High-toughness press-hardened steel component and method for manufacturing same

Abstract

The invention relates to a steel sheet and a press-hardened steel component having a composition comprising, in weight percent, 0.05% to 0.4% of C, 0.5% to 4% of Mn, 0.1% to 1.3% of Si, 0.01% to 0.1% of Al, 0.01% to 1.0% of Cr, 0.01% to 0.1% of Ti, 0.0005% to 0.08% of B, 0.05% to 0.4% of Cu, 0.002% to 0.1% of Sn, P < = 0.020%, S < = 0.010%, N < = 0.02%, and the balance being Fe and unavoidable impurities. The remainder of the composition is iron and unavoidable impurities resulting from the smelting process and depending on the process route. The press hardened steel component has a microstructure comprising, in surface fraction, more than 95% martensite, the remainder being optionally bainite and retained austenite.

Description

Technical Field

[0001] The present invention relates to a high-strength press-hardened steel component with high toughness. Background Art

[0002] High-strength press-hardened components can be used as structural elements for anti-intrusion or energy absorption functions in motor vehicles.

[0003] In applications of such a type, it is desirable to produce steel components that combine high mechanical strength, high impact resistance, and good corrosion resistance.

[0004] Furthermore, one of the main challenges in the automotive industry is to reduce the weight of vehicles to improve their fuel efficiency while taking into account global environmental protection without neglecting safety requirements, including the most severe environments.

[0005] This weight reduction can be achieved in particular by using steel components having a martensitic or bainitic / martensitic microstructure.

[0006] Publication WO2016163469 relates to a heat-treated steel sheet member of martensite, which has good scale characteristics and high yield strength, and is excellent in terms of toughness. A steel component having a toughness higher than 35 J / cm 2 (0.35 J / mm 2 ) measured by the Charpy impact test at -80 °C is considered to be excellent in terms of toughness. However, no steel component has reached a toughness value higher than 55 J / cm 2 (0.55 J / mm 2 ), which may cause the component to fracture under high stress. Summary of the Invention

[0007] Therefore, an object of the present invention is to solve the above problems and provide a press-hardened steel component with high toughness, the press-hardened steel component having an average Charpy impact value greater than or equal to 0.90 J / mm 2 , the average Charpy impact value being calculated as the average of the Charpy impact energy values measured at 20 °C, -40 °C, -60 °C, and -80 °C.

[0008] Preferably, the press-hardened steel component according to the present invention has a Charpy impact energy greater than or equal to 0.75 J / mm 2 measured at -80 °C.

[0009] Preferably, the ductility loss Δ between the Charpy impact energy measured at 20 °C and the Charpy impact energy measured at -80 °C of the press-hardened steel component according to the present invention is less than 25%.

[0010] Another object of the present invention is to obtain a steel sheet that can be transformed into such a press-hardened steel component by hot forming.

[0011] The object of the present invention is achieved by providing a steel plate according to claim 1. Another object is achieved by providing a steel component according to claim 2. The steel component may also include the features of any one of claims 3 to 5. Another object is achieved by providing a method according to claim 6. Another object is achieved by providing a method according to claim 7. Detailed Description of the Invention

[0012] The present invention will now be described in detail and illustrated by way of examples without imposing limitations.

[0013] Now the composition of the steel plate according to the present invention will be described, with the contents expressed in weight percentages (wt%).

[0014] According to the present invention, the carbon content is from 0.05% to 0.4% to ensure satisfactory strength. If the carbon is higher than 0.4%, the weldability and bendability of the steel may be reduced. If the carbon content is lower than 0.05%, the tensile strength will be too low.

[0015] The manganese content is from 0.5% to 4%. Adding more than 4% increases the risk of center segregation, which impairs toughness. Below 0.5%, the hardenability of the steel is reduced. Preferably, the manganese content is from 0.8% to 2%, more preferably from 0.8% to 1.6%.

[0016] According to the present invention, the silicon content is from 0.1% to 1.3%. Silicon is an element that participates in the hardening of the solid solution. Silicon is added to limit carbide formation. Above 1.3%, silicon is detrimental to toughness. In addition, silicon oxides are formed on the surface, which impairs the coatability of the steel and may reduce the weldability of the steel plate and steel components. Preferably, the silicon content is from 0.1% to 1%, more preferably from 0.1% to 0.5%, even more preferably from 0.1% to 0.4%.

[0017] The aluminum content is from 0.01% to 0.1% because aluminum is a very effective element for deoxidizing the steel in the liquid phase during processing. Aluminum can protect boron if the titanium content is insufficient. The aluminum content is below 0.1% to avoid oxidation problems and the formation of ferrite during press hardening. Preferably, the aluminum content is from 0.01% to 0.05%.

[0018] According to the present invention, the chromium content is from 0.01% to 1.0%. Chromium is an element that participates in the hardenability of the steel plate and must be higher than 0.01%. The chromium content is below 1.0% to limit machinability problems and costs.

[0019] According to the present invention, the boron content is from 0.0005% to 0.08%. Boron improves the hardenability of the steel. The boron content is not higher than 0.08% to avoid the risk of slab breakage during continuous casting.

[0020] The titanium content is from 0.01% to 0.1% to protect boron from forming BN. The titanium content is limited to 0.1% to avoid the formation of TiN. In a preferred embodiment, Ti / N > 3.42 is used for boron protection.

[0021] According to the present invention, the copper content is from 0.05% to 0.4% to increase the toughness of the steel component. The copper content is limited to 0.4% to limit the risk of hot brittleness that may weaken the slab. Preferably, the copper content is from 0.05% to 0.25%, more preferably from 0.07% to 0.25%. More preferably, the copper content is from 0.08% to 0.25%, even more preferably from 0.08% to 0.20%. More preferably, the copper content is from 0.08% to 0.18%.

[0022] The tin content is from 0.002% to 0.1% to improve the hardenability of the steel. Above 0.1%, tin may accentuate the risk of hot brittleness and limit the workability of the slab. Preferably, the tin content is from 0.002% to 0.050%.

[0023] Preferably, the sum of the copper content and the tin content is from 0.08% to 0.3%, more preferably from 0.09% to 0.3%, even more preferably from 0.1% to 0.3%.

[0024] Some elements can be optionally added.

[0025] Nickel can be added up to 0.4% to limit the hydrogen introduction during the production of the steel and limit the risk of delayed fracture due to hydrogen embrittlement. The nickel content is considered a residual element up to 0.020%. Preferably, if added, the nickel content is up to 0.1%, more preferably up to 0.05%.

[0026] The molybdenum content can be optionally added up to 0.40%. Like boron, molybdenum improves the hardenability of the steel. Molybdenum is not higher than 0.40% to limit the cost.

[0027] Niobium can be optionally added up to 0.08% to improve the ductility of the steel. Adding above 0.08%, the risk of forming NbC or Nb(C,N) carbides increases, thus impairing the bendability. Preferably, the niobium content is less than or equal to 0.05%.

[0028] Calcium can also be added as an optional element up to 0.1%, and is preferably added in a minimum amount of 0.0001%. Adding Ca in the liquid phase enables the production of fine oxides, which promotes the castability of continuous casting. In addition, calcium can help limit the formation of harmful MnS by promoting the formation of CaO-CaS.

[0029] The remainder of the composition of the steel is iron and inevitable impurities resulting from the melting process and depending on the process route. In the case of a production route using a blast furnace, the level of inevitable impurities is very low. In the case of a production route using an electric arc furnace charged with scrap, the steel plate may also contain residual elements from such scrap, such as antimony, arsenic, and lead up to 0.03%, which are considered inevitable impurities.

[0030] Regardless of the process route, P, S, and N are also part of the inevitable impurities. Their contents are ≤ 0.010% for S, ≤ 0.020% for P, and ≤ 0.02% for N.

[0031] In a specific embodiment, the chemical composition of the steel plate contains the following elements in weight percentages:

[0032] C: 0.062% to 0.095%

[0033] Mn: 1.4% to 1.9%

[0034] Si: 0.2% to 0.5%

[0035] Al: 0.020% to 0.070%

[0036] Cr: 0.02% to 0.1%

[0037] where 1.5% ≤ (C + Mn + Si + Cr) ≤ 2.7

[0038] Nb: 0.040% to 0.060%

[0039] Ti: 0.01% to 0.1%

[0040] B: 0.0005% to 0.004%

[0041] Cu: 0.05% to 0.4%

[0042] Sn: 0.002% to 0.1%

[0043] S ≤ 0.003%

[0044] P ≤ 0.020%

[0045] N ≤ 0.009%

[0046] and optionally contains one or more of the following elements in weight percentages:

[0047] 0.0001% ≤ Ca ≤ 0.003%

[0048] The remaining part of the composition is iron and inevitable impurities generated by the smelting process and depending on the process route.

[0049] In another specific embodiment, the chemical composition of the steel plate comprises the following elements in weight percentages:

[0050] C: 0.15% to 0.4%

[0051] Mn: 0.5% to 3%

[0052] Si: 0.1% to 0.5%

[0053] Cr 0.01% to 1%

[0054] Ti 0.01% to 0.1%

[0055] Al 0.01% to 0.1%

[0056] B: 0.0005% to 0.08%

[0057] Cu: 0.05% to 0.4%

[0058] Sn: 0.002% to 0.1%

[0059] S ≤ 0.010%

[0060] P ≤ 0.020%

[0061] N ≤ 0.02%

[0062] The remaining part of the composition is iron and inevitable impurities generated by the smelting process and depending on the process route.

[0063] In another specific embodiment, the chemical composition of the steel plate comprises the following elements in weight percentages:

[0064] C: 0.15% to 0.25%

[0065] Mn: 0.5% to 1.8%

[0066] Si: 0.1% to 1.25%

[0067] Cr 0.1% to 1%

[0068] Ti 0.01% to 0.1%

[0069] Al 0.01% to 0.1%

[0070] B: 0.001% to 0.004%

[0071] Cu: 0.05% to 0.4%

[0072] Sn: 0.002% to 0.1%

[0073] S ≤ 0.010%

[0074] P ≤ 0.020%

[0075] N ≤ 0.02%

[0076] and optionally containing one or more of the following elements by weight percentage:

[0077] Mo ≤ 0.40%

[0078] Nb ≤ 0.08%

[0079] Ca ≤ 0.1%

[0080] The balance of the composition is iron and unavoidable impurities resulting from the melting process and depending on the process route.

[0081] In another specific embodiment, the chemical composition of the steel plate contains the following elements expressed by weight percentage:

[0082] C: 0.24% to 0.4%

[0083] Mn: 0.5% to 3%

[0084] Si: 0.10% to 1.3%

[0085] Al: 0.015 to 0.070

[0086] Cr: 0.1% to 1.0%

[0087] Ni: 0.25% to 0.4%

[0088] Nb: 0% to 0.060%

[0089] B: 0.0005 to 0.0040

[0090] Cu: 0.05% to 0.4%

[0091] Sn: 0.002% to 0.1%

[0092] S ≤ 0.010%

[0093] P ≤ 0.020%

[0094] N ≤ 0.02%

[0095] Ti 0.01% to 0.1%

[0096] 2.6+(Mn / 5.3)+(Cr / 13)+(Si / 15) ≥ 1.1%

[0097] and optionally containing one or more of the following elements by weight percentage:

[0098] Mo: 0.05% to 0.40%

[0099] Ca 0.0005% to 0.005%

[0100] The balance of the composition is iron and unavoidable impurities resulting from the smelting process and depending on the process route.

[0101] In another specific embodiment, the chemical composition of the steel plate contains the following elements expressed by weight percentage:

[0102] C: 0.3% to 0.4%

[0103] Mn: 0.5% to 1.0%

[0104] Si: 0.4% to 0.8%

[0105] Cr: 0.1% to 1.0%

[0106] Mo: 0.1% to 0.4%

[0107] Nb: 0.01% to 0.08%

[0108] Al: 0.01% to 0.1%

[0109] Cu: 0.05% to 0.4%

[0110] Sn: 0.002% to 0.1%

[0111] Ti: 0.01% to 0.03%

[0112] B: 0.0005% to 0.003%

[0113] P ≤ 0.020%

[0114] Ca ≤ 0.0010%

[0115] S ≤ 0.010%

[0116] N ≤ 0.02%

[0117] and optionally containing:

[0118] Ni < 0.4%

[0119] The balance of the composition is iron and unavoidable impurities resulting from the smelting process and depending on the process route.

[0120] The steel plates according to the present invention can be produced by any suitable manufacturing method, and those skilled in the art can define the manufacturing method. However, it is preferred to use the method according to the present invention, which comprises the following steps:

[0121] Providing a semi-finished product having the above steel composition and capable of being further hot-rolled. Such a semi-finished product can be, for example, a slab.

[0122] The semi-finished product is obtained by casting molten steel, and the molten steel can be produced by a steelmaking process using, for example, the basic oxygen furnace (BOF) route. In the BOF route, hot molten iron or pig iron obtained, for example, in a blast furnace or a smelting furnace is decarburized to become molten steel. Optionally, iron-containing scrap containing elements such as copper, nickel, chromium, molybdenum, tin, arsenic, antimony or lead is charged into the furnace together with such hot molten iron or pig iron. Direct reduced iron (DRI) can also be charged.

[0123] The molten steel can also be produced in an electric arc furnace (EAF) by melting iron-containing scrap to directly produce molten steel. DRI can also be charged into the EAF together with the iron-containing scrap.

[0124] The semi-finished product is heated to a temperature of 1100 °C to 1300 °C. Then, the steel plate is hot-rolled at a finish rolling temperature (FRT) of 830 °C to 950 °C. Preferably, the FRT is 850 °C to 950 °C. Then, the hot-rolled steel is cooled and coiled at a temperature below 670 °C, and optionally pickled to remove oxidation.

[0125] In a preferred embodiment of the present invention, the hot-rolled steel plate is then cooled to room temperature.

[0126] In another preferred embodiment, the hot-rolled steel plate is annealed to an annealing temperature T of 700 °C to 850 °C A , and held at the annealing temperature T A for a holding time t of 10 seconds to 1200 seconds A , and optionally coated with an aluminum coating, or an aluminum alloy coating, or a zinc coating or a zinc alloy coating, and cooled to room temperature.

[0127] In another preferred embodiment of the present invention, the hot-rolled steel plate is cold-rolled and annealed to an annealing temperature T of 700 °C to 850 °C A , and held at the annealing temperature T A for a holding time t of 10 seconds to 1200 seconds A , and optionally coated with an aluminum coating, or an aluminum alloy coating, or a zinc coating or a zinc alloy coating, and cooled to room temperature.

[0128] In another preferred embodiment of the present invention, the hot-rolled steel plate is cold-rolled and annealed to an annealing temperature T of 500 °C to 750 °C A and held at the annealing temperature T A for a holding time t of 300 seconds to 80 hours A to obtain an annealed steel plate.

[0129] The microstructure of the steel plate according to the present invention contains 50% or more ferrite by surface fraction, and the remainder is pearlite or cementite.

[0130] The steel component according to the present invention can be produced by any suitable manufacturing method, and those skilled in the art can define the manufacturing method. However, it is preferred to use the method according to the present invention, which includes the following steps:

[0131] Provide a steel plate having the above chemical composition and microstructure and cut it into a predetermined shape to obtain a billet.

[0132] Then, the billet is heated to a temperature T1 of 800 °C to 980 °C and held at the T1 temperature for a dwell time t1 of 10 seconds to 900 seconds to obtain a heated billet. Then, the heated billet is transferred to a press and hot formed. After hot forming, the steel component is then die quenched.

[0133] Now, the microstructure of the steel component according to the present invention will be described.

[0134] During the heating of the billet cut from the steel plate, all the microstructure elements are transformed into austenite. Then, the heated billet is transferred to a press and hot formed. After hot forming, the steel component is then die quenched, converting the austenite into more than 95% martensite, and the remainder is optionally bainite and retained austenite. Preferably, the microstructure contains more than 98% martensite, and the remainder is optionally bainite and retained austenite.

[0135] The average Charpy impact energy value of the press-hardened steel component according to the present invention is greater than or equal to 0.90 J / mm 2 and the average Charpy impact energy value is calculated as the average of the Charpy impact energy values measured at 20 °C, -40 °C, -60 °C, and -80 °C. Preferably, the average value is greater than or equal to 0.95 J / mm 2 .

[0136] Toughness is measured by the Charpy impact energy at 20 °C, -40 °C, -60 °C, and -80 °C according to standards ISO 148-1:2006(F) and ISO 148-1:2017(F).

[0137] Preferably, the Charpy impact energy of the press-hardened steel component at -80 °C is higher than 0.75 J / mm 2 .

[0138] Preferably, for the press-hardened steel component according to the invention, the ductility loss Δ between the Charpy impact energy measured at 20 °C and the Charpy impact energy measured at -80 °C is lower than 25%.

[0139] Preferably, the tensile strength TS of the press-hardened steel component is greater than or equal to 950 MPa. More preferably, the TS of the press-hardened steel component is greater than or equal to 1350 MPa. The TS is measured according to standard ISO 6892-1.

[0140] In a preferred embodiment of the present invention, the martensitic steel sheet can be produced by a method comprising the following steps: providing a hot-rolled steel sheet having the above chemical composition and optionally annealing it to a temperature T of 500 °C to 750 °C and holding it at the annealing temperature for a holding time t of 300 seconds to 80 hours, and optionally performing cold rolling. Then, the steel sheet is annealed to a temperature T1 of 800 °C to 980 °C for t1 of 10 seconds to 900 seconds and cooled to below Ms. Before cooling to room temperature, the steel sheet is optionally reheated to a temperature of 150 °C to 270 °C and held at said temperature for a holding time of 1 second to 600 seconds to obtain a martensitic steel sheet having a microstructure comprising: more than 95% martensite, the remainder being optionally bainite and retained austenite.

[0141] Preferably, the average Charpy impact energy value of the martensitic steel sheet is greater than or equal to 0.90 J / mm 2 , and the average Charpy impact energy value is calculated as the average of the Charpy impact energy values measured at 20 °C, -40 °C, -60 °C and -80 °C. Preferably, the average value is greater than or equal to 0.95 J / mm 2 .

[0142] Preferably, the Charpy impact energy of the martensitic steel sheet at -80 °C is higher than 0.75 J / mm 2 .

[0143] Preferably, the ductility loss Δ between the Charpy impact energy measured at 20 °C and the Charpy impact energy measured at -80 °C for the martensitic steel sheet is lower than 25%.

[0144] Preferably, the tensile strength TS of the martensitic steel sheet is greater than or equal to 950 MPa. More preferably, the TS of the martensitic steel sheet is greater than or equal to 1350 MPa.

[0145] The present invention will now be illustrated by the following examples, which are in no way limiting.

[0146] Example

[0147] Five steel grades summarized in Table 1 were cast into semi-finished products, processed into steel plates, and then processed into steel components according to the process parameters summarized in Table 3.

[0148] Table 1 - Composition

[0149] The composition of the tests is summarized in the following table, where the element contents are expressed in weight percentages (wt%).

[0150] Steel C Mn Si Al Cr Ti B Cu Sn Ni P S N A 0.23 1.19 0.25 0.03 0.18 0.034 0.0025 0.12 0.003 0.015 0.013 0.0013 0.0038 B 0.23 1.21 0.26 0.04 0.19 0.037 0.0021 0.09 0.031 0.014 0.014 0.0011 0.0054 <![CDATA C > 0.23 1.14 0.26 0.04 0.18 0.040 0.0025 <![CDATA 0.01 > 0.005 0.015 0.013 0.0020 0.0043 <![CDATA D > 0.23 1.18 0.25 0.03 0.18 0.037 0.0024 <![CDATA 0.02 > 0.018 0.014 0.016 0.0012 0.0054 <![CDATA E > 0.22 1.20 0.25 0.03 0.18 0.037 0.0023 <![CDATA 0.04 > 0.012 0.017 0.012 0.0013 0.0046

[0151] Steels A to B are according to the present invention, and C to E are for reference.

[0152] Underlined values: do not correspond to the present invention

[0153] Table 2 - Microstructure of Steel Sheet

[0154] The cast steel semi-finished products were reheated at 1200 °C, hot-rolled at a finish hot-rolling temperature of 890 °C, and coiled at 550 °C. The microstructure of the steel plates expressed as surface fractions is summarized in the following table:

[0155]

[0156]

[0157] The surface fraction was determined by the following method: specimens were cut from the steel plates, polished and etched with a reagent known per se to reveal the microstructure. The cross-sections were then examined optically.

[0158] Table 3 - Process Parameters

[0159] The steel plates were then cut to obtain billet pieces, heated to temperature T1 and held at said temperature for a dwell time t1 and hot-formed. The following specific conditions were applied:

[0160] Test <![CDATA[T1(℃)]]> <![CDATA[t1 (seconds)]]> 1 920 575 2 920 575 <![CDATA 3 > 920 540 <![CDATA 4 > 900 540 <![CDATA 5 > 900 600

[0161] Underlined values: do not correspond to the present invention

[0162] The steel components were analyzed, and the corresponding microstructures are summarized in Table 4. The mechanical properties are summarized in Table 5.

[0163] Table 4 - Microstructure of Press-Hardened Steel Components

[0164] Test Martensite 1 100％ 2 100％ <![CDATA 3 > 100％ <![CDATA 4 > 100％ <![CDATA 5 > 100％

[0165] The surface fraction is determined by the following method: specimens are cut from the press-hardened steel component, polished and etched with a reagent known per se to reveal the microstructure. Subsequently, the cross-section is examined by optical microscopy or scanning electron microscopy, for example, with a scanning electron microscope with a field emission gun ("FEG-SEM") coupled to an EBSD (electron backscatter diffraction) device at a magnification greater than 5000 times.

[0166] Table 5 - Mechanical Properties of Press-Hardened Steel Components

[0167] The toughness of the component is measured by Charpy impact tests at four temperatures T 测试 20 °C, -40 °C, -60 °C and -80 °C, and summarized in the following table. The average Charpy impact energy value is calculated from the average of the four toughness values. The ductility loss Δ between 20 °C and -80 °C is calculated by the difference between the Charpy impact energy measured at 20 °C and the Charpy impact energy measured at -80 °C.

[0168]

[0169] Underlined values: do not match the target values

[0170] The examples show that the steel components according to the invention (i.e., Tests 1 and 2), due to their specific composition and microstructure, are the only steel components that exhibit the target properties.

[0171] The steel component of Test 3 has a chemical composition similar to that of the steel component of Test 1, except that the copper level is lower. At the same Charpy test temperature, the toughness of Test 3 is much lower than that of Test 1. The lower the temperature at which the Charpy impact is measured, the greater the toughness difference between the two tests. This can be demonstrated by the average Charpy impact energy value calculated from the average of the four toughness values. The higher the average value, the higher the toughness.

[0172] Furthermore, the copper content according to the invention allows the ductile-to-brittle transition temperature (DBTT) to be shifted to a lower temperature. This DBTT is the temperature at which a ductile material becomes brittle. This shift of the DBTT can be demonstrated by the average Charpy impact energy value. The higher the average value, the more the DBTT shifts towards lower temperatures.

[0173] Tests 4 and 5 relate to steel components with a low level of copper. The average Charpy impact energy value is less than 0.90 J / mm 2 , meaning that the steel components have low toughness and a high DBTT.

Claims

1. A steel plate made of steel having the following composition, the composition containing by weight percentage: C: 0.05% to 0.4% Mn: 0.5% to 4% Si: 0.1% to 1.3% Al: 0.01% to 0.1% Cr: 0.01% to 1.0% B: 0.0005% to 0.08% Ti: 0.01% to 0.1% Cu: 0.05% to 0.4% Sn: 0.002% to 0.1% P≤0.020％ S≤0.010％ N≤0.02％ And the composition optionally contains by weight percentage one or more of the following elements: Ni ≤ 0.4% Mo ≤ 0.40% Nb ≤ 0.08% Ca ≤ 0.1% The remainder of the composition is iron and inevitable impurities generated by melting, and the steel plate has a microstructure containing the following by surface fraction: 50% or more ferrite, and the rest is pearlite or cementite.

2. A press-hardened steel component made of the steel according to claim 1, the steel component having a microstructure containing the following by surface fraction: more than 95% martensite, and the rest is optionally bainite and retained austenite.

3. The press-hardened steel component according to claim 2, wherein the average Charpy impact energy value of the press-hardened steel component is greater than or equal to 0.90 J / mm 2 , and the average Charpy impact energy value is calculated as the average of the Charpy impact energies measured at 20 °C, -40 °C, -60 °C, and -80 °C.

4. The press-hardened steel component according to any one of claims 2 to 3, wherein the press-hardened steel component has a Charpy impact energy measured at -80 °C that is higher than 0.75 J / mm 2 .

5. The press-hardened steel component according to any one of claims 2 to 4, wherein the ductility loss Δ between the Charpy impact energy measured at 20 °C and the Charpy impact energy measured at -80 °C of the press-hardened steel component is less than 25%.

6. A method for manufacturing a press-hardened steel component, comprising the following sequential steps: - Providing the steel plate according to claim 1, - Cutting the steel plate into a predetermined shape to obtain a billet, - Heating the billet to a temperature T1 of 800 °C to 980 °C and holding at the T1 temperature for a dwell time t1 of 10 seconds to 900 seconds to obtain a heated billet, - Transferring the heated billet to a press, - Thermoforming the heated billet in the press to obtain a formed component, - Performing die quenching on the formed component.

7. A method for manufacturing a martensitic steel plate, comprising the following sequential steps: - Providing the steel plate according to claim 1, - Optionally annealing the steel plate to an annealing temperature T of 500 °C to 750 °C and holding at the annealing temperature for a holding time t of 300 seconds to 80 hours, - Optionally cold rolling the steel plate, - Annealing the steel plate to a temperature T1 of 800 °C to 980 °C and holding at the T1 temperature for a holding time t1 of 10 seconds to 900 seconds, - Cooling the steel plate to below Ms, - Optionally reheating the steel plate to a temperature of 150 °C to 270 °C and holding at the temperature for a holding time of 1 second to 600 seconds, - Cooling the steel plate to room temperature, To obtain a martensitic steel plate having a microstructure containing the following by surface fraction: more than 95% martensite, and the rest is optionally bainite and retained austenite.

Images