Phased array inspection of large size forged steel parts

Abstract

High strength forged steel requires uncompromising quality to warrant advance performance for numerous critical applications. Ultrasonic inspection is commonly used in nondestructive testing to detect cracks and other defects. In steel blocks of relatively small dimensions (at least two directions not exceeding a few centimetres), phased array inspection is a trusted method to generate images of the inside of the blocks and therefore identify and size defects. However, casting of large size forged ingots introduces changes of mechanical parameters such as grain size, the Young's modulus, the Poisson's ratio, and the chemical composition. These heterogeneities affect the wave propagation, and consequently, the reliability of ultrasonic inspection and the imaging capabilities for these blocks. In this context, a custom phased array transducer designed for a 40-ton bainitic forged ingot was investigated. Following a previous study that provided local mechanical parameters for a similar block, two-dimensional simulations were made to compute the optimal transducer parameters including the pitch, width and number of elements. It appeared that depending on the number of elements, backwall reconstruction can generate high amplitude artefacts. Indeed, the large dimensions of the simulated block introduce numerous constructive interferences from backwall reflections which may lead to important artefacts. To increase image quality, the reconstruction algorithm was adapted and promising results were observed and compared with the scattering cone filter method available in the CIVA software.

Investigation of Forging Metal Specimens of Different Relative Reductions Using Ultrasonic Waves

“…It is an important publication and provides a good overview of the issue. Other contributions, such as [ 6 , 7 ], deal with large forged steel parts, testing the phase field by ultrasound in each directional reaction. The CIVA software package (EXTENDE S.A., Massy, France) was used to optimize the phase field.…”

“…Article [ 25 ] describes the problem of the speed of ultrasonic waves as one of the suitable methods for investigating the properties of materials and forgings by non-destructive methods. The paper [ 27 ] focuses on the presented issue of large-scale parts [ 6 , 7 , 13 ]. In the paper [ 29 ], the authors dealt with a wide range of issues of analysis and research of texture issues in metals.…”

Design and optimisation of a phased array transducer for ultrasonic inspection of large forged steel ingots

“…Indeed, for some particular probe configurations with more than 64 elements with widths of 15.2 mm and greater, artefacts strongly decreasing the image quality. These artefacts are associated with constructive interferences which can be removed by selecting data based on the angle between emission and reception [14]. Finally, the lateral resolution was extracted and analysed following the same procedure, and results are presented in Figure 7.…”