TITANIUM ALLOY SCREW FORMED BY ROLLING

WIPO Patent Application WO/2010/082403

A1

A titanium alloy screw produced from a titanium alloy screw material which has undergone plasma carburizing.  The screw has a hardened groove bottom part and, hence, has a reduced coefficient of friction and improved fastening characteristics.  The groove bottom part is prevented from cracking and is less apt to suffer crack propagation.  A process for producing the screw is provided.  A carburized layer is formed in a titanium alloy material so that the material has a maximum value of hardness at a depth of 1 µm or smaller from the surface, and the surface having the carburized layer is rolled to obtain a rolled titanium alloy screw.  As a result of the rolling, a continuous flow of a metallic macrostructure in a region located deeper than about 1 µm from the surface of the carburized layer is formed in an ordered state along the shape of the groove bottom in a region extremely close to the groove bottom.  Such work hardening based on the surface-part structural configuration brings about a sufficient increase in strength and causes no decrease in fatigue strength.

TANAKA, Koichi (10-6, Tezukayamanaka 1-chome Sumiyoshi-ku, Osaka-shi, Osaka 53, 〒5580053, JP)
田中　弘一 (〒53 大阪府大阪市住吉区帝塚山中１丁目１０番６号 Osaka, 〒5580053, JP)

JP2009/070088

July 22, 2010

November 24, 2009

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TANAKA LIMITED (10-6, Tezukayamanaka 1-chome Sumiyoshi-ku, Osaka-shi, Osaka 53, 〒5580053, JP)
株式会社田中 (〒53 大阪府大阪市住吉区帝塚山中１丁目１０番６号 Osaka, 〒5580053, JP)
TANAKA, Koichi (10-6, Tezukayamanaka 1-chome Sumiyoshi-ku, Osaka-shi, Osaka 53, 〒5580053, JP)

C23C8/36; B21H3/02; F16B33/06; F16B35/00

KAMADA Bunji et al. (18-12, Nipponbashi 1-chome Chuo-ku, Osaka-sh, Osaka 73, 〒5420073, JP)

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