Detection of Crack Defect Covers All Section Mutation Position Using a Robot Ultrasonic C-scan System

The turbine pump wheel disc is a key component of the liquid rocket engine. Its 90° step root belongs to the section mutation position, which is prone to crack defects during the manufacturing process, causing safety hazards. At present, the ultrasonic vertical incidence method is usually used to perform C-scan detection on workpieces, so the detection of cracks is usually ignored. In this paper, the ultrasonic oblique incidence method is used for crack detection. First, a full coverage detection scheme for crack defects in the crack occurrence areas at the roots of the steps on both sides of the turbine pump wheel disc blanks is proposed. Then the detection sample is developed and a total of 10 artificial cracks including 3 angles were prefabricated at four section mutation positions. The robot detection system is used to conduct crack detection experiments on the sample, which verifies the effectiveness of the detection scheme. Finally, the results show that the scheme can realize the full coverage detection of crack defects with the equivalent of not less than 5 mm × 0.13 mm × 1 mm (length × width × height) at the section mutation positions on both sides of the turbine pump wheel disc blanks.