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:
Apr. 18, 1995
Filed:
Aug. 24, 1993
Nippon Steel Corporation, Tokyo, JP;
Abstract
A process of hot forging a steel at an ultrahigh temperature, including the steps of: heating a steel containing 0.1 wt % or more and less than 1 wt % carbon, in a non-oxidizing gas atmosphere, at a heating rate of from 3.degree. to 20.degree. C./sec, in a differential manner such that the steel shell having a thickness of from 0.5 mm to 1/5 of a maximum diameter of the steel is heated to a temperature within a range from a higher value selected from a temperature 45.degree. C. below a solidus line and a temperature of 1250.degree. C. to a temperature 20.degree. C. below a liquidus line while the steel core is heated to a temperature 20.degree. C. below the liquidus line or higher; blowing a cooling medium onto the surface of the heated steel to remove an oxide film from the steel furnace while cooling the steel shell having a thickness of from 1 mm to 1/5 of the maximum diameter of the steel, at a high cooling rate of 10.degree. C./sec or more to a hot forging temperature of 1200.degree. C. or lower; and hot forging the steel, after the blowing, either in a die at a working speed of 500 mm/sec or more or in a die preheated to a temperature of 200.degree. C. of higher at a working speed of 200 mm/sec or more.