Aim To investigate the spall characteristic of two different structural steels subjected to plane shock loading. Methods By means of metallurgical testing methods

the nucleation

growth and coalescence of damages formed in spall layer were analyzed in order to study the spall mechanism of structural steels. Results The microcracks were formed at regions containing dense inclusions. For vacuum arc remelted steel

because the inclusions are reduced to negligible levels

the cracks initiate at grain boundary or incompatible regions of plastic deformation. This result is different from that of quasi static. Conclusion The spall behavior of the structural steels is in direct close relationship with their metallurgical quality and structures.