Thermal fatigue behavior of a nickel-base single crystal superalloy DD5 with secondary orientation

The effect of cycle temperatures on the thermal fatigue behavior of a second generation Nickel-based single crystal superalloy DD5 with different secondary orientations was investigated. The experimental results show that the crack propagation rate increases with the rise of the upper limit temperature of the thermal fatigue test. It was found that the same initiation sites and propagation orientations of the thermal fatigue cracks were observed in samples with different secondary orientations. Thus, in samples with the second orientation of [110] and [100], thermal crack initiated at the edge of the holes with a directionally solidified direction of 45° and propagated along a direction of 45° with directional solidification. (paper)