• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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  • 优先权
    • 专利摘要:
    method for producing a flat steel product to produce a flat steel product with an elastic limit of> 700 mpa and with a bainitic structure of> 70% by volume, the following operational steps according to the invention are carried out: a) melting of a melt of steel, which (in% by weight) consists of c: 0.05-0.08%, si: 0.015-0.500%, mn: 1.60-2.00%, p: <0.025%, s: <0.010%, al: 0.020-0.050%, n: <0.006%, cr: <0.40%, nb: 0.060-0.070%, b: 0.0005-0.0025%, ti : 0.090-0.130%, as well as unavoidable impurities, the rest are fe; b) melting the melt to form an ingot; c) reheat the ingot to 1200-1300 ° c; d) pre-lamination of the ingot at 950-1250 ºc and with a total pass reduction of <50%; e) ready hot rolling of the pre-rolled ingot with a final hot rolling temperature of 800-880 ºc; f) cooling of the ready hot rolled steel flat product within <10 s after the ready hot rolling at 50-620 ºc with a cooling speed of <40 k / s; g) winding of the finished hot-rolled flat steel product.
    公开号:BR112016022053B1
    申请号:R112016022053-6
    申请日:2015-03-18
    公开日:2021-04-27
    发明作者:Alexander Gaganov；Wolfgang Gervers；Andreas Kern；Gabriel Kolek；Elena Schaffnit；Hans-Joachim Tschersich
    申请人:Thyssenkrupp Steel Europe Ag；Thyssenkrupp Ag；
    IPC主号:
    专利说明:

    [001] The invention relates to a method for the production of a flat steel product with an elastic limit of at least 700 MPa and with a bainitic structure of at least 70% by volume.
    [002] In the case of flat steel products of the type in question, these are typically rolling products, such as steel strips or sheets, as well as cutouts and platinum produced from them.
    [003] In particular, the invention relates to a method for the production of the so-called highly resistant "thick plates", which have a thickness of at least 3 mm.
    [004] All data relating to the contents of the steel compositions indicated in this application refer to weight, provided that it is not expressly stated otherwise. All "data in%" not specified in detail, which are related to an alloy of steel, should therefore be understood as data in "% by weight".
    [005] Highly resistant flat steel products are particularly important in the area of commercial vehicle construction, as these enable a reduction in the vehicle's dead weight and an increase in payload. A low weight not only contributes to the optimal use of the technical capacity of the respective drive unit, but also supports resource efficiency, cost optimization and climate protection.
    [006] A decisive reduction in the dead weight of steel sheet constructions can be obtained by increasing the mechanical properties, in particular, the stability of the respectively processed flat steel product. In addition to high stability, however, modern flat steel products, expected for the construction of commercial vehicles, are expected, but also good toughness properties, good resistance to fragile breaking, as well as an ideal aptitude for cold molding and welding.
    [007] It is known, that this combination of properties can be obtained through the selection of a suitable alloy concept and by a special production method. In the case of conventional methods for producing highly resistant thick plates with a minimum yield strength of 700 MPa, proceed as follows. Initially, the ingots are hot rolled and after lamination they are cooled in air. Then, the plates are reheated, hardened and subjected to a hardening treatment. The process therefore contains several steps to obtain the mechanical properties. The numerous production steps associated with this process lead to comparatively high production costs. An exact procedure is also required to obtain the desired toughness and surface qualities.
    [008] From EP 2.130.938 A1, a method is known for the production of a hot rolled flat steel product, in which a melt is melted to form an ingot, which in addition to iron and unavoidable impurities contains ( in% by weight) 0.01 - 0.1% by weight, of C, 0.01 - 0.1% by weight, of Si, 0.1 - 3% by weight, of Mn, not more than 0 , 1% by weight, of P, not more than 0.03% by weight, of S, 0.001 - 1% by weight, of Al, not more than 0.01% by weight, of N, 0.005 - 0 , 08% by weight, from Nb and 0.001 to 0.2% by weight, from Ti, and for the respective Nb content% Nb applies and for the respective C content% C:% Nb x% C <4.34 x 10-3.
    [009] After melting and solidifying the melt, in the known method, the steel ingot is reheated to a temperature range, the lower limit of which is determined according to the levels of C and Nb of the respective molten steel and the upper limit of which 1170 oC. Then, the reheated ingot is pre-laminated to a final temperature, which makes 1080 to 1150 oC. After a pause of between 30 and 150 seconds, in which the pre-laminated ingot is kept at 1000 to 1080 oC, the pre-laminated ingot is then hot-rolled, ready to form a hot-rolled strip. The degree of molding of the last pass of the hot rolling should be 3 to 15%.
    [0010] According to the known method, hot rolling is completed at a final hot rolling temperature, which corresponds at least to the Ar3 temperature of the processed steel and amounts to a maximum of 950 0oC. Upon completion of the hot rolling, the obtained hot rolled strip is cooled with a cooling speed of more than 15 oC / s to a winding temperature of 450 to 550 oC, in which it is wound to form a coil.
    [0011] In the hot-rolled strip produced in this way, the density of the carbon grain limit present in the solid solution must make up 1 to 4.5 atoms / nm2 and the size of the cementitious grains separated in the grain boundaries must not make more 1 μm. Flat steel products acquired in this way and produced according to the known method, must have, with sufficiently high dosed alloy levels, tensile strengths of more than 780 MPa and have elastic limits, which amount to up to 726 MPa. Thus, the hot-rolled strip produced in a known manner must have a particularly suitable combination of properties for use in the construction of automobiles. An ideal surface nature must be obtained, in this case, by the fact that the reheat temperature, to which the ingot is heated before hot rolling, is limited to the temperature range mentioned above and, thus, excessive formation is avoided. scale, which in the hot rolling would be incorporated into the surface of the hot rolled strip.
    [0012] In the context of the current state of the art explained above, the aim of the invention was to indicate a method, with which highly resistant steel sheets with optimized mechanical properties with respect to use in the construction of automobiles and with a surface nature also optimized, can be produced according to practice.
    [0013] The invention solves this objective through the method indicated in claim 1.
    [0014] Advantageous modalities of the invention are indicated in the dependent claims and are explained below, individually, as is the general idea of the invention.
    Consequently, a method according to the invention for the production of a flat steel product with an elastic limit of at least 700 MPa and with a bainitic structure of at least 70% by volume, comprises the following operational steps: a) melting of a melt of steel, which (in% by weight) consists of C: 0.05 - 0.08%, Si: 0.015 - 0.500%, Mn: 1.60 - 2.00%, P: up to 0.025%, S: up to 0.010%, Al: 0.020 - 0.050%, N: up to 0.006%, Cr: up to 0.40%, Nb: 0.060 - 0.070%, B: 0.0005 - 0.0025% Ti: 0.090 - 0.130%,
    [0016] as well as technically unavoidable impurities, which include up to 0.12% Cu, up to 0.100% Ni, up to 0.010% V, up to 0.004% Mo and up to 0.004% Sb and
    [0017] as remainder, in iron; b) melting the melt to form an ingot; c) reheating the ingot to a reheating temperature of 1200 - 1300 oC; d) pre-lamination of the ingot at a pre-lamination temperature of 950 - 1250 oC and a reduction in the total pass obtained through pre-lamination of at least 50%; e) ready hot rolling of the pre-laminated ingot, the finished hot rolling being completed at a hot rolling temperature of 800 - 880 oC; f) intense cooling that starts within a maximum of 10 s after the ready hot rolling of the ready hot rolled steel flat product with a cooling speed of at least 40 K / s and a winding temperature of 550 - 620 oC ; g) winding of the finished hot-rolled flat steel product.
    [0018] The method according to the invention is based on an alloy of steel, whose alloy components and alloy contents are coordinated within narrow limits in such a way that in a procedure to be carried out with safe operation respectively properties are obtained maximized mechanics and optimized surface natures.
    [0019] As explained below, the alloy components and alloy contents of the molten steel alloy according to the invention in operational step a) are selected in such a way that, while maintaining the predetermined operational steps according to the invention , a hot rolled flat steel product with a combination of properties can be produced, which makes it particularly suitable for use in the construction of light steel, in particular in the field of commercial vehicle construction:
    [0020] C: the carbon content of the steel processed according to the invention amounts to 0.05 - 0.08% by weight. To obtain the desired strength properties, a C content of at least 0.05% by weight is required. However, if the carbon content is too high, the toughness properties or weldability and moldability of the steel processed according to the invention will be impaired. For this reason, the carbon content is limited to a maximum of 0.08% by weight.
    [0021] Si: the silicon in the steel processed according to the invention is used as a deoxidizing agent, as well as to improve the resistance properties. If, however, the silicon content is too high, the toughness properties, in particular, the toughness in the heat influence zone of solder compounds, will be greatly impaired. For this reason, the silicon content of the steel processed according to the invention must not exceed 0.50% by weight. For the safe prevention of surface quality disturbances, the silicon content can be limited to a maximum of 0.25% by weight.
    [0022] Mn: manganese is added to the steel used in accordance with the invention to adjust the desired strength properties with good toughness properties at levels of 1.6 - 2.0% by weight. If the manganese content is less than 1.60% by weight, the required strength properties will not be achieved with sufficient security. Due to the limitation of the Mn content to a maximum of 2.00% by weight, worsening of weldability, toughness properties, moldability and increase behavior is prevented.
    [0023] P: The phosphorus accompaniment element worsens impact work and moldability. The phosphorus content should therefore not exceed the upper limit of 0.025% by weight. Ideally, the P content is limited to less than 0.015% by weight.
    [0024] S: sulfur worsens the impact work and the moldability of a steel processed according to the invention as a result of the formation of MnS. For this reason, the S content of a steel processed according to the invention must be a maximum of 0.010% by weight. Such a low sulfur content can be obtained in a manner known to you, for example, by treatment with CaSi. In order to safely exclude the negative influences of sulfur on the properties of the steel processed according to the invention, the S content can be limited to a maximum of 0.003% by weight.
    [0025] Al: Likewise, aluminum is used as a deoxidizing agent and, as a result of the formation of AlN, prevents the austenite grain from thickening during austenitization. If the aluminum content is below 0.020% by weight, the deoxidation processes do not proceed completely. If the aluminum content exceeds, however, the upper limit of 0.050% by weight, then inclusions of Al2O3 may form. These act negatively on the degree of purity and the toughness properties.
    [0026] N: The nitrogen accompanying element forms AlN with aluminum or titanium, TiN with aluminum. However, if the nitrogen content is too high, the toughness properties worsen. To avoid this, the upper limit for the nitrogen content in a steel processed according to the invention is set at 0.006% by weight.
    [0027] Cr: chromium can optionally be added to a steel processed according to the invention, to improve its strength properties. When the chromium content is very high, the weldability and toughness in the heat influence zone, however, are negatively influenced. Therefore, in a steel processed according to the invention, the upper limit for the chromium content is set at 0.40% by weight.
    [0028] Nb: niobium is contained in a steel processed according to the invention, to withstand the resistance properties through the fineness of the grain of the austenite structure in the temperature controlled rolling or through the hardening by separation in the winding. For that purpose, 0.060 - 0.070% by weight is present in the steel processed according to the invention. If the niobium content is below this range, the resistance properties are not obtained. If the niobium content is above the upper limit of this range, weldability and toughness worsen in the heat influence zone of a weld.
    [0029] B: the boron content of a steel processed according to the invention, makes up 0.0005 - 0.0025% by weight. B is used to support strength properties and to improve durability. Very high boron contents, however, worsen the toughness properties.
    [0030] Ti: titanium contributes, in the same way, to improve the resistance properties, preventing the growth of the grain during austenitization or through hardening by separation in the winding. To ensure this, the Ti contents of a steel processed according to the invention make up 0.09 - 0.13% by weight. If the titanium content is below 0.09% by weight, the desired resistance values according to the invention are not achieved. If the upper limit of the range of Ti content indicated above is exceeded, weldability and toughness worsen in the heat influence zone of a weld.
    [0031] Cu, Ni, V, Mo and Sb are present as accompanying elements, which occur as a technically unavoidable impurity in the steel production process in the steel processed according to the invention. Its contents are limited to quantities, which are ineffective in relation to the desired properties according to the invention of the steel processed according to the invention. For this purpose, the Cu content is limited to a maximum of 0.12% by weight, the Ni content to less than 0.1% by weight, the V content to a maximum of 0.01% by weight, the Mo content to less than 0.004% by weight and the Sb content, likewise, to less than 0.004% by weight.
    [0032] To obtain good weldability, the C, Mn, Cr, Mo, V, Cu and Ni content of the steel according to the invention, can be adjusted within the predetermined limits according to the invention in such a way that for the EC carbon equivalent calculated according to the EC formula =% C +% Mn / 6 + (% Cr +% Mo +% V) / 5 + (% Cu +% Ni) / 15 with% C = the respective C content in% by weight,% Mn = the respective Mn content in% by weight,% Cr = the respective Cr content in% by weight,% Mo = the respective Mo content in% by weight, % V = the respective V content in% by weight,% Cu = the respective Cu content in% by weight,% Ni = the respective Ni content in% by weight, applies: EC <0.5% by weight .
    [0033] After melting the ingot, it is reheated to an austenitization temperature, which amounts to 1200 - 1300 oC. The value of the upper limit of the temperature range, to which the ingot is heated for austenitization, should not be exceeded, to avoid a thickening of the austenite grain and an increase in scale formation. In the predetermined reheat temperature range according to the invention from 1200 - 1300 oC, there is still no increase in the formation of red scale, which would decrease the surface nature of the flat steel product produced according to the invention. The red scale is formed in the processing of composite ingots according to the invention, exclusively in the hot rolling procedure (operational steps d), e) of the method according to the invention), if after the reheating a lot of primary scale is present on the surface of the ingot.
    [0034] The value of the lower limit of the reheat temperature, on the contrary, is established in such a way that the desired homogenization of the structure is guaranteed with a uniform temperature distribution. After that temperature, a large part of the thick separations of Ti and Nb carbonitride in the austenite present in the respective ingot begins. In the final winding of the finished hot rolled flat steel product (operational step g) of the method according to the invention, new fine separations of Ti or Nb carbonitride can then be formed which, as explained, provide a essential contribution to increase the resistance properties. In this way it is guaranteed that the flat steel products composed and produced according to the invention regularly have a minimum elastic limit of 700 MPa.
    [0035] According to the invention, the reheat temperature in the austenitization of the respective ingot amounts to at least 1200 oC, to obtain the desired effect of the most complete possible dissolution of the TiC and NbC separations. At an austenitization temperature below 1200 oC, the amount of the Ti and Nb carbide separations dissolved in the austenite is, on the contrary, so low that the effects used according to the invention do not occur. A reheating temperature below 1200 oC would therefore have in the processing of flat steel products, which are composed in a way corresponding to the selection of the optimized alloy according to the invention, as a consequence, that the required strength properties would not be obtained. The most complete possible dissolution of the TiC and NbC separations can then be guaranteed in a particularly safe way, if the reheat temperature is at least 1250 oC.
    [0036] A flat steel product, which meets the highest requirements regarding the nature of the surface, can be produced by the fact that, before pre-lamination, the scale present in the ingot is completely removed. This may be due to the fact that the surface of the ingot, after unloading the oven and as much as possible directly before pre-lamination, is completely blasted. For this purpose, the ingot can pass through a conventional scale washer.
    [0037] To produce a flat steel product with optimized surface nature, the time t_l, which the transfer of the ingot from the operational station ("reheating (operational step c)") or "removal of the primary scale (operational step c ' ) ”) Optionally traveled after reheating requires until the start of the ready hot lamination (operational step e)), can be limited to a maximum of 300 seconds. This ideally includes pre-lamination. In such a short transfer time, only such a small amount of primary scale is regenerated, that the red scale that forms from it in hot rolling is harmless to the surface quality of the flat steel product obtained after hot rolling. In the case of stripping before pre-lamination, the duration of transport between the stripping unit and even the structure of the pre-lamination should be a maximum of 30 seconds. With such a short transport time, it is possible, in this way, that no form is formed or, in any case, that a thin layer of harmless oxide is formed in the previously blasted ingot.
    [0038] In operational step d), the ingot respectively processed is pre-laminated at a pre-lamination temperature of 950 - 1250 oC. The decrease in the pass obtained in the pre-lamination makes a total of at least 50%. As a total decrease in the pass Δhv designated, in this case, the proportion formed of the difference in the thickness of the ingot before (thickness dVv) and after (thickness dNv) of the pre-lamination and the thickness dVv of the ingot before pre-lamination (Δhv [% ] = (dVv = dNv) / dVv x 100%).
    [0039] The lower limit of the predetermined range for the pre-lamination temperature and the minimum value of the total pass decrease Δhv are established, in this case, in such a way that the recrystallization procedures in the respectively pre-laminated ingot can be performed completely. In this way, the formation of a fine-grained austenitic structure is guaranteed before the ready rolling, with which optimized toughness and elongation properties of the flat steel product produced according to the invention are obtained.
    [0040] The dwell time and pause t_2 between the pre-lamination and the ready lamination is limited to 50 seconds, to avoid an unwanted growth of austenite grains.
    [0041] The pre-lamination is followed in the operational step e) the hot lamination of the pre-laminated ingot to form a hot-rolled flat steel product with a thickness of the hot-rolled strip, which is typically 3 - 15 mm . Flat steel products of such thickness are also referred to in the technical language as "plate".
    [0042] The final temperature of the hot rolling mill is, in this case, at 800 - 880 oC. Maintaining this final temperature range of the hot rolling, a very stretched austenite grain is obtained in the structure of the obtained hot-rolled strip. Due to the comparatively low final hot rolling temperature, the effect of the hot rolling increases. In the structure of the hot-rolled strip obtained there is austenite rich in misalignment. After an intense cooling (operational step f)), it becomes a finely structured bainite, rich in misalignment, so that the elasticity limit is increased. The upper limit of the final hot rolling temperature range is set in such a way that no recrystallization of the austenite takes place during the rolling in the hot rolling production line. It also contributes to the expression of a fine-grained structure. The lower limit temperature is at least 800 oC, so that no ferrite is formed during lamination.
    [0043] The decrease in the Δhf pass obtained in the finished lamination makes a total of at least 70%, and here the decrease in the Δhf pass is calculated according to the formula Δhf = (dVf-dNf) / dVf x 100% (with dVf the thickness of the laminated material at the entrance of the finished hot rolling line and dNf is the thickness of the laminated material at the exit of the finished hot rolling line). Due to the high decrease in the Δhf pass, the phase transformation takes place from very molded austenite. This acts positively on the fineness of the grain, so that in the structure of the flat steel product produced according to the invention, small grain sizes are present.
    [0044] After the finished hot rolled flat steel product has left the last structure of the finished hot rolling line, intense cooling begins within a maximum of 10 seconds, in which the hot rolled flat steel product is cooled with a dT cooling speed of at least 40 K / s to a winding temperature of 550 - 620 oC.
    [0045] The cooling pause after the hot lamination is a maximum of 10 seconds, to avoid that, between the hot lamination and the controlled accelerated cooling, unwanted changes in the structure occur.
    [0046] Maintaining the predetermined coiling temperature range according to the invention, conditions are created for the formation of a bainitic structure of the flat steel product produced according to the invention.
    [0047] At the same time, the selection of the winding temperature has a decisive influence on the hardening by separation. For this, the winding temperature range is selected according to the invention in such a way that, on the one hand, it is below the starting temperature of the bainite, on the other hand, at the maximum separation for the formation of separations of carbonitride. A very low winding temperature, however, would lead to the fact that the separation potential would no longer be useful and, in this way, the minimum required elasticity limit would no longer be obtained. The cooling conditions, in this case, are selected according to the invention in such a way that the hot rolled flat steel product presents, immediately before winding, a bainitic structure with a phase ratio of at least 70% by volume . Another formation of bainite then ends at the coil. With regard to the required combination of properties, this is ideally proven in this case if the structure of the hot-rolled flat steel product produced according to the invention consists, after winding, in the technical sense, completely in bainite. This is achieved by maintaining the predetermined winding temperature range according to the invention.
    [0048] Due to the high cooling speed, the formation of undesirable components of the phases is avoided. In order to obtain an optimally flat steel product in this case, the cooling speed of the cooling after hot rolling can be limited to 150 K / s.
    [0049] The yield strength of hot-rolled flat steel products produced according to the invention in the manner explained above, safely amounts to 700 - 850 MPa. Its elongation at break is, in this case, at least 12%, respectively. Likewise, flat steel products according to the invention regularly achieve tensile strengths of 750 - 950 MPa. The impact work determined for the products according to the invention at -20 oC is in the range of 50 - 110 J and at - 40 oC, in the range of 30 - 110 J.
    [0050] Flat steel products produced according to the invention have a fine-grained structure with an average grain size of at most 20 μm, to obtain a good elongation at break and toughness.
    [0051] In this case, in the embodiment according to the invention, the above mentioned properties of a hot rolled flat steel product are present in the rolling state after winding. No further heat treatment is required to adjust or express certain properties important for use as a highly resistant sheet in the construction of commercial vehicles.
    [0052] In the following, the invention is clarified in detail based on examples of execution.
    [0053] A - E steel castings with the composition shown in table 1 were melted and melted in a known manner to form ingots 1 - 26.
    [0054] Then, the ingots formed from A - E steels were heated to a TW reheat temperature.
    [0055] The reheated ingots were transported from the reheating oven in less than 30 seconds to a scale washer, in which the primary scale adhering to it was removed from the ingots.
    [0056] The ingots removed from the scale washer were then transported to a pre-lamination structure, where these were pre-laminated with a TVW pre-lamination temperature and with a total decrease in the Δhv pass obtained through the pre -lamination.
    [0057] Then, the pre-laminated ingots were hot-rolled ready in a hot-rolled line ready to form hot-rolled strips with a BD thickness and a BB width. The hot rolling was completed respectively with a total decrease of the pass on the ready hot rolling line Δhf at a final temperature of the hot rolling TEW. The time, which elapsed between the departure of the scale washer and the beginning of the finished hot rolling, amounted to less than 300 seconds, respectively.
    [0058] The ready hot-rolled steel flat product that leaves the last structure, after a pause of 1 - 7 seconds t_p, in which it is slowly cooled in the air, was cooled by intense cooling with water at a rate cooling dT 50 - 120 K / s at a winding temperature HT. After cooling, flat steel products have already shown a bainitic structure of at least 70% by volume.
    [0059] At this HT winding temperature, the hot rolled strips obtained were respectively wound to form a coil. During the cooling of the flat steel products in the coil, the complete transformation of the structure into bainite occurred, so that the flat steel products obtained had a bainitic structure in the technical sense of 100% by volume.
    [0060] In table 2a, 2b, the parameters of the TW reheat temperature method, TVW pre-lamination temperature, the overall decrease in the Δhv pass obtained through pre-lamination, time t_1 between blasting after reheating and before of pre-lamination and the beginning of the ready hot lamination, the time t_2 between the pre-lamination and the hot lamination, the decrease of the pass Δhf obtained in total through the ready lamination, final lamination temperature TEW, cooling pause t_p between the end of the hot rolling and the beginning of the forced cooling, cooling speed dT, winding temperature HT, thickness of strip BD and width of strip BB, respectively adjusted in the processing of ingots 1 - 26.
    [0061] The mechanical properties as well as the structure of the hot rolled strips obtained were examined.
    [0062] The tensile tests to determine the ReH elastic limit, the tensile strength Rm and the elongation at break A were carried out according to DIN EN ISO 6892-1 on longitudinal samples of the hot-rolled strips.
    [0063] Shock flexion tests to determine Av impact work at -20 oC or -40 oC and -60 oC were performed on longitudinal samples according to DIN EN ISO 148-1.
    [0064] The structural examinations were carried out using a photomicroscope and an electronic scanning microscope. For this, the samples were taken from a quarter of the strip width, prepared as longitudinal polishing and etched with nital (that is, alcoholic nitric acid, which contains a proportion of nitric acid of 3% by volume) or sodium disulfite. The determination of the structural components was carried out by means of surface analysis at the sample location with 1/3 of the plate thickness, as described by H. Schumann and H. Oettel “Metallografie” 14. Auflage, 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    [0065] The mechanical properties and structural components of the hot-rolled strips produced according to the invention are shown in table 3. The strip sheets produced according to the method of the present invention have high strength properties with good toughness properties , as well as good elongation at break.
    [0066] The limits of elasticity of hot-rolled strips produced in the manner explained above are between 700 MPa and 790 MPa. The elongation at break is at least 12% and the tensile strength 750 - 880 MPa. The impact work at -20 oC is in the range of 60 to 100 J. At -40 oC, the impact work amounts to 40 to 75 J and at - 60 oC the impact work is at 30 - 70 J .


    [0067] Given in% by weight, the rest are iron and unavoidable impurities

    权利要求:
    Claims (13)
    [0001]
    1. METHOD FOR THE PRODUCTION OF A FLAT STEEL PRODUCT, with an elasticity limit of at least 700 MPa and with a bainitic structure of at least 70% by weight, characterized by comprising the following operational steps: a) melting of a mass cast steel, which (in% by weight) consists of C: 0.05 - 0.08%, Si: 0.015 - 0.500%, Mn: 1.60 - 2.00%, P: up to 0.025%, S: up to 0.010%, Al: 0.020 - 0.050%, N: up to 0.006%, Cr: up to 0.40%, Nb: 0.060 - 0.070%, B: 0.0005 - 0.0025% Ti: 0.090 - 0.130%, as well as in technically unavoidable impurities, which include up to 0.12% Cu, up to 0.100% Ni, up to 0.010% V, up to 0.004% Mo and up to 0.004% Sb and the rest, in iron; b) melting the melt to form an ingot; c) reheating the ingot to a reheating temperature of 1200 - 1300 oC; d) pre-lamination of the ingot at a pre-lamination temperature of 950 - 1250 oC and a total reduction of the pass obtained through pre-lamination of at least 50%; e) ready hot rolling of the pre-laminated ingot, the finished hot rolling being completed at a hot rolling temperature of 800 - 880 oC; f) cooling which starts within a maximum of 10 s after the ready hot rolling of the ready hot rolled steel flat product with a cooling speed of at least 40 K / s at a winding temperature of 550 - 620 oC; g) winding of the finished hot-rolled flat steel product, in which the elongation at break of the hot-rolled flat steel products obtained after winding amounts to at least 12%.
    [0002]
    2. METHOD, according to claim 1, characterized by the EC carbon equivalent of the melt of the operational step a) calculated according to the formula CE =% C +% Mn / 6 + (% Cr +% Mo +% V) / 5 + (% Cu +% Ni) / 15 with% C = the respective C content in% by weight,% Mn = the respective Mn content in% by weight,% Cr = the respective Cr content in% by weight, % Mo = the respective Mo content in% by weight,% V = the respective V content in% by weight,% Cu = the respective Cu content in% by weight,% Ni = the respective Ni content in% in weight weight, if applicable: EC <0.5% by weight.
    [0003]
    3. METHOD, according to claim 1 or 2, characterized by the reheat temperature to 1250 - 1300oC.
    [0004]
    4. METHOD, according to any one of claims 1 to 3, characterized by the operational step c ') that passes between the reheating (operational step c)) and the pre-lamination (operational step d)) to remove the adhering primary scales in the respective processed ingot.
    [0005]
    5. METHOD according to any one of claims 1 to 4, characterized by the transport time, which takes place for transporting the ingot from the operating station respectively previously passed (operational step c) or optionally operational step c ')) to ready hot rolling (operational stage e)), be limited to a maximum of 300 seconds.
    [0006]
    6. METHOD, according to any one of claims 1 to 5, characterized by the dwell time that elapses between pre-lamination (operational step d)) and the ready hot lamination (operational step e)) to make a maximum of 50 seconds .
    [0007]
    7. METHOD, according to any one of claims 1 to 6, characterized by the cooling speed in cooling in the operational step f) to a maximum of 150 K / s.
    [0008]
    METHOD according to any one of claims 1 to 7, characterized by the thickness of the hot rolled flat steel product obtained after hot rolling to 3 - 15 mm.
    [0009]
    9. METHOD according to any one of claims 1 to 8, characterized by the elasticity limit of hot-rolled flat steel products obtained after winding to 700 - 850 MPa.
    [0010]
    10. METHOD according to any one of claims 1 to 9, characterized by the tensile strength of the hot-rolled flat steel products obtained after winding to 750 - 950 MPa.
    [0011]
    11. METHOD according to any one of claims 1 to 10, characterized by the impact energy of the notched specimens of the hot-rolled flat steel products obtained after winding, at -20 ° C, to be in the range of 50 - 110 J.
    [0012]
    12. METHOD according to any one of claims 1 to 11, characterized in that the hot rolled flat steel products obtained after winding have an exclusively bainitic structure with the exception of other technically unavoidable structural components.
    [0013]
    13. METHOD according to any one of claims 1 to 12, characterized by the average grain diameter of the structure of hot-rolled flat steel products obtained after winding to a maximum of 20 μm.
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    同族专利:
    公开号 | 公开日
    MX2016012491A|2017-01-06|
    JP2017512905A|2017-05-25|
    WO2015144529A1|2015-10-01|
    DK3305935T3|2019-09-02|
    CA2941202A1|2015-10-01|
    PL2924140T3|2018-04-30|
    RU2016141474A3|2018-11-06|
    EP2924140A1|2015-09-30|
    PL3305935T3|2019-11-29|
    ES2745046T3|2020-02-27|
    DK2924140T3|2018-02-19|
    RU2675183C2|2018-12-17|
    UA117959C2|2018-10-25|
    RU2016141474A|2018-04-27|
    CN106133154A|2016-11-16|
    US20190203318A1|2019-07-04|
    US10934602B2|2021-03-02|
    ES2659544T3|2018-03-16|
    US20170137911A1|2017-05-18|
    EP3305935B1|2019-05-29|
    SI3305935T1|2019-11-29|
    SI2924140T1|2018-04-30|
    JP6603669B2|2019-11-06|
    EP3305935B9|2019-12-04|
    EP2924140B1|2017-11-15|
    EP3305935A1|2018-04-11|
    CA2941202C|2018-09-18|
    KR20160137588A|2016-11-30|
    US10280477B2|2019-05-07|
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    法律状态:
    2019-08-13| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-12-22| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2021-03-09| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-04-27| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 18/03/2015, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP14161606.0|2014-03-25|
    EP14161606.0A|EP2924140B1|2014-03-25|2014-03-25|Method for manufacturing a high strength flat steel product|
    PCT/EP2015/055685|WO2015144529A1|2014-03-25|2015-03-18|Method for producing a high-strength flat steel product|
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