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%

Definitions

• the present invention relates to corrosion resistant alloys of novel composition, particularly to improved alloys of the stainless type capable of markedly inhibiting the onset of both stress-corrosion cracking and grain boundary sensitization while affording enhanced resistance to crevice corrosion and pitting in various chloride media.
• Another object is to provide alloys of novel composition resistant to stress-corrosion cracking and intergranular corrosion attack while also offering outstanding resistance to crevice corrosion and pitting.
• alloys contemplated herein contain (in percent by weight) at least 30% nickel, about 17% to 22% chromium, from about 5.5%, e.g., 6%, to 9.25% molybdenum, at least 1%, e.g., at least 1.5%, and up to about 3.25% columbium, up to 0.03% carbon, up to about 1.5% manganese, up to 1% silicon, up to 0.6% titanium, up to 0.6% aluminum, and the balance essentially iron.
• vanadium and copper can be present in the alloys, it is preferred that the amounts of these constituents not exceed 2%, respectively, since it has been found that they often detract from corrosion resistance.
• Elements such as oxygen, nitrogen, phosphorus, sulfur and the like should be kept at low levels consistent with good commercial practice. In this regard, the respective amounts of phosphorus and sulfur should not exceed about 0.02% and 0.03%.
• the alloys should contain at least 30% nickel lest stress-corrosion cracking be promoted. It has been found that with alloys otherwise in accordance herewith, a range of about 31% to 34% nickel offers excellent resistance to stress-corrosion cracking even in the highly aggressive environment of boiling magnesium chloride. Up to 40% nickel can be present, but in amounts above about 35% and to consistently achieve highly satisfactory crevice corrosion resistance, it is quite advantageous that the nickel content be correlated with the molybdenum and columbium as shown in Table I.
• Molybdenum should not fall below about 5.5%; other- 0.25%, it being of advantage to observe a maximum of Wise resistance to stress-corrosion cracking is endangered 0.1%. Manganese preferably does not exceed 1%. While, and, at best, crevice corrosion resistance is impaired.
• the as indicated above herein, up to 2% each of vanadium or data in Table II is of interest in illustrating that although copper can be present, amounts up to 1% and 0.75%, inconsequential amounts of molybdenum are an open inrespectively, are satisfactory.
• Tungsten if present, should vitation to stress-corrosion cracking in magnesium c'hlonot exceed 1% and tantalum (if any) above 2% is not ride, the reverse is the case with molybdenum levels uprecommended.
• Provided at least 1% columbium is preswards of 5.5% or 6%.
• Usual testing procedures were emcut, it is considered that tantalum can be used in lieu of ployed, to wit, U-bend specimens (annealed condition).
• Alloys D, E, and F alloys Nickel, iron, chromium (vacuum grade), and carbon which otherwise would be expected to be virtually crackwere charged into a magnesium oxide crucible.
• Alloys H and L melting under an argon blanket columbium, molybdenum an M and N and P reflect that, geqefally Speaklng, and manganese were then added, the melt being brought molybdenum above about 3% reverses 1ts role as a subto a temperature f about 2900 R
• Verslve- I 2850 F., aluminum, titanium and, excepting Alloy Q
• the alloys beneficially contain at least 18% are given in Table III wherein in contrast to Alloys 1 chromium with 21.5% being a preferred maximum.
• Bal. Balance plus impurities witn manganese not morethan about 1%. 1 Average 012 s ecimens. 2 Contained 2.0 0 copper.
• the second test involved the extremely severe boiling magnesium chloride test referred to above herein. Test results are reported in Table IV regarding Alloys 1, 2, 3, 5 and 7 each of which is within the invention (Alloys 4 loys can be produced in various mill forms, including bar, rod, sheet, plate, strip, wire, etc.
• alloys in accordance herewith manifest high strength.
• Alloy 6 for example, when cold reduced to a wire (a reduction of over 90%) was characterized by an ultimate tensile strength of about 305,000 p.s.i. Equally important, the wire was sufiiciently ductile to pass the kink test (a test wherein the wire is formed into a loop and the ends are drawn together t tightly close the loop).
• kink test a test wherein the wire is formed into a loop and the ends are drawn together t tightly close the loop.
• Hot working operations can be carried out over a temperature range of about 1800 F. to 2300 F. and satisfactory annealing temperatures are from about 1900 F. up to about 2150 F.
• alloys of the subject invention are useful in resisting the corrosive effects of various chloride media in general, specific applications include vessels, containers, tubing, piping, valves and the like, employed in the chemi- 1% and up to 3.25% columbium, the nickel, molybdenum and columbium being correlated as follows when the nickel content is from 35% to 40% up to 0.03% carbon,
• a stainless alloy in accordance with claim 2 containing 6% to 9% molybdenum.
• a stainless alloy in accordance with claim 4 containing 1.5% to 3% columbium.
• a stainless alloy in accordance with claim 5 containing 18% to 21.5% chromium and in which the sum of the chromium plus molybdenum is at least 25%.
• a stainless alloy in accordance with claim 1 containing 31% to 34% nickel, 18% to 21% chromium, 6% to 9% molybdenum and 1.5 to 3% columbium.

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

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Cited By (8)

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Citations (4)

Family Cites Families (6)

• 1966
  • 1966-10-21 US US588341A patent/US3492117A/en not_active Expired - Lifetime
• 1967
  • 1967-09-29 GB GB44518/67A patent/GB1199436A/en not_active Expired
  • 1967-10-05 NO NO170007A patent/NO119921B/no unknown
  • 1967-10-18 NL NL6714164A patent/NL6714164A/xx unknown
  • 1967-10-19 AT AT943567A patent/AT275166B/de active
  • 1967-10-20 DE DE19671608180 patent/DE1608180B1/de active Pending
  • 1967-10-20 ES ES346269A patent/ES346269A1/es not_active Expired
  • 1967-10-20 BE BE705432D patent/BE705432A/xx unknown
  • 1967-10-20 SE SE14379/67A patent/SE322637B/xx unknown

Patent Citations (4)

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