Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/012—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D6/00—Heat treatment of ferrous alloys
  • C21D6/002—Heat treatment of ferrous alloys containing Cr
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0273—Final recrystallisation annealing

Definitions

• the invention proposes a steel having the alloy generally specified in claim 1.
• a steel according to the invention therefore contains besides iron and
• Co up to 1%
• Ni up to 2%
• the steel according to the invention has a ferritic microstructure.
• the density is reduced by the Al content of 3-7% by weight, in particular 3-6% by weight.
• the corrosion and oxidation resistance and the tensile strength at room temperature are markedly improved by Al contents of this order of magnitude.
• AI contributes to the stated strengths to the heat resistance.
• Al contents> 7 wt .-% however, the cold workability is difficult, the weldability deteriorates (AI forms stable welding slag of elevated electrical Welding resistance) and there are formed with N and C embrittling phases (Al-nitrides, kappa-carbides).
• the Al content can be limited to a maximum of 6% by weight, in particular 2.5-5.5% by weight, with optimized properties of the steel according to the invention being established with great certainty when the Al content is 4.0-5.5 wt%.
• the C content of a steel according to the invention is limited to up to 0.15% by weight, because C contents of more than 0.15% by weight cause a strong tendency to form brittle kappa carbides at grain boundaries. These carbides can not be adequately bound by micro-alloying elements, with the result that the hot and cold workability is reduced. High C contents also reduce weldability.
• the C content is therefore preferably at least 0.001 wt .-% and is
• Cr content of 3 - 1 1 wt .-% improves the corrosion and oxidation resistance significantly.
• Cr carbides can form detrimental Cr carbides with high C contents for corrosion resistance.
• Mn contents of up to 1% improve hot workability and weldability in steel alloyed according to the invention.
• Mn is also added for deoxidation. It increases the strength, but reduces the
• Mn contents of at least 0.2% by weight may be present in the steel according to the invention.
• Si contents of up to 2 wt .-% increase the strength and the
• Corrosion resistance of a steel according to the invention At levels greater than 2% by weight, the ductility and weldability of the steel decreases. Si is also added for deoxidation. To the positive effects of Si, Si contents of at least 0.2% by weight, in particular at least 0.25% by weight or at least 0.3% by weight, may be added.
• the P content of a steel according to the invention is up to 0.1 wt .-%.
• the presence of higher P contents increases the tendency for segregations that are difficult to balance. P also deteriorates the cold workability, weldability and oxidation resistance. Therefore, the P contents are to be set low, in particular to ⁇ 0.03 wt .-%, in particular less than 0.03 wt .-%, limit. Typical operationally achievable P contents are 0.02-0.03 wt%.
• the S content is limited to a maximum of 0.03 wt .-%, since sulfur, for example, the hot workability during hot rolling and the
• Mo contents of up to 2% increase the tensile strength at room temperature and the heat resistance in the steel according to the invention.
• Mo forms with C fine carbides, which contribute to a fine structure.
• higher contents of Mo deteriorate hot and cold workability.
• Mo contents of at least 0.004% by weight, in particular at least 0.1% by weight may be added.
• At least one element of the group "Zr, V, W, Nb, Ti" is present in amounts of up to 1% by weight each.
• the Zr optionally present in the alloy according to the invention forms strength-enhancing Zr carbides, but hinders recrystallization at high levels and reduces cold workability. At the same time, Zr can improve the oxidation resistance. Therefore, the Zr content of a steel according to the invention is preferably in the range of 0.002-1 wt%, especially 0.05-1 wt%, with the positive effects of Zr then give particularly safe if the content of Zr is at least 0.1% by weight or at least 0.2 wt .-%. To exclude possible negative influences particularly safe, the upper limit of the Zr content range to 0.9 wt .-%, in particular 0.85 wt .-% or
• V forms strength-enhancing carbides.
• a steel according to the invention can optionally contain 0.005-1% by weight, in particular 0.05-1% by weight, V, the positive effects of V then being set up particularly reliably when the content V is at least 0, 1 wt .-% or at least 0.2 wt .-%.
• V content range to 0.9 wt .-%, in particular 0.85 wt .-% or
• W also forms strength-enhancing carbides.
• the optional W content of a steel according to the invention can be adjusted to 0.002-1% by weight, in particular 0.05-1% by weight, with the positive effects of W then being particularly reliable when the content of W is at least 0.1% by weight or at least 0.2% by weight.
• the upper limit of the W content range can be set to 0.9% by weight, in particular 0.85% by weight or 0.8% by weight.
• Ti and Nb are optionally present in the following content ranges. With simultaneous presence of Ti and Nb Laves phases can be formed, which are high
• Ti in amounts of up to 1% by weight forms strength-enhancing Ti carbides and can improve the oxidation resistance as well as the heat resistance.
• the Ti content is preferably at least 0.1 wt .-%. In excessively high levels, Ti degrades cold formability and welding properties and forms undesirable Ti nitrides. To avoid this, the
• Ti can also form with Nb Laves phases. With the simultaneous presence of Nb, titanium contents of 0.3-0.6% by weight have proven to be particularly advantageous with regard to the formation of high volume fractions of Lavesphase.
• Nb forms strengthening Nb carbides, improves heat resistance and can form in simultaneous presence with Ti Laves phases.
• the optionally present Nb content is therefore preferably at least 0.1% by weight, with Nb contents of at most 0.7% by weight being found to be particularly advantageous when negative influences of the presence be excluded from Nb particularly safe.
• niobium contents of 0.3-0.6% by weight have also been found to be particularly advantageous with regard to the formation of high volume fractions of Lavesphase.
• the Co content should be limited to a maximum of 1% by weight in a steel according to the invention. Co increases the recrystallization temperature, is expensive and does not contribute to a property improvement at higher levels.
• Ni in amounts of up to 2% by weight increases the strength and toughness of a steel according to the invention and improves its corrosion resistance.
• Ni contents of at least 0.02% by weight, in particular 0.1% by weight, may be added.
• B can be present in a steel according to the invention in amounts of up to 0.1% by weight. Its presence causes a fine texture, but at high levels reduces cold workability and oxidation resistance. To make use of this, the B content is preferably set to 0.0005-0.1% by weight, in particular> 0.001% by weight. Cu contents of up to 3% by weight improve the corrosion resistance. However, higher contents of Cu deteriorate hot workability and weldability. In order to be able to use the positive effects of Cu, it is possible to add Cu contents of at least 0.01% by weight, in particular at least 0.05% by weight or at least 0.1% by weight.
• Ca contents of at least 0.001% by weight, in particular at least 0.003% by weight or at least 0.005% by weight, may be added.
• REM Rare earths
• REM contents of at least 0.002% by weight, in particular at least 0.01% by weight or at least 0.05% by weight, can be provided.
• the N content is limited to at most 0.1% by weight, preferably at most 0.015% by weight or at most 0.01% by weight. Typical operating values are in the range of 0.005-0.015% by weight.
• Heavy plate, hot strip or cold strip can be processed from Fe-Al-Cr steels according to the invention.
• the procedure may be as follows: a) Melting
• Elements (eg, C, N, O) in the pre-melt are beneficial to the properties of the steel. You can use today's high-performance secondary metallurgy (including vacuum equipment, but also ladle furnace,
• the melting of the steel according to the invention can be carried out in a conventional manner by melting the pre-melt, adding
• the casting takes place with a waiting time of about 15 minutes. after the last alloy addition.
• the casting temperature is specific to the analysis 1550 - 1600 ° C.
• the cooling takes place under vacuum. c) hot rolling
• the steel according to the invention can be hot rolled in a conventional manner in terms of temperature control, rolling forces and achievable degree of deformation.
• the rolling forces are comparatively low, but increase sharply at rolling temperatures below 950 ° C. Below 850 ° C is also expected to be a strong drop in ductility.
• Hot rolling rolling end temperature WET> 850 ° C;
• Coiling temperature HT from room temperature to 650 ° C, preferably HT is around 500 ° C.
• a hot strip annealing can optionally be performed. This is used in an optional optional subsequent cold rolling lowering the cold rolling resistance and increasing the maximum achievable degree of cold rolling. At the same time the annealing promotes a texture selection, which together with a high degree of cold deformation, the formation of a suitable ribbon texture with the desired
• Bepflles with common media may be difficult due to surface coverage with stable Al oxide, but is basically possible with all pickling media.
• the pickling time By adjusting the pickling time, the respective desired
• the recrystallizing final annealing in a continuous annealing process or in a bell annealing sets the desired recrystallized microstructure and texture. Suitable are continuous annealing processes with temperatures above 780 ° C and bell annealing processes above 650 ° C. g) coating
• a steel flat product according to the invention can be formed by hot forming.
• Steel flat products produced in accordance with the invention are suitable as materials for highly heat-stressed automobile components (eg exhaust systems) and can also include casting solutions (eg turbocharger housings and other turbocharger parts). replace. Also, the steel according to the invention is suitable for the production of pistons for internal combustion engines.
• steels according to the invention can be used for components which, for example, in petrochemical plants of a
• flat steel products according to the invention are suitable for steam boiler, container and pipeline construction.
• components made of steels according to the invention are suitable for use in incineration plants and power plants.
• cutlery, dishes, appliances and coverings can be produced for use in the home.
• steel according to the invention for example, pipes and other components for drilling for gas, oil, hot water production and components for fermentation in biogas plants as a substitute made of stainless steel or concrete components.
• steel according to the invention is suitable for the production of
• High-temperature energy storage high-temperature fuel cell stacks, High-temperature battery systems (housing and piping), heat storage (eg salt storage for solar systems).
• each of the longitudinal direction "L" and transverse direction "Q" are detected
• Tensile strength Rm, yield strength Rp0.2, uniform elongation Ag and elongation A50 are listed in Table 2.
• Tensile strength Rm which are obtained from the steels 1 - 14 hot strips, when they have a test temperature of 600 ° C.
• Table 5 summarizes the results of tests performed on steel 14 samples. In these experiments, the hot rolling end temperature WET and the coiling temperature HT have been varied. In addition, in some experiments, a bell annealing was performed at a temperature TG, while such annealing was omitted in other samples. This is also indicated in Table 5 for the samples produced from the steel 14, as in each case in
• Equal expansion Ag, elongation A and the modulus of elasticity are equal expansion Ag, elongation A and the modulus of elasticity.
• Yield strengths, tensile strengths and elongation values If a buffing is performed at room temperature, it results in lower elongation values than at a reel temperature which is in the range of 500 ° C. Highest ductilities can be achieved with a hot rolling end temperature WET of 850 ° C, a coiler temperature HT of 500 ° C in combination with a hot strip annealing.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Heat Treatment Of Sheet Steel (AREA)
• Heat Treatment Of Steel (AREA)

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Citations (12)

• 2013
  • 2013-05-28 WO PCT/EP2013/060960 patent/WO2013178629A1/fr not_active Ceased

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