The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 06, 1977
Filed:
Jun. 01, 1976
Rollin E Hook, Dayton, OH (US);
Armco Steel Corporation, Middletown, OH (US);
Abstract
A method for internal strengthening of articles formed from deep drawing quality low carbon steel strip or sheet containing about 0.02 to about 0.3% titanium in solution, up to about 0.3% columbium in solution, columbium when present being in an amount of at least 0.025% in solution, with the sum total of titanium and columbium in solution not exceeding about 0.3%, comprising the steps of heating the articles at a temperature of about 570.degree. to about 580.degree. C in a nitriding fluid for a time sufficient to form a total nitrogen concentration adjacent the surfaces of the articles at least substantially equal to the amount theoretically required to combine completely with the nitride-forming elements in the steel; and diffusion annealing the articles in a non-nitriding fluid at a temperature of about 595.degree. to about 815.degree. C for a time sufficient to complete through-thickness strengthening by reaction of the nitrogen with the nitride-forming elements. A preferred nitriding fluid is a fused cyanate salt bath.