Reliability Of Ultrasonic Inspection Research Articles

INCREASING THE RELIABILITY OF HIGH-SPEED RAIL TESTING BY THE BOTTOM-ECHO METHOD

The current regulatory documents do not take into account the peculiarities of rail monitoring by mobile flaw-detectors, are focused on compliance with the initially set parameters and cannot always provide the required reliability of defect detection. The issues of maintaining the required reliability of ultrasonic inspection under the influence of interfering factors at significant scanning speeds by adjusting the threshold level of defect detection are considered. When implementing the bottom-echo method of ultrasonic inspection, an informative feature is the amplitude of the bottom signal. When analyzing the envelope of the bottom signal amplitude, an important role is played by establishing a baseline level from which the magnitude of the amplitude decrease is calculated. To automate the process of decoding ultrasonic data of mobile flaw-detectors, a special algorithm for estimating the baseline level of the bottom signal has been developed, implemented in the corresponding software for automatic processing of acoustic inspection data.

Influence of Local Mechanical Parameters on Ultrasonic Wave Propagation in Large Forged Steel Ingots

In numerous applications, high strength forged steel requires uncompromising quality and mechanical properties to provide advanced performances. Ultrasonic testing are commonly used for material characterization to measure mechanical properties and for nondestructive testing to detect flaws or other features contained in metallic objects. In steel blocks of relatively small dimensions (at least two dimensions not exceeding a few centimeters), temperature and homogeneity are well controlled during the solidification. However, these parameters may become difficult to control during manufacturing of large objects. Forging and heat treatments are known to modify the microstructure and/or the grain size, therefore affecting elastic properties, and consequently, the ultrasonic inspection reliability. In this context, the relationship between ultrasonic group and phase velocity variations with local properties of a forged and heat-treated $$40{,}000~\mathrm {kg}$$ bainitic steel block manufactured in an industrial setting was investigated. The block was cut into a $$20~\mathrm {mm}$$ thick slice that was then divided into 875 parallelepiped samples. A subset was selected for ultrasonic measurements, metallurgical study, and chemical analysis. Ultrasonic phase velocity showed a strong correlation with grain size, whereas group velocity was shown to vary as a function of the Young’s modulus and the chemical composition. Tensile testing was performed to validate the Young’s modulus calculated from the ultrasonic group velocities.

Application of ultrasonic iterative deconvolution technique to the case of internal defect detection in multi-layered PCB components

Possibilities of improvement in detection and characterisation accuracy concerning internal defects in multi-layered printed circuit boards (PCB) and electronic components by applying the ultrasonic immersion technique have been investigated. The experiments have been carried out on a real PCB with a mounted defective microchip. Defect-free and defective high-voltage semiconductor components have also been investigated. The investigations have been performed using the acoustic microscope produced by Ultrasonic Science Ltd and ultrasonic measurement system developed at the Ultrasound Institute of Kaunas University of Technology. The novel signal processing method based on the adaptive numerical model of ultrasonic wave propagation through a multi-layered electronic component and respective selection of signal components in time and frequency domains have been proposed. Two different signal processing techniques have been used to increase the contrast of defective regions and so improve reliability of ultrasonic inspection.

Reliability of Ultrasonic Inspection of Welded Joints with Incomplete Structural Fusion

Reliability of Ultrasonic Inspection of Welded Joints with Incomplete Structural Fusion

Reliability of ultrasonic inspection of welded joints with incomplete structural fusion

A correlation is established between the depths of incomplete-fusion areas along the surfaces of welded flanges in T-joints and incomplete structural fusion. A rejection level is chosen for the echo-signal amplitude that makes it possible to decrease errors in ultrasonic testing.

Effects of alternative inspection strategies on piping reliability

This paper applies probabilistic fracture mechanics calculations to determine the effects of inspection on leak probabilities for piping. The approach has been to perform calculations in a structured parametric format, with the parameters selected to cover the range of pipe sizes, degradation mechanisms, operating stresses, and materials relevant to the piping systems of interest. In this paper, the calculations were intended to be generally applicable to mechanical and thermal fatigue of stainless steel piping. Specific areas of uncertainty addressed by the probabilistic calculations of this paper are the numbers of initial flaws, the distributions of flaw sizes, the crack growth rates for these initial flaws, and the probability of detection curves and inspection schedules that describe inservice inspections which are performed to detect these growing flaws. The effectiveness of an inspection strategy is quantified by the parameter ‘Factor of Improvement’, which is the relative increase in piping reliability due to a given inspection strategy as compared with the strategy of performing no inspection. The results of a systematic set of calculations are presented in this paper that address inspection effectiveness for operating stresses giving crack growth rates ranging from very low to very high. Inspection strategies are described that address three reference levels of ultrasonic inspection reliability, intervals between inspections ranging from 1 to 10 years, and both preservice and inservice inspections.

New capabilities of ultrasonic inspection of metals

The constantly increasing volumes of nondestructive inspection of objects and equipment having critical service lives requires an increase in inspection productivity and in the reliability of the most widely used methods, radiographic and manual ultrasonic. The advantages and disadvantages of these methods for inspection of weld joints, vessels, metal structures, etc. are widely known. Manual ultrasonic inspection done with use of general purpose instruments, both imported and domestic, has not only low productivity but also insufficient reliability [ 1]. The presence of a subjective factor in interpretation of the inspection results and the absence of an inspection record of the whole weld joint (current imported inspection instruments deriver printouts of tuning a~ echo pulses) also reduces the reliability of the method. In addition, current requirements for conducting inspections include taking into consideration corrections in sensitivity with a change in surface finish and waviness of the impeeted part on the side of which iuspeetion is conducted and also the temperature of the environment and the inspected part [2]. An increase in productivity and reliability of ultrasonic inspection of objects and equipment is possible with use of small units having a multiehannel inspection instrument and multielement acoustic systems and also with use of new methods of rapid diagn~ing. In connection with this the development and use of new equipment and methods simultaneously ~r~mg inspection productivity and reliability becomes increasingly pressing. The rapid development of electronics makes it possible to develop small right multiclmnnel inspection instnnnents and, together with use of multielement acoustic blocks to substa~tially increase the capabilities of ultrasonic inspection. "ALTES Ltd." Scientific and Technical Company has developed and is producing the small "SKARUCh" manual u~msonic inspection instrument combining the advantages of manual inspection (small and right equipment, high effectiveness) and automatic output of the document. The unit is designed for detection and determination of the characteristics of defects in weld joints (butt, T-, lap) and base metal of piping and metal structures with a wall thickness of 4-60 ram, The unit has an eight-el~nnel electronic block which is connected to the meehanoacousfic block through the information cable. The electronic block, equipped with an electroluminescent screen, operates either as a general purpose inspection instrument or thickness gauge, or as an automatic inspection unit. In automatic inspection a special meclmnoacoustic block, which consists of a mechanical device (one-sided MAB1 or two-sided MAB2), acoustic blocks with a system of frET) piezotrausducers built-in to them, and a sensor for measurement of the path covered (SP), is used. The MAB2 has an exteusible housing, which makes it possible to change the distance between the acoustic blocks (right and left) depending upon the thickness of the part and the width of the fdlet. The MAB2 is used for inspection of butt and lap weld joints by symmetric placement of the blocks on both sides of the weld joint and the MAB1 for inspection of weld joints with limited (one-sided) access, T- and comer joints, and'longitudinal butt joints of piping, and also for determining the remaining thickness and detection of separations in the base metal. The acoustic blocks have the capability of horizontal and vertical movement during movement of them along the weld joint and are equipped with exteusible stocks, which provide a stable position of the block on a working surface with curvature (such as in inspection of a butt joint of piping). The multielement acoustic block (AB) consists of 3-10 PETs (depending upon the inspected thickness) probing the whole cross section from one or two sides of the joint by different methods of ultrasonic inspection (combined, "duet," "tan

Reliability of nondestructive checking of the strength characteristics of metal in power-plant equipment

Nondestructive inspection methods can be changed from passive methods which merely record the quality of the product to active methods capable of regulating and controlling quality, determining the reasons for deviations from the manufacturing and service routines, making recommendations to eliminate these deviations, and checking the effectiveness of the corrective measures. Among the quality control tasks that must be performed are statistical analysis, statistical regulation of quality, probability substantiation of inspection plans and reliability of inspection, probability substantiation of norms for possible deviations in the strength properties of materials, and optimization of inspection parameters. This paper examines the determination of the reliability of ultrasonic inspection of the mechanical properties of power-plant equipment metal, an inspection which is a component of a larger inspection system which includes specimen-less, electromagnetic and acoustic measurements.