HOT PRESS FORMED PARTS HAVING EXCELLENT BENDABILITY, AND METHOD FOR THE SAME

摘要

The present invention provides a hot press formed (HPF) member having an excellent bendability and a method for manufacturing the same. The HPF member has a melted aluminum planting layer formed on a surface of a planted steel sheet. The planted steel sheet comprises: 0.18-0.25 wt% of carbon; 0.1-0.5 wt% of silicon; 0.9-1.5 wt% of manganese: 0.03 wt% or less of phosphorus; 0.01 wt% or less of sulfur; 0.01-0.05 wt% of aluminum; 0.05-0.5 wt% of chromium; 0.01-0.05 wt% of titanium; 0.001-0.005 wt% of boron; 0.009 wt% or less of nitrogen; iron as a remaining part; and other impurities. The planted steel sheet has a surface layer where a ferrite phase is continuously and non-continuously formed on an interior thereof to have a thickness within 50 μm. The ferrite phase occupies 5% or less of the surface layer. Carbides having a size of 1 μm or less are distributed on the surface layer to occupy 90% or more of entire distribution of carbides. As such, the purpose of the present invention provides the HPF member having a high tensile strength of 1300 MPa or more and an excellent bendability, which can be used as a structural member for a vehicle requiring a collision resistance property.