HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLENT IN COATING ADHESION, WORKABILITY AND HYDROGEN EMBRITTLEMENT RESISTANCE, AND STEEL COMPONENT FOR AUTOMOBILE

摘要

A cold rolled steel sheet satisfying on the basis of percent by mass the chemical composition of 0.06-0.6% C, 0.1-2% Si, 0.01-3% Al, 1-4% Si + Al, 1-6% Mn, Si/Mn ‰ 0.40, in which there exists 10 or more pieces/100 µm 2 of Mn-Si composite oxide having Mn-Si atom ratio (Mn/Si) of 0.5 or over and major axis of from 0.01 µm to 5µm and also having a covering ratio of 10% or below at which the surface of the steel sheet is covered with oxide containing Si as the main component.