Production of non-heattreated high-tensile steel plate

Abstract

Abstract PURPOSE:To produce a non-heattreated high-tensile hot rolled steel plate at a low cost by hot rolling a specifically composed steel consisting of C, Si, Mn, Nb and Fe at the temp. in excess of the Ar3 point, then cooling the steel under specific conditions. CONSTITUTION:The steel contg. 0.02-0.20wt% C, <=2.0% Si, 0.5-2.0% Mn, 0.010-0.100% Nb, and the balance consisting of Fe and unavoidable impurities is hot rolled at the temp. in excess of the Ar3 point. The hot rolled plate is thereafter quickly cooled down to the Ar3 point at >=10 deg.C/sec cooling rate. The hot rolled plate is cooled or held at <10 deg.C/s cooling rate for the time (t)sec or above and >=40sec to be given by the equation; t=eXp[a1+ a2X(lnNb)<2>+a3XlnNb] (where, a, a2; constant) to finely disperse the deposit of Nb into the formed ferrite particles. The hot rolled steel plate is thereafter quickly cooled down to <=450 deg.C at >=10 deg.C/s cooling rate to prevent the formation of the coarse grains of the deposit. The non-heattreated high-tensile hot rolled steel plate contg. Nb at a low ratio is thus obtd. at a low cost.

Inventors

• 👤 Junichi Wakita
• 👤 淳一 脇田
• 👤 Osamu Kono
• 👤 治 河野
• 👤 Manabu Takahashi
• 👤 学 高橋
• 👤 Kazuaki Ezaka
• 👤 江坂　一彬

Bibliographic Details