VEHICLE COLLISION ENERGY ABSORBING MEMBER HAVING HIGH COLLISION ENERGY ABSORBING POWER, AND METHOD FOR MANUFACTURING SAME

摘要

Provided is a vehicle collision energy absorbing member which has high collision energy absorbing power in an axial direction. The vehicle collision energy absorbing member is formed of a high-strength thin steel sheet having a TS of at least 980 MPa, and an N value and a limit bend radius (Rc) satisfying the following formula: Rc?1.31×ln(n)+ 5.21. By using the high-strength thin steel sheet, the member may be buckled stably in the axial direction and crushed into a bellows shape during vehicular collision even when the TS is 980 MPa or higher. Preferably, the high-strength thin steel sheet has a weight percentage composition of C: 0.14%~0.30%, Si: 0.0.1~1.6%, Mn: 3.5~10%, N: 0.0060% or less, and Nb: 0.01~0.10%. The high-strength thin steel sheet includes in terms of volume fraction with respect to the entire structure: 30 to 70% of ferrite phase having an average particle diameter of 1.0 µm or less; and a second phase having at least 10% of a residual austenite phase, the average gap of the residual austenite phase being 1.5 µm or less.