PROBLEM TO BE SOLVED: To provide a TRIP type high strength steel plate selected based on optimum characteristics and standards as the one for absorbing impact energy in the case of a collision and certainly contributable to the security of safety. ;SOLUTION: This steel plate is the one having components of, by weight, 0.04 to 0.30% C, either or both of Si and Al by 0.3 to 3.0% in total, and the balance Fe with inevitable impurities and having a composite structure composed of ferrite as main phases and secondary phases including 3 vol.% austenite, in which the ratio of the initial volume rate V(0) of the austenitic phases to the volume rate V(10) of the austenitic phases in the case that predeformation of 10% as equivalent distortion is applied, i.e., V(10)/V(0) is regulated to 0.3, and after the application of predeformation of 0 to 10% as equivalent distortion, the difference (σd-σs) between the qualistatic deformation strength σs and the dynamic deformation strength σd is regulated to ≥60 MPa. Furthermore, it lies in the range satisfying (σd-σs)≥4.1×σs0.8-σs. Also, as for the case in which predeformation is applied by skinpass rolling or/and a tension leveller, prescriptions are made.;COPYRIGHT: (C)1999,JPO
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