| abstract |
An impact absorbing element having an impact absorbing part that absorbs impact energy by being crushed and axially folded, wherein the impact absorbing part is made of a sheet steel comprising: a chemical composition consisting of ,% by mass, C: at least 0.08% and maximum 0.30%, Mn: at least 5 1.5% and maximum 3.5%, Si + Al: at least 0 , 50% and maximum 3.0%, P: maximum 0.10%, S: maximum 0.010%, N: maximum 0.010%, Cr: 0 to maximum 0.5% , Mo: 0 to maximum 0.5%, B: 0 to maximum 0.01%, Ti: 0 to less than 0.04%, Nb: 0 to less than 0.030%, V: 0 to less than 0.5%, Ca: 0 to maximum 0.010%, Mg: 0 to maximum 0.010%, REM: 0 to maximum 0.050%, and Bi: 0 to as maximum 0.050%, the rest being Fe and impurities; a microstructure containing, in% area, bainite: more than 50%, martensite: at least 3% and maximum 30%, and retained austenite: at least 3% and maximum 15%, the remainder consisting of ferrite with an average grain diameter of less than 5 µm; and mechanical properties in which the product of the uniform elongation and the orifice expansion ratio is at least 300% 2, and an effective flow stress when a true strain of 5% is applied is at least 900 MPa. |