• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a method for producing stainless steel sheet finished in at least two different ways including a 2D or a 2B finish and a BA finish. After an initial annealing and pickling of the sheet steel, it is cold rolled and then annealed and pickled again. For the BA finish, annealing takes place under a reducing atmosphere and no further pickling is required. For the sheet steel intended for the BA finish, the cold rolling takes place in the presence of a mineral oil that is free from water, while for the sheet steel intended for the 2D or the 2B finish, the cold rolling takes place in the presence of an oil in water emulsion, or optionally also of a mineral oil that is free of water. For the sheet steel with the 2D or the 2B finish it was found that before re-annealing the cold-rolled sheet steel on its surface, an extra layer of oil is preferably applied to thus prevent the formation of spots on the surface of the sheet metal. .
    公开号:BE1026913B1
    申请号:E20195932
    申请日:2019-12-18
    公开日:2020-07-22
    发明作者:Yves Dufrane
    申请人:Aperam Stainless Belgium；
    IPC主号:
    专利说明:

    The present invention relates to a method for producing at least two different ways of finished stainless steel sheet including a 2D finish and a BA finish (high gloss or annealed - “Bright Annealed”). By means of a surface roller, the sheet steel with the 2D finish can be further finished into sheet steel with a 2B finish that is more glossy than the matt sheet steel with the 2D finish. The production of the finished sheet steel is based on rolls of hot-rolled, not yet pickled sheet steel, the so-called black rolls. These are unrolled and are each passed through a substantially constant speed through at least a first production line containing at least a first annealing furnace, a series of at least four consecutive pickling baths and at least one subsequent passivating pickling bath.
    In the first production line, stainless steel with a so-called HRAP finish (“Hot Rolled Annealed and Pickled”) is produced. At least one of said rolls is unrolled hot-rolled, not yet pickled sheet steel and passed through the first production line at a substantially constant speed such that the sheet steel is successively annealed, pickled and passivated.
    The annealing is intended to remove the stresses created in the steel during the hot rolling while the pickling is intended to remove the oxide skin that has formed on the hot rolled sheet steel. The self also serves here
    D BE2019 / 5932 underneath the chromium-poor layer to be stained away so that a thin chromium oxide layer can be formed in the passivating pickling bath, which provides the stainless character of the steel.
    In the method of producing the stainless steel sheet with the 2D finish, the sheet steel produced in the first production line with the HRAP finish is further finished in at least a first or in at least a second cold rolling mill and in a second production line. This second production line contains at least one further annealing furnace, a number of further successive pickling baths and at least one further passivating pickling bath. The sheet steel with the HRAP finish is thus cold-rolled and re-annealed, pickled and passivated. The cold roll has working cylinders to which oil is applied during cold rolling.
    Cold rolling of the sheet metal, with the thickness of the sheet steel decreased by at least 25%, produces a smoother surface compared to the HRAP finish. Re-annealing is necessary to relieve the stresses in the material and re-pickling is required to re-remove the oxide layer formed during annealing, after which the sheet metal must then be passivated again. The matt surface of the 2D finish thus obtained is then usually made more glossy by further treating the sheet steel with a so-called surface roller. In this way, a 2B finish with a smooth surface is obtained.
    In the method for producing the stainless steel sheet with the BA finish, the sheet steel produced in the first production line with the HRAP finish is further finished in said first cold rolling mill and in a third production line. This third production line contains at least one BA annealing furnace with a reducing atmosphere therein. The sheet steel with the HRAP finish is thus cold rolled and re-annealed. It has cold rolling cylinders to which oil is applied during cold rolling. Due to the presence of the reducing atmosphere in the BA annealing furnace, only the stresses are removed from the material without the material oxidizing in the BA annealing furnace.
    The steel is given a glossy surface, whereby autopassivation then automatically forms a thin oxide layer again, which does not, however, negate the glossy character of the material.
    The following acids or combinations thereof are usually used for pickling stainless steel, in particular stainless chrome nickel steel: nitric acid (HNOs), hydrogen fluoride (HF), sulfuric acid (H2SO4) and hydrochloric acid (HCI). The action of these acids is described, for example, in the American Iron and Steel Institute's “Cleaning and descaling stainless steels” manual, which was reprinted in 1988 by the Nickel Development Institute.
    A problem which arises in the production of the sheet metal with the different finishes is that for the production of sheet metal with the 2D or 2B finish, during the cold rolling, in said second cold rolling mill, an emulsion of oil in water is normally applied to the sheet steel. is applied while, for the production of sheet steel with the BA finish, oil, which contains virtually no water, is applied to the sheet steel during the cold rolling, in said first cold rolling mill. For the production of sheet metal with the BA finish it is essential that the oil contains little or no water, as this can cause oxidation of the steel during annealing.
    For optimal use of the first cold mill that works with pure oil instead of an oil emulsion, this first cold mill is also used in the production of sheet steel with the 2D or 2B finish. The disadvantage of this, however, is that the oil that remains on the surface of the sheet metal after cold rolling during the re-annealing of the sheet steel under a non-reducing atmosphere causes stains on the sheet metal which are so burned into the sheet metal that they are difficult to subsequent stains can be removed. Removing the oil from the surface of the cold-rolled steel is not easy without creating further stains or would require a large amount of solvent, such as acetone, avoiding the use of such solvents due to fire and explosion hazard. Also, when the sheet metal was first cold-rolled in the second cold roll, in which an oil-in-water emulsion is used, it has been found that the presence of this emulsion on the surface of the sheet metal may cause stains.
    The object of the invention is therefore to provide a new method for producing stainless steel sheet which can overcome the problem of stains caused by the presence of oil or an oil emulsion on the cold-rolled steel sheet.
    For this purpose, the method according to the invention is characterized in that before re-annealing the cold-rolled sheet steel for the production of the sheet metal with the 2D finish, at least one surface of this sheet steel is covered with an extra layer of oil.
    The oil can be applied to both the top and the bottom of the sheet metal. Usually, however, it will only be applied on the top, namely on that surface of the sheet steel that will later be used as the visible side.
    Surprisingly, it was found that due to the presence of the continuous layer of oil on the surface of the sheet metal to be re-annealed, virtually no stains could be found on the sheet steel produced, in particular not on the sheet steel with the 2D or the 2B finish. The extra amount of oil that has to be applied to the sheet metal for this purpose burns completely in the annealing furnace used for the production of the sheet steel with the 2D or 2B finish and thus leaves no residue.
    In an embodiment of the method according to the invention, said oil is sprayed onto the surface of the cold-rolled steel sheet before re-annealing and preferably distributed thereon, for example by means of a roller.
    In this way, the oil can be applied quickly and easily in a continuous layer.
    In a further embodiment of the method according to the invention, said oil used for applying said extra layer is spread and / or rolled over said surface. The oil itself can be sprayed on the roller and / or on the surface of the sheet metal.
    In this embodiment, a thin oil film can be applied to the surface of the sheet metal in a simple and quick manner.
    In an embodiment of the method according to the invention, said oil which is used for applying said extra layer consists of mineral oil.
    In an embodiment of the method according to the invention, said oil used for applying said additional layer is substantially free of water.
    With water-free oil, the best results are obtained for avoiding stains on the sheet metal with the 2D or 2B finish.
    In an embodiment of the method according to the invention, said extra layer of oil is applied in an amount of at least 1.0 ml, preferably at least 1.5 ml and more preferably at least 2.0 ml of oil per square meter of said surface.
    In an embodiment of the method according to the invention, the sheet steel has a thickness before cold rolling which is reduced by cold rolling by at least 25%, preferably by at least 30% and more preferably by at least 35%.
    The stronger flat rolling offers the advantage that the sheet material is not only thinner but also smoother.
    In an embodiment of the method according to the invention, during the annealing and re-annealing of the steel sheet, the steel sheet is heated to a temperature of at least 800 ° C, preferably to a temperature of at least 900 ° C.
    At these temperatures, the oil applied to the sheet metal burns or disappears / decomposes.
    In an embodiment of the method according to the invention, at least a part of the sheet metal with the 2D finish, and preferably almost all the sheet steel with the 2D finish, is passed through a surface roller at least once in order to obtain stainless steel with a 2B finish that has a shinier surface than the stainless steel sheet with the 2D finish. Preferably, the sheet metal has a thickness before the treatment with the surface roller which is not reduced, or at the most by 1%, by the treatment with said surface roller.
    In this embodiment, the surface quality of the sheet metal is improved. A further annealing step is not necessary here because the internal structure of the sheet metal has not been changed by the surface roller.
    In an embodiment of the method according to the invention, at least a part of the sheet metal with the BA finish, and preferably almost all the sheet steel with the BA finish, is passed through a surface roller at least once in order to obtain a shinier surface obtained. Preferably, the sheet metal has a thickness before the treatment with the surface roller which is not reduced, or at the most by 1%, by the treatment with said surface roller.
    Also in this embodiment the surface quality of the already glossy sheet steel is further improved. A further annealing step is not necessary here because the internal structure of the sheet metal has not been changed by the surface roller.
    In one embodiment of the method according to the invention, it is characterized in that, for producing the stainless steel sheet with the 2D finish, said pickling paths are in a first configuration, in which said series of pickling baths are divided into a first series with at least the first three pickling baths and in a second series of at least one acid pickling bath, and wherein the pickling baths of said first series of pickling baths each contain a mixed acid pickling agent based on at least hydrogen fluoride and sulfuric acid and / or nitric acid, wherein said acid pickling bath is an acid pickling agent based on at least hydrogen fluoride and wherein the passivating pickling bath contains a passivating pickling agent based on at least hydrogen fluoride and nitric acid, or in a second configuration, wherein the pickling baths of said first series each contain a hydrochloric acid pickling agent based on at least hydrochloric acid, wherein said acid pickling bath contains a further acid picking agent on base of at least hydrogen fluoride and wherein the passivating pickling bath contains a further passivating pickling agent based on at least hydrogen fluoride and nitric acid; and that, for producing the stainless steel sheet with the BA finish, said pickling baths are in said second configuration.
    It has been found that for the annealed BA finish, the best surface quality of the glossy sheet steel can be obtained by the second pickling bath configuration, namely by a sequence of pickling baths in which the first series contains a hydrochloric acid based pickling agent. The hydrochloric acid pickling agent, in particular, makes it possible to pickle away the grain boundary attack in order to obtain the desired gloss effect. For the 2D, or the 2B finish to be further produced therefrom, it was found that in order to obtain a good surface quality, it was possible to use the first configuration of pickling baths, namely to mix the acid with hydrogen fluoride and sulfuric acid and / or nitric acid. to be used in the first series of pickling paths and thus it was not necessary to use hydrochloric acid which is difficult to regenerate or recycle. For the 2D and 2B finishes, the use of the mixing acid of the first configuration in the successive pickling baths of the first series was found to be most suitable.
    In an embodiment of the method according to the invention, said passivating mordant is a mordant based on hydrogen fluoride, nitric acid and sulfuric acid and said further passivating mordant is a mordant based on hydrogen fluoride and nitric acid.
    Thus, in this embodiment, the pickling agent in the passivating pickling bath contains additional sulfuric acid for stronger pickling when the pickling baths are in their first configuration in which pickling is mainly done with the less strong mixed acid pickling agent.
    Preferably, during the production of the stainless steel with the 2D finish, with the pickling baths in said first configuration, sulfuric acid is metered into said passivating pickling bath to compensate for sulfuric acid reacting therein during pickling.
    In this way, an improved pickling can be obtained without using the stronger pickling hydrochloric acid pickling agent in the first set of pickling baths.
    In an embodiment of the method according to the invention, said acid pickling agent is a hydrofluoric acid and sulfuric acid pickling agent and said further acid pickling agent is a hydrogen fluoride based pickling agent.
    In this embodiment, the pickling agent in the acid pickling bath contains additional sulfuric acid so as to be able to pick more strongly when the pickling baths are in their first configuration in which pickling is mainly done with the less strong mixed acid pickling agent.
    Preferably, during the production of the stainless steel with the 2D finish, with the pickling baths in said first configuration, sulfuric acid is metered into said pickling pad to compensate for sulfuric acid which reacts during pickling.
    In this way, an improved pickling can be obtained without using the stronger pickling hydrochloric acid pickling agent in the first set of pickling baths.
    In an embodiment of the method according to the invention, said mixed acid pickling agent, said acid pickling agent and said passivating pickling agent contain sulfuric acid, wherein during the production of the stainless steel sheet with the 2D finish, with the pickling baths in said first configuration, sulfuric acid in said pickling baths, in said acid pickling bath and dosed into said passivating pickling bath to compensate for sulfuric acid which reacts away during pickling.
    In this way, the required pickling action of the mixed acids in the different baths during pickling can be maintained.
    In an embodiment of the method according to the invention, the mixed acid pickling agent which is in the first configuration in the last or the last pickling baths of said first series is a mixed acid pickling agent based on hydrogen fluoride and sulfuric acid and the mixed acid pickling agent which is at least in the first configuration in the first or at least in the first two pickling paths of said first series there is a mixed acid pickling agent based on hydrogen fluoride, sulfuric acid and nitric acid.
    In this embodiment, the pickling action of the first or the first two pickling baths is enhanced in order to be able to optimally address the part of the black oxide skin that is still on the sheet steel at that time.
    In an embodiment of the method according to the invention, said first series of pickling baths contains at least four pickling baths.
    In an embodiment of the method according to the invention, the mordant is sprayed onto the sheet steel in said pickling paths, the sheet metal preferably also being dipped in the mordant.
    By spraying the mordant onto the sheet metal, the stained material is removed more efficiently, so that pickling can be done more efficiently, especially when the sheet metal is also immersed in the mordant.
    Further advantages and details of the invention will become apparent from the following description of some special embodiments of the method according to the invention. This description is made with reference to the accompanying drawings in which: Figure 1 schematically shows an overview of the first production line used in an embodiment of the method according to the invention for producing sheet steel with an HRAP finish; Figures 2A to 2C schematically show three different cold rolling used for cold rolling a part of the sheet steel with the HRAP finish produced in the first production line shown in Figure 1; Figure 3 schematically shows an overview of a first Embodiment of a second production line used in an Embodiment of the method according to the invention for further processing of the cold-rolled sheet steel into sheet metal with a 2D finish; Figure 4 schematically shows a surface roller for making the sheet steel smoother and more glossy, in particular for further finishing the sheet steel with the 2D finish obtained in the second production line according to Figure 3, to sheet steel with a 2B finish; Figure 5 schematically shows an overview of a second embodiment of the second production line used in an embodiment of the method according to the invention for further processing of the cold-rolled sheet steel, which second production line corresponds to the second production line according to Figure 3, inline a surface roller as shown in Figure 4, thus producing sheet metal with a 2B finish directly; Figure 6 schematically shows an overview of a third production line, namely a blank annealing line, used in an embodiment of the method according to the invention for further processing the cold-rolled sheet steel into sheet steel with a BA finish; and Figure 7 shows two successive pickling baths from the first production line shown in Figure 1 with the associated reservoirs required to replace the pickling solution in both pickling baths.
    The invention generally relates to a method of producing stainless steel sheet with different finishes. In particular, sheet steel with an HRAP finish (hot rolled, annealed and pickled - “Hot Rolled Annealed and Pickled”), sheet steel with a 2D finish (cold rolled, annealed and pickled) and sheet steel with a BA finish (cold rolled and bright annealed - "Bright Annealed") produced. Both the sheet metal with the BA finish and the sheet steel with the 2D finish are usually made more glossy by passing it through a surface roller. The matte 2D finish is thus converted into the more glossy 2B finish.
    The stainless steel contains iron and at least 10.5% by weight of chromium. The carbon content is a maximum of 1.2% by weight. The stainless steel can further contain other elements such as nickel, molybdenum, titanium, manganese, copper, aluminum, etc. The stainless steel can be of the austenitic, ferritic or duplex type. The invention applies in particular to the production of stainless steel of the austenitic type, but can also be used in the production of the other steel types.
    In particular, all steel grades described in EN 10088-1: 2014 can be produced.
    After producing the stainless steel material itself in the various electric arc furnaces and the AOD refining units, it is cooled and solidified in a continuous casting plant and burned to length. These slabs are, at a high temperature, hot rolled into rolls of sheet steel 1 with a thickness of, for example, 1.85 to 13.5 mm. Due to the high temperature to which the steel has been subjected, a relatively thick, black oxide skin has formed on the sheet steel. Furthermore, the steel has hardened during hot rolling and tensions have built up in it. The method according to the invention now relates to the further processing of these black rolls of sheet steel into the sheet steel with the finishes described above.
    A first continuous production line that is used for this is shown schematically in figure 1. At the beginning of the line, the black rolls of sheet steel 1 are unrolled and welded together by means of a welding machine 2 to form a continuous strip of sheet steel 3. This continuous strip of sheet steel 3 is guided over different rollers 4 through the first production line. A number of the rollers 4 are arranged in an S-configuration in order to be able to exert sufficient grip and traction on the strip of sheet steel 3 and are each driven by means of electric motors 5 through a reduction gearbox 6. The speed of the electric motors 5 can be controlled to adjust the line speed, depending on the thickness and / or material of the sheet steel 3 passing through the production line. The gearbox 6 also allows shifting in high or low gear. The production line must always be shut down to change the gear.
    In a first section of the production line, the sheet steel accumulator 7, the strip of sheet steel 3 is guided zigzag over rollers 4. The distance between these rollers 4 can be changed in order to accumulate more or less sheet steel in this first zone, such that, for instance during welding of the rolls of sheet steel 1, the sheet steel 3 still remains at a constant speed throughout the production line and in particular can continue to move through its annealing furnace.
    After all, after the first section there is an annealing furnace 8 in the first production line in which the sheet steel 3 is heated to a temperature of at least 800 ° C, and more particularly to a temperature of at least 900 ° C. The temperature in the annealing furnace 8 is usually below 1200 ° C. In the annealing furnace 8, the sheet metal 3 undergoes a certain temperature profile, as a result of which the stresses disappear from the sheet steel 3 and the desired internal structure is obtained.
    After the annealing furnace 8, a quench section 9 follows in which the sheet steel 3 is cooled again by means of water and, optionally, air. The sheet steel 3 then passes through a dryer 10 in which it is dried. After the dryer 10, an oxide breaker 11 follows, in which the relatively thick, black oxide skin on the sheet steel 3 is broken.
    In a next step, the sheet metal 3 is passed through a blasting machine 12 with which metal grains are blasted on the oxide skin of the sheet steel 3 to make it loose and porous. The oxide skin is then mechanically removed as much as possible by means of brushes 13.
    After an electrochemical pickling, in the electrochemical pickling baths 14, the sheet steel 3 is brushed again, with the brushes 15, and the sheet steel 3 is then rinsed, in the rinsing bath 16 in which the rinsing agent is sprayed on the sheet steel 3.
    In the chemical pickling section, with six successive chemical pickling baths 17A-F, the sheet steel 3 is then pickled and passivated in the last pickling bath 17F. The last pickling bath is therefore a passivating pickling bath 17F. After the chemical pickling, the sheet steel 3 is again rinsed in a rinsing bath 55, dried in a dryer 18 and then zigzagged through an accumulator 19. In an inspection station 20, the quality of the steel can be monitored, after which the continuous strip of sheet steel 3 is cut into pieces again, with metal shears 21, and rolled into rolls 22 with the sheet steel with the HRAP finish. A part of these rolls 22 can be used as a final product, optionally after first cutting them into plates. The stainless steel sheet with the HRAP finish is matte and gray in color and has a fairly rough surface. The thickness of this sheet steel is the same as the thickness of the hot-rolled sheet steel, and is in particular included between 1.85 and 13.5 mm.
    In the first place, this can be cold-rolled for the further finishing of the HRAP sheet steel. The HRAP sheet steel with a maximum thickness of 10 mm and preferably with a thickness less than or equal to 8 mm is particularly suitable for this. By cold rolling, the thickness of the sheet steel 3 is firstly reduced to the desired final thickness. In particular, this thickness is reduced by 25 to 75%, and preferably by at least 30%, and more preferably by at least 35%. In addition to obtaining the desired final thickness, the rolling has additional objectives, such as obtaining good flatness, a high surface quality and the desired mechanical properties (crystal structure). Different types of rollers can be used for cold rolling.
    The first type is a quarto roll 23, which is shown schematically in Figure 2a. The roller group of such a roller consists of two working cylinders 24 between which the sheet metal 3 is rolled and two much larger supporting cylinders 25. The supporting cylinders 25 serve to absorb the enormous forces acting on the working cylinders 24. The desired decrease in thickness is obtained by passing the sheet steel 3 through this roller 23 one or more times, the sheet steel being unrolled and rolled in front and behind the sheet. To avoid damage to the sheet metal 3 and to the cylinders, the roll gap is cooled with an oil emulsion which in particular contains only a small percentage of oil.
    A second type of roller is a sexto roller 26 which is shown schematically in Figure 2b. This roller again contains two working cylinders 24 and two supporting cylinders 25, but an intermediate cylinder 27 is still arranged between the working and supporting cylinders. Both in the quarto roller 23 and in the sexto roller 26, an oil-in-water emulsion is used for lubricating the rolling and crushing action of the working cylinders 24 on the sheet steel 3.
    The roller 28, shown in figure 2C, is a twenty roller roller and contains two working cylinders 24, eight supporting cylinders 25 and ten intermediate cylinders 27 therebetween. This roller 28 allows optimum pressure distribution and very finely ground working cylinders 24, in combination with clean mineral oil instead of the oil emulsion, a high-quality surface quality can be obtained. This twintig roller 28 is used in particular for the production of sheet steel with the high-gloss or BA finish. After all, due to the absence of water in the oil of the twintig roller 28, this oil does not cause oxidation of the sheet metal in the BA annealing furnace.
    After cold rolling, the sheet metal 3 must be re-annealed to remove the stresses from the material again and to obtain the desired crystal structure therein.
    This can happen in a second production line that is built approximately the same as the first.
    The main parts of a possible embodiment of the second production line are shown in figure 3.
    These parts again include a welder 29, an accumulator 30, an annealing furnace 56, electrochemical pickling baths 31, chemical pickling baths 32A-F including a passivating pickling bath 32F, a dryer 33, an accumulator 34, and a metal shear 35. The sheet steel thus produced has a 2D finish, and has a rather matte appearance, and is rolled up into rolls 36. To improve the surface quality of this sheet steel, the rolls 36 are further treated with a surface roller 37, shown in figure 4. This surface roller has only two working cylinders 38 which exert only a limited pressure on the sheet steel 3, such that the thickness of the sheet steel is not reduced, or in any case reduced by less than 1%.
    By the action of the surface roller 37, the quality of the surface of the sheet steel 3 can be further improved and in particular the rather matte 2D finish is transformed into the more glossy 2B finish.
    In order to make optimum use of the twintig roller 28, it is used not only in the production of the sheet steel 3 with the BA finish, but also in the production of part of the sheet steel with the 2D or 2B finish.
    In order to avoid stains on the sheet steel with the 2D or 2B finish as a result of the oil remaining on the surface thereof after cold rolling, a spraying installation 57 is provided for the further annealing furnace 56, with which an extra layer of oil is applied to the the top surface of the cold-rolled steel sheet 3 is sprayed, which is then further rolled out by means of a roll. The same oil or a different type of oil can be used here as it was applied to the working cylinders 24 of the cold roll 28 with which the relevant sheet steel 3 was cold-rolled. It was found that in this way the appearance of stains on the end product due to the presence of the rolling oil could be optimally avoided.
    Even if the sheet metal is first cold-rolled in the quatro roller 23 or in the sexto-roller 26, in which an oil emulsion is always used, it is advantageous to apply a continuous layer of oil on the surface of the cold-rolled sheet steel before after all, it is also possible to prevent the occurrence of stains caused by the presence of the limited amount of oil-in-water emulsion on the surface of the sheet metal.
    Figure 5 schematically shows a second embodiment of the second production line in which the surface roller 37 is incorporated at the back of the production line itself. In this way, sheet metal with the 2B finish is produced immediately and the rollers 36 therefore no longer have to be treated separately with the surface roller 37.
    Figure 6 shows the main parts of a third production line, namely a production line for producing sheet steel 3 with a high-gloss finish (BA finish). This third production line contains a welding machine 39, an accumulator 40, a BA annealing furnace 41 with a reducing atmosphere, in particular with an atmosphere based on hydrogen gas, a further accumulator 42 and a metal shears 43. The produced sheet metal with the BA finish is rolled up into rollers 44. These rollers 44 are preferably also treated with the surface roller 37 to improve the gloss and the surface quality of the sheet metal.
    The rolls of sheet steel with the HRAP finish, the 2D finish, the 2B finish and the BA finish can be such a hot end product, but can also be cut into plates or strips.
    In the method of producing steel sheet with the different finishes, the first production line, shown in Figure 1, is used in the production of all the different finishes. A problem here is that the composition of the acids in the pickling paths 17A-F has to be adjusted. For the production of sheet steel with the HRAP finish, the 2D finish and the 2B finish, the pickling baths can use a mixed acid pickling agent, while for the production of sheet steel with the BA finish it is essential that the sheet steel in the first production line is treated with hydrochloric acid pickling agent. Such hydrochloric acid pickling agent can in theory also be used for the production of the other finishes, but in practice this is not possible due to the fact that it is not possible to process all the chlorinated waste water that would be created by this. In the method according to the invention, therefore, the composition of the pickling baths is changed regularly in order to be able to produce the different finishes alternately, on order.
    Figure 7 gives a schematic overview of the first two pickling seams 17A and B of the first production line. The other pickling baths are constructed in the same way. As can be seen in more detail in this overview, the pickling baths are thus contained two by two in separate tanks 45. The pickling agent in both pickling baths is separated by a partition 46 such that it cannot flow from one pickling bath to another. The mordant itself is introduced into the mordant baths by spraying the mordant both at the top and at the bottom of the sheet metal by means of nozzles 47.
    The pickling agent sprayed into the pickling baths, in particular in the first pickling bath 17A, according to the first configuration described below, is pumped via the discharge pipes 48 and the pump 49A into a settling tank 50A from which it overflows into a reservoir 51A. The mordant is then again sprayed from this reservoir 51A by means of a pump 52A through a conduit 53A into the mordant bath 17A. The sediment formed in the settling tank 50A can be pumped out by means of a pump 54A.
    In order to be able to exchange the pickling agent in the pickling baths in order to thus obtain the second configuration described below, the same second system for the second pickling agent is provided, namely a discharge pump 49A ', a settling tank 50A', a reservoir 51A ', a pump 52A', a line 53A 'and a sedimentation pump 54A'. For the second pickling bath, also shown in Figure 7, and for the subsequent pickling paths, the same numbers are used for these elements but with the letter corresponding to the letter of the pickling bath.
    In the first configuration, namely in the configuration with the mixed acid pickling agent for the production of the HRAP, 2D or 2B finish, the first and second pickling baths 17A and B contain a mixed acid pickling agent containing mainly hydrogen fluoride, sulfuric acid and nitric acid, the third and fourth pickling pads 17C and D a mixed acid pickling agent with predominantly hydrogen fluoride and sulfuric acid, the fifth pickling bath, namely said acid pickling bath 17E, an acid pickling agent again containing mainly hydrogen fluoride and sulfuric acid, and the sixth pickling bath, said passivating pickling bath 17F, a passivating pickling agent with mainly hydrogen fluoride, nitric acid and sulfuric acid.
    Through a connection (not shown) between the reservoirs 51A-E for this mixed acid pickling agent, the pickling agent is preferably flowed in cascade from the fifth 51E to the first reservoir 51A so as to be able to pickling in the fifth pickling bath 17E with purer pickling agent, i.e. pickling agent with less salts dissolved therein.
    In each of the pickling baths, the free acid content is preserved during the pickling by additionally adding sulfuric acid. In the first and second pickling bath, the nitric acid is dosed to enhance its pickling action.
    In the second configuration, namely in the configuration with the hydrochloric acid pickling agent for the production of the BA finish, the first to the fourth pickling bath 17A-D contains a hydrochloric pickling agent with mainly hydrochloric acid, the fifth or said acid pickling bath 17E, a further acid pickling agent with mainly hydrogen fluoride, and the sixth or said passivating pickling bath 17F, a further passivating pickling agent containing mainly hydrogen fluoride and nitric acid.
    To switch from the first to the second configuration or vice versa, the first production line is no longer shut down. The switch from the first to the second configuration or vice versa is carried out during the production of sheet metal with the 2D or 2B finish.
    To switch from the first to the second configuration, one continues to produce sheet steel with the 2D or 2B finish. In a first step, the mixed acid pickling agent in the fourth pickling bath 17D is replaced by the hydrochloric acid pickling agent by first pumping the pickling bath into the reservoir 51D, which takes about fifteen minutes, and then the sheet metal in the fourth pickling bath 17D with the hydrochloric pickling agent from reservoir 51D to spray. Subsequently, the dosage of sulfuric acid in the acid pickling bath 17E and in the passivating pickling bath 17F can be stopped such that the sulfuric acid can be used therein to form the further acid pickling agent and the further passivating pickling agent with no or virtually no sulfuric acid. After all, the hydrochloric acid pickling agent in the fourth pickling bath 17D has a sufficiently strong effect at that time to sufficiently stain away any drying stains.
    After all, in the next step, the third pickling bath 17C is emptied and the mixed acid pickling agent therein is replaced by the hydrochloric acid pickling agent. The same then happens for the second pickling bath 17B and finally for the first pickling bath 17A. As soon as the hydrochloric acid pickling agent is sprayed onto the sheet metal in the first pickling bath 17A, this sheet steel can be used for the production of sheet metal with the BA finish.
    In order to switch from the second configuration to the first configuration again, production of sheet metal with the 2D or 2B finish is started again. In a first step, the hydrochloric acid pickling agent in the first pickling bath 17A is replaced by the mixed acid pickling agent by first pumping the pickling bath empty into the reservoir 51A ', which takes about fifteen minutes, and then placing the sheet steel in the first pickling bath 17A with the mixed acid pickling agent from the reservoir. 51A. In the next step, the second pickling bath 17B is emptied and the hydrochloric acid pickling agent therein is replaced by the mixed acid pickling agent. The same then happens for the third pickling bath 17C and finally for the fourth pickling bath 17D.
    Before the fourth pickling bath 17D is emptied, sulfuric acid is added to the acid pickling pad 17E and to the passivating pickling bath 17F, preferably when the hydrochloric acid pickling agent in the third pickling pad 17C is replaced by the mixed acid pickling agent. In this way, the acid pickling bath 17E and the passivating pickling bath 17F have a stronger pickling action when the fourth pickling bath 17D becomes empty and thus dry spots can be formed on the sheet metal. After all, these drying spots are already at least partially eliminated by the stronger pickling action of the latter two pickling baths 17E and F.
    As soon as the mixed acid pickling agent is sprayed onto the sheet steel in the fourth pickling bath 17D, this sheet steel can no longer be used for the production of sheet steel with the 2D or 2B finish, but also for the HRAP finish.
    Inspection of the produced sheet steel with the different finishes showed that during the exchange of the pickling bath configuration in the manner described above, no significant quality deviations of the sheet steel produced during the exchange with the 2D or the 2B finish could be detected, and that the prescribed quality requirements have been met. However, if sheet metal with the BA finish, or with the HRAP finish, was produced during the exchange, quality deviations were found, which in particular for the BA finish were such that the prescribed quality requirements were no longer met. The same was noted when the replacement of the pickling solutions in the different pickling baths was not carried out in the order described above.
    For the tests carried out, the different pickling baths each had a length of approximately seventeen meters. Because the sheet steel with the 2D or 2B finish had a thickness of less than 8 mm, and was thus guided through the first production line relatively quickly, the residence time thereof in the different baths varied between 15 and seconds.
    权利要求:
    Claims (18)
    [1]
    Method for producing stainless steel sheet finished in at least two different ways, including a 2D finish and a BA finish ("Bright Annealed"), in which the method is based on rolls (1) of hot-rolled, not yet pickled sheet steel that which are each unwound at a predetermined, substantially constant speed, through at least one first production line, said first production line comprising at least one annealing furnace (8), a series of at least four successive pickling baths (17A-E) and at least one thereon subsequently contains a passivating pickling bath (17F), the process for producing the 2D finished stainless steel sheet being carried out in said first production line and further in at least a first (28) or in at least a second cold rolling mill (23, 26 ) and in a second production line containing at least one further annealing furnace (56), a number of further successive pickling baths (32A-E)) and at least one further passiver end pickling bath (32F), and comprising the following steps: - providing at least one of said rollers (1) hot-rolled, un-pickled sheet steel (3); - unrolling the sheet metal roll; - guiding the unrolled sheet steel (3) at a substantially constant speed through said first production line for successively annealing, pickling and passivating the unrolled sheet steel; - cold rolling of the passivated sheet steel, wherein during cold rolling in said first cold rolling mill (28) oil substantially free of water is applied to the sheet metal and in said second cold rolling mill (23, 26) an emulsion of oil in water; - re-annealing, pickling and passivation
    24, BE2019 / 5932 cold-rolled sheet steel in said second production line; and - removing from the second production line the thus obtained sheet steel with the 2D finish; and wherein the method for producing the BA finished stainless steel sheet is carried out in said first production line and further in said first cold rolling mill (28) and in a third production line, without pickling baths but with at least one BA annealing furnace (41) containing a reducing atmosphere, and comprising the following steps: - providing at least one of said rollers (1) hot-rolled, not yet pickled sheet steel (3); - unrolling the sheet metal roll; - guiding the unrolled sheet steel (3) at a substantially constant speed through said first production line for successively annealing, pickling and passivating the unrolled sheet steel; - cold rolling of the passivated sheet steel, wherein during the cold rolling said oil which is substantially free of water is applied to the sheet steel; re-annealing the cold-rolled steel sheet under said reducing atmosphere in said third production line; and - removing the thus obtained sheet metal with the BA finish from the third production line, characterized in that before annealing the cold-rolled sheet steel for the production of the sheet steel with the 2D finish, at least one surface of this sheet steel is covered with an extra layer of oil.
    [2]
    Method according to claim 1, characterized in that said oil is sprayed onto the surface of the cold-rolled steel sheet before re-annealing.
    [3]
    Method according to claim 1 or 2, characterized in that said oil used for applying said additional layer is spread and / or rolled over said surface.
    [4]
    Method according to any one of claims 1 to 3, characterized in that said oil used for applying said additional layer consists of mineral oil.
    [5]
    Method according to any one of claims 1 to 4, characterized in that said oil used for applying said additional layer is substantially free of water.
    [6]
    Method according to any one of claims 1 to 5, characterized in that said additional layer of oil is applied in an amount of at least 1.0 ml, preferably at least 1.5 ml and more preferably at least 2.0 ml oil per square meter of said surface.
    [7]
    Method according to any one of claims 1 to 6, characterized in that before the cold rolling, the sheet steel (3) has a thickness which by cold rolling by at least 25%, preferably by at least 30% and more preferably by at least Is reduced by 35%.
    [8]
    Method according to any one of claims 1 to 7, characterized in that during the annealing and re-annealing of the sheet metal, the sheet metal is heated to a temperature of at least 800 ° C, preferably to a temperature of at least 900 ° C C.
    [9]
    Method according to any one of claims 1 to 8, characterized in that at least a part of the sheet steel with the 2D finish, and preferably almost all the sheet steel with the 2D finish, at least once through a surface roller (37 ) in order to produce stainless steel sheet with a 2B finish that has a shinier surface than the stainless steel sheet with the 2D finish.
    [10]
    Method according to any one of claims 1 to 9, characterized in that at least part of the sheet metal with the BA finish, and preferably almost all sheet steel with the BA finish, at least once through a surface roller (37 ) is obtained in order to obtain a shinier surface.
    [11]
    Method according to claim 9 or 10, characterized in that before the treatment with the surface roller (37), the sheet steel (3) has a thickness which is not reduced, or at the most by 1%, by the treatment with said surface roller.
    [12]
    Method according to any one of claims 1 to 11, characterized in that, for producing the stainless steel sheet with the 2D finish, said pickling baths (17A-E) are in a first configuration, wherein said series of pickling baths is divided into a first series comprising at least the first three pickling baths (17A-D) and in a second series comprising at least one acid pickling bath (17E) and wherein the pickling baths (17A-D) of said first series pickling paths each comprise a mixed acid pickling agent based on at least hydrogen fluoride and sulfuric acid and / or nitric acid, wherein said acid pickling bath (17E) contains an acid pickling agent based on at least hydrogen fluoride and wherein the passivating pickling bath contains a passivating pickling agent based on at least hydrogen fluoride and nitric acid, or in a second configuration, wherein the pickling baths (17A-D) of said first series each contain a hydrochloric acid pickling agent based on at least hydrochloric acid, wherein said pickling pad (17E) e and further comprising at least hydrogen fluoride acid pickling agent and wherein the passivating pickling bath contains a further passivating pickling agent based on at least hydrogen fluoride and nitric acid; and that, for producing the stainless steel sheet with the BA-
    finish, said pickling baths (17A-E) are in said second configuration.
    [13]
    Method according to claim 12, characterized in that said passivating mordant is a hydrofluoric, nitric and sulfuric acid mordant and said further passivating mordant is a hydrofluoric and nitric acid mordant.
    [14]
    Method according to claim 12 or 13, characterized in that during the production of the stainless steel sheet with the 2D finish, with the pickling baths (17A-E) in said first configuration, sulfuric acid is metered into said passivating pickling bath (17F) to compensate sulfuric acid which reacts during pickling.
    [15]
    Method according to any one of claims 12 to 14, characterized in that said acid pickling agent is a hydrofluoric acid and sulfuric acid pickling agent and that said further acid pickling agent is a hydrogen fluoride based pickling agent.
    [16]
    Method according to claim 15, characterized in that during the production of the stainless steel sheet with the 2D finish, with the pickling baths (17A-E) in said first configuration, sulfuric acid is metered into said acid pickling bath (17E) to compensate for during the pickling reactive sulfuric acid.
    [17]
    Method according to any one of claims 12 to 16, characterized in that said mixed acid pickling agent, said acid pickling agent and said passivating pickling agent contain sulfuric acid, wherein during the production of the stainless steel sheet with the 2D finish, with the pickling paths (17A-E) said first configuration, sulfuric acid is metered into said pickling baths (17A-E) and into said passivating pickling bath (17F) to compensate for sulfuric acid which reacts away during pickling.
    [18]
    A method according to any one of claims 12 to 17,
    characterized in that the mixed acid pickling agent which is in the first configuration in the last or last pickling seams (17C and D) of said first series is a hydrofluoric acid and sulfuric acid mixing acid pickling agent and that the mixed acid pickling agent which is at least in the first or at least in the first configuration at least in the first two pickling baths (17A and B) of said first series is a hydrofluoric, sulfuric and nitric acid mixed acid pickling agent.
    类似技术:
    公开号 | 公开日 | 专利标题
    JP3888396B2|2007-02-28|Continuous production method of rolled stainless steel sheet and production line for carrying out it
    KR900007072B1|1990-09-28|Method and apparatus for manufacturing coldrolled steel strip
    US5759307A|1998-06-02|Method of producing a cold-rolled strip in one pass
    AU2003271666B2|2009-03-12|Method and device for descaling and/or cleaning a metal casting
    JP2613317B2|1997-05-28|Annealing and descaling of stainless steel strip
    KR100331193B1|2002-10-18|Method of Manufacturing Hot Rolled Mild Steel Strip. Descaling Method and Equipment thereof
    CN108031717A|2018-05-15|A kind of pickling phosphorus removing method of Cold-strip Steel Surface
    BE1026913B1|2020-07-22|Process for producing stainless steel sheet finished in at least two different ways
    BE1026911B1|2020-07-22|Method for producing stainless steel sheet finished in at least three different ways
    US5725696A|1998-03-10|Process and plant for production of raw stainless steel castings
    BE1026912B1|2020-07-22|Method for producing stainless steel sheet finished in at least three different ways
    JP2006502003A|2006-01-19|Method and apparatus for continuously producing metal strip
    CN106521523A|2017-03-22|Pickling system and method for hot-rolled strip steel
    JP3370618B2|2003-01-27|Pickling method for stainless steel cold rolled steel strip
    JP2517353B2|1996-07-24|Descaling method for stainless steel strip
    JP2689845B2|1997-12-10|Descaling method for hot rolled steel
    JPH05177238A|1993-07-20|Method for descaling hot-rolled steel strip
    KR102020438B1|2019-09-10|Pickling Device and Pickling Method
    JP2001191108A|2001-07-17|Descaling method and device for the same
    JP3457464B2|2003-10-20|Method for smooth pickling of hot-rolled austenitic stainless steel strip
    JPH0949092A|1997-02-18|High efficient pickling process of austenitic stainless steel plate
    JP2002294477A|2002-10-09|Pickling method for hot rolled steel strip superior in surface quality after pickling
    SU637438A1|1978-12-15|Method of rolled stock treatment
    JPH07138800A|1995-05-30|Production of hot rolled ordinary steel strip, descaling method and its equipment
    JPH1161466A|1999-03-05|Production of stainless steel strip having excellent surface characteristic, and continuous annealing and pickling device
    同族专利:
    公开号 | 公开日
    BE1026913A1|2020-07-14|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2020-08-26| FG| Patent granted|Effective date: 20200722 |
    优先权:
    申请号 | 申请日 | 专利标题
    BE201805928|2018-12-20|
    [返回顶部]