| 摘要 |
<p>The present invention provides a high strength galvanized steel sheet having strength of 440 MPa or more and less than 590 MPa, excellent uniform elongation from the viewpoint of formability, suppressed yield point elongation from the viewpoint of quality of an outer panel and excellent zinc coatability and a method for manufacturing the steel sheet. The steel sheet comprises steel having a chemical composition containing C:0.06% or more and 0.20% or less, Si: less than 0.50%, Mn: 0.5% or more and less than 2.0%, P: 0.05% or less, S: 0.02% or less, Al: 0.60% or more and 2.00% or less, N: less than 0.004%, Cr: 0.10% or more and 0.40% or less and B: 0.003% or less (including 0%), satisfying the relationships 0.8‰¤Mn eq ‰¤2.0 and Mn eq +1.3[%Al]‰¥2.8, and a microstructure containing a ferrite phase as a parent phase and a second phase whose volume fraction is 15% or less, the second phase having a martensite phase whose volume fraction is 3% or more, a retained austenite phase whose volume fraction is 3% or more and a sum of the volume fractions of a pearlite phase and a bainite phase being equal to or less than the volume fraction of the martensite phase and the volume fraction of the retained austenite phase.</p> |
