Method of manufacturing a composite steel sheet, particularly for the protection of vehicles against bombardment

A composite maraging steel sheet is produced from a tough steel inner layer and a hard outer layer of zone refined aluminum-containing steel with high titanium and manganese contents. A composite maraging steel sheet is produced from: (a) a tough steel inner layer of composition (by weight ) ≤ 0.01% C, ≤ 0.1% Si, ≤ 0.1% Mn, ≤ 0.005% P, ≤ 0.0 S, ≤ 0.1% Cu, 4.80-5.20% Mo, 17.5-18.5% Ni, ≤ 0.1% Cr, 0.55-0.70% Ti, 8.0-9.0% Co, optionally 0.05-0.15% Al, balance Fe and impurities; and (b) a zone refined hard steel outer layer of composition (by weight ) ≤ 0.01% C, ≤ 0.1% Si, 0.02-0.20% Mn, ≤ 0.005 ≤ 0.005% S, 0.01-0.20% Cu, 4.80-5.20% Mo, 17.5-18.5% Ni, 0.01-0.20% Cr, 1.80-1.95% Ti, 14.0-15.5% Co, 0.05-0.15% Al, balance and impurities. Preferred Features: Both steel layers are zone refined and are joined by explosive or roll cladding.