First creep results on thin-walled single-crystal superalloys

The knowledge of creep behavior of structural materials for high temperature applications is prerequisite for lifetime predictions. In order to optimize both the cooling efficiency and the weight of fast rotating turbine blades a general trend to reduce the wall thickness of the hollow investment casting parts is observed. In order to determine the influence of wall thickness on creep properties, constant-load tensile creep tests of samples with different thickness of the single-crystalline nickel-base superalloy René N5 are performed at high temperatures. The test equipment uses resistance heating to achieve fast heating and cooling rates. Creep strain is measured with an accuracy better than 0.1% by a non-contact imaging technique. The tests were performed at 1253 K at different stress levels. Specimens were tested uncoated and aluminized.