot and cold, or to provide high-quality base materials for ultra-ultra-deep drawing and ultra-deep drawing cold-rolled sheets.

Description of drawings

Fig. 1 is a production line flow chart of a ferrite rolling method for ultra-low carbon steel coils for endless continuous casting and rolling for ultra-deep drawing. In the figure: slab continuous casting machine 1, high-pressure water descaling device 1 2, rough rolling unit 3, rapid cooling device 4, rolling shear 5, high-pressure water descaling device 2 6, finishing rolling unit 7 (supporting purge water device 8), layer cooling device 9, high-speed flying shear 10, coiler 11.

Fig. 2 is a temperature distribution diagram of a production line of an ultra-low carbon steel coil ferrite rolling method for endless continuous casting and rolling for ultra-deep drawing.

Fig. 3 is a production line thickness distribution diagram of an ultra-low carbon steel coil ferrite rolling method for endless continuous casting and rolling ultra-deep drawing.

Detailed ways

Example 1:

According to the chemical composition and mass percentage of ultra-low carbon steel: C: 0.007%, Si: 0.05%, Mn: 0.25%, Nb: 0.003%, Ti: 0.070%, Als: 0.045%, P: 0.015%, S : 0.010%, N: 0.005%, O: 0.0035%, and the rest is Fe and unavoidable impurities for smelting. The slab is cast in a continuous casting machine, the temperature of the continuous casting ladle is 1560°C, the casting speed is 4m/min, and the thickness of the slab is 130mm. It is directly sent to the rough rolling unit for rough rolling. The rough rolling temperature is 1100°C-1050°C. After rough rolling, the thickness of the intermediate billet is 25mm. The intermediate billet enters the cooling channel to control the temperature, the cooling speed is 38°C/s, the rolling shear head is descaled by high-pressure water, the descaling water pressure is 30MPa, the finishing rolling unit is finishing rolling, the purge water between the stands is put into use, and the finishing rolling temperature Controlled at 800°C-730°C, lubricated rolling can be used in the last 3 passes, and the thickness of the finished product is 4mm. The layer cooling device cools, the cooling speed is 40°C/s, the high-speed flying shear is divided into coils according to the coil weight, the coiling temperature is controlled at 600°C, and then natural cooling or slow cooling to room temperature can be used. The performance meets the requirements of deep drawing, the tensile strength is 375MPa, the elongation is 40%, the n value is 0.21, and the r value is 2.1.

Example 2:

According to the chemical composition and mass percentage of ultra-low carbon steel: C: 0.005%, Si: 0.03%, Mn: 0.18%, Nb: 0.020%, Ti: 0.050%, Als: 0.060%, P: 0.010%, S : 0.008%, N: 0.004%, O: 0.0030%, and the rest is Fe and unavoidable impurities for smelting. The slab is cast in a continuous casting machine, the temperature of the continuous casting ladle is 1563°C, the casting speed is 5m/min, and the thickness of the slab is 110mm. It is directly sent to the rough rolling unit for rough rolling. The rough rolling temperature is 1110°C-1060°C. After rough rolling, the thickness of the intermediate billet is 18mm. The intermediate billet enters the cooling channel to control the temperature, the cooling speed is 27℃/s, the rolling shear head is descaled by high-pressure water, the descaling water pressure is 28MPa, the finishing rolling unit is finishing rolling, the purge water between the stands is put into use, and the finishing rolling temperature Controlled at 830°C-750°C, lubricated rolling can be used in the last 3 passes, and the thickness of the finished product is 2.8mm. The layer cooling device cools, the cooling speed is 30°C/s, the high-speed flying shear is divided into coils according to the coil weight, the coiling temperature is controlled at 650°C, and then natural cooling or slow cooling to room temperature can be used. The performance meets the requirements of deep drawing, the tensile strength is 345MPa, the elongation is 43%, the n value is 0.20, and the r value is 2.5.

Example 3:

According to the chemical composition and mass percentage of ultra-low carbon steel: C: 0.003%, Si: 0.02%, Mn: 0.12%, Nb: 0.035%, Ti: 0.030%, Als: 0.025%, P: 0.012%, S : 0.005%, N: 0.0035%, O: 0.0020%, and the rest is Fe and unavoidable impurities for smelting. The slab is cast in a continuous casting machine, the temperature of the continuous casting ladle is 1570°C, the casting speed is 6m/min, and the thickness of the slab is 90mm. It is directly sent to the rough rolling unit for rough rolling. The rough rolling temperature is 1130°C-1070°C. After rough rolling, the thickness of the intermediate billet is 11mm. The intermediate billet enters the cooling channel to control the temperature, the cooling speed is 15°C/s, the rolling shear head is descaled by high-pressure water, the descaling water pressure is 30MPa, the finishing rolling unit is finishing rolling, the purge water between the stands is put into use, and the finishing rolling temperature Controlled at 850°C-780°C, lubricated rolling can be used in the last two passes, and the thickness of the finished product is 1.5mm. The layer cooling device cools, the cooling speed is 18°C/s, the high-speed flying shear is divided into coils according to the coil weight, the coiling temperature is controlled at 690°C, and then natural cooling or slow cooling to room temperature can be used. The performance meets the requirements of deep drawing, the tensile strength is 300MPa, the elongation is 46%, the n value is 0.23, and the r value is 2.9.

Example 4:

According to the chemical composition and mass percentage of ultra-low carbon steel: C: 0.001%, Si: 0.01%, Mn: 0.06%, Nb: 0.050%, Ti: 0.005%, Als: 0.012%, P: 0.008%, S : 0.003%, N: 0.0030%, O: 0.0023%, and the rest is Fe and unavoidable impurities for smelting. The slab is cast in a continuous casting machine, the temperature of the continuous casting ladle is 1573°C, the casting speed is 7m/min, and the thickness of the slab is 70mm. It is directly sent to the rough rolling unit for rough rolling. The rough rolling temperature is 1150°C-1090°C. After rough rolling, the thickness of the intermediate billet is 6mm. The intermediate billet enters the cooling channel to control the temperature, the cooling speed is 7.5°C/s, the rolling shear head is descaled by high-pressure water, the descaling water pressure is 27MPa, the finishing rolling unit is finishing rolling, the purge water between the stands is put into use, and the finishing rolling temperature It is controlled at 880°C-810°C, and the thickness of the finished product is 0.6mm. The layer cooling device cools, the cooling speed is 15°C/s, the high-speed flying shear is divided into coils according to the coil weight, the coiling temperature is controlled at 730°C, and then natural cooling or slow cooling to room temperature can be adopted. The performance meets the requirements of deep drawing, the tensile strength is 270MPa, the elongation is 48%, the n value is 0.25, and the r value is 3.3.

Example 5:

According to the chemical composition and mass percentage of ultra-low carbon steel: C: 0.002%, Si: 0.01%, Mn: 0.10%, Nb: 0.020%, Ti: 0.035%, Als: 0.035%, P: 0.010%, S : 0.003%, N: 0.0035%, O: 0.0025%, and the rest is Fe and unavoidable impurities for smelting. The slab is cast in a continuous casting machine, the temperature of the continuous casting ladle is 1570°C, the casting speed is 5.5m/min, and the thickness of the slab is 95mm. It is directly sent to the rough rolling unit for rough rolling. The rough rolling temperature is 1140°C-1080°C. After rough rolling, the thickness of the intermediate billet is 14mm. The intermediate billet enters the cooling channel to control the temperature, the cooling speed is 10°C/s, the rolling shear head is descaled by high-pressure water, the descaling water pressure is 27MPa, the finishing rolling unit is finishing rolling, the purge water between the racks is put into use, the finishing rolling temperature It is controlled at 860°C-790°C, and the thickness of the finished product is 1.2mm. The layer cooling device cools, the cooling speed is 20°C/s, the high-speed flying shear is divided into coils according to the coil weight, the coiling temperature is controlled at 715°C, and then natural cooling or slow cooling to room temperature can be adopted. The performance meets the requirements of deep drawing, the tensile strength is 295MPa, the elongation is 43%, the n value is 0.23, and the r value is 3.1.

Claims (3)

1. A ferrite rolling method of ultralow carbon steel coil for headless continuous casting and rolling ultra-deep drawing is characterized by comprising the following steps: the ultra-low carbon steel for ultra-deep drawing comprises the following chemical components in percentage by mass: c is less than or equal to 0.007%, si is less than or equal to 0.05%, mn is less than or equal to 0.25%, nb is less than or equal to 0.003% and less than or equal to 0.050%, ti is less than or equal to 0.005% and less than or equal to 0.070%, als: 0.010-0.060 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.010 percent, N is less than or equal to 0.005 percent, O is less than or equal to 0.0035 percent, and the balance is Fe and unavoidable impurities;

the production line comprises the process flows of continuous casting and blank forming, high-pressure water descaling, rough rolling by a rough rolling unit, quick cooling, phase change control, high-pressure water descaling, ferrite rolling by a finishing rolling unit, purging water between frames, cooling by a layer cooling device, high-speed flying shear rolling separation and coiling by a coiling machine;

adopting a continuous casting and rolling technology without heads, wherein the continuous casting pulling speed is 4-8 m/min, the thickness of a plate blank is 70-130 mm, the thickness of an intermediate blank is 6-25 mm, and the thickness of a finished product is 0.6-4 mm;

the finish rolling adopts a ferrite zone rolling technology, and a roughing mill unit rolls in an austenite temperature zone of 1150-1050 ℃; rolling in ferrite region of 880-730 deg.c in finishing mill group; the rapid cooling device is used for controlling phase transformation, realizing transformation from austenite to ferrite, ensuring finish rolling temperature hit, realizing ferrite rolling, and adopting a water cooling or steam cooling forced cooling mode at a cooling speed of 7 ℃/s-40 ℃/s; the cooling of the layer cooling device is to ensure the hit of the coiling temperature, and the cooling speed is less than or equal to 40 ℃/s; the coiling temperature is 730-600 ℃, so that AlN and cementite with proper sizes can be obtained, more {111} textures can be obtained, n value and r value are improved, and the ultra-deep drawing requirement is met;

the performance of the produced ultra-low carbon steel coil for ultra-deep drawing meets the tensile strength of 270 MPa-380 MPa, the elongation is more than or equal to 40%, the n value is 0.20-0.25, and the r value is 2.0-3.3.

2. The method for rolling the ferrite of the ultralow-carbon steel coil for the headless continuous casting and rolling ultralow-depth drawing, which is characterized by comprising the following steps of: in order to obtain the hot coil with high surface quality, descaling before rough rolling and descaling before finish rolling are required, the pressure of the descaling water is more than or equal to 26MPa, and meanwhile, purging water between frames of a finishing mill is used to prevent the influence of iron scale pressing and residual water.

3. The method for rolling the ferrite of the ultralow-carbon steel coil for the headless continuous casting and rolling ultralow-depth drawing, which is characterized by comprising the following steps of: the rolling device consists of a slab continuous casting machine (1), a first high-pressure water descaling device (2), a roughing mill set (3), a rapid cooling device (4), a rolling shear (5), a second high-pressure water descaling device (6), a finishing mill set (7), a purging water device (8), a layer cooling device (9), a high-speed flying shear (10) and a coiling machine (11), wherein each finishing mill set is provided with the purging water device, and all the components are arranged in sequence.