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
  • C22C38/18—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
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • 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

Definitions

• the invention relates to a deformable, ferritic steel alloy.
• Such alloys are used inter alia for the production of electrical Heating elements and catalyst supports used. These materials form one dense, adherent alumina layer that protects it from destruction. This Protection is improved by additions of so-called reactive elements such as for example, Ca, Ce, La, Y, Zr, Hf, Ti, Nb, which improve the adhesiveness and / or reduce layer growth, as described in the "Handbook of the High-temperature materials technology, Ralf Bürgel, Vieweg Verlag, Braunschweig 1998 ", from page 274 onwards.
• the aluminum oxide layer protects the metallic material from faster Oxidation. At the same time she is growing herself, albeit very slowly. This growth takes place using consumption of the aluminum content of the material. Is not a Aluminum more present, so grow other oxides (chromium and iron oxides). The metal content of the material is consumed very quickly and the material failed. The time to failure means life. An increase in the Aluminum content thus extends the life.
• EP-B 0387670 an alloy with (in mass%) 20 to 25% Cr, 5 to 8 % Al and additions of 0.03 to 0.08% yttrium 0.004 to 0.008% nitrogen, 0.020 to 0.040% carbon, as well as about equal parts 0.035 to 0.07% Ti and 0.035 to 0.07% zirconium, and max. 0.01% phosphorus, max. 0.01% magnesium, Max. 0.5% manganese, max. 0.005% sulfur, residual iron is addressed, the Sum of the contents of Ti and Zr in% from 1.75 to 3.5 times as large as the sum the contents of C and N in mass% as well as melting Impurities. Ti and Zr may be wholly or partially hafnium and / or Tantalum or vanadium are replaced.
• EP-B 0290719 is an alloy with (in mass%) 12 to 30% Cr, 3.5 to 8% Al, 0.008 to 0.10% carbon, max. 0.8% silicon, 0.10 to 0.1% manganese, Max. 0.035% phosphorus, max. 0.020% sulfur, 0.1 to 1.0% molybdenum, max.
• Nickel 1 % Nickel, and the additives 0.010 to 1.0% zirconium, 0.003 to 0.3% titanium and 0.003 to 0.3% nitrogen, calcium plus magnesium 0.005 to 0.05%, as well rare earth metals from 0.003 to 0.80%, nlob from 0.5%, remaining iron with usual Accompanying elements described, for example, as a wire for heating elements for electrically heated ovens and as a construction material for thermally loaded Parts and is used as a film for the preparation of catalyst supports.
• the iron - chromium - aluminum alloy Cr Al 14 4 can indeed by the to about 4 to 4.5 mass% lowered aluminum content easier than the alloys described above with more than 5% by weight of aluminum. She shows, however still embrittlement, which increased to an Manufacturing costs during hot forming lead.
• GB-A 476,115 is an iron alloy, in particular usable as electrical resistance, which includes the following elements: 6.1 - 30 % Cr, 3 - 12% Al, 0.07 - 0.2% C, ⁇ 4% Ti, balance Fe as well melting impurities.
• the Ti content is in this case on the C content is bound to be not less than 3 times the C content should be.
• Preferred ranges for Cr are> 8%, for Al> 5%, for C> 0.085 %.
• the metal composite foil includes a carrier layer of ferritic steel strip, the both sides with a Outer layer of aluminum or an aluminum alloy is provided.
• the Carrier layer is formed of an alloy with (in mass%) 16-25% Cr, Rare earths, Y or Zr, in contents between 0.01 - 0.1%, Fe remainder.
• Femer Al may be added in levels between 2 and 6%. Preferred Cr contents are above 20%.
• EP-A 0 402 640 discloses a stainless steel foil as a carrier element for catalysts and their preparation.
• the film is formed from a Alloy of the following composition (in% by mass): 1.0 -20% Al, 5 - 30% Cr, Up to 2% Mn, up to 3% Si, up to 1% C, balance Fe and production-related Impurities.
• Preferred ranges for Al are between 5.5 and 20%.
• Y, Sc or rare earths can be added within limits of 0.3% wherein at least one of the elements Ti, Nb, Zr, Hf, V, Ta, Mo, W in Levels up to 2% can be provided. Contents ⁇ 4% Al require in this case Cr contents > 25%.
• JP-A 06330248 is an alloy having the following composition from 2.5 to 4.5% Al, 9 to ⁇ 18% Cr, ⁇ 1% Si, ⁇ 1% Mn, ⁇ 0.02% C, ⁇ 0.02 % N, balance Fe.
• a reactive element should Hf in limits of 0.01 - 0.2% to Get used.
• JP-A 0611 6686 discloses an iron-chromium-aluminum alloy Composition: 1 - 6% Al, 10 - 28% Cr, ⁇ 1% Si, ⁇ 1.5% Mn, ⁇ 0.05% Ti + Nb, ⁇ 0.01% Ce, ⁇ 0.05% C, ⁇ 0.02% N, Fe as the remainder Zr in contents of 0.01 - 1.0% and La in contents of 0.01 - 0.2% be added.
• JP-A 08269730 discloses an alloy of the following Composition: 3 - 8% Al, 9 - 30% Cr, ⁇ 1.0% Si, ⁇ 1.0% Mn, ⁇ 0.05% C, ⁇ 0.05% N, Fe as the remainder.
• the alloy can have in excess of> 1% elements such as Nb, Ti, Zr, V, Hf, Mo, Ta and Co are added.
• the invention is based on the object, a cost-effective iron-chromium-aluminum Alloy to provide a similar or better life as Cr Al 14 4 has, but even less brittleness and therefore improved Formability has, but at the same time the same technical functionality as Cr Al 14 has 4.
• an iron-chromium-aluminum alloy with high durability with (in mass%) 2.5 to 3.0% aluminum and> 10 to ⁇ 20% Chromium and additions of 0.1 to 1% Si, max. 0.5% Mn, 0.01 to 0.2% yttrium and 0.01 to 0.2% Hf and / or 0.01 to 0.3% Zr, max. 0.01% Mg, max. 0.01% Ca, max. 0.08% carbon, max. 0.04% nitrogen, max. 0.04% phosphorus max.
• DE-A-198 34 552 discloses: an iron-chromium-aluminum alloy as a metal foil for Schuleiterwiederplace or as a carrier for Catalytic converters is used, wherein the film has the following composition Al: 4-10%; Cr: 18-25%; Si: 0.5-1.5%; Y: 0:03 to 12:08%; Zr: 0:01 to 12:05%; Hf: 0.01-0.05%; Ti: max. 00:01% and balance Fe and common impurities. 0.01% sulfur, max. 0.05% copper and max. 0.1% molybdenum and / or Tungsten and production-related impurities, the rest iron
• the Al content in limits of 2.5 - 3.55% and the Cr content in Set limits of 13 -17%.
• a reduction in brittleness is most effective by reducing reach the aluminum content.
• this has the disadvantage that the Specific electrical resistance also decreases and the service life decreases.
• the brittleness is also due to chromium, silicon, carbon and nitrogen increased, which is why these elements are kept as low as possible should.
• the same technical functionality for a heating conductor used for electrical Generation of heat is achieved when the surface power, the Power at the heating element, the total resistance of the heating element and the Service life of the heating element in any change of the material remains constant.
• Diameter D B / D A 3 ⁇ B / ⁇ A
• Length L B / L A 3 ⁇ A / ⁇ B
• Weight M B / M A 3 ⁇ B / ⁇ A • ⁇ B / ⁇ A
• the oxidation constant k is a measure of the quality of the oxide layer. At a Oxide layer with very good protective effect, k is smaller than a worse one Oxide layer. The smaller k is, the longer the life.
• an alloy with the same functionality would have a minimum of 12% have longer life, to the disadvantage of smaller wire diameter to compensate. Additional lifetimes offer even more the advantage of a longer life, that is an improved functionality.
• the subject invention is in addition to heating conductors for heating elements, eg. B. one Household appliance, or as a construction material in the furnace construction as a film, For example, used as a carrier film for catalysts.
• Table 1 lists various iron-chromium-aluminum alloys, the table containing both large-scale and laboratory molten batches.
• heating elements heating conductors
• Lifetime tests to compare materials with each other, for example, with following conditions possible:
• the test is carried out on wires with a diameter of 0.40 mm, from which Wire spirals with 12 turns, a spiral diameter of 4 mm and a Spiral length of 50 mm can be made.
• the wire spirals are between 2 Power supply clamped and by applying a voltage up to 1200 ° C. heated. The heating takes place for 2 minutes, then the power supply for 15 Seconds interrupted. At the end of the life of the wire fails, that the remaining cross section melts through. As a lifetime, the Total time the wire was heated, without the break times indicated in the following burning time.
• the large-scale batch T1 and the laboratory batches T2 and T3 represent the state technology for Cr Al 14 4, with (in% by mass) approx. 14.5% chromium, 4.5% Aluminum, about 0.3% manganese, about 0.2% silicon and as a reactive element 0.17 to 0.18% zirconium. They have 49-hour lifetimes for the lab batch T3, 63 hours for the laboratory batch T2 and 77 hours for the large-scale Batch T1.
• Batches H1 to H6 are batches with an aluminum content of over 5 mass% and different additions of silicon, manganese, zirconium, Titanium, hafnium and yttrium and other admixtures such as calcium, Magnesium, carbon and nitrogen.
• the laboratory batch K1 is compared to the laboratory batch according to the state of Technique T2 the aluminum content has been lowered from 4.5 to 3.55 mass%.
• the Lifespan decreased, as expected, from 63 hours to 34 hours.
• the batch M1 achieved with an aluminum content of 2.78% and a Zirconium content of 0.05% and a hafnium content of 0.03% and a Yttrium content of 0.02% a life of 92 hours.
• the batch M2 achieved with an aluminum content of 2.71% and a zirconium content of 0.05% and a hafnium content of 0.03% and an yttrium content of 0.04% Life of 126 hours.
• the batch M4 reaches with an aluminum content of 2.8% and a zirconium content of 0.03% and a hafnium content of 0.03 % and an yttrium content of 0.03%, a life of 85 hours.
• the alloy according to the invention Additions of 0.01 to 0.08% yttrium, and / or 0.01 to 0.08% Hf and / or 0.01 to 0.08% Zr must contain.
• Charge L1 shows that even with the addition of zirconium, hafnium and yttrium at a Aluminum content of 1.55% only reached a life of 9.3 hours becomes. Even Charge M3, despite the addition of zirconium, hafnium and yttrium at one Aluminum content of only 2.24% only a life of 72 hours, the in the range of batches according to the prior art.
• the alloy according to the invention should therefore have an aluminum content of more than 2% to have.
• Chromium contents between 14 and 17% have no significant effect on the lifetime as compared to the zirconium, hafnium and yttrium containing batches M1 with 14.85% chromium and 2.78% aluminum and batch L2 with 16.86% chromium and 2.55 % Aluminum shows.
• a certain chromium content is necessary because chromium promotes the formation of the particularly stable and protective ⁇ - Al 2 O 3 layer.
• the impact work is at room temperature, 50 ° C, 100 ° C and 150 ° C on DMV standards (See W. Domke, Maschinenstoff ambience and Material Testing, Verlag W. Gerardet, Essen, 1981, from page 336).
• the Impact energy is low at a ferritic steel Temperatures occurring brittle fracture low (low position), in the case of higher Temperatures ductile, well deformable behavior high (high) with a steep rise within a few degrees from the low altitude to the high altitude. there can strongly spread the impact work in this area.
• the temperature, at the transition from high to low is made Notch impact transition temperature.
• a material is all the more brittle, depending the grain size is larger or in the case of the iron-chromium-aluminum materials, the higher the content of alloying elements such as aluminum, chromium, silicon, Nitrogen, carbon, phosphorus and sulfur is.
• alloying elements such as aluminum, chromium, silicon, Nitrogen, carbon, phosphorus and sulfur is.
• all notched specimens in Table 1 have a very large grain size of about 200 to 400 microns, which is very unfavorable. Therefore all samples are at room temperature in the low position, with the samples with the lowest aluminum content, the lowest chromium content and the lowest carbon content have the highest impact energy, as is the Batches M1, M2, M3, M4 and L1 show.
• the batch M4 has a bit worse lower impact work than the batch M2 with a similar one Aluminum and chromium content, as it has a higher carbon content.
• the Charge L2 has a slightly lower impact performance than the Charge M2, as it does has a higher chromium content. Similar to carbon, nitrogen, Phosphorus and sulfur, whose contents therefore advantageously kept low should be. It turns out that the aluminum content does not exceed 3.0% may be used to minimize the embrittling effect of aluminum hold.
• the brittle behavior of the iron - chromium - Aluminum alloys is significantly reduced by lowering the Aluminum content to less than 3.0%.
• This is additionally supported by low levels of silicon, carbon, nitrogen, phosphorus and sulfur.
• the Carbon content is therefore limited to max. 0.08%, the nitrogen content to max. 0.04 %, the phosphorus content to max. 0.04% and the sulfur content to max. 0.01 Mass% limited.
• Phosphorus and sulfur are additionally unfavorable on the life, so that the lowest possible content of these elements are also advantageous from this perspective.
• the chromium content should be as low as be provided possible. Because of the life requirements can the silicon and chromium levels are not lowered to near zero, but must be at least 0.1% silicon and 10% chromium. It should but not more than 20% chromium and 1% silicon are added to one to achieve the lowest possible brittleness.
• the alloy of the invention must be at least 10% larger Lifespan to have the disadvantage of smaller wire diameter too compensate.
• the batches of the invention all at least one 50% longer life, brings the use of the alloy according to the invention additionally has the advantage of increased Lifespan.
• Manganese is limited to 0.5% by weight, as this element reduces the oxidation resistance. The same applies to copper.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Resistance Heating (AREA)
• Powder Metallurgy (AREA)
• Cookers (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Carbon Steel Or Casting Steel Manufacturing (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Conductive Materials (AREA)
• Catalysts (AREA)

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• 2002
  • 2002-04-25 CN CN02808847.6A patent/CN1226439C/zh not_active Expired - Lifetime
  • 2002-04-25 EP EP02730208A patent/EP1381701B1/de not_active Expired - Lifetime
  • 2002-04-25 AT AT02730208T patent/ATE274605T1/de active
  • 2002-04-25 BR BRPI0209166-6A patent/BR0209166B1/pt not_active IP Right Cessation
  • 2002-04-25 AU AU2002302575A patent/AU2002302575A1/en not_active Abandoned
  • 2002-04-25 WO PCT/EP2002/004571 patent/WO2002088404A2/de not_active Application Discontinuation

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