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:
Nov. 12, 1991
Filed:
Jul. 30, 1990
Koji Sato, Yasugi, JP;
Rikizo Watanabe, Yasugi, JP;
Hitachi Metals, Ltd., Tokyo, JP;
Abstract
A heat resistant steel for use as a material of engine valves, having a composition containing, not less than 0.01% and below 0.20% of carbon, from 0.05% to 1.0% of silicon, from 7.5% to 15.0% of manganese, from 2.0% to 20.0% in total of at least one of nickel and cobalt, from 15.0% to 25.0% of chromium, not more than 3.0% of molybdenum, above 2.0% and not more than 10.0% of tungsten, not less than 0.01% and below 0.50% of niobium, from 0.30% to 0.65% of nitrogen, not more than 0.02% of boron, and the balance incidental inclusions and iron. Cobalt content is determined to meet the condition of % Co=(Ni.+-.5)%. The heat resistant steel meets the conditions of: oxidation weight loss when held at 1000.degree. C. for 100 hours being not greater than 0.15 mg/cm.sup.2 /hour in atmosphere; tensile strength being not less than 20 kgf/mm.sup.2 at 900.degree. C. after a solution treatment at 1030.degree. to 1070.degree. C. and a subsequent aging treatment; and creep rupture life at 900.degree. C. under stress load of 6 kgf/mm.sup.2 being not less than 25 hours.