11Ni-13Co Maraging Steel (var. 4)

11Ni-13Co maraging steel (variant 4) is an ultra-high-strength iron-nickel-cobalt alloy strengthened primarily through precipitation hardening rather than carbon content, making it exceptionally tough and damage-tolerant compared to conventional high-carbon steels. It is widely used in aerospace, defense, and precision tooling applications where extreme strength combined with adequate fracture toughness is critical—particularly in rocket motor cases, landing gear, ejection seats, and high-performance die-casting dies. Engineers select this material when conventional alloys cannot meet simultaneous demands for very high strength and impact resistance, or when tight dimensional tolerances and excellent machinability in the solution-treated condition are essential before final aging.