JP2012518720A - Flexible strip processing line suitable for production of various high-strength steels - Google Patents

Abstract

  A high hydrogen jet cooling station and a water quenching cooling station are installed in parallel after the decoiling and cleaning station, heating station, soaking station, and slow cooling station, which are installed in sequence, and reheating is performed after the high hydrogen jet cooling station. Station, over-aging station, final cooling station, temper station, finish station, oiling station and winding station are provided in sequence, and pickling station and electroplating station are provided in sequence after water quenching cooling station for melting The galvanizing station is connected after the reheating station, the plating layer alloying annealing station is connected after the hot dip galvanizing station, and is connected through the connecting passage. Connected to the final cooling station, the pickling station and the electroplating station communicate with the reheating station via the connecting passage, respectively, and the electroplating station directly connects to the uncoiling and cleaning station via the connecting passage. The water quenching and cooling station communicates with the slow cooling station via a fixed bypass, and the re-heating station is followed by an overaging station via a movable bypass. According to the present invention, the production of various high-strength steels was integrated into one apparatus, and flexible production was realized.

Description

TECHNICAL FIELD The present invention relates to a steel strip heat treatment and surface treatment technology, and more particularly to a flexible production line suitable for production of various high-strength steels.

Protecting the background technology environment and achieving sustainable development has become a common consensus for mankind in the 21st century. With the development of modern automobile industry, energy saving by light weight has already been on the trend. According to the research results of vehicle weight reduction, in order to achieve the objective of “energy saving and emission reduction by light weight”, high-strength steel must be extensively used in the automobile industry to reduce the thickness of the steel sheet. Therefore, the needs for high-strength cold-rolled plates and hot-dip galvanized plates are greatly increasing.

  When producing high-strength cold-rolled sheets with continuous annealing equipment equipped with a rapid cooling device, continuous annealing equipment is used for water quenching, aerosol cooling, and so on in order to achieve strength of 980 MPa or higher and excellent post-processing performance. It must be equipped with emergency equipment such as high hydrogen jet cooling. The main process of the continuous annealing is as follows.

  Uncoiling-Washing-Heating-Soaking-Slow cooling-Rapid cooling-(Pickling)-(Reheating)-Overaging (Tempering)-Cooling-Temper-Finish-High strength cold rolled sheet.

  In the continuous annealing process, the cold-rolled steel strip that has undergone uncoiling and cleaning is heated to a certain temperature, kept warm for a while, gradually cooled to a certain temperature, and then rapidly cooled to room temperature or overaging temperature in a quenching device. Cooling.

  Water quenching cooling is currently the fastest cooling method and an inexpensive method for producing high strength steel. By adding a small amount of alloying elements, it is also possible to produce high-strength steels with high strength levels of duplex, multiphase and martensite. In this method, since an oxide film layer is formed on the surface of the steel strip during water cooling, it is necessary to add pickling. And when water quenching cooling is adopted, it is difficult to finish the cooling at the overaging temperature, and the steel strip must be cooled to 100 ° C or less, so that the aging stability of the steel strip is secured. In addition, it is necessary to reheat the steel to the tempering temperature and temper it.

  When adopting the high hydrogen jet cooling method as a continuous annealing process, the cooling end temperature is easy to control, it is not necessary to cool the steel strip to room temperature, and oxidation does not occur, so without pickling the steel strip, Overaging can be started directly, or overheating can be started by reheating. However, since the cooling rate in the high hydrogen jet cooling method is slower than that in the water quenching cooling method, the strength level of the cold-rolled sheet produced by the high hydrogen jet cooling method is the water quenching cooling under the precondition that the same alloy element is added. Much lower than in the case of the method.

  When producing high-strength hot-dip galvanized plates with a continuous hot-dip galvanizing device equipped with a rapid cooling device, in order to improve the strength of the base material as much as possible and to ensure hot-dip galvanizing properties, a continuous hot-dip galvanizing device Must be equipped with high hydrogen quenching equipment, water quenching or aerosol cooling and pickling equipment. The main processes of the continuous hot dip galvanizing are as follows.

  Uncoiling-Cleaning-Heating-Soaking-Slow cooling-Rapid cooling-(Pickling)-(Reheating)-Hot dip galvanizing (or including plating layer alloying annealing furnace)-Cooling-Temper-Finish-High strength melting Galvanized plate.

  In the continuous hot dip galvanizing process, the cold rolled steel strip that has undergone uncoiling and cleaning is heated to a certain soaking temperature, kept warm for a while, gradually cooled to a certain temperature, and then the steel strip is rapidly cooled in a quenching device. Cool to near the zinc pot temperature or room temperature. The steel strip after water quenching is further washed with acid pickling to remove the oxide film on the surface of the steel strip, reheated, enters the zinc pot, undergoes hot dip galvanization and / or plating layer alloying annealing, and finally It is necessary to enter a post-processing step such as tempering after cooling.

  The hot dip galvanizing treatment of the strip steel must be completed at about 460 ° C, and the plating layer alloying annealing treatment after the hot dip galvanizing must be completed at about 500 ° C. Therefore, when a high-strength hot-dip galvanized plate is produced in a conventional continuous hot-dip galvanizing line, it is necessary to put a large amount of alloy elements in the base material. However, in this case, alloy elements such as Mn and Si are collected on the surface of the steel plate before galvanization, so that a hot dip galvanized plate and a plated layer alloyed hot dip galvanized plate with good surface quality are obtained. It becomes impossible. Therefore, by adopting the process of water quenching cooling + pickling + reheating + hot dip galvanization (or including plating layer alloying annealing), the steel steel strength level is greatly improved and the steel strip is pickled. The alloy elements collected on the surface of the steel can be washed away, and a high-strength hot-dip galvanized plate and a plated layer alloyed hot-dip galvanized plate having good surface quality can be secured.

  When adopting the high hydrogen quenching process, the steel strip is not pickled but directly put into a zinc pot for hot dip galvanization (or including plating layer alloying annealing) or reheated to melt. Zinc plating (or plating layer alloying annealing) is performed, and then, after cooling, it can enter a post-treatment process such as a temper. However, when such a process is employed, a large amount of alloy elements cannot be added in order to ensure plating properties, so that the strength level of the finished product is low under the same chemical composition conditions. Therefore, compared with the case of water quenching cooling, the strength level of the hot dip galvanized plate and the plated layer alloyed hot dip galvanized plate produced within a certain range of alloy components is low.

  As described above, in the process of producing high-strength cold-rolled sheets and hot-dip galvanized sheets, the substrate inlet cleaning device, the heating and soaking device for annealing, the rapid cooling and related devices (for example, water quenching and cooling) Since the structures of the pickling and reheating equipment, etc., the temper at the outlet, and the oiling and winding equipment are basically the same, the production of high-strength cold-rolled sheets and hot-dip galvanized sheets is integrated into one device. can do. More importantly, the market demand for high-strength cold-rolled sheets and hot-dip galvanized sheets is not so large, so when building a production line for high-strength cold-rolled sheets and a production line for high-strength hot-dip galvanized sheets, While the investment cost is greatly increased, the production performed by the two devices is both unsaturated, and the device that produces high-strength steel plates, especially ultra-high strength steel plates, produces high surface quality mild steel products. Can only produce ordinary low grade mild steel products with low surface quality, resulting in serious waste of resources. Therefore, the equipment in each section of the equipment is rationally arranged, research and development of switching equipment for passing through the steel sheet, high-strength and ultra-high-strength cold-rolled sheet and hot-dip galvanizing with many specifications and types The integration of plate production into the same equipment is gaining more and more attention in the steel industry.

  Japanese Unexamined Patent Publication No. 2003-253413 provided a combined manufacturing facility and a combined manufacturing method for a high-strength cold-rolled steel sheet and a galvanized steel sheet. In this method, a steel sheet from an annealing furnace having a heating section, a soaking section, and a jet cooling section is supplied to a galvanizing apparatus to manufacture a galvanized steel sheet, that is, through a galvanizing path route. On the other hand, the steel sheet from the annealing furnace can be supplied to a water quenching tank without passing through a galvanizing apparatus to produce a high-strength cold-rolled steel sheet, that is, it can pass through a cold-rolled bare plate pass route.

  This patent is a combined manufacturing method for a galvanized plate and a high-strength cold-rolled plate, characterized by comprising a switching device for switching between two process routes. In order to achieve combined production of a galvanized plate and a high-strength cold-rolled plate, the following three means are employed in the method. 1. After the jet cooling section, a switching device is provided directly between the zinc pot and the water quenching tank. 2. Switching is realized by raising and lowering the sink roll in the zinc pot and water quenching tank. 3. Switching is realized by injecting molten zinc or water into the zinc plating / water quenching shared tank.

However, this patent mainly has the following drawbacks.
First, the combined manufacturing method of this patent did not adopt high hydrogen jet cooling with rapid cooling performance, water quenching and pickling process, so high-strength cold-rolled plate, hot-dip galvanized plate and alloyed hot-dip galvanized plate Not only can the plate not be produced, but also the production of cold rolled, hot dip galvanized and galvannealed plates that are strengthened by phase change at a low strength level with good surface quality.

  And because the pickling process after water quenching and the tempering process by reheating were not adopted, the high-strength cold-rolled sheet produced by the combined manufacturing method of this patent is not only poor in surface quality but also stable in plasticity and aging resistance Poor nature.

  Lastly, 2 and 3, which are the means for realizing the combined manufacturing method of this patent, are difficult to operate in actual production, and when switching between the galvanized plate and the cold rolled plate, the residual zinc on the roll surface is If the surface quality of the rolled plate and the normal operation of the apparatus are affected, and if the zinc pot and the water quenching tank are shared, unsolvable technical problems such as rupture of the zinc pot occur, and the cost of switching increases.

Inventive subject object of the present invention is to provide a flexible steel strip processing line suitable for production of various high strength steels. This processing line uses cold-rolled and hardened rolled hardened material and hot-rolled pickling plate, high-strength cold-rolled plate, pure hot-dip galvanized plate, plated layer alloyed hot-dip galvanized plate, electrogalvanized, nickel Since plated plates can be manufactured, resources can be used effectively and investment can be saved. And, by integrating the production of cold-rolled plate, hot-dip galvanized plate and alloyed hot-dip galvanized plate into one device and adopting the connection passage, it is possible to produce electric Zn, Ni-plated plate, ultra high strength level Cold rolled and galvanized plates and alloyed galvanized plates can also be produced. And, by adopting pickling process or electric Fe, Ni plating process before hot dip galvanization, the production process and equipment has the disadvantage that hot galvanizing ability of high strength steel, especially ultra high strength steel is poor Can be completely eliminated, and good surface quality of high-strength hot-dip galvanized products and alloyed hot-dip galvanized products can be guaranteed.

In order to achieve this object, the technical solution of the present invention is as follows.
A high hydrogen jet cooling station and a water quenching cooling station are provided in parallel after the sequential decoiling and cleaning station, heating station, soaking station, and slow cooling station, and reheating is performed after the high hydrogen jet cooling station. Station, over-aging station, final cooling station, temper station, finish station, oiling station and winding station are provided in sequence, pickling station and electroplating station are provided in sequence after water quenching cooling station, A hot-dip galvanizing station connected after the reheating station, and a hot-dip galvanizing station connected after the hot-dip galvanizing station and connected to the final cooling station via a connecting passage A pickling layer alloying annealing station, wherein the pickling station and the electroplating station are each connected to a reheating station through a connection passage, and the electroplating station is uncoiled through the connection passage. And the water quenching cooling station is in communication with the slow cooling station through a fixed bypass, and after the reheating station is over-aging station through a movable bypass. Is communicated, and this movable bypass is introduced when producing a continuously annealed product, while this movable bypass is used when producing a hot dip galvanized product and a plated layer alloyed hot dip galvanized product. The two joints exposed by evacuation are sealed. Various high strength steel flexible steel strip processing line suitable for production of a.

  Further, an electroplating station, a passivation and other post-treatment stations connected after the temper station and before the finish station via the connection passage are further provided.

  Further, the bypass is a sealed passage unlike the connection passage. The atmosphere in the passage and the atmosphere in the annealing furnace are basically the same, and is a mixed protective gas of nitrogen and hydrogen containing 2% to 7% hydrogen.

  Then, a high-power induction heater is disposed after the high hydrogen jet cooling section, and preferably the induction heater has a frequency of 1000 Hz or more. Compared with other patents, the treatment line of the present invention can control the heating rate after rapid cooling and does not require pickling, and can sufficiently satisfy the requirements of equipment in the manufacturing process of high-strength plates.

  Further, the high hydrogen jet cooling gas according to the present invention is a mixed gas of nitrogen and hydrogen containing hydrogen occupying a volume percentage of 20% or more.

  In a flexible steel strip processing line suitable for production of various high-strength steels of the present invention, a part of the steel strip cooled through uncoiling, cleaning, heating, soaking, slow cooling and high hydrogen jet cooling is partially over. After aging, it enters into cooling and tempering and other post-processing to become cold-rolled high-strength steel, while the other parts undergo reheating and enter into post-processing equipment such as zinc pot and plating layer alloying annealing furnace, and high strength. It becomes a hot dip galvanized plate or an alloyed hot dip galvanized plate.

  Moreover, in a flexible steel strip processing line suitable for production of various high-strength steels of the present invention, the steel strip cooled through pickling, washing, heating, soaking, slow cooling and water quenching cooling and pickling is It may enter a zinc pot through reheating and become high-strength hot-dip galvanized steel, or may directly enter an overaging section to become an ultra-high-strength cold-rolled sheet. And, after passing through the electroplating of Zn and Ni, it can be put into post-treatment such as passivation to become an ultra-high strength electrogalvanized plate, and the electroplating improves the plating performance by attaching a very thin Ni and Fe layer. After that, reheat and enter the post-process equipment such as zinc pot and plating layer alloying annealing furnace to become ultra high strength pure hot dip galvanized plate and plated layer alloyed hot dip galvanized plate Good.

  In the current cold rolling continuous heat treatment equipment, normally, high-strength plates and high-surface quality plates (for example, automobile outer plates) are produced simultaneously, but high-strength steel, especially ultra-high-strength steel and high-surface quality plates. Have completely different requirements for surface quality. In general, high-strength steel is applied to automobile structural parts, so the requirements for surface quality are not severe. On the other hand, the outer panel of an automobile requires a very high surface quality. When producing a small amount of high-strength steel, especially ultra-high-strength steel with a large-scale continuous heat treatment device, it is easy to cause lumps or local scratches or wear on the roller due to high steel plate strength and poor plate shape. As a result, it was not possible to produce high surface quality plates after producing high strength steel, and the equipment had to be stopped and damaged rollers replaced. And because the loss due to the stoppage of large-scale continuous heat treatment furnace and roller replacement is very large, it is very difficult to produce both high-strength steel sheets, especially ultra-high-strength steel sheets and high-surface quality boards with the same equipment. is there.

  In terms of specifications, in general, high surface quality plates such as automobile outer plates are wide and thin, but high strength steel plates, especially ultra high strength steel plates, are thick and narrow. . When designing a continuous heat treatment apparatus, it is necessary to consider these two products, the technical difficulty is high, the apparatus becomes complicated and large-scale, and the investment becomes very large.

  There are different requirements in terms of furnace cooling technology. In equipment that produces high surface quality plates, there is no high requirement for the cooling rate of the furnace, but there is a demand for high passage technology that is stable at high speed to prevent buckling and fracture of mild steel at high temperatures. Also, low tension and stability are necessary. On the other hand, in equipment that produces high-strength steel sheets, there is a high demand for the cooling rate in the fast cooling section of the furnace, and the thick and narrow high-strength steel sheets themselves are easily separated from the correct conveyance path, and such steel strips are rapidly cooled. After the phase transition, the plate shape becomes worse and the separation becomes more serious. Therefore, the demand for the tension in each furnace section of the apparatus is high, and the demand for the correction capability is high.

  The demands also differ in terms of temper mill. For products with high surface quality requirements, the temper is extremely important in improving and improving surface quality in addition to the purpose of controlling material properties and improving plate shape. For this reason, a large temper roller diameter and rolling force are required. However, high strength steel products have high yield strength, so if the diameter of the temper roller is too large, the rolling force of the temper mill will be greatly improved, and the energy consumption and investment of the temper mill will increase. Therefore, generally, the shape of a high-strength steel plate is improved with a small-diameter temper roller and a large temper rolling force and tension.

  In terms of switching specifications and types, high-strength steel, especially ultra-high-strength steel, has a small amount for each type and specification, but because there are many comprehensive types and specifications, switching increases when producing with continuous heat treatment equipment. , The transition time becomes longer. The stability and productivity of large continuous heat treatment equipment are greatly affected.

  The flexible steel strip processing line suitable for production of various high-strength steels in the present invention has a unique advantage and has the following prominent and prominent features and advantages as compared with the conventional heat treatment apparatus.

1. There are many types of products.
The most common continuous annealing equipment can only produce ordinary cold rolled products, while the most common continuous hot dip galvanizing equipment can produce only pure hot dip galvanized products and plated layer alloyed hot dip galvanized products. Even recently developed equipment for both continuous annealing and hot dip galvanizing can produce only two types of products, ordinary cold rolled products and hot dip galvanized products. Such a continuous annealing / hot dip galvanizing apparatus does not use a high-strength steel sheet, particularly an ultra-high-strength steel sheet as a target product, and therefore, the superiority of various products is not remarkable.

  The flexible high-strength thin steel strip processing line in the present invention is equipped with both a high-hydrogen high-speed jet cooling device and a water quenching device. Suitable for production of high strength steel plates. Not only can cold-rolled high-strength steel and ultra-high-strength steel of various strength levels (up to 1470 MPa), but also various hot-dip galvanized high-strength steels with maximum strength levels of 980 MPa can be produced. Furthermore, electrogalvanized products, electronickel plated products and electrozinc-nickel alloy products of various strength levels can be produced. In short, compared to other cold-rolled steel strip processing lines, the multi-function processing line is characterized by many functions and many varieties, and includes various types including hot-dip plated products, ordinary cold-rolled products, and electroplated products. High-strength steel products can be obtained with minimal investment and can meet various needs for various high-strength steels in the current automobile industry.

2. Production cost is low.
First, as a raw material, not only a rolled hardened material but also a hot rolled pickled plate can be used. Since the present invention is equipped with a new high-hydrogen high-speed jet cooling device and a new water quenching device, when producing high-strength steel of the same strength level, it can be produced with fewer alloy components, saving alloy elements, Production costs can be reduced. And the request | requirement with respect to each process of steelmaking, hot rolling, pickling, and cold rolling becomes low, production is advanced more stably and smoothly, and cost also correspondingly reduces. In addition, since this flexible processing line can be dedicated to the production of various high-strength steels, continuity and transition when producing various high-strength steels become more convenient. On the other hand, since it is not necessary to increase the investment in large quantities to produce a small amount of ultra-high-strength steel, other apparatuses are released and the production cost of the entire company is greatly reduced.

3. Product quality is high.
Since the processing line of the present invention is dedicated to the processing of various high-strength steel products, the quality of the product can be improved by taking more effective measures according to the needs of the production process of high-strength steel. For example, in contrast to the problem that ordinary continuous heat treatment equipment has a slow cooling rate, this equipment adopts a new high-hydrogen high-speed jet cooling and a new water quenching technology to greatly increase the cooling rate. The content of the alloy component in the chemical component of the high strength steel at the strength level can be greatly reduced, the production cost can be reduced, and the welding performance and plating performance of the high strength steel product can be remarkably improved. In addition, according to the present invention, a new technique of performing hot dipping and pickling, and thus hot dipping after electroplating is adopted, so that the plateability of high-strength steel is further fundamentally improved and high hot dip galvanizing is achieved. The surface quality and corrosion resistance of high-strength steel were significantly improved.

Brief Description of Drawings
FIG. 1 is a block diagram of a process according to the first embodiment of the present invention. FIG. 2 is a block diagram of a process according to the second embodiment of the present invention. FIG. 3 is a block diagram of a process according to the third embodiment of the present invention. FIG. 4 is a block diagram of a process according to the fourth embodiment of the present invention. FIG. 5 is a block diagram of a process according to the fifth embodiment of the present invention. FIG. 6 is a block diagram of a process according to the sixth embodiment of the present invention. FIG. 7 is a block diagram of a process according to the seventh embodiment of the present invention. FIG. 8 is a block diagram of a process according to the eighth embodiment of the present invention. FIG. 9 is a block diagram of a process according to the ninth embodiment of the present invention.

Invention based on examples and drawings EMBODIMENTS In the various high flexible steel strip processing line suitable for production of strength steel will be described (the drawings of the present invention, the solid arrows employed in the Examples Processes are shown, and dashed arrows indicate processes that can be selected for other embodiments).

Example 1
As shown in FIG. 1, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-High hydrogen jet cooling 6-Overaging 10-Final cooling 11-Temper 12-Finish 13-Oiling and post-treatment 14-Winding 15 -Finished product 16.

  The process according to the embodiment of the present invention can produce a high-strength steel cold-rolled sheet strengthened by a common cold-rolled sheet and phase transition, and in particular, cold-rolled TRIP steel and DP steel of 80 kg class or less. Fit for production. Table 1 shows the process parameters for producing 80 kg cold rolled TRIP steel and 80 kg DP steel. As shown in Table 1, in the 80 kg TRIP steel, it is important to control the soaking temperature of continuous annealing and the aging temperature and time, but the requirement for the rapid cooling rate is not high. . On the other hand, in the DP steel of 80kg class, the important process control parameters for continuous annealing are soaking temperature and quenching speed, and the demand for quenching speed is particularly high. The aging is required to be performed at a low temperature and in a short time so that the decomposition of martensite is avoided.

  In the process of this embodiment, since the pickling step and the reheating step are not necessary, the production cost of the heat treatment step is low and the surface quality of the product is high.

Example 2
As shown in FIG. 2, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-High hydrogen jet cooling 6-Reheating 9-Overaging 10-Final cooling 11-Temper 12-Finish 13-Oiling and post-treatment 14 -Winding 15-Finished product 16.

  Compared to Example 1, the process of the example in the present invention can be performed at an overaging step performed at a low temperature and then at a high temperature. According to such a process, it is possible to produce a mild steel product having excellent aging resistance characteristics with a low carbon aluminum killed steel. Table 2 shows the process parameters for producing low carbon aluminum killed steel mild steel products with excellent aging resistance. As shown in Table 2, it is important to control the soaking temperature and aging process of continuous annealing in producing low carbon aluminum killed steel with excellent aging resistance. And in order to precipitate solid carbon in steel completely, you have to implement | achieve the over aging process performed at high temperature after it is performed at low temperature. The treatment line of the present invention satisfactorily met the process requirements by reheating after quenching.

  Compared to other patents, in the treatment line of the present invention, by arranging a high-power induction heater after the high hydrogen jet cooling section, it is possible to control the heating rate after rapid cooling, without requiring pickling, It can fully meet the equipment requirements in the manufacturing process of the strength plate.

  More importantly, in the process of the embodiment of the present invention, the steel strip is once cooled to the martensite transformation point or lower, transformed to martensite and then tempered again, thereby realizing quenching and tempering, and tempering martensite structure. And the overall performance of the steel sheet can be adjusted. Thereby, compared with Example 1, the high-strength steel plate with which the balance of the intensity | strength and plasticity of a duplex stainless steel product becomes better can be produced, and the martensitic steel with low strength and high plasticity can also be produced. Table 2 also shows the parameters of the process for producing martensitic steel products. As can be seen from Table 2, the key to producing high-strength martensitic steel is to control the soaking temperature and quenching rate of continuous annealing. Among them, the rapid cooling rate and the rapid cooling end temperature are the main factors in generating sufficient martensite to ensure strength.

  Compared to normal reheating after rapid cooling, in the treatment line of the present invention, by arranging a high-power induction heater after the high hydrogen jet cooling section, the heating rate and temperature after rapid cooling can be controlled and pickling can be performed. Can be fully satisfied with the equipment requirements in the manufacturing process of high-strength steel sheets. The realization of this process is one of the features of the present invention.

Example 3
As shown in FIG. 3, the process of this example is as follows. Raw materials 1-Uncoiling and cleaning 2-Electroplating 17 (Fe or Ni electroplating)-Reheating 9-Hot dip galvanizing 18 (or plating layer alloying annealing 19)-Final cooling 11-Temper 12-Passivation 20-Finish 13 (or oiling included)-Winding 15-Finished product 16.

  In the process of the embodiment of the present invention, using a high-strength or ultra-high-strength hot-rolled pickled plate (for example, hot-rolled martensitic steel) as a raw material, plating an extremely thin Ni, Fe, etc. on its surface, Improve hot dip galvanization of high strength steel. Thereafter, the mixture is heated to 450 ° C. to 550 ° C., put in a zinc pot and hot dip galvanized (and / or plated layer alloying annealing treatment), and then cooled and enters a subsequent step such as a temper. Because the time for hot dip galvanization after reheating is short (within 1 minute), the decomposition of martensite can be greatly reduced or avoided, so ultra high strength hot rolled hot dip galvanized plate with excellent surface quality The cost can be greatly reduced. Table 3 shows the process parameters for producing ultra-high strength hot rolled hot dip galvanized martensitic steel products. The processing line of the present invention can produce ultra-high strength hot-rolled galvanized sheets. This is also one of the features of the present invention.

Example 4
As shown in FIG. 4, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-Water quenching cooling 7-Pickling 8-Reheating 9-Overaging 10-Final cooling 11-Temper 12-Finish 13-Oil coating 14 And post-processing-winding 15-finished product 16.

  The process of the embodiment of the present invention using tempering in addition to water quenching can produce ultra high strength cold-rolled sheets with good surface quality. By adopting water quenching that is faster than high hydrogen jet cooling, the strength level of cold-rolled sheet can be significantly increased under the same chemical composition, or when producing high strength steel with the same strength level The alloy components can be significantly reduced, and the welding performance of the product can be greatly improved. Moreover, by adopting a pickling process after water quenching, the oxide film on the surface of the steel strip can be washed away, and good surface quality of the steel sheet can be ensured.

Example 5
As shown in FIG. 5, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-High hydrogen jet cooling 6-Hot dip galvanizing 18 (or plating layer alloying annealing 19)-Final cooling 11-Temper 12- Post-treatment such as passivation 20 (or including finish 13 and oiling 14)-winding 15-finished product 16.

  The process of the embodiment of the present invention can be applied to the production of high-strength hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet with relatively high strength level, especially for the production of hot-dip galvanized TRIP steel and DP steel with low strength level. Fits. Since the production process is simple, the operating cost of the apparatus is low.

Example 6
As shown in FIG. 6, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-High hydrogen jet cooling 6-Reheating 9-Hot dip galvanization 18 (or plating layer alloying annealing 19)-Final cooling 11 -Temper 12-Post-treatment (preliminary phosphoric acid treatment, passivation 20, finish 13, oiling 14, etc.)-Winding 15-Finished product 16.

  The process of the embodiments of the present invention can produce hot dip galvanized high strength steel sheets with relatively high strength levels and good surface quality. In the process of the present invention, the steel strip is quenched by rapidly cooling the steel strip to below the phase change point by high hydrogen jet cooling, completing the martensitic transformation and then heating to about 460 ° C to complete hot dip galvanizing. Can reduce the demand for safety and eliminate some of the disadvantages of conventional processes. That is, by adding a large amount of alloying elements to the steel (to improve the hardenability of the steel sheet so as to complete the martensitic transformation after hot dip galvanization), alloy elements such as Mn and Si are collected on the surface of the steel sheet, Affects hot dip galvanizing. In the process of the present invention, the strength of the steel sheet can be improved, and at the same time, the content of the alloy element in the substrate can be reduced. And since there are few alloy elements in steel, plating property and weldability can be ensured, and finally the hot-dip galvanized high strength steel plate with favorable surface quality and use performance can be obtained. It should be pointed out that it is necessary to increase the cooling capacity after plating in order to enhance the effect of this embodiment. Preferably, the cooling capacity after plating in the present example is 1.5 times or more that of a conventional hot dip galvanizing apparatus so that the decomposition of the strengthening phase is reduced.

Example 7
As shown in FIG. 7, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-Water quenching cooling 7-Pickling 8-Reheating 9-Hot dip galvanizing 18 (or plating layer alloying annealing 19)- Final cooling 11-Temper 12-Post-treatment (preliminary phosphoric acid treatment, passivation 20, finish 13, oil coating 14 etc.)-winding 15-finished product 16.

  The process of the example of the present invention can produce a hot dip galvanized high strength steel sheet having higher strength and better surface quality than Example 6. In the process of the present invention, the strength of the steel sheet can be greatly improved on the premise that the chemical components of the base material are the same by adopting water quenching with a higher cooling rate instead of high hydrogen jet cooling. By adopting the pickling process, it is possible to wash away the oxide film on the surface of the steel strip by water quenching and to wash away alloy elements such as Mn and Si collected on the surface. Subsequent hot dip galvanizing properties can be ensured, and hot dip galvanized high strength steel sheets with good surface quality can be obtained.

Example 8
As shown in FIG. 8, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-Water quenching cooling 7-Pickling 8-Electroplating 17 (Fe or Ni plating)-Reheating 9-Hot dip galvanizing 18 (or Plating layer alloying annealing 19)-Final cooling 11-Temper 12-Post-treatment (pre-phosphoric acid treatment, passivation 20, finish 13, oil coating 14, etc.)-Winding 15-Finished product 16.

  The process of the example of the present invention is similar to the process of Example 7, except that an electroplating treatment of Fe or Ni is added after pickling to produce a plated layer of Fe or Ni on the surface of the steel sheet. It is only a point to do. In this way, the surface condition of the steel sheet before the hot dip galvanizing process was changed, and the problem that hot dip galvanizing property was not good in the ultra high strength steel was completely solved. The process of the embodiment of the present invention can produce a double-plated ultra-high strength hot-dip galvanized steel sheet with higher corrosion resistance and superior surface quality. This is also one of the features of the present invention.

Example 9
As shown in FIG. 9, the process of the present embodiment is as follows. Raw material 1-Uncoiling and cleaning 2-Heating 3-Soaking 4-Slow cooling 5-Water quenching cooling 7-Pickling 8-Electroplating 17 (Ni or Zn electroplating)-Post-treatment (preliminary phosphoric acid treatment, passivation) 20, Finish 13, Oil 14 etc.)-Winding 15-Finished product 16.

  In the process of the embodiment of the present invention, both the continuous annealing process and the electroplating process for producing cold-rolled Zn and Ni electroplated steel sheets are combined into one, and the Zn and Ni electroplating that has undergone continuous annealing in one apparatus. Steel plate can be produced. In this way, not only was the investment cost reduced and the productivity increased, but also the yield was improved by reducing the amount of successful resection. On the other hand, by using water quenching in addition to slow cooling, it is possible to produce a high-strength cold-rolled Zn and Ni electroplated steel sheet using a steel type having a low alloying element component.

Claims (6)

  A high hydrogen jet cooling station and a water quenching cooling station are provided in parallel after the sequential decoiling and cleaning station, heating station, soaking station, and slow cooling station, and reheating is performed after the high hydrogen jet cooling station. Station, over-aging station, final cooling station, temper station, finish station, oiling station and winding station are provided in sequence, pickling station and electroplating station are provided in sequence after water quenching cooling station, A hot galvanizing station connected after the reheating station, and a hot galvanizing station connected after the hot dip galvanizing station. A galvannealing plating layer connected to the galvannealing, the pickling station and the electroplating station communicated with the reheating station via connection passages, respectively. Communicated directly to the decoiling and cleaning station via a passage, the water quenching cooling station communicated to a slow cooling station via a fixed bypass, and a movable bypass after the reheating station The over-aging station is communicated with the product, and when the product is continuously annealed, this movable bypass is introduced, while the hot-dip galvanized product and the plated layer alloyed hot-dip galvanized product are produced. Evacuate this movable bypass and expose the two exposed by evacuation Sealing technique port, various high strength steels of flexible steel strip processing line suitable for production, wherein the.   The various high-strength steels according to claim 1, further comprising a passivation and other post-treatment station connected via a connecting passage after the electroplating station, after the temper station and before the finish station. Flexible steel strip processing line suitable for production.   2. The flexible steel strip processing line suitable for production of various high-strength steels according to claim 1, wherein an induction heater is disposed in the reheating station after the high hydrogen jet cooling station.   4. The flexible steel strip processing line suitable for production of various high-strength steels according to claim 3, wherein the frequency of the induction heater is 1000 Hz or more.   The bypass according to claim 1, wherein the bypass is a sealed passage, and the atmosphere in the passage is a mixed gas of nitrogen and hydrogen containing hydrogen occupying a volume percentage of 2% to 7%. Flexible strip processing line suitable for production of various high-strength steels.   2. The flexible gas suitable for production of various high-strength steels according to claim 1, wherein the high hydrogen jet cooling gas is a mixed gas of nitrogen and hydrogen containing hydrogen occupying a volume percentage of 20% or more. Steel strip processing line.

Images