STUDY OF STATIC AND FATIGUE PROPERTIES OF AN AIRCRAFT CASTING (18% Ni MARAGING STEEL),

Tests on aircraft wing root end fittings with integrally cast clover leaf test bars made in 18 Ni maraging steel by the ceramic shell moulds process have demonstrated that it is practicable to produce castings with asymmetric casting geometry having tensile strength of 110-115 tonfsqin with adequate ductility and impact resistance. Both the static mechanical properties and fatigue strength are marginally influenced by the cooling rate during solidification. Whilst the static strength for the steel castings in 18 Ni maraging steel can be increased for 80 tonfsqin T.S. to 100 tonfsqin T.S., the fatigue strength is reduced, following the reduction previously noted with 80 tonfsqin T.S. steel as compared with 64 tonfsqin T.S. steel. However, where the maximum fatigue strength is not the predominant criterion, the designer can usefully take advantage of the increase of 20 tonfsqin T.S. with adequate ductility. Author