| 摘要 |
Provided is a steel material, which provides a material for an impact absorbing member which exhibits a high absorption of impact energy and in which occurrence of cracking under an impact load is suppressed, the steel material having: a chemical composition containing: by mass%, C: 0.05 to 0.18%, Mn: 1 to 3%, Si+Al: at least 0.5% and less than 2.5%, and N: 0.001 to 0.015%, and in some cases, Cr: at most 0.5%, Mo: at most 0.2%, Ti: at most 0.05%, Nb: at most 0.05%, V: at most 0.2%, and B: at most 0.002%, the remainder being Fe and impurities; and a steel structure containing: by area % bainite made up of a lath structure having an average interval of at most 1 µm: at least 70%, and martensite: 5 to 30%, and which satisfies the following Formulas (1) and (2): (1) 1.2 ‰¤ H M0 /H B0 ‰¤ 1.6, (2) 0.90 ‰¤ {(H M10 (/H M0 )/(H B10 (/H B0 ) ‰¤ 1.3, where H M0 and H M10 represent average nano hardness in an initial state and after 10% tensile deformation of the martensite, and H B0 and H B0 represent that of the bainite, respectively. |
