Abstract: The present invention relates to a process for producing a structural steel plate, which process greatly improves the excellent brittle crack propagation arrest characteristics and Charpy characteristics at the same time without relying on the addition of costly alloying elements such as Ni. The steel plate is characterized in that the steel plate comprises, based on weight, 0.04 to 0.30% of C, up to 0.5% of Si, up to 2.0% of Mn, up to 0.1% of Al, 0.001 to 0.10% of Ti, 0.001 to 0.01% of N and the balance Fe and unavoidable impurities, that the structure in the front surface region and the back surface region each having a thickness corresponding to 2 to 33% of the plate thickness has an average grain size d of up to 3 .mu.m, and that the structure has a controlled Vickers hardness.

Abstract: A steel containing predetermined components is rolled in a recrystallization temperature region or a non-recrystallization temperature region of an austenite and is subsequently subjected to repeated hot bending. Alternatively, a surface layer portion is cooled during rolling of the steel described above to an .alpha. single phase or a .gamma./.alpha. dual phase temperature region, rolling is then effected and is finished at the point of time when the surface temperature of the plate rises above an Ac.sub.3 point due to recuperative heat, and repeated bending is carried out. Still alternatively, the steel described above is rolled to a cumulative reduction ratio of at least 20% in the non-recrystallization temperature region and is then subjected to repeated bending. Further alternatively, the surface layer portion is cooled during hot rolling of the steel described above to an .alpha. single or .gamma./.alpha.