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US4007038A Expired / Lapsed US ⏱️ 0.0 years remaining

Pitting resistant stainless steel alloy having improved hot-working characteristics

Assignee: Allegheny Ludlum Corp
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Filing: 1975-04-25
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Granted: 1977-02-08
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Expires: 1995-04-25
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Abstract

Abstract An austenitic stainless steel alloy which has extremely good pitting resistance and at the same time has good hot-workability characteristics. The alloy contains, as essential constituents, chromium, nickel, molybdenum, calcium and cerium. In achieving the desirable characteristics of the invention, the molybdenum and chromium levels are important in determining pitting resistance; while recoveries of cerium and calcium in the final alloy are important in determining the hot-workability of the alloy, although cerium is the more important of the two. Sulfur levels are preferably maintained low, on the order of 0.006% or less. Also disclosed is a method for making an alloy of the type described above wherein the finishing temperature of hot-rolled strip is maintained around or above 1800° F to reduce edge cracking and preferably is maintained at about 2000° F.

Inventors

  • 👤 Harry E. Deverell

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-27 19:42
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/40; C22C38/44; C21; C21D; C21D8/00; C21D8/02

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 48 words
An austenitic stainless steel consisting essentially of about 20% to 40% nickel, 14% to 21% chromium, about 6% to 12% molybdenum, up to 0.2% carbon, up to 2% manganese, 0.010% to 0.080% cerium, 0.005% to 0.015% calcium, up to about 0.006% sulfur, and the remainder essentially all iron.
Claim 2
Dependent Claim 48 words
An austenitic stainless steel consisting essentially of about 20% to 40% nickel, 14% to 21% chromium, about 6% to 12% molybdenum, up to 0.2% carbon, up to 2% manganese, 0.010% to 0.080% cerium, 0.005% to 0.015% calcium, up to about 0.006% sulfur, and the remainder essentially all iron.
Claim 3
Dependent Claim 62 words
An austenitic stainless steel alloy consisting essentially of about 20% to 40% nickel, 14% to 21% chromium, 6% to 12% molybdenum, up to 0.2% carbon, up to 2% manganese, about 0.010% to 0.080% cerium, about 0.005% to 0.015% calcium, the sum of calcium plus cerium being in the range of 0.03% to 0.10% and the remainder essentially all iron with incidental impurities.
Claim 4
Dependent Claim 62 words
An austenitic stainless steel alloy consisting essentially of about 20% to 40% nickel, 14% to 21% chromium, 6% to 12% molybdenum, up to 0.2% carbon, up to 2% manganese, about 0.010% to 0.080% cerium, about 0.005% to 0.015% calcium, the sum of calcium plus cerium being in the range of 0.03% to 0.10% and the remainder essentially all iron with incidental impurities.
Claim 5
Dependent Claim 35 words
The alloy of claim 2 wherein calcium is present in an amount of about 0.01%, cerium is present in the amount of about 0.05%, the sum of cerium and calcium being about 0.06% by weight.
Claim 6
Dependent Claim 17 words
The alloy of claim 3 wherein sulfur is present in an amount no greater than about 0.006%.

References Cited (Backward Citations)

US2553330A Cited
US3547625A Cited
US3729308A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1980-02-08 1980-08-09 1981-02-08 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1984-02-08 1984-08-09 1985-02-08 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1988-02-08 1988-08-09 1989-02-08 $7700.00 Window Closed / Lapsed

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