HOT ROLLED STEEL SHEET FOR HOT GALVANIZED IRON HAVING HIGH SURFACE QUALITY AND HIGH STRENGTH, AND METHOD FOR PRODUCING THE SAME

摘要

The present invention relates to a hot-rolled steel sheet for a high-strength galvanized steel sheet with an excellent surface quality and a manufacturing method thereof. The present invention provides the hot-rolled steel sheet for a high-strength galvanized steel sheet comprises: 0.08-0.2 wt% of C; 0.03-0.15 wt% of Si; 1.4-2 wt% of Mn; 0.001-0.05 wt% of P; 0.001-0.03 wt% of S; 0.002-0.05 wt% of Al; and the remainder consisting of Fe and inevitable impurities and the manufacturing method thereof. A weight ratio of Mn to Si is 20-30. A weight ratio of C to Si is 1-5. A weight ratio of Si to P is 3-10. A fine structure comprises, in area fraction: 10-40% of bainite; 20-30% of pearlite; and 40-60% of ferrite. A ternary eutectic compound comprising FeO, Fe_2SiO_4, and Fe_3 (PO)_4 is formed within 50 m from a surface.