Nippon Steel Sumitomo Metal Corporation

Mayuko Kikuzuki

Takeshi Toyoda

Yuuki Kanzawa

Daiki Kamada

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.

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Tokyo, Japan

Mayuko Kikuzuki