High-strength steel sheet having excellent workability

Abstract

According to the present invention, there is provided a high strength steel sheet, which has, for example, a tensile strength of 590 to 980 MPa or more, which has favorable workability, and which is useful for an automobile, etc. The high strength steel sheet of the present invention comprises 0.03 to 0.20% C (% by mass in chemical compositions; hereafter, the same holds true), 0.50 to 2.5% Si, 0.50 to 2.5% Mn, and further, preferably 0.02 to 0.2% Mo. Moreover, its metal structure includes ferrite and low temperature transformation phase. The mean grain size of the low temperature transformation phase is 3.0 μm or less. Further, grains whose size is 3.0 μm or less occupy 50% or more by area ratio of the low temperature transformation phase, and an average aspect ratio of the low temperature transformation phase is 0.35 or more.

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