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Abstract

The present invention relates to a hot press forming steel plate made of a composition comprising: 0.3-1.0 wt % of C; 0.0-4.0 wt % of Mn; 1.0-2.0 wt % of Si; 0.01-2.0 wt % of Al; 0.015 wt % or less of S; 0.01 wt % or less of N; and the remainder being Fe and unavoidable impurities. Further, the present. invention relates to a method for manufacturing the hot press forming steel plate, characterized by comprising the steps of: heating, to between 1100 and 1300° C., a steel slab having the composition; performing hot rolling finishing between. an Ar3 transformation point and 950° C.; and performing winding between MS and 720° C. Further, the present invention. relates to a hot press formed member characterized by having the composition, and having a dual phase microstructure made of bainite and residual austenite. In addition, the present invention relates to a method for manufacturing the hot press formed member, characterized by comprising the steps of: heating the steel plate having the composition to a temperature of an Ac3 point or higher; hot press molding the heated steel plate; performing cooling at a cooling speed of 20° C./sec or higher to a temperature between MS and 350° C.; and performing a heat treatment in a heating furnace between MS and 550° C.

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First Claim