Influence of local mechanical properties of high strength steel from large size forged ingot on ultrasonic wave velocities

Abstract

In the metallurgical industry, ultrasonic inspection is routinely used for the detection of defects. For the nondestructive inspection of small high strength steel parts, the material can be considered isotropic. However, when the size of the parts under inspection is large, the isotropic material hypothesis does not necessarily hold. The aim of this study is to investigate the effect of the variation in mechanical properties such as grain size, Young's modulus, Poisson's ratio, chemical composition on longitudinal and transversal ultrasonic wave velocities. A 2 cm thick slice cut from a 40-ton bainitic steel ingot that was forged and heat treated was divided into 875 parallelepiped samples of 2x4x7 cm 3 . A metallurgical study has been performed to identify the phase and measure the grain size. Ultrasonic velocity measurements at 2.25 MHz for longitudinal and transversal waves were performed. The original location of the parallelepiped samples in the large forged ingot and the measured velocities were used to produce an ultrasonic velocity map. Using a local isotropy assumption as well as the local density of the parallelepiped samples calculated from the chemical composition of the ingot provided by a previously published study [1], Young's modulus and Poisson's ratio were calculated from the longitudinal and transversal wave velocities. Microtensile measurements were used to validate Young's modulus obtained by the ultrasonic wave velocity and an excellent match was observed. References

Phased array inspection of large size forged steel parts

“…A 40-ton bainitic steel ingot that was forged and heat treated was used in this study. This work was based on a previous ultrasonic study [7] that provided metallurgical and ultrasonic wave propagation properties for this particular material. As the dimensions of the block were more than 1 m in all directions, its casting was hard to control and by extension so were the mechanical parameters.…”

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

“…Accuracy and SNR are presented for the 3 emission sequences and the 3 notches in Figure11. The error on the notch positions appeared to be very low (below 1.2%), considering the measurement uncertainties and the velocity variation (0.85%[13]). It is also noteworthy that the images from FMC sequences seemed to be more affected by velocity variation, with errors increasing with the distance of propagation.…”

“…Modelling was performed with the CIVA UT simulation package [12], a specialised NDT simulation platform. In the present work, a 1000 mm thick block was simulated using parameters obtained from measurements performed on a similar block in a previous study by our team [13]. The aim of this work was also to evaluate the anisotropy of the material from an ultrasonic point of view.…”

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

“…In addition to these papers, there is also [ 22 ], where the authors present an interesting area of pulsed compression ultrasonic technology, where a detailed course of steel inspection is described. The following literature [ 23 , 24 , 25 , 26 , 27 , 28 ] deals with and presents in detail non-destructive evaluation systems with the application of ultrasound, so it is probably not necessary to discuss these articles in more detail. 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.…”

“…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.…”