Nippon Steel Corporation

Norihiro Fujita

Masayuki Abe

Jun Maki

Kazuhisa Kusumi

Masahiro Ohgami

Shinya Nakajima

A method is proved for hot pressing hot rolled steel sheet, cold rolled steel sheet, Al-based plated steel sheet or Zn-based plated steel sheet, where the hot pressed sheet can exhibit a strength of at least about 1200 Mpa, and my be prevented from exhibiting hydrogen embrittlement. The steel sheet may include between about 0.05 to 0.5 wt % C, and/or it may be plated with an Al-based or Zn-based plating material. The steel sheet may be heating to a temperature greater than an Actemperature and not more than about 1100&#xb0; C. before pressing. An atmosphere can be provided during heating which contains not more than about 6 vol % of hydrogen and a dew point of not more than about 10&#xb0; C. The exemplary methods may be used to form high strength parts which may be used, e.g., in automobiles.

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Tokai, Japan

Norihiro Fujita