Galvanized steel sheet and method for manufacturing the same

A galvanized steel sheet comprising:

• a basal steel sheet containing elements C:
• 0.01 to 0.15%, Si:
• 0.001 to 2.0%, Mn:
• 0.1 to 3.0%, Al:
• 0.001 to 1.0%, P:
• 0.005 to 0.060%, S≦0.01%, and one or more kinds of elements selected from B:
• 0.001 to 0.005%, Nb:
• 0.005 to 0.05%, Ti:
• 0.005 to 0.05%, Cr:
• 0.001 to 1.0%, Mo:
• 0.05 to 1.0%, Cu:
• 0.05 to 1.0%, and Ni:
• 0.05 to 1.0%, all in percent by mass, and Fe and unavoidable impurities as the balance;
• a zinc plating layer formed on both sides of the basal steel sheet with an amount of plating per side in a range of 20 to 120 g/m2;
• one or more kinds of oxides selected from Fe, Si, Mn, Al, P, B, Nb, Ti, Cr, Mo, Cu, and Ni oxides and existing in a steel sheet superficial portion, namely, a portion located in direct contact with the zinc plating layer and extending from each surface of the basal steel sheet to a depth of 100 μm, with a total amount of the oxides per side in a range of 0.01 to 0.5 g/m2;
• and
• a crystalline oxide existing in a region from each surface of the basal steel sheet to a depth of 10 which is also located in direct contact with the zinc plating layer, the crystalline oxide composed of an Fe crystal grain in which Si and Mn atoms are so contained as to be distributed in a region from a grain boundary to a depth of 1 μm.

A high-strength galvanized steel sheet comprising:

• a basal steel sheet containing elements C:
• 0.01 to 0.15%, Si:
• 0.001 to 2.0%, Mn:
• 0.1 to 3.0%, Al:
• 0.001 to 1.0%, P:
• 0.005 to 0.060%, and S≦0.01%, all in percent by mass, and Fe and unavoidable impurities as the balance;
• a zinc plating layer formed on both sides of the basal steel sheet with an amount of plating per side in a range of 20 to 120 g/m2;
• one or more kinds of oxides selected from Fe, Si, Mn, Al, and P oxides and existing in a steel sheet superficial portion, namely, a portion located in direct contact with the zinc plating layer and extending from each surface of the basal steel sheet to a depth of 100 μm with a total amount of the oxides per side in a range of 0.01 to 0.5 g/m2;
• and
• a Si-and-Mn-based crystalline complex oxide existing in a region from each surface of the basal steel sheet to a depth of 10 μm, which is also located in direct contact with the zinc plating layer, the Si-and-Mn-based crystalline complex oxide composed of a basal iron grain in which Si and Mn atoms are so contained as to be distributed in a region from a grain boundary to a depth of 1 μm.