Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon

Definitions

• the invention relates to metallurgic engineering, to nickel-based alloys intended for use in aggressive oxidizing environments.
• a corrosion-resistant alloy Nicrofer 6616 hMo alloy C-4 (No. 2.4610), containing wt.%: 14.5-17.5 Cr, 14.0-17.0 Mo, ⁇ 3.0 Fe, ⁇ 0.009 C, ⁇ 1.0 Mn, ⁇ 0.05 Si, ⁇ 2.0 Co, ⁇ 0.7 Ti, ⁇ 0.020 P, ⁇ 0.010 S, nickel and other unavoidable impurities is known from the prior art ( Catalogue "Corrosion-resistant, heat-resistant and high-strength steels and alloys", M., Prometey-Splav, 2008, pp. 304 - 306 ).
• the alloy is used for the manufacture of equipment operated in a wide range of chemical environments, at room and elevated temperatures.
• adsorbers in flue gas desul-phuring for adsorbers in flue gas desul-phuring; etching baths and acid recovery plants; acetic acid and agrochemicals plants.
• the nearest analogue of the given invention is an alloy XH65MB ( ⁇ 760) containing, wt.%: ⁇ 0.02 C, ⁇ 0.1 Si, ⁇ 1.0 Mn, 14.5-16.5 Cr, 15.0-17.0 Mo, 3.0-4.5 W, ⁇ 0.5 Fe, ⁇ 0.012 S, ⁇ 0.015 P, nickel and other unavoidable impurities (GOST 5632-2014 - prototype).
• the alloy is used for the manufacture of welded structures (columns, heat exchangers, reactors) operating under elevated temperatures in aggressive redox environments, in the chemical, petrochemical industry (production of acetic acid, epoxy resins, vinyl acetate, melamine, complex organic compounds) and other industries in the temperature range -70 to 500°C.
• the XH65MB alloy and its welded joints can be used in KCl - AlCl3 - ZrCl4 media only up to 500 °C, because at a temperature above this value, the alloy, in addition to intergranular corrosion and corrosion cracking, sharply decreases the percentage elongation from 48% to 7.3-13% at 550°C and up to 2.5% at 625°C and the embrittlement of the metal appears when deformation is applied.
• the technical result of the invention is to obtain an alloy with a high level of plastic properties for the operation in the temperature range 550°C to 625°C and increased corrosion cracking resistance in chlorides KCl, AlCl3 + (ZrCl4 HfCl4) molten metal, at temperatures up to 650°C.
• the alloy containing carbon, silicon, manganese, chromium, molybdenum, phosphorus, sulphur, iron, nickel and unavoidable impurities additionally contains titanium, aluminium, niobium, magnesium with the following components ratio, wt.% : Carbon ⁇ 0.006 Silicon ⁇ 0.1 Manganese ⁇ 1.0 Chromium 22.8-24.0 Iron ⁇ 0.75 Molybdenum 12.0-14.0 Niobium 0.01-0.03 Titanium 0.01-0.06 Aluminium 0.1-0.2 Magnesium 0.005-0.01 Phosphorus ⁇ 0.015 Sulphur ⁇ 0.012 Nickel and unavoidable impurities balance
• the content of chromium, molybdenum and iron is related by the ratio: Cr + ⁇ ⁇ ⁇ Fe ⁇ 46,4 (the ratio of the total weight percentage of chromium and molybdenum to the percentage of iron is not less than 46.4)
• the content of niobium and carbon is related by the ratio: Nb C ⁇ 1,66 (the ratio of the weight percentage of niobium to the weight percentage of carbon is not less than 1.66).
• the content of chromium, molybdenum, iron, niobium and carbon is related by the ratios: Cr + ⁇ ⁇ ⁇ Fe ⁇ 46,4
• the chromium content was found to be 22.8 - 24.0% to ensure the required heat resistance in hafnium and zirconium oxides.
• chromium is introduced into the alloy in the amount of less than 22.8%, the required heat resistance is not ensured, and exceeding the content above 24.0% impairs the heat resistance of the alloy.
• the range of molybdenum content of 12.0-14.0% is selected to provide the required mechanical properties for both short-term and long-term loads and high temperatures. With the introduction of less than 12.0% of molybdenum, the mechanical properties are not met. When the content is above 14.0%, there is a decrease in ductility and, accordingly, a decrease in the processability of the alloy during metallurgical processing.
• Niobium in an amount of 0.01-0.03% binds residual carbon and nitrogen to carbides, nitrides and carbonitrides, prevents the formation of chromium carbides and carbonitrides along the grain boundaries.
• the addition of niobium in an amount 6 to 10 times higher than the carbon content in the alloy eliminates intergranular corrosion of the alloys and protects the welds from destruction. When the niobium content is less than 0.01%, its interaction with residual carbon is ineffective, and the niobium content above 0.03% is not reasonable for carbide formation.
• Nickel is stable in HCl even at boiling point. However, in the presence of chlorides, ions of Fe(III) and other oxidizing agents corrosion of nickel and nickelchrome molybdenum alloys is enhanced, the limitation of the iron content of not more than 0.75% is due to this.
• titanium in an amount of 0.01-0.06% increases the corrosion resistance in melts of zirconium and hafnium salts, binds residual carbon to carbides and leads to the formation of a sufficient amount of Ni3Ti type intermetallic compound, which, at an operating temperature of 500-700C, positively affects the heat resistance of the alloy.
• the titanium content is less than 0.01%, the requirements for corrosion resistance are not met, and the excess of the titanium content above 0.06% leads to a decrease in the processability of the alloy and the formation of undesirable phases due to the reactivity of titanium.
• Aluminium and magnesium in the amount of 0.1-0.2% and 0.005-0.01% are introduced into the alloy to remove residual oxygen, as well as, with regard to aluminium, to form an intermetallic compound of the Ni3Al type, which positively affects the heat resistance of the alloy.
• these elements are introduced in amounts less than specified, the necessary removal of residual oxygen is not achieved. If the content of these elements is exceeded, gross non-metallic inclusions are formed.
• the proposed ratio of the elements in the alloy were found experimentally and are optimal, since they allow obtaining the claimed comprehensive technical result.
• breaking the ratios of the elements the properties of the alloy deteriorate, their instability is observed, and the complex effect is not achieved.
• Alloy ingots were smelted in vacuum induction furnaces.
• the change in the plastic properties of the studied alloys under the influence of temperatures of 550°C and 625°C after long exposure in the furnace for more than 1000 hours was controlled by bending samples to an angle of 90 degrees or more according to GOST 14019-2003.
• Industrial corrosion cracking resistance tests of alloys were carried out in molten chlorides KCl, AlCl3 + (ZrCl4 HfCl4)
• Table 1 shows the chemical composition of alloy ingots with various compositional options, as well as the prototype alloy.
• Table 2 shows the results of determining the plastic properties of the alloys indicated in table 1 by bending at an angle of 90 degrees according to GOST 14019-2003.
• alloys 1, 2 are higher than the properties of the prototype alloy, alloy 3, not satisfying the claimed composition, has lower plastic characteristics than alloys 1, 2, which leads to the formation of cracks as a result of bending tests according to GOST 14019-2003.
• the corrosion rate of alloys (alloys 1, 2) that satisfy the claimed composition is lower than the corrosion rate of the prototype alloy, visual inspection did not reveal the cracks, unlike the prototype alloy.

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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)
• Powder Metallurgy (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

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• 2017
  • 2017-08-01 RU RU2017127607A patent/RU2672647C1/ru active
  • 2017-12-29 CA CA3093022A patent/CA3093022C/fr active Active
  • 2017-12-29 US US16/627,736 patent/US20210164075A1/en not_active Abandoned
  • 2017-12-29 JO JOJO/P/2019/0301A patent/JOP20190301B1/ar active
  • 2017-12-29 MY MYPI2019007591A patent/MY192470A/en unknown
  • 2017-12-29 JP JP2019572506A patent/JP6974507B2/ja active Active
  • 2017-12-29 WO PCT/RU2017/001014 patent/WO2019027347A1/fr not_active Ceased
  • 2017-12-29 CN CN201780092598.3A patent/CN111094603B/zh active Active
  • 2017-12-29 KR KR1020197038839A patent/KR20200060694A/ko not_active Ceased
  • 2017-12-29 EA EA201992733A patent/EA201992733A1/ru unknown
  • 2017-12-29 EP EP17919968.2A patent/EP3663422A4/fr not_active Withdrawn

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