BRPI1008468B1 - FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE FOR PRODUCING VARIOUS HIGH STRENGTH STEEL - Google Patents

Abstract

flexible thin strip steel processing line suitable for producing various high strength steels, a flexible thin strip steel processing line suitable for producing various high strength steels is defined as follows: an unwinding and washing station, a heating, a soaking station, a delayed cooling station, a gas jet cooling station, a water suppression station, an acid washing station, a reheating station, an overdosing station, a cooling station end, a leveling station, a finishing station, a lubrication station and a winding station in turn. Additionally, there is configured an electroplating station connected to the uncoiling and washing station, the acid washing station and the reheating station separately via the connecting passages; a hot galvanizing and galvanizing station connected to the reheating station via a hot galvanizing furnace nose and to the post-galvanizing cooling station and final cooling station via the connecting passages; and a pickling station and another post-treatment station connected to the electroplating station, the leveling station and the finishing station separately via the connecting passages. the reheating station is connected to the overdosing station via a movable secondary passage. according to the invention, the production of ordinary cold-rolled sheet, hot-dip galvanized sheet and galvanized sheet, and the production of zn or ni electrogalvanized sheet, specifically ultra-high strength cold-rolled sheet, zinc electrogalvanized sheet and Hot-dip galvanized sheet as well as galvanized sheet are integrated into a single unit for flexible production.

Description

Technical Field

[001] The invention relates to a technology for heat treatment and surface treatment of strip steel, specifically to a flexible strip steel processing line suitable for producing various high strength steels.

State of the Art

[002] The need for environmental protection and sustainable development has been recognized as one of the most common visions of humanity in the 21st century. A general trend in the development of the modern automobile industry is to reduce weight and save energy. Lightweight automobile research has indicated that high strength steel should be used in large school in the automobile industry to thin the steel sheet so as to achieve the goal of “reducing weight, saving energy and reducing emissions” . The demand for high strength cold-rolled sheet and hot-dip galvanized sheet is therefore greatly increased.

[003] Generally, both the high strength sheet and the high surface quality sheet (eg automobile outer panel) are produced in the same prior art continuous heat treatment/cold rolling unit. However, high strength steel, specifically ultra high strength steel, has demands on surface quality that are entirely different from those of a high surface quality blade. Due to its use in automobile structures, the demands of high strength steel on surface quality are very high. Otherwise, an automobile's exterior panel is extremely critical of its surface quality. When a small amount of high strength steel, specifically ultra high strength steel, specifically ultra high strength steel, is produced in a large continuous heat treatment unit, local nodulation or scraping and abrasion, etc., may occur in kiln rolls due to the high strength and inefficient shape of the steel plate.

[004] Therefore, the unit cannot still be used to produce the high quality surface plate after the high strength steel is completed, and the unit must be turned off to replace the damaged furnace rollers. The waste of time and spare oven rolls resulting from shutting down the massive continuous heat treatment oven to cool and replace the rolls is staggering. Therefore, organizing the production of high strength steel, specifically ultra high strength steel, and high surface quality sheet in the same unit is very difficult.

[005] In terms of specifications, the high-quality surface sheet represented by the automobile outer panel is generally broad and thin, while high-strength steel, specifically ultra-high-strength steel, is usually thick and narrow. When a continuous heat treatment unit must be designed to accommodate both products, what can be foreseen is not only the high technical difficulty, but also the complexity and enormous volume of the unit, in addition to a large investment.

[006] The difference also exists in the oven cooling technology. A unit to produce high surface quality sheet does not have high demands on furnace cooling rate, however its demands are high on high speed fixed pass technology to prevent deformation and breakage of flexible steel tape at high temperatures, and voltage is required to be lower and stable for each furnace section. In contrast, a unit to produce high strength steel has high demands on the cooling rate in the blast chilling section of the furnace. Furthermore, thick and narrow high strength steel tends to deflect, and this tendency is exacerbated after such ribbon steel undergoes phase change in rapid cooling and the sheet shape is thereby deteriorated. Therefore, the tension in each furnace section of the unit is required to be large, and the correction capacity of the unit's roller system is required to be superior.

[007] The demands on the leveling machine are also different. For products demanding high surface quality, it is extremely important to improve surface quality by leveling, in addition to controlling material properties and improving sheet shape by leveling. Therefore, a large diameter leveling roller and a large rolling force are required. On the other hand, since high strength steel products have high yield strength, if the diameter of the leveling roller is too high, the rolling force of the leveling machine will be greatly increased, and the energy consumption of the leveling machine will be greatly increased. leveling and investment will increase. In this way, a small diameter of the leveling roller, a large leveling stress and an adequate rolling force during leveling are generally applied to improve the shape of high strength steel sheet.

[008] Regarding the change between specifications and varieties, according to each specification under each variety of high strength steel, specifically ultra high strength steel, is used in small quantity, but the total number of specifications and varieties is large , the switching frequency in production with a continuous heat treatment unit is increased, and the transition time is prolonged. This has a major impact on the fixed operation and production efficiency of a large continuous heat treatment unit. Thus, for a large unitized steel company, when it has several continuous heat treatment units at the same time, a unique continuous heat treatment unit is urgently needed to produce the high strength steel so as to ensure fixed operation. from other high speed continuous heat treatment units, the good condition of the units at all times and the good quality of the product surface.

[009] Cold rolled high strength sheet is produced using a continuous annealing unit comprising a rapid cooling device. In order for the product to obtain a strength of 980Mpa and above, as well as superior subsequent processing performances, the continuous annealing unit must be equipped with a rapid cooling device such as water suppression devices, spray cooling or water cooling. High hydrogen jet. The main continuous annealing process involves: - Uncoiling - washing - heating - soaking - delayed cooling - rapid cooling - (acid washing) - (reheating) - overdosing (tempering) - cooling - leveling - finishing - high strength sheet laminated to cold.

[010] In the continuous annealing process, the cold rolled steel that has been unrolled and washed is heated to a temperature, held for a period of time, and then slowly cooled to a temperature followed by cooling to room temperature or temperature of overdose at a rapid cooling rate in a blast chiller device.

[011] As a cooling method that has the fastest cooling rate currently, water suppression is also an inexpensive procedure used in the production of high strength steel. Adding a small amount of alloying elements can produce high strength steel. The addition of a small amount of alloying elements can produce high strength biphasic, multiphase and martensitic steels also of a high level of strength. However, an oxide film layer can be formed on the steel tape surface during water suppression, and acid washing is thus required in addition. Furthermore, when water suppression is used, it is difficult to finish cooling to an overdose temperature. Therefore, the ribbon steel must be cooled to less than 100°C, and it is necessary to reheat the ribbon steel to an annealing temperature to quench in order to ensure the anti-aging stability of the ribbon steel.

[012] When high hydrogen jet cooling is used in the continuous annealing process, the terminal cooling temperature has strong controllability, and overcooling at room temperature and oxidation of the steel strip is avoided. Therefore, ribbon steel can proceed to overdosing directly or after reheating, without acid washing.

[013] However, the cooling rate of the high hydrogen jet cooling method is slower than the water suppression. Consequently, when the same alloying elements are added, the strength level of the cold rolled sheet produced by high hydrogen jet cooling is much lower than that produced by water suppression.

[014] The hot galvanized high strength sheet is produced by a continuous hot galvanizing unit comprising a quick cooking device. In order to maximize substrate strength and ensure hot-dip galvanizing capability, the continuous hot-dip galvanizing unit shall be equipped with a high hydrogen jet cooling rapid cooling device, a water suppression device or cooling device. spray and an acid washing device.

[015] The main continuous hot galvanizing process involves: - Uncoiling - washing - heating - soaking - delayed cooling - rapid cooling - (acid washing) - (reheating) - hot galvanizing (or comprising galvanizing) - cooling - leveling - finishing - high heat resistance sheet.

[016] In the continuous hot galvanizing process, the cold rolled steel that has been unrolled and washed is heated to a soak temperature, held for a period of time, and then slowly cooled to a temperature, followed by cooling at about the zinc pot temperature or ambient temperature at a blast chilling rate in a blast chiller. Water quenched fibre steel needs to be acid driven to remove the oxide film on its surface, and then heated before entering the zinc pan for hot-dip galvanizing or galvanizing. Finally, the ribbon steel is subjected to subsequent treatment procedures, such as leveling, etc., after being cooled.

[017] Since the hot-dip galvanizing of strip steel must be carried out at about 460°C, and after the hot-dip galvanizing has to be carried out at around 500°C, a large amount of the alloying elements must be added on the substrate if the grade high strength hot-dip galvanized sheet is being produced on a continuous conventional hot-dip galvanized line. However, this will result in the enrichment of alloying elements such as Mn, Si on the surface of the steel sheet before it is galvanized, and thus hot-dip galvanized sheet, including galvanized sheet, which has good surface quality, cannot be produced.

[018] Therefore, when a process involving water suppression + acid washing + reheating + hot galvanizing (or comprising galvanizing is used, the strength level of the steel sheet can be greatly increased, on the one hand, and on the other , the alloy elements enriched in the steel strip surface can be removed by acid washing, so as to ensure the acquisition of the high strength hot-dip galvanized sheet as well as the galvanized sheet which has good surface quality. High hydrogen cooling is used, steel strip can enter the zinc pan for galvanizing (or comprising galvanizing) directly or after reheating, without acid washing, followed by subsequent treatment procedures such as leveling, etc. ., after cooling. However, when such a process is used, the alloying elements may be added in excess to ensure the galvanizing ability. Considering the same composition chemical, the end product of this process has a resistance level that is certainly low.

[019] Consequently, compared to water suppression, high hydrogen cooling provides the hot-dip galvanized sheet as well as the galvanized sheet with a low level of strength in a given range of alloy composition.

[020] Composition to be seen from the above description, in the production processes to produce high-strength cold-rolled sheet and hot-dip galvanized sheet, the configuration of the inlet washing device for the original sheet, the heating devices and soaking for annealing, the rapid cooling device and associated devices (eg, water suppression, acid washing and reheat devices, etc.), as well as the output leveling, lubrication, and winding devices, etc. are substantially the same. Therefore, the production of cold-rolled high-strength sheet and that of hot-dip galvanized high-strength sheet can be integrated into a single unit. More importantly, as the market demand for cold-rolled high-strength sheet or hot-dip galvanized high-strength sheet is very large, if the production lines to produce cold-rolled high-strength sheet and high-strength sheet If hot-dip galvanized are built separately, the cost of capital will be greatly increased, and neither unit is saturated in its production. Meanwhile, such a unit for producing high strength steel, specifically ultra high strength steel, is not suitable for producing flexible steel products having high surface quality, but can only be used to produce low common products. flexible steel grade having relatively poor surface quality, leading to severe waste of resources. Therefore, increasing attention is being paid in the steel industry to the reasonable arrangement of devices in various sections of the unit and research and development of a changeover device to pass the steel plate, with the aim of integrating in a single unit the production of steel. ultra high strength and high strength cold rolled sheet as well as hot galvanized sheet which has many specifications and varieties but not much demand.

[021] Japanese patent application publication (kokai) H2003-253413 discloses a dual-purpose mechanism and a dual-purpose method for producing high strength hot rolled steel sheet and hot galvanized steel sheet. In this method, steel sheet from an annealing furnace equipped with a heating section, a soaking section and a gas jet cooling section can be fed to a galvanizing device in a galvanizing passage to produce the sheet. of hot-dip galvanized steel. Alternatively, the preceding steel sheet from the annealing furnace can be supplied to a water-suppressing bath, rather than the galvanizing device in an open plate cold-rolling passage to produce the high-grade hot-rolled steel sheet. resistance.

[022] This patent is related to a dual-purpose method to produce hot-dip galvanized steel sheet and high-strength hot-rolled steel sheet, featuring a changeover device for changing between two process passes. To perform dual-purpose production of hot-dip galvanized steel sheet and high-strength hot-rolled steel sheet, three ways are obtained in this method to effect the process: (1) a changeover device is disposed between a zinc pan and a water suppression bath immediately behind the gas jet cooling section; (2) the change is performed by raising or lowering the rollers immersed in the zinc tub and water suppression bath; (3) the change is carried out by introducing the zinc or water solution into an ordinary bath for galvanizing and water suppression. However, the main disadvantages of this patent include: - First, for high hydrogen jet cooling processes and water suppression capable of rapid cooling as well as acid washing process, they are not used in the production of the dual purpose method of this patent, phase transformation hardened hot-dip galvanized sheet and galvanized sheet which have good surface quality but lower strength level cannot even be produced, let alone high strength hot-dip galvanized sheet and galvanized sheet. - Second, for the acid washing process after the process of water suppression and reheat quenching are not used in the dual-purpose production method of this patent, the cold-rolled high strength sheet has poor surface quality, plasticity and anti-aging stability. - Finally, the second and third process modes to realize the dual-purpose production method of this patent are practically difficult. Specifically, when switching between galvanized sheet and cold rolled sheet occurs, residual zinc on the roller surface will inflict severe impact on the surface quality of cold rolled sheet and unit operation. Furthermore, the common use of zinc tub and water suppression bath will bring many difficult technical problems to be solved, such as zinc tub cracking, and entail costly changing. Brief presentation of the invention

[023] The object of the invention is to provide a flexible thin strip steel processing line suitable for producing various high strength steels, characterized by the fact that high strength cold rolled sheet, hot galvanized sheet, sheet Galvanized sheet, as well as electro-galvanized sheet and nickel-rolled sheet may be produced from laminated rigid material, which is cold-rolled and hardened, and hot-rolled pickled sheet in this processing line. By integrating the production of common cold-rolled sheet, hot-dip galvanized sheet and galvanized sheet in a single unit, resources are put to effective use and investment cost is saved. Furthermore, electro-galvanized sheet and nickel-rolled sheet can also be produced on this processing line by using a connecting passage, and ultra-high strength cold-rolled sheet, hot-dip galvanized sheet and galvanized sheet can also be produced. . In addition, by using the acid wash process before hot or Fe galvanizing, the Ni-plating process, the disadvantage of poor galvanizing ability of high strength steel, specifically ultra high strength steel, is eliminated completely into the production process and mechanism of the invention, so that the good surface quality of high strength hot-dip galvanized sheet and galvanized sheet is guaranteed. To achieve the above objective, the following technical solution of the invention is adopted: a flexible thin ribbon steel processing line suitable for producing various high strength steels is defined as follows: one unwinding station, one soaking station, one station of delayed cooling, a gas jet cooling station, a water suppression station, an acid wash station, a reheat station, an overdosing station, a final cooling station, a leveling station, a station finishers, a lubrication station and a coil station.

[024] Additionally, an electroplating station connected to the unwinding and washing station, acid washing station and reheating station is further defined separately via the connection passages; a hot-dip galvanizing station and galvanizing station connected to the reheating station via a hot-dip galvanizing furnace nose and to the final cooling station via a connecting passage, and a pickling station and another pickling station and another blasting station. aftertreatments connected to the electroplating station, the leveling station and the finishing station separately via the connection passages. The reheat station is connected to the overdosing station via a mobile bypass, characterized in that the mobile bypass is joined when a continuously annealed product from the cold rolled sheet is to be produced, and the mobile bypass is removed with the union nipple sealed when a hot-dip galvanized product or its corresponding galvanized product is to be produced.

[025] Gas jet cooling is high hydrogen jet cooling. The pickling station and another aftertreatment station are connected to the finishing station, lubrication station or winding station. The secondary passage is different from the connecting passage in that the former is an airtight passage in which the atmosphere is substantially the same as the annealing furnace, ie, a shielding gas from a mixture of nitrogen and hydrogen in which hydrogen is responsible by 2%-7%. The connection passage is not hermetic and does not need protective gas. In addition, an induction heater is arranged behind the acid wash section.

[026] The high hydrogen jet cooling section is followed by an induction heater, preferably an induction heater having a frequency of 1000Hz or greater. Comparing with the previous processing line, the inventive processing line can control the temperature of rapidly cooled ribbon steel and reheat rate and temperature, and dispense with acid wash, so as to sufficiently meet the requirements of the production process of the high-strength plate in its mechanism.

[027] Flexible thin strip steel processing line suitable for producing various high strength steels of the invention has peculiar superiorities. Compared to previous heat treatment units, the processing line of the invention has the following significant and notable features and advantages.

[028] 1. Rich product varieties. The most common continuous annealing unit can only be used to produce common cold rolled products, and the most common continuous hot-dip galvanizing unit can only be used to produce the galvanized and hot-dip galvanized products. Even the dual purpose continuous annealing/hot galvanizing unit, which was developed recently, can only be used to produce two types of products, i.e., common rolled products and hot galvanized products. Additionally, the target product of this dual purpose continuous annealing/hot galvanizing unit is not high strength steel, specifically ultra high strength steel. Therefore, there is no obvious superiority in product variety.

[029] The flexible processing line suitable for producing the high strength steel of the invention, in which a high speed high hydrogen jet cooling device and a water suppression device are installed simultaneously, is specifically useful for producing the high strength steel and ultra high strength steel featuring abundant specifications and varieties, but small amount of demand. This processing line can be used to produce not only high strength cold rolled steel and ultra high strength steel of various strength levels (up to 1470Mpa), but also various high strength hot galvanized steels having a higher grade of resistance up to 980Mpa, as well as electro-galvanized, nickel-plated and zingo/nickel-alloy laminated products of various strength levels. Overall, in contrast to other cold-rolled phyto steel processing lines, this multi-purpose processing line is characterized by multiple functions and its ability to produce multi-purpose products and its ability to produce products of multiple varieties.

[030] 2.Low production cost First, with regard to the starting material, not only the laminated rigid sheet can be used as the starting material, but also the hot rolled pickled sheet can be used directly as the starting material . Since a new high speed high hydrogen jet cooling device and a new water suppression device are used in the invention, the alloy content can be reduced to produce high strength steel of the same strength level, saving elements alloy and reducing the course of production. Meanwhile, the production requirements of steelmaking, hot rolling, acid washing and cold rolling procedures are reduced, leading to more stable production operation and lower cost. In addition, as various high strength steels can be specially produced on this flexible processing line, the interconnection and transition between the production of different high strength steel products will be more convenient, and there is no need to increase large investment of others. units to produce a small quantity of ultra high strength steel so that other units are released and the production cost is reduced overall.

[031] 3.High Quality Product As the processing line of the invention is specially designed for the treatment of various high strength steel products, more effective measures can be taken to improve the product quality by considering the process requirements of the production of high strength steel. For example, in light of the low cooling rate problem of a common continuous heat treatment unit, the unit of the invention uses new high-speed, high-speed hydrogen jet cooling and water suppression technologies to increase the cooling rate significantly. , resulting in remarkable decrease of the alloy content in the chemical composition of high strength steel of the same strength level. In this way, the welding property and the rolling capacity of high strength steel products are significantly increased in addition to the decrease in production cost. As another example, a new hot galvanizing process after water suppression, acid washing and even plating is used to further improve the rolling ability of high strength steel substantially, thus the surface quality and corrosion resistance of a high strength hot-dip galvanized steel.

Brief Description of the Drawings

[032] Fig. 1 is a block diagram showing the process scheme of the first example according to the invention; Fig. 2 is a block diagram showing the process scheme of the second example according to the invention; Fig. 3 is a block diagram showing the process scheme of the third example according to the invention; Fig. 4 is a block diagram showing the process scheme of the fourth example according to the invention; Fig. 5 is a block diagram showing the process scheme of the fifth example according to the invention; Fig. 6 is a block diagram showing the process scheme of the sixth example according to the invention; Fig. 7 is a block diagram showing the process scheme of the seventh example according to the invention; Fig. 8 is a block diagram showing the process scheme of the eighth example according to the invention; Fig. 9 is a block diagram showing the process scheme of the ninth example according to the invention;

Best Ways to Carry Out the Invention

[033] The flexible strip steel processing line suitable for producing various high strength steels of the invention will be described in detail in the following examples with reference to the drawings (where the solid arrow indicates the process scheme used in the example, while the dotted lines indicate optional process schemes that can be adopted in other examples). Example 1

[034] Referring to Fig. 1, the process scheme of this example involves the starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 - gas jet cooling 6 (hydrogen jet cooling high) - overdose 10 - final cooling 11 - leveling 12 - finishing 13 - lubrication and after-treatment 14 - winding 15 - final product 16.

[035] The process of the invention can be used to produce common cold rolled sheet and phase transformation hardened high strength hot rolled steel sheet, specifically suitable for producing cold rolled TRIP steel and lower grade DP steel 80Kg, in which the process parameters for the production of cold-rolled 80Kg grade TRIP steel and 80KG grade DP steel are shown in Table 1. As can be seen from Table 1, it is important to control the soaking temperature, aging temperature and respective times during continuous annealing for TRIP steel, and the demands on the quench rate are not critical. However, when high strength DP steel is concerned, the soak temperature and blast chilling rate are the fundamental process parameters to control continuous annealing, and specifically, there are high demands on the blast chilling rate. With respect to aging, it is required to take place at a low temperature and for a short time to avoid martensite decomposition.

Exemplo 2[036] The acid wash and reheat procedures are left out of this process, and the heat treatment procedure is performed at low cost. The surface quality of the products is good. Table 1 Process Parameters for Cold Rolled Grade 80Kg TRIP Steel and 80Kg Grade DP Steel.

Example 2

[037] Referring to Fig. 2, the process scheme of this example involves the starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 - gas jet cooling 6 (hydrogen jet cooling high) - reheat 9 - overdose 10 - final cooling 11 - leveling 12 - finishing 13 - lubrication and after-treatment 14 - winding 15 - final product 16.

[038] In contrast to Example 1, this process of the invention uses an overdosing process that is carried out first at low temperature and then at high temperature, whereby process flexible steel products that have good anti-aging properties can be produced to from low carbon aluminum alloy steel having good antiaging properties are shown in Table 2. As can be seen from Table 2, for the purpose of producing low carbon aluminum alloy steel having good antiaging properties, it is It is important to control the soaking temperature and aging process during continuous annealing, where the overdosing process must be carried out first at low temperature and then at high temperature to achieve sufficient segregation of dissolved carbon from the steel. The processing line of the invention satisfies such process requirements by applying a blast chilling procedure followed by reheating. This process is also suitable for producing phase transformation hardened martensite and double phase steel.

[039] In contrast to other patents, a high energy induction heater is disposed behind the high hydrogen jet cooling section in the process line of the invention, allowing for the control of heating rate and temperature after blast chilling, and leaving out the acid wash. The process requirements for producing the high-strength sheet on equipment are thus satisfied. Table 2 Process Parameters for Low Carbon Aluminum Calm Steel and Martensitic Steel

[040] More importantly, in this example of the invention, the ribbon steel can be cooled to a temperature below the martensite phase transformation point. After the martensite phase transformation takes place, the steel is quenched to effect further quench suppression, generating the in-season martensitic texture so as to regulate the comprehensive performances of the steel sheet. High strength double-phase steel sheet having better balanced strength and plasticity than the double-phase steel products of Example 1 is thus produced. Additionally, Martensitic steel having lower strength level but better plasticity can also be produced. The process parameters for producing the martensitic steel products are also shown in Table 2. As can be seen from Table 2, the key to producing high strength martensitic steel is the control of the soak temperature and cooling rate blast during continuous annealing, where blast chilling rate and blast chilling end temperature are the main considerations for obtaining the proper martensite to ensure its strength.

[041] In contrast to the conventional blast chilling procedure followed by reheating, the heating rate and temperature after blast chilling in the inventive process line can be controlled due to the arrangement of a high energy induction heater behind the step of high hydrogen jet cooling. Furthermore, acid washing is not required. The process requirements for producing the high strength steel sheet in the equipment are thus satisfied. The ability to carry out this process is one of the features of the invention. Example 3

[042] Referring to Fig. 3, the process scheme of this example involves the starting material 1 - uncoiling and washing 2 - reheating 9 - hot galvanizing 18 - metal melting 19 - final cooling 11 - leveling 12 - passivation ( or comprising lubrication) and post-treatment 20 - finishing 13 - lubrication and post-treatment 14 - winding 15 - final product 16.

Exemplo 4[043] High strength or ultra high strength hot rolled pickled sheet (eg hot rolled high strength steel) is used as the starting material in the process in this example. The hot-dip galvanizing ability of high-strength steel is improved by galvanoplastic onto an extremely thin layer of elements such as Ni, Fe, etc., on the surface of the starting material, and then the resulting material is heated to 450- 500°C before entering a zinc vat to be hot-dip galvanized (or/and galvanized), followed by subsequent procedures such as leveling, etc. Due to the short reheating time and hot galvanizing (within 1 minute), the decomposition of the strengthening phase is greatly reduced or even avoided, leading to the production of ultra-high strength hot galvanized, pickled and hot rolled sheet having good surface quality at much lower cost. The process parameters for producing advanced ultra-high strength hot-rolled pickled steel products and a hot-dip galvanized steel are shown in Table 3. As one of the features of the invention, the processing line of the invention is suitable for producing the ultra high strength hot rolled hot galvanized sheet without any continuous cold rolling procedure. Table 3 Process Parameters for Advanced High Strength Hot Rolled Hot Galvanized Steel

Example 4

[044] Referring to Fig. 4, the process scheme of this example involves starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 (comprising high hydrogen section which also serves as delayed cooling) - water suppression 7 - acid wash 8 - reheat 9 - overdose 10 - final cooling 11 - leveling 12 - finishing 13 - lubrication and after-treatment 14 - winding 15 - final product 16.

[045] The process of this example comprises a water suppression plus quenching process and can be used to produce ultra high strength hot rolled steel sheet having good surface quality. As the water suppression process having faster rate of cooling than high hydrogen jet cooling is used, the strength level of the cold rolled sheet can be greatly increased for the same chemical composition, or the alloy content can be greatly increased. be reduced significantly to the same strength level as high-strength steel, resulting in remarkably better welding property. Additionally, the ferric oxide skin on the strip steel surface can be removed by acid washing after water suppression, ensuring good surface quality of the steel sheet. Example 5

[046] With reference to FI. 5, the process scheme of this example involves the starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 - high hydrogen cooling 6 (high hydrogen jet cooling) - hot dip galvanizing 18 or comprising melting metals 19 - final cooling 11 - leveling 12 - passivation and other aftertreatment 20 - finishing 13 - lubrication 14 - winding 15 - final product 16, where leveling 12 is followed by passivation 20, and then further followed by the finish 13.

[047] This process of the invention can be used to produce both high strength hot galvanized sheet and high strength galvanized steel sheet with a relatively higher level of strength, specifically suitable for producing a hot galvanized TRIP steel and lower strength DP steel. Due to the simple production process, the unit can be operated at low cost. Example 6

[048] With reference to FI. 6, the process scheme of this example involves starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 - high hydrogen cooling 6 (high hydrogen jet cooling) - reheating 9 - hot dip galvanizing 18 or comprising metal melting 19 - final cooling 11 - leveling 12 - passivation and other post-treatment 20 - finishing 13 - lubrication 14 - winding 15 - final product 16, wherein the post-treatment comprises pre-phosphorization and passivation.

[049] This process of the invention can be used to produce high strength hot-dip galvanized steel sheet having relatively high level of strength and good surface quality. In this process of the invention, the ribbon steel is rapidly cooled below the martensitic phase transformation point, and then heated to about 460°C to carry out hot galvanizing. The demands on the stiffening capacity of the starting steel sheet are thus reduced, and a portion of the disadvantages of the earlier processes are eliminated. In the above processes, the addition of abundant alloying elements to the steel (to improve the steel sheet's hardening capacity to facilitate the phase transformation of martensite after hot-dip galvanizing) leads to enrichment of alloying elements such as Mn , SI on the surface of the steel sheet, inflicting an impact on the hot-dip galvanizing ability. In addition to increasing the strength of the steel sheet, this process of the invention can reduce the content of alloying elements in the substrate to a certain degree. Meanwhile, the content of alloying elements in steel is very low. Therefore, the lamination ability and the welding property can be guaranteed, providing the finally resulting high strength hot-dip galvanized steel sheet with good surface quality and user applicability. Example 7

[050] Referring to Fig. 7, the process scheme of this example involves starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 (comprising the high hydrogen section which also serves as delayed cooling ) - water suppression 7 - acid washing 8 - reheating 9 - hot galvanizing 18 - metal melting 19 - final cooling 11 - leveling 12 - finishing 13 - lubrication and after-treatment 14 - winding 15 - final product 16, in that post-treatment comprises pre-phosphorization and passivation.

[051] This process of the invention can be used to produce the high strength hot-dip galvanized steel sheet which has good surface quality and superior strength than in Example 6. In this process of the invention, the high hydrogen jet cooling is replaced by water suppression which has faster rate of cooling, so the strength of the steel sheet is significantly improved for the same chemical composition of the substrate. Due to the use of the acid washing process, the oxide hair resulted from water suppression and enriched alloying elements such as, Mn, Si on the steel tape surface can be removed. In that way, the hot-dip galvanizing ability in the subsequent procedure can also be guaranteed, and high-strength hot-dip galvanized steel sheet having good surface quality can be obtained. Example 8

[052] Referring to Fig. 8, the process scheme of this example involves starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 (comprising the high hydrogen section which also serves as delayed cooling ) - water suppression 7 - acid wash 8 - electroplating 17 (Fe or Ni from electroplating) - reheat 9 - hot dip galvanizing 18 - metal fusion 19 - final cooling 11 - leveling 12 -passivation and other aftertreatment 20 - finishing 13 - lubrication 14 - winding 15 - final product 16, in which the post-treatment comprises pre-phosphorization and passivation.

[053] This process of the invention is similar to the process in Example 7, except for the addition of the Fe or Ni electroplating process after acid washing, whereby a layer of Fe or Ni is electrogalvanized on the surface of the steel sheet of ultra-high strength is deficient is resolved completely. According to the process of this example, the double coating of hot-dip galvanized ultra-high strength sheet having good corrosion resistance and high surface quality can be produced. This is another feature of the invention. Example 9

[054] Referring to Fig. 9, the process scheme of this example wraps the starting material 1 - uncoiling and washing 2 - heating 3 - soaking 4 - delayed cooling 5 (comprising the high hydrogen section which also serves as delayed cooling ) - water suppression 7 - acid washing 8 - electroplating 17 (Fe or Ni for electroplating) - passivation and post-treatment 20 - finishing 13 - lubrication and post-treatment 14 - winding 15 - final product 16.

[055] In one aspect of the process in this example, the continuous annealing procedure and electroplating procedure to produce the hot rolled electro-galvanized sheet, ash or nickel are incorporated into a single unit to perform continuous annealing and electroplating. This not only reduces the amount to be cut from both ends of the sheet and increases throughput. In another aspect, due to the use of a delayed cooling process plus water suppression, high-strength cold-rolled steel sheet, electro-galvanized with zinc or nickel, can be produced from steel containing a low content of alloying elements, and zinc or nickel electrogalvanized flexible steel products having extremely good stamping property can also be produced.

[056] In Examples 7, 8 and 9, as a high hydrogen cooling device having strong cooling capacity is used in the delayed cooling section preceding the water suppression section, good conditions are created for the water suppression, of so that the inlet temperature of the water suppression can be approximately decreased. This creates conditions to improve the sheet format of the final products.

Claims (6)

1) FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE FOR PRODUCING VARIOUS HIGH STRENGTH STEEL, the flexible tape steel processing line comprises successively: an unwinding and washing station (2), a heating station (3), a soaking station (4), a delayed cooling station (5), a gas jet cooling station (6), a water suppression station (7), an acid wash station (8), a water-supply station. reheat (9), an overflow station (10), a final cooling station (11), a leveling station (12), a finishing station (13), a lubrication and winding station (14); and further comprise: an electroplating station (17) connected to the unwinding and washing station (2), the acid washing station (8) and the reheating station (9) separately through the connecting passages; a hot-dip galvanizing station and a galvanizing station connected to the reheat station by means of a hot-dip galvanizing furnace nose (18) and to the final cooling station (11) by a connecting passage; a passivating station and another post-treatment station (20) connected to the electroplating station (17), to the leveling station (12) and to the finishing station (13) separately through connection passages, characterized by said reheating station (9) being connected to the overflow station (10) via a mobile bypass passage, wherein, when a continuously annealed product of the cold rolled sheet is produced, the mobile bypass passage is joined; when a hot dip galvanized product (18) or its corresponding galvanized product is to be produced, the movable bypass passage is removed with the union nipple sealed; and wherein the bypass passage is an airtight passage in which the atmosphere is the same as that of the annealing furnace and comprises a shielding gas of a mixture of nitrogen and hydrogen, where hydrogen accounts for 2% to 7%. 2) FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE FOR PRODUCING VARIOUS HIGH STRENGTH STEEL, according to claim 1, characterized in that the gas jet cooling (6) is high hydrogen jet cooling. 3) FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE TO PRODUCE VARIOUS HIGH STRENGTH STEEL, according to claim 1, characterized in that the passivating station and another post-treatment station (20) are connected to the lubrication station or winding station (15). 4) FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE FOR PRODUCING VARIOUS HIGH STRENGTH STEEL, the flexible tape steel processing line suitable for producing various high strength steels according to claim 1, characterized by the fact that a heater by induction is arranged behind the acid wash section. 5) FLEXIBLE TAPE STEEL PROCESSING LINE SUITABLE FOR PRODUCING VARIOUS HIGH STRENGTH STEEL, the flexible tape steel processing line suitable for producing various high strength steels according to claim 1, characterized in that the heater by induction is disposed behind the high hydrogen jet cooling section. 6) FLEXIBLE RIBBON STEEL PROCESSING LINE SUITABLE TO PRODUCE VARIOUS HIGH STRENGTH STEEL, according to claims 4 or 5, characterized in that the induction heater has a frequency of 1000Hz or more.

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