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US4180420A Expired / Lapsed US ⏱️ 0.0 years remaining

Razor blades

Assignee: Gillette Co LLC
•
Filing: 1977-12-01
•
Granted: 1979-12-25
•
Expires: 1997-12-01
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Abstract

Abstract The instant disclosure is concerned with martensitic stainless steel cutting edges such as razor blades which have superior corrosion resistance and which, although containing only between 0.30% to 0.45% carbon have hardnesses which are equal or better than cutting edges made from martensitic stainless steels containing 0.6% or more carbon which are widely sold commercially. Generally the blades are produced by treating them prior to hardening so that they will have a fine carbide microstructure comprising about 200 to about 500 carbides per 100 square microns, hardening them under conditions in which the fine microstructure will be substantially retained, i.e. subsequent to hardening they will still have about 200 to 500 carbides per 100 square microns, and forming the cutting edge.

Inventors

  • 👤 Suri A. Sastri
  • 👤 Ben H. Alexander

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 20:34
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/22

Claims Analysis

Total Claims: 3
Claim 1
Independent Claim 58 words
A martensitic stainless steel razor blade; said blade comprising 0.30% to 0.45% carbon; 11% to 16% chromium; 0 to 2.5% molybdenum; 0 to 4% tungsten; 0 to 0.70% silicon; 0 to 1.5% manganese, and the balance iron with incidental impurities and said blade having a fine carbide microstructure comprising about 200 to 500 carbides per 100 square microns.
Claim 2
Dependent Claim 58 words
A martensitic stainless steel razor blade; said blade comprising 0.30% to 0.45% carbon; 11% to 16% chromium; 0 to 2.5% molybdenum; 0 to 4% tungsten; 0 to 0.70% silicon; 0 to 1.5% manganese, and the balance iron with incidental impurities and said blade having a fine carbide microstructure comprising about 200 to 500 carbides per 100 square microns.
Claim 3
Dependent Claim 17 words
A blade as defined in claim 1 in which the steel comprises about 0.35% to 0.45% carbon.

References Cited (Backward Citations)

US3116180A Cited
GB1108377A Cited
US3595643A Cited
US3672877A Cited
US3826697A Cited
US3756865A Cited
US4021272A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1982-12-24 1983-06-25 1983-12-25 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1986-12-24 1987-06-25 1987-12-25 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1990-12-24 1991-06-25 1991-12-25 $7700.00 Window Closed / Lapsed

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