ИСТИНА

High Pressure Turbine (HPT) blades operate at extremely high temperatures, high centrifugal loads and thermal cycling. The use of conventional alloys is not feasible for the turbine engine operation, as they do not provide the desired properties and usually have their melting point below the operating temperature. Thus, the heavier Nickel base superalloys are used. Moreover, the material HPT blades made of has to be resistant to the property of stresses to accelerate the growth of any flaws or defects present in the alloy. The special single crystal process is used for these purposes to harden superalloy during the investment casting. Unfortunately, even in this case defects called as high temperature crystallization (HTC) cracks can appear on the grain boundaries within manufacturing. There are several conventional techniques are used to detect such a defect, but disadvantages they have complicate to apply ones at the manufacturing conditions. The possibility of macrostructure control in thin walls of the blade root section using laser ultrasound to solve conventional techniques limitations was experimentally investigated. Testing system design was described. Laser-ultrasonic evaluation results of the blade samples with artificial defects and HTC cracks was presented. Nickel based superalloy acoustoelasticity properties for the grain boundaries to detect were analyzed.