COLD-ROLLED STEEL SHEET

Abstract: this cold-rolled steel sheet has a predetermined chemical composition, in which a metallographic structure at a � depth position, which is a � thickness position from a surface, contains, by volume percentage, retained austenite: more than 1.0% and less than 10.0%, tempered martensite: 80.0% or more, ferrite and bainite: 0% or more and 15.0% or less in total, and martensite: 0% or more and 3.0% or less, and an average grain size of a first grain counted in a sheet thickness direction from the surface when viewed at a cross section parallel to a rolling direction and parallel to the sheet thickness direction is 20.0 �m or less, and an average grain size of the first grain when the surface is viewed in a plan view is 30.0 �m or less.

Inventor(s): Takuya NISHIO, Shintaro OKURA, Yu MATSUMOTO, Masafumi AZUMA, Kojiro AKIBA

CPC Classification: C22C38/50 (ALLOYS (flints ; treatment of alloys , ))

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