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US3861906A Expired / Lapsed US ⏱️ 0.0 years remaining

Calcium deoxidized, fine grain steels

Assignee: Ltv Steel Co Inc
•
Filing: 1972-12-29
•
Granted: 1975-01-21
•
Expires: 1992-12-29
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Abstract

Abstract Low carbon and low alloy fine grain steels exhibiting improved machinability, especially by high speed steel tools used in gear cutting operations, are produced by a new calcium deoxidation practice in which: (1) the amount of calcium added to the molten steel in pounds per ton is at least 0.25 plus 13.33 times the oxygen content (percent by weight) of the steel at the time of addition, (2) the temperature of the steel at the time of the calcium addition is from 30* to 120* F. above the calculated liquidus temperature, and (3) the calcium addition is at least in part made to the ladle when it is from about one-third to twothirds full. The calcium deoxidized steels are characterized by calcium aluminate instead of alumina inclusions and by type I instead of type II sulfides, with the sulfides being present as manganese sulfide and/or calcium manganese sulfide coatings which surround the calcium aluminate particles.

Inventors

  • 👤 Vijayakumar A Tipnis
  • 👤 James Harmon Doubrava
  • 👤 Roger A Joseph

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-04 16:08
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/002; C21; C21C; C21C7/00; C21C7/04; C21C7/06

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 58 words
13 TO 0.70% CARBON, FROM 0.45 TO 1.65% MANGANESE, FROM 0.015 TO 0.10% ALUMINUM, AT LEAST 0.0002% CALCIUM, UP TO 0.09% SULFUR, UP TO 3.5% NICKEL, UP TO 3.5% CHROMIUM, UP TO 0.35% VANADIUM, UP TO 0.80% MOLYBDENUM, AND UP TO 0.0015% BORON, SAID STEEL BEING CHARACTERIZED BY CALCIUM ALUMINATE INCLUSIONS AND BY THE ABSENCE OF ALUMINA INCLUSIONS.
Claim 2
Dependent Claim 56 words
A steel as claimed in claim 1 including from 0.01 to 0.15% by weight of at least one member selected from the group consisting of selenium and tellurium, said steel being further characterized by the presence of manganese and calcium sulfide (with partial substitution of tellurium and/or selenium for sulfur) coatings on the calcium aluminate inclusions.
Claim 3
Dependent Claim 28 words
A steel as claimed in claim 1 including from 0.01 to 0.30% by weight of at least one member selected from the group consisting of lead and bismuth.
Claim 4
Dependent Claim 75 words
A steel as claimed in claim 1 including from 0.01 to 0.15% by weight of at least one member selected from the group consisting of selenium and tellurium and from 0.01 to 0.30% by weight of at least one member selected from the group consisting of lead and bismuth, the selenium and/or tellurium and the lead and/or bismuth being combined with sulfur and present in calcium manganese sulfide coatings which surround the calcium aluminate inclusions.
Claim 5
Dependent Claim 42 words
A calcium deoxidized, fine grain steel containing from 0.13 to 0.70% by weight carbon, at least 0.015% by weight aluminum, and at least 0.0002% by weight calcium, and characterized by the presence of calcium aluminate inclusions and the absence of alumina inclusions.
Claim 6
Dependent Claim 71 words
A steel as claimed in claim 5 made by adding the calcium to the molten steel when at a temperature in the range of from 30* to 120*F. above the calculated liquidus temperature, the amount of the calcium addition in pounds per ton of steel being at least equal to 0.25 plus 13.33 times the oxygen content (percent by weight) of the molten steel at the time of the calcium addition.
Claim 7
Dependent Claim 48 words
A steel as claimed in claim 6 in which the molten steel is melted in a furnace and tapped or poured into a ladle, at least part of the calcium being added to the steel at a time when the ladle is from about one-third to two-thirds full.
Claim 8
Dependent Claim 21 words
A steel as claimed in claim 7 in which the aluminum is added no later than simultaneously with the calcium addition.

References Cited (Backward Citations)

US2127245A Cited
US2687954A Cited
US2901346A Cited
US2853379A Cited
US2950187A Cited
US3110798A Cited
US3130045A Cited
US3115406A Cited
US3132938A Cited
US3314828A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-01-20 1978-07-22 1979-01-21 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-01-20 1982-07-22 1983-01-21 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-01-20 1986-07-22 1987-01-21 $7700.00 Window Closed / Lapsed

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