Nippon Steel Corporation

Yukio Tsuda

Ryota Yamaba

Atsuo Tanaka

Yukio Tomita

Tatsuya Kumagai

Katsuyoshi Yamanaka

Keiichi Hattori

High-strength steel having a tensile strength of 80 kgf/mm.sup.2 or more is produced by one-line quenching or on-line quenching and tempering. The steel has also excellent low-temperature toughness and excellent weldability, which makes high temperature preheating unnecessary prior to welding. The composition is: C=0.04% to 0.11%; Si.ltoreq.1.0%; Mn=0.5% to 2.00%, Mo=0.10% to 1.0%, Nb=0.005% to 0.05% B=0.0009% to 0.0012% Al.ltoreq.0.1%; and N.ltoreq.0.0060%.

Method for producing high-strength steel having improved weldability

A method of producing non-oriented magnetic steel heavy plate that has good magnetic properties in a low magnetic field that comprises hot-rolling high-purity steel, adjusting the crystal grain size and dehydrogenation treatment, whereby the a uniform ferrite grain diameter is imparted to the steel.

Method of producing non-oriented magnetic steel heavy plate having high

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Tokai, Japan

Yukio Tsuda