Nippon Steel Corporation

Masanobu Yamaguti

Hajime Nakasugi

Turugi Kimura

Hiroshi Tamehiro

Hisashi Gondo

Masatoki Nakayama

A method for obtaining a weld metal having excellent toughness at low temperatures as below -40.degree. C, which method comprises heating the weld metal having a specific steel composition to its austenitizing temperature and cooling it or holding it at the temperature for not longer than 25 minutes and then quenching and tempering it. In order to further improve the low temperature toughness, the weld metal is reheated again to the Ac.sub.1 to Ac.sub.3 range. Excellent low temperature toughness of the weld metal can be obtained without the necessity of using any special welding materials.

Method for heat treatment of high-toughness weld metals

A method for producing a high tensile strength and toughness bend pipe in which a heat treatment is done as a pretreatment prior to bending, and a tempering treatment is done, if necessary, after the bending, and the bend pipe produced by the present invention is useful for pipe line construction and shows excellent properties at low temperatures.

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Kimitsu, Japan

Masanobu Yamaguti