High strength cold-rolled steel sheet and automobile components of steel having excellent properties in coating film adhesion, workability, and hydrogen embrittlement resistivity

摘要

A cold rolled steel sheet satisfying on the basis of percent by mass of the chemical composition of 0.06 to 0.6% C, 0.1 to 2% Si, 0.01 to 3% Al, 1 to 4% Si + Al, 1 to 6% Mn, and in which there exists no crack of 3 µm or less in width and 5 µm or over in depth in any 10 fields of view when observation at 2000X magnification by SEM is made of a cross section in the proximity of the surface of said steel sheet.