The focus of this work is the near net shape casting of single crystal thin-walled specimens of the nickel-based superalloy MAR M247LC with a minimum wall thickness down do 0.4 mm and the investigation of the influence of the wall thickness and surface conditions on the microstructure and creep behaviour. Therefore, thin-walled single crystal specimens with different wall thicknesses (0.4/0.8/1.0/2.0 mm) are manufactured using the Bridgman process. For the casting of these extremely thin-walled structures a process is developed by replacing conventional investment casting wax positive models (injection moulding of wax in negative molds) with 3D printed polymer models. The surface of the thin cast specimens (with/without cast skin) is varied and the behaviour of the thin cast specimens is compared to thin specimens that are prepared from bulk material.

The comparison of the creep behaviour of thin cast specimens with and without cast skin shows that there is no significant influence of the casting skin on creep properties. The investigation of the thickness influence at a temperature of 980°C and an external stress of 230 MPa shows, that no significant thickness debit effect can be detected either in air or under vacuum. Creep properties are retained down to a wall thickness of 0.4 mm due to the relatively short testing/oxidation times (< 100h).

A significant deterioration of the creep properties with decreasing wall thickness is evident in creep tests at lower stress level (150 MPa, 980°C) due to significantly higher oxidation times, since the volume fraction of the oxide layers and γ'-free regions increases in thin-walled samples. Accordingly, the time and temperature dependence of diffusion processes (formation of oxide layer and γ'-free regions) plays the decisive role regarding thickness debit effect.