Abstract: Fragmentation body for fragmentation projectiles and warheads, including an integral fragmentation shell structure made of cast metal, and the shell structure has an outer wall surface and an inner wall surface separated by a thickness of the shell, where at least one of the inner or outer surfaces includes recesses formed through part of the thickness of the shell to define a plurality of fragments which remain integrated with the shell structure until an explosive force is detonated in proximity of the shell, wherein the shell material comprises a steel alloy including carbon, chromium, nickel, molybdenum, cobalt, and the balance essentially being iron. Shell structures of the inventive fragmentation body also have a fragmentation pattern defined via recesses or grooves provided in at least one of the inner or outer wall surfaces thereof to define the size and shapes of the fragment projectiles desired.