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:
Jun. 27, 1995
Filed:
Nov. 30, 1993
Sumitomo Electric Industries, Ltd., Osaka, JP;
Abstract
A low alloy sintered steel contains at least 0.15 percent by weight and less than 0.8 percent by weight of carbon. Its matrix is formed by a tempered martensite containing prior austenite crystal grains of not more than 15 .mu.m in mean grain size. Pores and nonmetallic inclusions contained in the matrix are not more than 50 .mu.m in maximum diameter, and the density of the low alloy sintered steel is at least 96 percent of theoretical density. A raw material powder for forming the low alloy sintered steel includes iron alloy powder which is prepared by an atomizing process, and is treated with a dry mill in an inert gas atmosphere or in the atmospheric air. Thus, dislocations are introduced into the raw material powder, and nonmetallic inclusions contained in the raw material powder are pulverized to be not more than 50 .mu.m in maximum diameter. Not only static characteristics but also dynamic characteristics, such as fatigue strength, of the low alloy sintered steel are improved.