Posco

Jea-Chun Jeon

Chang-Hoon Lee

Kyoo-Young Lee

Young-Roc Im

Han-Chul Shin

Gyo-Sung Kim

Jong-Sub Lee

Byoung-Ho Lee

Kee-Cheol Park

Ki-Soo Kim

The present invention relates to a high carbon hot rolled steel sheet having excellent material uniformity and a method for manufacturing the same, in which components and structure of the steel are precisely controlled and manufacturing conditions are adjusted to achieve excellence in material uniformity among hot rolled structures, thereby improving the dimensional precision of parts after formation, preventing defects during processing, and obtaining uniform structures and hardness distribution even after a final heat treatment process.

High carbon hot rolled steel sheet having excellent material uniformity and method for 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 method for manufacturing a fine spheroidized steel sheet having an excellent heat treatment characteristic, the method including: i) manufacturing a high carbon slab that is formed of 0.3 to 1.0 wt % C, 0.1 to 1.2 wt % Mn, 0 to 0.4 wt % Si, 0.01 to 0.1 wt % Al, 0 to 0.01 wt % S, and balance Fe and an inevitably added impurity as residuals; ii) reheating the slab to a temperature of Ar3 transformation point or more; iii) roughing rolling the slab, and manufacturing a thin plate by performing finish rolling in an austenite region; iv) cooling the thin plate at a cooling speed of 50 to 300&#xb0; C./sec; v) finishing the cooling of the thin plate at a temperature region of 400 to 650&#xb0; C. and maintaining the temperature; vi) winding the thin plate at a temperature region of 450 to 700&#xb0; C.; vii) performing cold rolling at a reduction ratio of 30% or more; and viii) spheroidizing annealing the cold rolled thin plate.

Fine spheroidized steel sheet with excellent heat treatment characteristic and method for manufacturing the same

Growing community of inventors

Pohang-si, South Korea

Jea-Chun Jeon