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. 25, 2000
Filed:
May. 29, 1998
Daien Yokoi, Himeji, JP;
Nobuhiro Tsujii, Himeji, JP;
Sanyo Special Steel Co., Ltd., Himeji, JP;
Abstract
Disclosed are a cold working tool steel suitable for plastic cold working tools used under severe service conditions, such as forming dies, forming rolls, and form rolling dies, and a process for producing the same. The cold working tool steel has wear resistance and tensile compression fatigue strength and at the same time can provide improved die life. The cold working tool steel is characterized by comprising by weight 0.65 to 1.3% of carbon, not more than 2.0% of silicon, 0.1 to 2.0% of manganese, 5.0 to 11.0% of chromium, 0.7 to 5.0%, in terms of molybdenum equivalent (molybdenum+tungsten/2), of at least one member selected from molybdenum and tungsten, 0.1 to 2.5%, in terms of vanadium equivalent (vanadium+niobium/2), of at least one member selected from vanadium and niobium, and optionally 0.010 to 0.10% of sulfur with the balance consisting of iron and unavoidable impurities, an M.sub.7 C.sub.3 carbide having a grain diameter of 5 to 15 .mu.m being present in a percentage area of 1 to 9%. The process is characterized by comprising the steps of: providing a steel product having the above chemical composition; and tempering the steel product at a temperature of 150 to 500.degree. C., preferably 150 to below 450.degree. C.