Ultrasonic Immersion Research Articles

Enhancing NDE Reliability for Grade 91 Steel Welds: Ultrasonic Imaging and Microstructural Correlations

Ensuring the integrity of Grade 91 (9Cr-1Mo-V) steel welds is vital for the safe and reliable operation of fossil fuel–fired and nuclear power plants. This study applies an imaging technique for the ultrasonic characterization of two Grade 91 steel welds created with cold metal transfer and flux-cored arc welding processes. Ultrasonic immersion testing in the through-transmission configuration was employed to generate shear waves, which helped identify the weld metal, heat-affected zone, and base metal regions. These weld microstructures were also correlated to their ultrasonic images using metallography, ultrasonic amplitude, hardness measurements, and grain size. The findings from this study can assist practitioners in developing new nondestructive evaluation technologies, improving the inspection reliability of creep strength–enhanced ferritic steel welds by potentially identifying weld microstructure regions susceptible to creep-type failures.

Determination of surface density of nonporous membranes with ultrasonic immersion measurements

ABSTRACT The surface density of nonporous membranes is estimated with a conventional ultrasonic immersion measurement system without need for a priori information about the membrane such as wave speed, density, thickness or impedance under most testing conditions. The derivation, theoretical limitations and practical restrictions of the technique are discussed. The broadband nature of the measurement allows the surface density values to be estimated at multiple discrete frequencies within the useful bandwidth of the transducer. In experimentation, the technique was used to measure surface densities in a range of 0.044–0.328 kg/m2. All calculated surface densities are within 5% or less of their nominal values with an average percent difference of 1.7%.

Quantitative Measurement and Evaluation of High-Resolution Ultrasonic Sound Fields using a Novel Automated Ultrasonic Immersion Scanner

Ultrasonic probes are an integral part of the automated ultrasonic non-destructive testing and evaluation (NDT&E) systems to detect and size the defects in a wide range of structural materials in production lines. A complete quantitative assessment of the performance characteristics of an application-specific UT probe is needed to be evaluated on the basis of the international standard DIN EN ISO 22232-2. This requirement of full assessment not only improves the quality assurance of the manufactured probes by evaluating the acceptance criteria but also provides the useful technical information to the end-user to optimize the automated ultrasonic testing on-site. In addition, the evaluation of probe characteristics should be carried periodically throughout their service life. In this work, we developed a novel high-precision ultrasonic immersion scanner to evaluate the full ultrasonic probe characteristics which include the squint angle measurement in three different reference planes (XY, XZ, and YZ), RF-signal and its frequency spectrum at water-steel interface, focal distance, focal range, focal width, focal length and also the angle of beam divergence in different planes of the sound field distribution. In the newly developed UT immersion scanner, for the first time, we successfully integrated the high-precision Hexapod with six axes to achieve a few micrometer (~15 µm) spatial-resolution in the measured sound field patterns and a good angular resolution (~0.05°) in the squint angle measurement. In addition, we used a verified UT instrument in accordance with the standard DIN EN ISO 22232-1 to obtain more accurate amplitude values (±0.5 dB) while scanning a test block. The automated scanning, data acquisition, evaluation, visualization and the automated test report generation are carried based on the standard DIN EN ISO 22232-2. The measured sound beam characteristics of both focused and non-focused application-specific ultrasonic probes with center frequencies ranging from 0.2 - 15 MHz using the pulse-echo technique on a 3 mm half-ball steel reflector are presented. In addition, the measured sound beams of an application-specific 5 MHz multi-element transmit-receive (TR) probe using the 3 mm flat-bottomed-hole (FBH) reflector in a steel reference plate are discussed. Finally, the quantitative analysis of the measured sound field results and the acceptance criteria in accordance with DIN EN ISO 22232-2 are discussed.

Ultrasonic immersion testing of residual stress in plates using collinear Lamb wave mixing technique

Nondestructive estimation of residual stresses has been a major challenge in engineering. Herein, the collinear Lamb wave mixing method is proposed for residual stress measurement in metal plates under immersion ultrasonic testing. Numerical simulations have been conducted to investigate the influences of excitation parameters on the performance of the wave mixing method. The results showed that the receiver position and cycle numbers of primary waves affect the amplitude of the method, and optimal excitation parameters recommended. Ultrasonic immersion experiments are conducted on two types of plate-like specimens using the collinear Lamb wave mixing method. Experimental results showed that the proposed method is effective for measuring the residual stress in metal plates. The immersion ultrasonic testing can significantly reduce the influence of inconsistent coupling conditions between the transmitters and the specimen on experimental results, therefore it is more reliable than conventional contact testing.

High fidelity ultrasonic measurements for defect detection and characterisation

Repeatable measurements with detachable transducers such as phased arrays have much potential for enhancing the sensitivity of nondestructive evaluation (NDE), as baseline subtraction can be employed. This paper aims to develop post-processing methods to overcome the variation between inspections which leads to poor subtraction performance. In this paper, ultrasonic immersion inspections are performed on a brass sample and a steel sample with a corroded backwall. Reference measurements are taken, and then small defects are machined to simulate defect growth in industrial applications. Defect types include two 1 mm diameter flat bottom holes (FBH) extending from 15 mm to 17 mm in the brass sample and two 2 mm diameter holes drilled to 1 mm depth from the corroded surface of the steel sample to represent the growth of localised pits. Although FMC/TFM is used in this paper, the defects have similar response amplitudes to the structural noise, and they cannot be detected or characterised directly from the images by the conventional 6 dB drop method. This paper demonstrates the utilisation of ultrasonic measurements, together with cross-correlation, to obtain inspection variables which include array position and couplant wave velocity. By knowing the variations between inspection conditions, compensation is made in post-processing to improve image repeatability, and hence the performance of baseline subtraction. The SNR is improved by approximately 10–25 dB depending on how great the actual variations are. It is shown that these previously undetectable defects can be seen and accurately sized after conducting baseline subtraction with compensation.

Green perspective of N-CDs towards energy crisis and photodegradation of toxic dyes

Here we have presented a general overview of an environmental friendly, one-step, cost-effective, and efficient microwave irradiation method for the preparation of self heteroatom doped Nitrogen doped carbon dots (N-CDs) which demonstrated an average size of less than 10 nm and an interplaner distance of 0.334 nm. These N-CDs possess 2.35 eV energy gap with 65.5% fluorescence quantum yield. The surfaces of these graphitic-like structures are doped with (S, P, K, Mg, Zn) = 1% along with the extra passivating agent nitrogen (N). They have demonstrated wider absorption (between 300 and 550 nm) and emission (between 400 and 600 nm) bands and also managed enormous active surface sites and defects, that further extend its usage in energy harvesting, storage and photo catalysis owing to their unique property of electron transport and collection system. In addition, we have prepared, tested, and optimised new TiO2/N-CDs composite as photo anode and N-CDs/CB composite as photo cathode for application in dye-sensitized solar cells (DSSC). The achieved power conversion efficiency of the DSSC employed photoanode N-CDs/TiO2 and counter electrode carbon black/N-CDs, demonstrated a substantial improvement, in photo current and photo voltage owing to their multiple factor visible light absorption, effective electron separation, and longer recombination time resulted a Jsc. of 22.90 mA cm2, Voc. of 0.780 V, FF. of 74% and an overall PCE of about 13.22% approximating 2.5-fold increase in power conversion efficiency as compared to that of pure TiO2 and platinum based DSSC, where Jsc. (= 10 mA cm2), Voc. (= 0.750 V) and a total of 5.42% power efficiency. Furthermore, TiO2 was modified with Heteroatom-doped N-CDs using a novel ultrasonic immersion technique, and demonstrated greater photocatalytic activity for the degradation of methylene blue (85%) with a rate constant of 0.1068 in accordance with the pure TiO2 film and N-CDs which have showed only 20% and 30% photodegradation with lower rate constants under short UV irradiation, demonstrating the formation of reactive oxygen species and H+ ions in the sample solution resulting enhanced effective mobility of electrons and holes between TiO2/N-CDs composite nanomaterial, resulted greater photo degradation.

Quantitative ultrasonic characterization of Ti-6Al-4V components with surface roughness

Ultrasonic immersion testing enables nondestructive characterization of material microstructure through quantitative linkages between wave propagation parameters and features of interest. However, accurate measurements of metrics such as wave speed and attenuation generally require smooth test samples to ensure the reflected wave packets are not distorted. Thus, rough surfaces are mechanically polished before ultrasonic testing, which compromises the nondestructive nature of the measurement, distorting the sample geometry and imparting local damage. This challenge is particularly salient with the advent of manufacturing processes, such as metal additive manufacturing, that result in rough samples that must be characterized for heterogeneities in their as-manufactured state. This work examines the influence of surface roughness on longitudinal wave speed and attenuation in wrought and additively manufactured Ti-6Al-4V specimens. Samples are measured in an ultrasonic immersion setup before and after mechanical polishing using varying transducer frequencies and focal profiles. The resulting data informs the error generated in ultrasonic measurements as a function of roughness parameters, thereby informing the sample preparation needed for desired precision levels. Lastly, new measurement protocols are explored to correct for the presence of surface irregularities in a point-by-point fashion. This work was supported by the Robert W. Young Award for Undergraduate Student Research.

Ultrasonic scattering behavior in austenitic NiTi with varying grain size and precipitate characteristics

Shape memory alloys like NiTi exhibit high strain recovery due to a reversible martensitic transformation when cooled or stressed, enabling actuation and biomedical applications. The characteristics of the stress-induced martensitic transformation in Ni-rich NiTi depend on the heat treatment. For example, aging induces the precipitation of Ni;4Ti;3 and lowers the critical stress needed for martensitic transformation. However, comprehensive characterization of these nanoscale precipitates is challenging as only small areas can be inspected efficiently. Ultrasonic immersion testing may assist in developing linkages between structure and transformation behavior as ultrasonic scattering is sensitive to the microstructure and easily mapped on the bulk scale. To this end, the ability of scattering behavior to discern between different precipitation characteristics must be probed to establish the sensitivity of ultrasonic parameters to changes in precipitation. This work explores the dependence of wave speed, attenuation, and backscattered energy on varying annealing and aging heat treatments of Ni-rich NiTi. The annealing treatments result in a gradient of grain sizes, while the aging treatments result in nucleation and growth of precipitate phases with increasing hold time. Variations in the ultrasonic parameters elucidate the sensitivity to changes in the microstructure, which are more quantitatively explored through existing analytical scattering models.

Acoustic field simulation-based ultrasonic water immersion non-destructive testing for titanium alloy plate

ABSTRACT Titanium alloy plate is widely used in automotive, aerospace, medical and other fields. Ultrasonic testing is a highly efficient non-destructive testing method for the inspection of titanium alloy components. However, there are strong distortion and attenuation of sound wave propagation in titanium alloys due to the presence of anisotropy and inhomogeneities, making it difficult to detect tiny defects in such components. In addition, some configuration parameters, such as the water path depth also affect the distribution of the acoustic field in the detected components. It is necessary to predict the acoustic field distribution to achieve a better testing accuracy. An acoustic field simulation method based on a multi-Gaussian beam is proposed, which can model the focused acoustic field in a multilayer anisotropy medium. The relationship between the acoustic focused area and the water path depth was explored and optimised comprehensively. C-scan imaging of specimen with flat bottom holes was performed at different water path depths. The results show that the proposed method can optimise the configuration parameters to improve the accuracy of the flaw sizing. This study provides an effective method for testing titanium alloy plate.

Chemical Cleaning of Crude Oil Fouling Deposits; Applying the Coke Spectrum

Fouling of heat exchangers and refining equipment by crude oil deposits is a chronic operating problem. In general, many such deposits are narrowly defined as coke fouling, for which the prescribed cleaning has traditionally been high-pressure water blasting. The results for this type of cleaning are mixed at best. Heat exchangers are often returned to service at conditions less than 85% clean performance, driving the need for more efficient cleaning regimens. A detailed characterization of 62 field-based crude oil fouling deposits from hydrocarbon process units was presented by the authors in 2019. This paper demonstrated that such deposits are exceptionally complex, resulting in the introduction of the Coke Spectrum. Here, these deposits are revisited, and chemical cleaning methods are applied. Chemical cleaning encompasses a variety of applications. Circulation, ultrasonic immersion, and clean-in-place techniques were reviewed on laboratory-scale samples to determine what chemical cleaning agents are most effective toward the various categories of foulant making up the Coke Spectrum. Combination techniques which employ both chemical and mechanical applications simultaneously or in sequence are considered in depth. The correlation between chemical composition and the effectiveness of the cleaning method is explored with considerations for scaling from laboratory to industrial application.

Study on the mechanism of rapid degradation of Rhodamine B with Fe/Cu@antimony tailing nano catalytic particle electrode in a three dimensional electrochemical reactor

A novel particle electrode based on antimony tailings microspheres was successfully constructed by ultrasonic immersion calcination method, and the degradation of RhB was studied in a three-dimensional electrochemical reactor (3DER). It was characterized by XRD, SEM, EDS, XPS, cyclic voltammetry and linear sweep voltammetry. When the pH value is 5.00, the dosage of Fe/Cu@antimony tailing is 1.50 g/L, the initial concentration is 100 mg/L, and the current density is 20 mA/cm2, the degradation efficiency is the best (99.40% for RhB and 98.81% for TOC) within 15 min. The results show that in the three-dimensional electrochemical oxidation system, electrochemical oxidation and electro Fenton oxidation occur at the same time to cause the increase of hydroxyl radicals. According to LC-MS analysis and EPR characterization, it can be found that the main degradation mechanism of RhB is that hydroxyl radicals continuously attack RhB, and realize rapid degradation of RhB through deethylation, deamination, dealkylation, decarboxylation, chromophore splitting, ring opening and mineralization. Fe/Cu@antimony tailing particles are both electrodes for electrochemical oxidation and catalysts for Fenton oxidation. The degradation effect of RhB remained at 94% after 6 cycles, and the leaching rates of Fe and Cu are only 1.20% and 0.79%, indicating that Fe/Cu@AT had significant stability. This work provides a new insight into the establishment of an efficient and stable three-dimensional electrocatalytic particle electrode.

Using DICONDE for NDT Data Exchange

The processing of multiple data sets from different NDT vendors and systems can be challenging. Accessing the data requires dealing with different and often proprietary data formats. In addition to that the correct spatial alignment requires knowledge and information about the acquisition system and must consider different approaches for markers and reference coordinate systems. The key features of NDE 4.0 and digital twin concepts are storage and interoperability with standard data formats. In this example data from thermography, manual ultrasonic testing and immersion ultrasonic testing are considered. For established devices multiple tools exist for the conversion of data into image-based formats. However, besides the lack of spatial alignment there is a need to access the raw data for further processing. In medical and CT-like applications the DICOM format has become a widely used exchange format. Its derivative DICONDE transfers this into the field of NDT. This study demonstrates the use of this format for data processing from multiple NDT methods and addresses issues related to interoperability and the integration of less structured data from inspections.

Experimental verification of phased array annular probe in ultrasonic immersion setting

With the ongoing development of materials and manufacturing techniques, new product design opportunities manifest themselves. However, care must be taken when applying techniques and material where there is less inherent knowledge about different parameters’ effect on the integrity of the final component. In conjunction with destructive testing of components, non-destructive evaluation (NDE) provides valuable insight into the manufacturing process reliability, as well as the possibility for subsequent future in-service inspection. Phased array ultrasonic testing (PAUT) facilitates the inspection of complex geometries on a wide set of material. Mathematical modelling of ultrasonic signal facilitates the optimization of inspection procedures by e.g., maximizing the probability of detection (POD) of specific defect types. In this paper, the response from an immersion annular phased array probe is experimentally validated to the output of the simulation software simSUNDT. In order to only validate the probe model (as both transmitter and receiver) a set of well-defined defects are used. The validity of the simulated amplitude response from side-drilled holes at a depth range of 20-115 mm is investigated. A total of 14 SDH holes in one test piece of is used as cases for validation. The results show a good correspondence between simulated and experimental data for the case where the probe is normal to the component surface.

Quantitative Measurement and Evaluation of High-Resolution Ultrasonic Sound Fields using a Novel Automated Ultrasonic Immersion Scanner

Ultrasonic probes are an integral part of the automated ultrasonic non-destructive inspection machines to detect and size the defects in a wide range of materials in production lines. A complete quantitative assessment of the performance characteristics of an application-specific ultrasonic probe is needed to be evaluated on the basis of the European Standard DIN EN ISO 22232-2. This requirement not only improves the quality assurance of the manufactured probes but also provides the useful technical data to the end-user to optimize the ultrasonic testing on-site. In addition, the evaluation of probe characteristics should be carried periodically throughout their service life. The main aim of this work is to develop and validate a novel ultrasonic immersion scanner for the quantitative measurement and evaluation of ultrasonic sound beam characteristics of an application-specific UT Probe. A novel ultrasonic immersion scanner integrated with high-precision motion control unit (Hexapod) with six axes is developed to measure the full ultrasonic probe characteristics, which include the squint angle measurement in three different planes (XY, XZ, and YZ), RF-signal and its frequency spectrum at watersteel interface and sound beam parameters including the angle of beam divergence in different directions. The automated scanning, data acquisition, evaluation, visualization and test report generation are performed based on DIN EN ISO 22232-2. The measured sound beam characteristics of both focused and non-focused applicationspecific ultrasonic probes with center frequencies ranging from 0.2 - 15 MHz using the pulse-echo technique on a 3 mm half-ball steel reflector are presented. The quantitative analysis of the measured sound field parameters and the acceptance criteria in accordance with DIN EN ISO 22232-2 are discussed. By using the newly developed automated immersion scanner, we achieved a few micrometer (~15 µm) spatial resolution in the measured sound field patterns and a good angular resolution (~0.05°) in the squint angle measurement of a wide range of UT probes.

Integration of Robotics and Artificial Intelligence in Non-Destructive Testing: A Review of Applications and Challenges

This study aims to examine the existing applications of robotics and artificial intelligence (AI) in non-destructive testing (NDT) and evaluate their effectiveness compared to traditional methods. The research methodology involves the use of a robotic arm equipped with a Panametrics ultrasonic immersion transducer for NDT experiments. The strengths and limitations of various applications, including weld inspection, visual inspection, ultrasonic testing, magnetic particle inspection, and eddy current testing, are evaluated through numerical scoring. The results demonstrate the capabilities of robotic systems with AI algorithms in achieving accurate and consistent inspections, although certain limitations exist. Additionally, the effectiveness of these robotic systems in performing NDT tasks is compared to traditional methods, revealing their superiority in terms of accuracy, efficiency, and defect detection. Overall, this research provides insights into the integration of robotics and AI in NDT and highlights their potential for advancing inspection capabilities. Keywords: robotics, artificial intelligence, non-destructive testing (NDT).

Study on the mechanism of organic ligand-assisted synthesis of superwater-stable CsPbBr3 quantum dots

Although lead halide perovskites have demonstrated excellent optical properties, their commercialization has been hindered due to environmental stability issues, in particular water stability. Here, CsPbBr3@PbBr(OH) perovskite quantum dots (PQDs) were successfully synthesized at room temperature with the assistance of organic ligands. These PQDs exhibited excellent water stability, which were validated by the retention of more than 90% of the original luminescence intensity under ultrasonic treatment and water immersion for up to one year. The photoluminescence quantum yield (PLQY) of the CsPbBr3@PbBr(OH) powder reached 51%, which is similar to the PLQY (53%) of pure CsPbBr3 prepared by hot-injection by us. In addition, the Lewis acidity and basicity of the organic ligand will affect the synthesis rate of PbBr(OH) during the reaction, which further affects the number and size of quantum dots, the color of luminescence could be modified. Due to the CsPbBr3@PbBr(OH) has such excellent stability and high PLQY, we tested its potential as a perovskite LED. The emission attenuation is only 7% after the LED device works continuously for 12 h.

Measurements of the Thickness and Area of Thick Oil Slicks Using Ultrasonic and Image Processing Methods

The in situ measurement of thick oil slick thickness (>0.5 mm) and area in real time in order to estimate the volume of an oil spill is very important for determining the oil spill response strategy and evaluating the oil spill disposal efficiency. In this article, a method is proposed to assess the volume of oil slicks by simultaneously measuring the thick oil slick thickness and area using ultrasonic inspection and image processing methods, respectively. A remotely operated vehicle (ROV), integrating two ultrasonic immersion transducers, was implemented as a platform to receive ultrasonic reflections from an oil slick. The oil slick thickness was determined by multiplying the speed of sound by the ultrasonic traveling time within the oil slick, which was calculated using the cross-correlation method. Images of the oil slick were captured by an optical camera using an airborne drone. The oil slick area was calculated by conducting image processing on images of the oil slick using the proposed image processing algorithms. Multiple measurements were performed to verify the proposed method in the laboratory experiments. The results show that the thickness, area and volume of a thick oil slick can be accurately measured with the proposed method. The method could potentially be used as an applicable tool for measuring the volume of an oil slick during an oil spill response.

Ultrasonic Water Immersion Nondestructive Testing for Nylon Bars Based on a Multi-Gaussian Beam Model

Ultrasonic Water Immersion Nondestructive Testing for Nylon Bars Based on a Multi-Gaussian Beam Model

Lead‐free versus PZT: Acoustic characterization of ultrasonic immersion transducers fabricated with lead‐free NBT‐BT piezoceramic

AbstractAn evaluation of the performance of a recently developed formulation of (lead‐free) Sodium‐Bismuth titanate – Barium Titanate (NBT‐BT) piezoceramic is presented through the construction and testing of several immersion transducers based around a new material formulation “Pz12” from CTS Ferroperm (Kvistgaard, Denmark). Results are intended to yield insight into the applicability of this lead‐free material for use within industrial, NDT, medical or underwater sectors through the reporting of experimentally realised performance characteristics. Results of several performance tests are reported including: pulse‐echo amplitude, electrical insertion loss, transducer efficiency, power output and transmitting voltage response (TVR). Benchmarking is provided against comparable lead zirconate‐titanate (PZT) based transducers using an industry standard Navy Type 1 (Pz26, CTS Ferroperm). Performance of the Pz12 transducers was found to exceed expectations, although was lower than that of the comparable Pz26 transducers. Pulse‐echo amplitudes indicated a −4.3 dB relative amplitude between lead and lead‐free variants with electrical insertion loss and transmitting voltage response both showing an average −3.1 dB between the Pz12 and Pz26. Electroacoustic conversion efficiencies of up to 52% are reported for the Pz12 transducers compared with a 62% maximum efficiency for the Pz26 variant. Temperature stability is also investigated in the 10–70 ˚C range.

Study of the attenuation of ultrasonic oscilliations in 3D-orthogonal woven composite

The particularities of 3D-woven composite’s defects are observed. Automated ultrasonic immersion through-transmission technique for their non-destructive testing is offered. X-ray computed tomography (X-ray CT) application for the definition of the reasons of ultrasonic waves high attenuation in 3D-orthogonal woven composite sample is described. The analysis of defects detected with X-ray CT is shown. The suggestion about connection between quantity of projection of defects total area at the plane which is perpendicular to ultrasonic wave propagation and ultrasonic wave attenuation has been made.