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
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • 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
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

• the invention relates to an austenitic nitrogen-containing CrNiMoMn steel and to a method for its production and its use.
• a nitrogen-containing steel with a high yield strength and good toughness properties which contains up to 0.6% carbon, 5 to 40% chromium, up to 30% manganese, up to 5% molybdenum, up to 20% Contains nickel, 1.5 to 5% nitrogen and balance iron and has an austenitic structure.
• the nitrogen content is introduced into the steel in that the melt initially contains nitrogen-containing iron-chromium or. Iron-manganese alloys are added and then gaseous nitrogen is introduced into the melt or into the slag.
• AT-PS 277 301 is based on the long-known knowledge that austenitic chromium-nickel and chromium-manganese alloys increase austenite stability by nitrogen and that in semi-ferritic and ferritic chromium steels with more than 18% chromium nitrogen occur of austenite or leads to an increase in the part of the structure that can be converted, whereby 0.1% nitrogen can replace 2% nickel with regard to austenite stabilization (see E. Houdremont, Handbuch der Sonderstahlischen constitution, 1956, pages 1327 to 1331).
• An improvement in the mechanical-technological properties can be achieved by introducing nitrogen contents that are below or close to the respective nitrogen solubility limit of the CrNiMoMn steels.
• the addition of nitrogen also has a positive effect with regard to the long-term behavior at room temperature under mechanical stress.
• An austenitic CrNiMoMn steel with a nitrogen content of 0.03% has a yield strength R p0.2 220 N / mm 2 and a flexural fatigue strength 5 bw of 260 N / mm 2 .
• a yield strength Rp o , 2 of 380 N / mm 2 and a flexural fatigue strength b bw of ⁇ 360 N / mm 2 are achieved.
• the invention is therefore based on the object of providing an austenitic, nitrogen-containing CrNiMoMn steel which has a creep behavior at high temperatures which is comparable to nickel-based alloys and which has property values at low temperatures which are comparable to the properties of cold-formed CrNiMoMn steels are.
• Another object of the invention is to create a method for producing the austenitic, nitrogen-containing CrNiMoMn steel and to show particularly advantageous possible uses for this steel.
• the object on which the invention is based is achieved by creating a steel which has all of the features specified in claim 1.
• the object is also achieved by creating a method for producing this steel, which is characterized by all of the features mentioned in claim 11.
• the object on which the invention is based is achieved in that the steel is used in the manner as proposed in claim 2.
• the steel of the invention has the advantage that it can replace heat-resistant nickel-based alloys in solution-annealed condition at high temperatures and that its mechanical-technological properties at low temperatures are comparable to the properties of cold-formed austenitic CrNiMoMn steels.
• the method according to the invention has proven to be particularly suitable for the production of the steel, since its use achieves a very uniform structure which ultimately ensures the good properties of the steel.
• the use of the steel provided according to the invention makes components available which can be exposed to high loads, particularly at high and low temperatures.
• a corrosion-resistant chrome steel is known from DE-OS 3 310 693, which consists of 3 to 45% Cr, 0 to 10% Mn, 0.001 to 0.5% C, 0.2 to 5% N, 0 to 2% Si , 0 to 10% Ni, 0 to% Mo, 0 to 5% V, 0 to 2% Ti, Nb and / or Ta, 0 to 0.3% Al, 0 to 1% Ce and rest Fe, the structure of which contains at least 50% ferromagnetic structure components and which has a yield strength Rp o , 2 of more than 400 N / mm 2 at 400 ° C and a yield strength Rp o , 2 of more than 250 N / mm 2 at 600 ° C, and although in The same document describes a process for the production of this steel, in which a nitrogen content is introduced into a master alloy by nitrogen nitrogen pressure, which is between 0.2 and 5% and must be at least 10% greater than the nitrogen solubility limit of the master alloy at 1 bar and 20 ° C, at which
• the steel is particularly suitable for the production of components that are used in the construction of cryogenerators and steam turbines.
• the steel is particularly suitable for the production of components that are used in gas and steam turbine construction.
• the steel is particularly suitable for the production of components that are used in gas turbine construction.
• the steel is particularly suitable for the production of components that are used in cryogenerators.
• Pressure electroslag remelting is a known process which is described, for example, in DE-OS 2 924 415. According to the information given there, a deoxidizing agent, for example, is also used in the process according to the invention during the electroslag remelting at the same time as the Si 3 N 4 .
• B. CaSiMg added to the slag.
• the nitrogen content of the master alloy, which is remelted by pressure electroslag remelting, can be increased by adding metallic nitrogen carriers, e.g. As chromium nitride or manganese nitride, are introduced into the master alloy.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Manufacture And Refinement Of Metals (AREA)

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Publications (1)

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Cited By (8)

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Citations (5)

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• 1985
  • 1985-12-20 DE DE19853545182 patent/DE3545182A1/de not_active Withdrawn
• 1986
  • 1986-12-13 EP EP86117381A patent/EP0231492A1/fr not_active Withdrawn
  • 1986-12-18 JP JP30022086A patent/JPS62211356A/ja active Pending

Patent Citations (5)

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