US3740213A - Stainless ferrite-austenitic steel - Google Patents

Stainless ferrite-austenitic steel Download PDF

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Publication number
US3740213A
US3740213A US00823744A US3740213DA US3740213A US 3740213 A US3740213 A US 3740213A US 00823744 A US00823744 A US 00823744A US 3740213D A US3740213D A US 3740213DA US 3740213 A US3740213 A US 3740213A
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United States
Prior art keywords
steel
columbium
content
corrosion
percent
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Expired - Lifetime
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US00823744A
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English (en)
Inventor
L Hellner
N Hede
H Johansson
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Saab Bofors AB
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Bofors AB
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    • 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/06—Bandages or dressings; Absorbent pads specially adapted for feet or legs; Corn-pads; Corn-rings
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

Definitions

  • the present invention relates to a method of producing a stainless ferrite-austenitic steel with a high resistance to intercrystalline corrosion.
  • Said ferrite austenitic steel can advantageously contain:
  • the invention also relates to steels produced according to any of the above-mentioned methods.
  • columbium nitrate CbN
  • a certain quantity of columbium can also be fixed in the form of columbium oxide or other slag containing co lumbium, but since, as is usually the case in steel of this type, aluminium is present in a content of a few hundredths percent, such a binding of columbium to oxygen is of no practical significance.
  • columbium should not be too great, as the undesirable tendency towards a phase formation already found in steel according to 81$ 2324 increases with the addition of columbium.
  • This tendency towards incerased 0' phase formation at an in creased addition of columbium will be noted from table 3, in which the 0' phase formation for most of the steels listed in table 1 has been investigated at two different heat-treatment conditions, heating to 975C for 1 hour and cooling in water, followed by sensitizing at 700 for 2 hours as well as the same quenching annealing at 975for 1 hour followed by sensitizing for 2 hours, but this time at 800C.
  • Table 3 also gives the austenite content of the steel after quench annealing from heating for 1 hour at 975C. It then proved that steel No. 2 had a considerably higher austenite content than the other steels, and this high austenite content also proved to be less favourable, as the malleability was substantially impaired, at the same time as the yield point was lowered.
  • the austenite content should be between 5 and 30 percent, particularly between 15 and 25 percent.
  • a low austenite content primarily has an unfavourable influence on the impact strength, and in order to obtain a suitable austenite content in the steel, the contents of nickel, manganese and chromium must be appropriately balanced. Moreover, chromium is necessary in order to give the steel the good corrosion properties desired, but its content should not exceed approx.
  • the carbon content can be kept low for two reasons; the low carbide content consequently obtained has a favourable influence on the malleability and impact strength and, moreover, a lower carbon content will reduce the content of columbium additive required in order that the ratio Cb /C shall amount to at least eight. In order to obtain carbon contents below 0.04 percent, however, sepcial metallurgical proce dures are required, which make the steel considerably more expensive, and in the present case, approx. 0.05 percent carbon therefore seems to be appropriate. Also the nitrogen content should be kept low, in order to limit the columbium additive required.
  • Table 4 shows some physical properties of the steels investigated. These physical properties have been determined according to the ISO Recommendations No. R82 (1959) and R 148 (1960). As will be noted from table 4, the physical properties have mainly been retained, in spite of the columbium content, and through the present invention it has therefore become possible to achieve a stainless ferrite austenitic steel that has physical properties which are practically equal to those of the previously used ferrite-austenitic steel according to SIS 2324, but which has considerably less sensitivity to intercrystalline corrosion.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Health & Medical Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Vascular Medicine (AREA)
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  • Animal Behavior & Ethology (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • Biomedical Technology (AREA)
  • Heat Treatment Of Steel (AREA)
  • Soft Magnetic Materials (AREA)
  • Hard Magnetic Materials (AREA)
US00823744A 1968-05-16 1969-05-12 Stainless ferrite-austenitic steel Expired - Lifetime US3740213A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE06611/68A SE347534B (enrdf_load_stackoverflow) 1968-05-16 1968-05-16

Publications (1)

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US3740213A true US3740213A (en) 1973-06-19

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US00823744A Expired - Lifetime US3740213A (en) 1968-05-16 1969-05-12 Stainless ferrite-austenitic steel

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US (1) US3740213A (enrdf_load_stackoverflow)
DE (1) DE1924487A1 (enrdf_load_stackoverflow)
GB (1) GB1204453A (enrdf_load_stackoverflow)
SE (1) SE347534B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3833359A (en) * 1973-08-13 1974-09-03 Kubota Ltd High cr low ni stainless steel
US4055448A (en) * 1973-04-10 1977-10-25 Daido Seiko Kabushiki Kaisha Ferrite-austenite stainless steel
US4391635A (en) * 1980-09-22 1983-07-05 Kubota, Ltd. High Cr low Ni two-phased cast stainless steel

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2590074A (en) * 1948-12-28 1952-03-25 Armco Steel Corp Stainless steel process and product
US3337331B1 (enrdf_load_stackoverflow) * 1964-01-29 1967-08-22
US3499802A (en) * 1966-05-04 1970-03-10 Sandvikens Jernverks Ab Ferritic,martensitic and ferriteaustenitic chromium steels with reduced tendency to 475 c.-embrittlement

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2590074A (en) * 1948-12-28 1952-03-25 Armco Steel Corp Stainless steel process and product
US3337331B1 (enrdf_load_stackoverflow) * 1964-01-29 1967-08-22
US3337331A (en) * 1964-01-29 1967-08-22 Sandvikens Jernverks Ab Corrosion resistant steel alloy
US3499802A (en) * 1966-05-04 1970-03-10 Sandvikens Jernverks Ab Ferritic,martensitic and ferriteaustenitic chromium steels with reduced tendency to 475 c.-embrittlement

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4055448A (en) * 1973-04-10 1977-10-25 Daido Seiko Kabushiki Kaisha Ferrite-austenite stainless steel
US3833359A (en) * 1973-08-13 1974-09-03 Kubota Ltd High cr low ni stainless steel
US4391635A (en) * 1980-09-22 1983-07-05 Kubota, Ltd. High Cr low Ni two-phased cast stainless steel

Also Published As

Publication number Publication date
SE347534B (enrdf_load_stackoverflow) 1972-08-07
GB1204453A (en) 1970-09-09
DE1924487A1 (de) 1969-11-27

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