High-strength hot-dip galvanized steel sheet with excellent formability and process for producing same

Abstract

Provided are a high-strength hot-dip galvanized steel sheet with excellent formability and a process for producing same. The steel sheet comprises, in mass %: 0.005 to 0.009% of C; 0.05% or less of Si; 0.3 to 0.8% of Mn; 0.06 to 0.09% of P; 0.01% or less of S; 0.005% or less of N; 0.1% or less of Al; 0.05 to 0.08% of Mo; 0.01 to 0.03% of Ti; 0.03 to 0.045% of Nb; 0.06 to 0.1% of Cu; 0.0015% or less of B; and a balance of Fe and inevitable impurities, and 95% or more of ferrite in terms of area fraction. The ferrite has an average grain size of 15 μm or less, with ultrafine grains of 6 μm or less occupying 5 to 10% in a 1 mm×1 mm, and the steel sheet has a surface nanohardness value of 1 to 1.5 GPa.