Nkk Corporation

Nippon Kokan Kabushiki Kaisha

Tsunemi Wada

Yoshio Saito

Kozo Fukuda

Shinichi Nagahashi

Akio Fujibayashi

Kiyotaka Morioka

Toyokazu Teramoto

Minoru Tanaka

Masahiro Ueda

Hiroaki Sato

Yuzuru Kataoka

Takao Gino

Ichiro Nakauchi

Yuzu Kato

Mashiro Ueda

Yazuru Kataoka

A method for manufacturing a high strength rail with good toughness, comprises cooling a rail to Ar.sub.3 transformation point or less after hot rolling; heating said cooled rail at a temperature of an austenite temperature zone ranging from Ac.sub.3 transformation point to 950.degree. C.; and cooling the heated rail. The chemical composition of the rail consists of 0.50 to 0.85 wt. % C, 0.50 to 1.50 wt. % Mn, 0.035 wt. % S or less, 0.10 to 1.00 wt. % Si, 0.035 wt. % P or less, 0.050 wt. % Al or less and the balance of Fe and inevitable impurities.

Method for manufacturing a high strength rail with good toughness

A method for heat-treating a steel rail head, which comprises: heating a steel rail head to the austenization temperature; then, cooling the rail head by means of a hot water jet until a surface temperature of the rail head decreases to a temperature not below 420.degree. C.; and then cooling the rail head by means of an air jet at least to the pearlite transformation temperature, thereby transforming the structure of a surface portion of the rail head into a uniform and fine pearlite structure. The above-described method includes a method in which the rail head is previously cooled by means of a water spray until the surface temperature of the rail head decreases to a temperature not below 530.degree. C. prior to the cooling of the rail head by means of the above-mentioned hot water jet.

Method for heat-treating steel rail head

A wear resistance rail which comprises 0.50 to 0.85 wt. % of C, 0.10 to 1.0 wt. % of Si, 0.50 to 1.50 wt. % of Mn, less than 0.035 wt. % of P, less than 0.035 wt. % of S, less than 0.050 wt. % of Al, and the balance of iron and impurities. The web has a high toughness tempered bainite structure, tempered martensite structure or a tempered mixed structure of bainite and martensite and the head rail has high wear resistance which prevents unstable destructive cracks from propagating. The rail can further contain one or more of 0.05 to 1.50 wt. % of Cr, 0.05 to 0.20 wt. % of Mo, 0.03 to 0.10 wt. % of V, 0.10 to 1.00 wt. % of Ni, and 0.005 to 0.050 wt. % of Nb.

Wear resistant rails having capability of preventing propagation of

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Tokyo, Japan

Tsunemi Wada