Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Daiki Kamada

Koichi Sato

Teruo Ito

Takeshi Toyoda

Toru Yonebayashi

Yuuki Kanzawa

Hitoshi Nikaido

Mayuko Kikuzuki

A method for producing a metal sheet with raised lines uses a rolling mill including roll stands. In a preparing step, a grooved roll is prepared, the grooved roll including grooves. In a choosing step, a stand at least one stage before the last stand is chosen. In an incorporating step, the grooved roll is incorporated in as an upper roll of the chosen, specified stand. In a forming step, a workpiece is formed into a metal sheet with raised lines formed corresponding to the respective grooves. In the forming step, a maximum rolling reduction achieved by rolls of the specified stand is set to a provisional value that is lower than a required value. After the leading edge of the workpiece reaches the stand next to the specified stand, the maximum rolling reduction of the specified stand is changed to the required value.

Method for producing metal sheet with raised lines, metal sheet with raised lines, and structural component

This high strength hot rolled steel sheet has a predetermined chemical composition, in which the structure of the high strength hot rolled steel sheet contains martensite in an area ratio of 20% or more and 60% or less and ferrite in an area ratio of 40% or more, and the total area ratio of the martensite and the ferrite is 90% or more, the average grain size of the martensite is 5.0 &#x3bc;m or more and 50 &#x3bc;m or less, the ratio of the hardness of the martensite to the hardness of the ferrite is 0.6 or more and 1.6 or less, and the tensile strength of the high strength hot rolled steel sheet is 980 MPa or more.

High strength hot rolled steel sheet and manufacturing method thereof

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Tokyo, Japan

Daiki Kamada