Dependence of the static and cyclic crack resistances of large forged semifinished products from aluminum alloys 1933 and V95 on the cooling rate in quenching

Complexly shaped monolithic parts of the airframe of a modern airplane are produced from forged preforms and castings of high-strength aluminum alloys and are designed in accordance with the principle of ''safe resource,'' i.e., before the appearance of a crack. Critical large-size parts or separate zones are calculated by the principle of ''safe damage,'' according to which the length of the crack in operation should not exceed the critical value. In this connection the most important characteristics are the parameters of static and cyclic crack resistances (the fracture toughness in plane deformation K-Ic, the rate of fatigue crack propagation (RFCP), the residual strength of specimens with a fatigue crack sigma(cr)(net), the fracture tougness in the plane strain state K-c) and the corrosion resistance of the material. In the present work these characteristics are considered for alloys 1933 and V95och after quenching at different rates.