Nippon Steel Corporation

Nippon Steel Bolten Co., Ltd.

Hiroki Masumoto

Hideaki Kageyama

Kazuo Sugino

Tomomi Murata

Eiji Sato

Kazunari Yamato

Yasuhiko Miyoshi

Sinichi Nisida

Chikayuki Urashima

Yasuo Sogo

A method for manufacturing high strength rail having excellent weldability comprises subjecting a steel rail of specific composition to specific heat treatment conditions at the surface layer portion of the head thereof, to impart high strength to the rail and to assure that the welded portion as well as the welded heat affected zone are free from deterioration caused by the welding process. The heat treatment conditions include a cooling rate which is substantially equivalent to that in a conventional welding process so as to impart high tensile strength to the treated portion of the rail.

Method for manufacturing high strength rail of excellent weldability

Steel plates having excellent resistance to nitrate stress corrosion cracking often encountered in hot stoves, and high temperature heating furnaces, etc., and comprising:

Structural steel plate highly resistant to nitrate stress corrosion

A screw-bolt having crest-cut-off threads with their heights progressively decreased to not more than 3/4 times the basic height in the screwing up direction at a gradient ranging from 60/100 to 3/100 over that of the axial length of the threaded part of the bolt which is located between the unthreaded part and the complete thread upon setting up engagement with a nut therefor to allow a fraction of 0.1 to 0.2 unengaged with the nut, whereby the fatigue strength is increased in terms of the endurance limit from 6 kg/mm.sup.2 for the prior art bolt and nut to more than 11 kg/mm.sup.2 independently of whether SCM 14 or SNCM 5 steel is used in making the bolt and nut.

Screwed connection having improved fatigue strength

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Kitakyushu, Japan

Hiroki Masumoto