Classifications

• • 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 by deformation combined with, or followed by, heat treatment
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/18—Hardening; Quenching with or without subsequent tempering
• • 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
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • 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
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • 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
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • 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 by deformation combined with, or followed by, heat treatment
  • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies

Definitions

• the invention relates to a fire-resistant weldable steel, in particular in Form of hot-rolled hollow profiles, beams, shaped steel or heavy plate for steel construction as well as a process for the production of hot-rolled hollow profiles, beams or shaped steel or heavy plate from it.
• Fire-resistant steels must have high heat resistance so that they can be used in steel construction Reduction of expensive fire protection measures is made possible.
• steel parts are covered either by spray plaster or panels, or provided with filling material.
• the aim of these measures is to ensure that the time until To reach a critical temperature as long as possible or to extend this temperature not to be reached at all.
• these requirements are classified as fire resistance class, z. B. F30, F60, F90 etc., where F is the abbreviation for fire resistance class and the number 30, 60 or 90 indicates the time in minutes until after the outbreak fire, the supporting structure must still be functional.
• EP 0347156 B2 discloses a fire-resistant steel which has a Mn content in the range from 0.5 to 1.6% by weight, in particular a Mo content in the range from 0.2 to 0.7% by weight. having.
• This steel grade is combined with a rolling technology, which is characterized by hot finish rolling at a temperature of 800 to 1000 ° C, then air cooling to a temperature from A r3 -20 ° C to A r3 -100 ° C and a subsequent water cooling to a temperature below of 550 ° C with a cooling rate of 3 to 40 ° C / sec. distinguished.
• the steel produced in this way has a hot yield point at 600 ° C of approx. 230 MPa.
• This steel is also easy to weld with a CE IIW value ⁇ 0.5 1 ,
• a comparable steel is known from EP 0470055 A2.
• the steel grades have Mn, Cr, Mo, Nb, Ti and Cu as main elements.
• This steel grade is also combined with a specific rolling technology. In this case, the final rolling temperatures are between 800 and 950 ° C with subsequent water cooling to 550 to 700 ° C with a cooling rate of 5 to 35 ° C / sec.
• the disclosed method is limited to thicknesses between 1.5 and 12 mm.
• the weldability of this steel is good because the CE IIW value is less than 0.3. No statement can be made about the hot stretch limit, since information on this is missing in the writing. Only the relative decrease in the yield strength with increasing temperature is shown. Such a representation is useless for the designer who is responsible for the design of the component made from this steel, since he needs quantitative values for his design, which he can use in his calculation formulas.
• a fire-resistant nickel-free steel for steel construction and a method for producing heavy plate therefrom is known from EP 0882807 B1.
• This steel grade is characterized by a Mn content in the range from 0.5 to 1.6% by weight and a Mo content in the range from 0.10 to 0.40% by weight.
• Cr in the range from 0.5 to 0.9% by weight and V in the range from 0.01 to 0.05% by weight are also added.
• the hot stretch limit of this known steel is at least 250 MPa at a temperature of 600 ° C.
• the CE IIW value is in the range from 0.27 to 0.79. It is emphasized as essential to the invention that the steel has a yield strength ratio R e / R m at room temperature of between 0.4 and 0.6.
• the object of the invention is to provide a fire-resistant weldable steel which in particular in the form of a hot-rolled hollow profile, beam, shaped steel or heavy plate can be used in steel construction without protective measures where the fulfillment the fire resistance class F30 is an approval requirement.
• a fire-resistant weldable steel is proposed in particular in the form of hot-rolled hollow profiles, beams, shaped steel or heavy plate for steel construction with the following chemical composition and other features: 0.06-0.13% C; 0.15-0.50% Si; 1.0 - 2.0% Mn; Max. 0.025% P; Max. 0.02% S; 0.005-0.040% Al; 0.20-0.40 Mo; 0.40 - 0.70% W; 0.02 - 0.05% Nb remainder iron with melting-related impurities, whereby the component made from this steel has a hot yield strength at 600 ° C of at least 200 MPa and a CE IIW value ⁇ 0.5.
• Essential to the invention is the alloying of W with a balanced ratio of C, Mn and Mo.
• the good weldability even with larger wall thicknesses is guaranteed by a CE IIW value ⁇ 0.5.
• the advantage of the proposed steel is that if the expensive elements, such as Mo and W, are alloyed only slightly, the hot stretching limit is higher, in particular beyond the range of 600 ° C., than with comparable steels. This takes advantage of the effect that tungsten is more effective than chromium in increasing the hot stretch and does not restrict welding suitability, since tungsten is not included in the formula for the CE IIW value. For this reason, the elements Ni and Cu are not alloyed.
• Another advantage is that the yield strength values at RT or at minus temperatures are high, so that the designer does not have any restrictions in his design is subject.
• the designer in structural steel construction is provided with a structural steel given the hand that enables him to produce the component produced from it without complex Fire protection measures or without enlarging the cross-section or increasing the wall thickness, in the sense of meeting fire resistance class F30.
• the good Suitability for welding, even with larger thicknesses, also makes it possible on site at the construction site to be able to weld without problems.
• the hollow profile, the carrier, shaped steel or heavy plate, hard rolled, d. H. without subsequent heat treatment become. If necessary, straightening is necessary beforehand.
• Normalization is required if the customer places high demands on the toughness of the component or remuneration, d. H. Hardening and tempering of the rolled product, required. alternative it can also be advantageous to use inline normalization.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Steel (AREA)

Applications Claiming Priority (4)

Publications (1)

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Cited By (2)

Citations (4)

• 2002
  • 2002-12-11 EP EP02090400A patent/EP1319731A1/fr not_active Ceased

Patent Citations (4)

Non-Patent Citations (4)

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