STEEL SHEET FOR HOT PRESS FORMING HAVING LOW-TEMPERATURE HEAT TREATMENT PROPERTY, METHOD OF MANUFACTURING THE SAME, METHOD OF MANUFACTURING PARTS USING THE SAME, AND PARTS MANUFACTURED BY THE SAME

摘要

A steel sheet for forming having low-temperature heat treatment property, in which heat treatment is performed within a range of lower temperature than a conventional steel sheet in the event of hot press forming or post-heat treatment after cold forming, a method of manufacturing the same, and a method of manufacturing parts using the same. The steel sheet has a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein Ti/N: less than 3.4, where Ti/N is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670° C. to 725° C. Wherein Ceq=C+Si/24+Mn/6+Ni/40+Cr/5+V/14 where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.