Posco

Han-Chul Shin

Kyoo-Young Lee

Gyo-Sung Kim

Chang-Hoon Lee

Kee-Cheol Park

Kyong-Su Park

Jea-Chun Jeon

Jae-Chun Jeon

Provided is a method of manufacturing a high-carbon hot-rolled steel sheet, including the steps of i) preparing high-carbon steel materials comprising C: 0.7 to 0.9%, Si: 0.5% or less, Mn: 0.1 to 1.5%, Cr: 0.5% or less, P: 0.05% or less, and S: 0.03% or less in wt % and remaining Fe and other inevitable impurities; ii) heating the high-carbon steel materials again and manufacturing a steel sheet by performing hot rolling in an austenite region in which a finishing temperature for the hot rolling is an Ar3 transformation temperature or higher; iii) rapidly cooling the steel sheet at 520 to 620&#xb0; C. before phase transformation is started in a Run-Out Table (ROT); iv) uniformly maintaining a cooling retention temperature so that the cooled steel sheet is subject to phase transformation in any one temperature between 520 to 620&#xb0; C.; and v) winding the steel sheet in the cooling retention temperature. Also provided is the high-carbon steel sheet made by the above-described method.

High-carbon hot-rolled steel sheet, high-carbon cold-rolled steel sheet, and method of manufacturing the same

A carbon steel sheet having high formability due to a microscopic and uniform carbide distribution and having a good characteristic of final heat treatment, and a manufacturing method thereof. The carbon steel sheet having excellent formability includes, in wt %, C at 0.2-0.5%, Mn at 0.1-1.2%, Si at less than or equal to 0.4%, Cr at less than or equal to 0.5%, Al at 0.01-0.1%, S at less than or equal to 0.012%, Ti at less than or equal to 0.5&#xd7;48/14&#xd7;[N]% to 0.03% when the condition of B and N is not satisfied, B at 0.0005-0.0080%, N at less than or equal to 0.006%, Fe, and extra inevitable elements; an average size of carbide is less than or equal to 1 &#x3bc;m; and an average grain size of ferrite is less than or equal to 5 &#x3bc;m.

Manufacturing method of carbon steel sheet superior in formability

A carbon steel sheet having high formability due to a microscopic and uniform carbide distribution and having a good characteristic of final heat treatment, and a manufacturing method thereof. The carbon steel sheet having excellent formability, includes, in wt %, C at 0.2-0.5%, Mn at 0.1-1.2%, Si at less than or equal to 0.4%, Cr at less than or equal to 0.5%, Al at 0.01-0.1%, S at less than or equal to 0.012%, Ti at less than or equal to 0.5&#xd7;48/14&#xd7;[N]% when the condition of B(atomic %)/N(atomic %)&#x3e;1 is satisfied or by 0.5&#xd7;48/14&#xd7;[N]% to 0.03% when the condition of B and N is not satisfied, B at 0.0005-0.0080%, N at less than or equal to 0.006%, Fe, and extra inevitable elements; an average size of carbide is less than or equal to 1 &#x3bc;m; and an average grain size of ferrite is less than or equal to 5 &#x3bc;m.

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Pohang-shi, South Korea

Han-Chul Shin