Special linear phased array probes used for ultrasonic examination of complex turbine components

A large variety of linear phased array probes (LPAP) [size, frequency, bandwidth, multi-heads, pitch size] were designed and manufactured for examination of complex-shape turbine components, such as blade roots, rotor steeples, narrow-gap welds, disk blade rim attachment. The probes were designed and characterized for the following features: geometric dimensions, centre frequency, pulse duration, beam features (focal depth, beam spread in both directions, signal-to-noise ratio). Multi-head LPAP were manufactured to optimise detection and sizing for limited accesses contact areas. Examples of probe characterization, detection and sizing of artificial and natural defects are given for the following applications: blade roots, rotor steeple, and disk rims. Examples of probe beam features are also presented. Some aspects of lmasonic and OPG QA program for phased array probe characterization will be illustrated. (author)