Invention Grant
- Patent Title: Fine spheroidized steel sheet with excellent heat treatment characteristic and method for manufacturing the same
- Patent Title (中): 具有优异热处理特性的精细球状钢板及其制造方法
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Application No.: US13141739Application Date: 2009-12-21
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Publication No.: US08440030B2Publication Date: 2013-05-14
- Inventor: Chang-Hoon Lee , Jea-Chun Jeon , Jong-Sub Lee , Ki-Soo Kim
- Applicant: Chang-Hoon Lee , Jea-Chun Jeon , Jong-Sub Lee , Ki-Soo Kim
- Applicant Address: KR Pohang-shi
- Assignee: POSCO
- Current Assignee: POSCO
- Current Assignee Address: KR Pohang-shi
- Agency: The Webb Law Firm
- Priority: KR10-2008-0133357 20081224
- International Application: PCT/KR2009/007625 WO 20091221
- International Announcement: WO2010/074463 WO 20100701
- Main IPC: C22C38/04
- IPC: C22C38/04 ; C22C38/06 ; C21D8/02

Abstract:
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° C./sec; v) finishing the cooling of the thin plate at a temperature region of 400 to 650° C. and maintaining the temperature; vi) winding the thin plate at a temperature region of 450 to 700° C.; vii) performing cold rolling at a reduction ratio of 30% or more; and viii) spheroidizing annealing the cold rolled thin plate.
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