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
  • 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
  • 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
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1222—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 by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
  • C21D8/1227—Warm rolling
• • 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
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
  • C22C38/40—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 a method for producing a paramagnetic material, particularly corrosion-resistant in media with a high chloride concentration, with a high yield strength, strength and toughness consisting of in% by weight Max. 0.1 carbon 0.21 to 0.6 silicon 17.0 to 24.0 chromium as well as manganese and nitrogen up to 2.5 nickel up to 1.9 molybdenum Max. 0.3 copper up to 0.002 boron up to 0.8 elements of groups 4 and 5 of the periodic table Remainder iron, melting-related accompanying elements and impurities.
• the invention further relates to an austenitic, paramagnetic material good corrosion resistance, especially in media with high Chloride concentration, and high yield strength, strength and toughness made of carbon, manganese, silicon, chromium and nitrogen, and optionally Nickel, molybdenum, copper, boron, carbide-forming elements, remainder iron, Melting-related accompanying elements and impurities.
• the invention includes the use of one at the beginning mentioned method manufactured material.
• High-strength materials that are paramagnetic and corrosion-resistant economic reasons mainly from chromium-manganese-iron alloys exist for chemical apparatus engineering, for facilities for electrical power generation and especially for components in the Oilfield technology used. Both the corrosion chemical and the mechanical properties of such materials are described in increasingly higher demands.
• Iron-manganese-chromium alloys were also used for economic reasons developed that without pressure melting and the like casting process, so at Atmospheric pressure can be produced (WO 98/48070), whereby alloying measures a desired property profile of the Material should be achieved. Alloys of this type point to Improvement in corrosion resistance to a molybdenum content of over 2%, which brings advantages in particular with hole and crevice corrosion behavior.
• molybdenum is a ferrite former and can be found in segregation areas lead to unfavorable magnetic properties of the material. Increased Nickel contents stabilize the austenite, but may also contribute higher copper concentrations worsening the mechanical Properties and intensify the crack initiation.
• the invention aims to provide a method which Exhaustion of alloying measures includes deformation and synergistically a manufacture of a highly magnetic paramagnetic, in Media with a high chloride concentration are corrosion-resistant, ferrite-free Material with high yield strength, strength and toughness indicates.
• Another object of the invention is a fully austenitic paramagnetic Material with good corrosion resistance and high mechanical values create.
• the advantages achieved by the invention are essentially to be seen in that with high efficiency regarding the material costs and Manufacturing process by an alloy-technical optimization largest Corrosion resistance and a desired paramagnetic behavior of the Material can be achieved, whereby its high mechanical characteristics, especially the yield strength, without adversely affecting the above properties mentioned by a targeted cold forming increased temperature experienced a further significant improvement.
• the carbon content of the alloy is max. 0.1% by weight, because higher levels result in both pitting and stress corrosion cracking chloride-containing media as well as intercrystalline corrosion from it manufactured parts. Compliance with this upper limit, with levels of Max. 0.06 and 0.05% by weight is preferred, as mentioned above, from Corrosion-chemical reasons important, although carbon increases the yield strength and has a strong austenite-forming effect.
• Silicon is said to be a deoxidation metal with a concentration of at least 0.21 % By weight is present in the metal, an upper limit of 0.6% by weight being provided. Higher silicon levels lead to nitride formation and deterioration of the Resistance to stress corrosion cracking of the material. Because silicon is also strong Magnetic permeability can also have a ferrite-forming effect due to higher contents be adversely affected. A maximum content of 0.48 is advantageous % By weight effective.
• Corrosion behavior especially resistance to Stress corrosion cracking and pitting corrosion is caused by the chromium content of the Alloy determined. It is important that a largely homogeneous Chromium distribution in the material is present; in other words, the so-called Weak spots in the passive layer due to segregation and inclusions avoided are. To be largely secured, a desired corrosion resistance too chromium contents of more than 17% by weight, preferably of more than 19% by weight required.
• Chromium increases the solubility of the alloy for Nitrogen, however, has a ferrite-forming effect and is therefore unfavorable with regard to the desired one non-magnetic or paramagnetic behavior of the material, so that the highest chromium concentration is 24.0% by weight, preferably 22.0% by weight.
• Nickel can increase the mechanical properties of the alloy and the stability the austenitic structure can be improved for sufficiently good ones Corrosion properties of the material, especially the Regarding stress corrosion cracking, nickel contents are less than 2.5% by weight. better, but less than 0.96 wt .-% required. Due to low nickel contents From 0.21% by weight up to the above maximum values it is possible without disadvantages in the corrosion behavior of the desired alloy, an increase in To reach yield strength.
• the alloy element molybdenum improves the durability of the material against corrosion, especially against chloride-induced crevice and pitting corrosion.
• this element is a strong ferrite former and the like
• Carbide formers and formers of socialized phases are the Molybdenum caps at 1.9% by weight, but better at 1.5% by weight.
• Low Levels from 0.28 wt .-% molybdenum up to the above limits can Precipitation-free austenite structure of the micro-chemical structure Advantages bring.
• the element copper which is often effective against corrosion attack, has been used in the
• the alloy according to the invention was found to have a disadvantageous effect, wherein the copper contents less than 0.3% by weight, but better less than 0.25% by weight to achieve resistance to corrosion.
• Boron can be used to improve the hot forming behavior of the material an amount of up to 0.002% by weight, preferably up to 0.0012% by weight. Higher amounts of boron lead to grain boundary deposits, Signs of embrittlement and undesirable structures.
• elements of group 4 and group 5 of the periodic table are particularly important for preventing stress cracking and pitting corrosion low levels of elements of group 4 and group 5 of the periodic table.
• These elements Ti, Zr, Hg, V, Nb, Ta
• These elements are extremely strong carbide and nitride or Carbonitride formers and have values of less than 0.8 in total % By weight, better of less than 0.48% by weight. Higher concentrations cause excretions and thereby weak points in the passive layer on the Workpiece surface, which affects the corrosion resistance.
• the element nitrogen is a strong austenite former.
• the yield strength and the resistance of the material to hole and Crevice corrosion due to nitrogen increased.
• Nitrogen is in iron based alloys however, only soluble to a limited extent, with increasing chromium and manganese contents Solubility limit is increased.
• the chromium-manganese and Nitrogen concentrations of the alloy synergistically for the invention To see material or for its properties.
• Preferred nitrogen concentration ranges are: 0.64 to 1.3 wt .-%, in particular 0.72 to 1.2 wt .-% N.
• manganese contents of 30% by weight and more and with nitrogen contents of 0.6% by weight and less high yield strengths cannot be achieved and embrittlement of the material can occur.
• this or this diffusion annealing which is a homogenization of the Serves microstructure or a compensation of micro segregations become.
• This annealing can be carried out, for example, at a temperature of around 1200 ° C up to 60 hours.
• the hot forming of the casting which represents the first deformation step, mostly done by forging, whereby the forming temperature is higher than 850 ° C, to ensure a correspondingly favorable recrystallization of the mixed structure.
• the forging shaped in this way is, as a rule, from the forging heat cooled down at increased speed.
• This cooling the avoidance of Excretions, especially at the grain boundaries, can be in one Water basin or with a continuous cooling section.
• the forging is made at a temperature below 600 ° C reshaped, a solidification of the material, in particular a desired increase in the proof stress occurs.
• a solidification of the material in particular a desired increase in the proof stress occurs.
• the material fully austenitic or ferrite-free; there is therefore no expected partial folding to form a structure with deformation martensite. It turned out to be proved favorable when the deformation of the forged casting in the second Step at elevated temperature, but safely below 600 ° C and then the deformed shaped part is allowed to cool to room temperature.
• Manufacturing technology but also in terms of improved homogeneity and Material quality can be favorable if the block uses an ESR process will be produced.
• the material quality can be further increased if the block in the first step with a degree of deformation, which is defined: output cross section through Final cross-section is at least 4 times thermoformed. This makes a fine, recrystallized, uniform ferrite-free austenite structure achieved.
• the forging in the second step in a To transform temperature in the range of 400 to 500 ° C.
• An austenitic, paramagnetic material with the composition mentioned with good Corrosion properties that are thermoformed at least 3.5 times and below the Elimination temperature of nitrides and associated phases, however is cold-formed above a temperature of 350 ° C, shows the slightest traces of ferrite, practically no ferrite content in the preferred ranges of the composition on and behaves essentially paramagnetically with a relative Permeability below 1.05, in particular below 1.016.
• the yield strength R P0.2 of the material at room temperature is higher than 700 N / mm 2 .
• the values for the impact strength at room temperature are greater than 52J and the FATT (Fracture Appearance Transition Temperature) is lower than -25 ° C.
• Table 1 shows the chemical composition of all reference materials and, additionally, the deformation data for samples 1 to 3 and A to E.
• Samples 4 to 6 come from comparative material that was available on the market.
• Table 2 summarizes the results regarding the magnetic property, the mechanical values and the corrosion behavior.
• Samples 2 and A were made from steel that was melted in the induction furnace and cast into blocks under protective gas.
• Samples 1, 3, B to E come from ESR material.
• the materials of samples 1 and 3 have low magnetic data with good magnetic data Yield strengths and strength values.
• Good toughness and sufficient FATT and the corresponding oxalic acid test pattern show low hole potentials opposite, whereby the materials due to an insufficient Eliminate property profile for high loads. The causes of this are in the low chromium and manganese contents as well as in the consequence low nitrogen concentrations.
• the material of sample 2 does have a sufficiently high chromium content, however, low manganese and the like cause nitrogen in particular poor corrosion resistance.
• the samples A to E produced by means of the method according to the invention are significantly improved in leaps and bounds in the entirety of the usage properties. Synergistically, the respective, coordinated concentrations of the alloying elements and the solidifying cold forming of the material produced without precipitation provide superior corrosion resistance with a low relative magnetic permeability and a substantial increase in the strength values of the same. This is also shown by the test results or measured values of the freely obtained alloy samples 4 to 6.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Electromagnetism (AREA)
• Heat Treatment Of Steel (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Earth Drilling (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Heat Treatment Of Articles (AREA)
• Sampling And Sample Adjustment (AREA)

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• 1999
  • 1999-07-15 AT AT0123299A patent/AT407882B/de not_active IP Right Cessation
• 2000
  • 2000-06-29 EP EP00890207A patent/EP1069202B1/de not_active Expired - Lifetime
  • 2000-06-29 DE DE50000903T patent/DE50000903D1/de not_active Expired - Lifetime
  • 2000-06-29 AT AT00890207T patent/ATE229575T1/de active
  • 2000-06-29 ES ES00890207T patent/ES2187434T3/es not_active Expired - Lifetime
  • 2000-07-14 US US09/617,541 patent/US6454879B1/en not_active Expired - Lifetime
  • 2000-07-14 CA CA002313975A patent/CA2313975C/en not_active Expired - Lifetime

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