Birch, Stewart, Kolasch & Birch, LLP
High-strength steel sheet having excellent processability and paint bake hardenability, and method for producing of high-strength steel sheet
The high-strength steel sheet includes, by mass %: C: 0.01% to 0.10%; Si: 0.15% or less; Mn: 0.80% to 1.80%; P: 0.10% or less; S: 0.015% or less; Al: 0.10% to 0.80%; Cr: 0.01% to 1.50%; N: 0.0100% or less; and a balance consisting of iron and inevitable impurities, in which a metallic structure is composed of ferrite and a hard second phase, the area fraction of the ferrite is 80% or more, the area fraction of the hard second phase is 1% to 20%, the fraction of unrecrystallized ferrite in the ferrite is less than 10%, the ferrite grain sizes are 5 μm to 20 μm, and the fraction of the ferrite crystal grains having an aspect ratio of 1.2 or less in the entire ferrite crystal grains is 60% or more.
Nippon Steel & Sumitomo Metal Corporation
C C Y C C C C C C C C C C C C C C C C B C C C B C
C21D C22C Y10T C22C C22C C22C C22C C23C C22C C22C C22C C22C C21D C22C C23C C21D C21D C21D C22C B32B C23C C22C C22C B32B C21D
additional inventional additional inventional inventional inventional inventional inventional inventional inventional inventional inventional additional inventional inventional additional inventional additional inventional inventional inventional inventional inventional inventional inventional
Toshio Nobuhiro Shinichiro Toshiki Koichi Naoki
Ogawa Fujita Watanabe Nonaka Goto Matsutani