Ultrasonic Testing Method Research Articles

Effect of the loading frequency on fatigue properties of JIS S15C low carbon steel and some discussions based on micro-plasticity behavior

Ultrasonic testing method has been often used to investigate fatigue properties of various metallic materials. Since ultrasonic fatigue tests are conducted at a very high loading frequency, they are particularly convenient for fatigue tests in the very high cycle regime. Indeed, ultrasonic fatigue method allows us to conduct fatigue tests up to 109–1010cycles in a definite period. However, due to the huge gap of loading frequency between ultrasonic testing method (around 20kHz) and usual testing method (most of the cases in the range 1–100Hz), the frequency effect on the fatigue property is still unclear. Low carbon steel is one of typical metallic materials to provide a significant discrepancy between fatigue strengths obtained under ultrasonic testing frequency and under usual testing frequency range.Thus, by preparing a lot of specimens of JIS S15C low carbon steel (0.15% C), fatigue tests were carried out in a wide range of the loading frequency. The frequency effect on the S–N property was first examined and a useful procedure was proposed to obtain a common S–N property normalized by the lower yield stress. In addition, micro-plasticity behavior such as the stress–strain hysteresis loop and the local misorientation were also measured and the frequency effect on the fatigue property was discussed.

Very high cycle fatigue of nitrided 18Ni maraging steel sheet

Thin sheets of nitrided 18Nimaraging steel are tested under cyclic tension (load ratio R=0.1) in the very high cycle fatigue (VHCF) regime. The ultrasonic fatigue testing method with a cycling frequency of about 20kHz has been further developed for these experiments. Sheet specimens with 0.35mm thickness are mounted on a carrier specimen, they are pre-stressed and are forced to vibrate jointly. Between 107 and 109 cycles, fatigue cracks are initiated exclusively at internal TiN inclusions. The areas of the crack initiating inclusions projected perpendicular to the applied tensile stress are evaluated. The square root of inclusion areas, (areaINC)1/2 lies between 2.5μm and 5.3μm. Considering inclusions as cracks, their stress intensity range is between ΔKINC=1.3MPam1/2 and 2.4MPam1/2. The sizes of crack initiating inclusions influence fatigue lifetimes. This is considered in a crack propagation model and by presenting lifetimes versus the stress amplitudes multiplied by (areaINC)1/12. A mean lifetime of 109cycles is found at a stress amplitude of 22% of the tensile strength, which is comparable to other high strength steels tested under cyclic tension.

Annular Phased Array Dynamic Focusing Method for Large Target Ultrasonic Testing

A novel method called dynamic focusing immersed ultrasonic testing (DFIUT) is proposed which utilizes an annular phased array ultrasonic transducer (APAUT) and one of the distinguished advantages is dynamic focusing. The proposed DFIUT is aimed at solving the focus deviation problem in the detection of large targets. The design methodology of APAUT and implementation of DFIUT method are presented in this paper. Furthermore, an annular phased array immersed ultrasonic testing (APAIUT) system is also set up. An experiment over the large molybdenum target using the DFIUT is conducted to verify the effectiveness of the proposed method.

Ultrasonic examination of LP steam turbine shrunk-on discs: method (designed through modelling), process and tools, data capture, analysis and post processing)

The different manufacturing technologies of LP steam turbines include solid turbines (monoblock), welded turbines, and shrunk–on disc turbines. For shrunk–on disc LP turbines, the turbine rotor is constructed by thermally expanding the discs and mounting each disc onto the spindle allowing it to 'shrink fit'. The discs are aligned and locked in their circumferential positions by way of a pin and drive pin hole arrangement. This type of assembly is a source of risk of cracking due to the inherent stress. Additional factors contribute to the risk stress corrosion, fretting action, and fatigue. The areas of concern are the shrink–fit area between shaft and disc, drive pin holes on the lateral face of the discs. Without any dismantling the only means of inspecting the suspect area is to use an ultrasonic test method. This paper presents through modelling (CIVA) the process followed from the stage of receiving the specification to the inspection.

Reconfirmation and new discussions on frequency effect of fatigue property of materials based on numerous published data

Ultrasonic fatigue testing is a convenient method to examine the S-N property in long life region, within a definite period. However, a distinct gap of the loading stressing frequency between conventional and ultrasonic testing methods (100–1,000 times larger) urges us to study a potential effect of the loading frequency. The present paper deals with a comparison of results obtained from conventional and ultrasonic tests, in the high cycle fatigue region, from two viewpoints. Firstly, a short direct comparison of fatigue data from conventional and ultrasonic tests, with similar conditions, has been undertaken. Secondly, overview analyses based on a far larger amount of data have been carried out for structural steels and aluminium alloys. Results obtained from this work give us some idea of the extent of differences between fatigue test results obtained at usual and ultrasonic frequencies in the fatigue regime of N f < 10 7 cycles. Particularly, the second study gives a potential 18% difference of fatigue strength for steels, whereas it reveals only a slight difference of fatigue behaviours for aluminium alloys.

Research on Evaluation Method of Ultrasonic Testing for Inspection of Concrete Jointing Surface Quality

The combining Part Of new-old concrete is a weak link. The cohesive strength of the combining layer is generally lower than the strength of the concrete poured completely. It will greatly affect the reliability of structure, when the combining layer is bad. It is a effective method to Inspect combining surface conditions by ultrasonic method. But related specification for defect judgment method of ultrasonic method, which is not fit to detect the defect area is larger in detect area, the overall quality of members is poor, make the discreteness of data less, those causes low judgment value, and the defects to leakage. In addition, the less data is not easy to found out the outliers. We adopted ultrasonic angle measurement method for concrete jointing surface of 50 pillars testing analysis, Method to determine the critical value of defect of abnormal value, and studied critical value determination method of defects outliers, propose a method of defects determination base on the common probability method. As detection is shown, first, with this method detect the joint surface of the concrete columns, contrasted core drilling results, prove the method is effective and feasible. Second, For new pouring concrete quality is poorer near surface, defect points too much, contrasted core drilling results, prove the method is effective and feasible. In addition, using this method for detecting data less, contrasted core drilling results, prove the method is effective and feasible.

Process Characteristics of Friction Bonding of Stainless Steel 430, Aluminum 1100 and 3003

Friction bonding process is a method of joining two or more metal sheets by using heat and force to soften and yield an atomic adhesion between the two work layers. Using the insufficient heat and force, it can result in a non-bonded section or delamination, where a gap is appeared in between the two metal sheets after the process. With a very limited knowledge in relation to the friction bonding process, this study aims at revealing the effect of work temperature and force on the size of non-bonded section. Stainless steel 430, aluminum 1100 and 3003 sheets were bonded in this study, where the non-destructive ultrasonic testing method was employed to measure the defect size beneath the bonded sample. The results showed that a reduction in defect size can be obtained by increasing the work temperature as well as the stamping force. In addition, the optimal condition of the study case is also obtained through the experimental design. It can be concluded from the analysis that at the voltage of 595 Volt, 65 Watt and the stroke distance of 80mm which is equivalent to 540 Celcius and force of 2590kN provide the smallest delamination size. The regression model was also developed to show the relationship of factors to the delamination size. This equation can be used to predict the mentioned delmination size at various conditions.

The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite

The influence of hot pressing conditions on mechanical properties of nickel aluminide/alumina composite has been investigated in the present paper. In particular, effect of the process parameters, viz. compacting pressure, sintering temperature and sintering time on the evolution of density, elastic constants and tensile strength properties of the intermetallic-ceramic composite has been studied. Elastic constants, the Young's modulus and Poisson's ratio, have been evaluated using an ultrasonic testing method, and the tensile strength has been determined by a Brazilian-type splitting test. Microscopic observations of microstructure evolution complemented the experimental procedure. Experimental results have been confronted with theoretical models showing a good agreement between the data compared.

Concrete Compression Strength Non-Destruction Detecting with Rebounding and Ultrasonic Synthesis Method

Regional materials and mixing ratio in Datong region are used to make the concrete testing blocks. The rebounding and ultrasonic non-destruction detecting testing for concrete compression strength were done by using the six types of strength grades concrete standard specimens according to the technical regulation. By using the common software Matlab7.0, the mathematical models between rebounding values, ultrasonic velocity values, rebounding- ultrasonic method values and concrete compression strength were set up by three kinds of functions’ regression analysis. The error analysis showed that the rebounding-ultrasonic non-destruction detecting testing method had higher precision results and was used firstly when the conditions were permitted, compared with the rebounding testing method or the ultrasonic testing method.

Large Ranging of Ultrasonic Testing Inspection Internal Defects of Mass Concrete Structure

The ranging greater than 3m is not accorded with china engineering construction standardization association standard TECHNOLOGICAL SPECIFICATION FOR INSPECTION OF CONCRETE DEFECTS BY ULTRASONIC METHOD[CECS 21:200 (Transducer spacing is 2~3m). This paper studied large ranging of ultrasonic test mass concrete structure, and analyzed a project instance that was inspected the internal defects of mass concrete structures with various test methods, compared of those results. As detection is shown, first, with the test distance increased to 5.1m, the velocity of sound shows a linear trend of continuous development trend. Second, responds to improve of concrete strength, the velocity of sound increases, but not shows a linear trend. In addition, with the test distance increasing, concrete strength increases, but the velocity is down. A large ranging of ultrasonic test method was developed based on these observations.

Experimental study of hydrogen embrittlement on AISI 304 stainless steels and Rayleigh wave characterization

Many failures due to hydrogen embrittlement or hydrogen damage are widely reported in oil and refinery industry. Despite many ultrasonic testing methods have been developed to assess hydrogen embrittlement, they are applied well to serious hydrogen attack instead of earlier degradation. This paper aims to characterize nascent hydrogen embrittlement of AISI 304 austenitic stainless steels under cathodic hydrogenation using Rayleigh wave. After cathodic hydrogen charging of AISI 304 stainless steel, XRD and metallographic examination show that martensite transformation occurs within the subsurface region of the specimens. Microhardness testing indicates that hydrogen leads to hardening of the material. It is found that Rayleigh wave are better to inspect local degradation than bulk waves. Rayleigh wave velocity of 5MHz and 10MHz decreases significantly with cathodic charging time, while longitudinal wave velocity changes not. Acoustic velocity change is due to elastic modulus reduction resulting from hydrogen-induced phase transformation in the subsurface region.

Combined Application of Three Nondestructive Testing Methods in Simulation Test of a Large Concrete-Filled Steel Tube

Bonding quality is the key factor that affects the safety of concrete-filled steel tube (CFST) structure, so it is a very important research that how to judge the bonding quality. This paper expounded the theory of three methods used in nondestructive testing of CFST, and introduced the combined application of the methods of artificial tapping, ultrasonic testing, and strain analysis in a large simulation test.

A Brief Review on Inspection Methods of High Pressure Vessels Applied in Food Processing

In this review, inspection methods used in the high pressure vessel in-service, such as strain electrical measuring method, eddy current testing, ultrasonic testing, acoustic emission and optical measurement methods were summarized. The principles, characters and research progress of the above mentions inspection methods when they are used for inspecting HPV were reviewed. Finally, an attempt is made to look into the future of inspection methods of HPV with personal opinions.

Small‐Scale Deformation of Pulsed Electric Current Sintered Silicon Oxycarbide Polymer Derived Ceramics

The deformation behavior of pulsed electric current sintered silicon oxycarbide ceramics produced by the solid‐state thermolysis of polyhydridomethylsiloxane at small‐scale is investigated. The ceramics remained X‐ray amorphous after sintering at 1300 °C in vacuum and a high density of ≈2.35 g cm−3 is achieved. The elastic constants of these ceramics are determined using non‐destructive ultrasonic testing method. The elasto‐plastic deformation under contact loading is determined using depth sensing nanoindentation technique. An indentation hardness of ≈11 GPa and reduced elastic modulus of ≈105 GPa is observed. The load–displacement curves display significant elastic recovery with an elastic work ratio of ≈0.71. The evolution of Hertzian cone cracks upon microindentation indicates an anomalous deformation behavior.

Evaluation of the Fatigue Life in Aluminum Alloy Welded Joint by Nonlinear Ultrasonic Testing

Fatigue is a common phenomenon in welded structures. Prediction of fatigue life of welded joints in-service is still an unsolved puzzle by the conventional linear ultrasonic testing method. However, the nonlinear ultrasonic waves or the acoustic nonlinear signal can provide clear signs of the accumulative fatigue damage in materials, as reported by a number of researchers. Hence, the nonlinear ultrasonic testing method has revealed a tremendous potential for fatigue damage evaluation. This paper presents a study to characterize the fatigue damage using the analysis of the signal characteristics and a new nonlinear parameter. Based on the very high-cycle fatigue testing results for a 6N01 aluminum alloy welded joint, the relationship between the amplitude of the second-order harmonic and fatigue cycling has been established. The nonlinear ultrasonic system test results show that the amplitude of the second-order harmonic increases at the early fatigue stage, with further increase in cyclic loading until reaching a peak. Metallographic examinations show that a fatigue crack will nucleate in the weld joint in the stage as the amplitude reaches the peak value. Finally, theoretical and experimental results confirm that the amplitude of the second-order harmonic is useful for assessing the fatigue life of a 6N01 aluminum alloy welded joint.

Compressive strength of calcium aluminate mortar determined by ultrasonic non-destructive test method

The early-age hydration of a number of calcium aluminate cement pastes and mortar materials was investigated using compressive strength and ultrasonic through-transmission measurements. Ultrasonic signals obtained were successfully described in the temporal domain by a single Gaussian wave packet equation giving five characteristic parameters – amplitude A, angular frequency ω, phase shift, wave centre arrival time and signal width. The group velocity of ultrasonic wave propagation (vG) is suggested to be a more sound parameter characterising the material under study than the generally employed ultrasound velocity determined from the ‘time of flight' parameter. The combination of parameters AωρvG showed a linear correlation with the measured compressive strengths for all the samples tested. The physical meaning of the AωρvG group of parameters is given and its application is further discussed in relation to other testing procedures.

A Study of Total Focusing Method for Ultrasonic Nondestructive Testing

Abstract Commercial ultrasonic phased array (PA) systems can perform multiple inspections in real-time using array transducers. This approach involves firing array elements in a particular sequence to produce high-resolution images at a high frame rate with excellent signal-to-noise ratio (SNR). Unfortunately, PA systems are complex and expensive. This study proposes a simpler, cheaper, non-real-time ultrasonic array system incorporating the total focusing method (TFM), and the performance of the proposed system is compared with that of a commercial PA system. Studying results shows that both systems have similar apparent axial resolution, but the apparent lateral resolution of the proposed system is far better than the L-scan but falls short in S-scan of a commercial PA system under a quiet testing environment. Moreover, the array performance indicator (API) values of TFM are lower than those of S-scan and L-scan, and the TFM has the highest SNR than the other methods. These results show that the performance of TFM array system is better than the commercial PA system, except for time consumption when switching the channels. Automatically switching the source and receiver channels could further the development of inexpensive, high-performance TFM arrays for ultrasonic nondestructive testing (NDT). It is anticipated that rapid advancements in electronic components, computer science, and digital signal processing will lead to improvements in near-real-time TFM array systems.

Detection and characterization of defects in aerostructures using non-contact ultrasonic transducers

This paper describes an investigation into the possibility of using non-contact ultrasonic transducers for detecting and characterizing defects in aerostructures. Our study deals with an ultrasonic method that underscores the recent advances in non-contact and analytical methodologies. Ultrasonic waves are generated by a transducer connected to a Sonatest DryScan 410D using through-transmission mode. In this investigation, ultrasonic through-transmission signals are analyzed for their amplitudes. We treat this problem analytically and experimentally. Various aspects of our approach are presented. The observations reported in this paper deal with defects in aluminum structures. Confirmation of defect geometry is obtained by comparing the results of the non-contact ultrasonic sensors with a conventional ultrasonic testing method. The results obtained are in good agreement with those of the conventional ultrasonic method, indicating that both techniques can be considered as quantitative nondestructive tools ...

Signal quality enhancement using higher order wavelets for ultrasonic TOFD signals from austenitic stainless steel welds

Time of flight diffraction (TOFD) technique is a well-developed ultrasonic non-destructive testing (NDT) method and has been applied successfully for accurate sizing of defects in metallic materials. This technique was developed in early 1970s as a means for accurate sizing and positioning of cracks in nuclear components became very popular in the late 1990s and is today being widely used in various industries for weld inspection. One of the main advantages of TOFD is that, apart from fast technique, it provides higher probability of detection for linear defects. Since TOFD is based on diffraction of sound waves from the extremities of the defect compared to reflection from planar faces as in pulse echo and phased array, the resultant signal would be quite weak and signal to noise ratio (SNR) low. In many cases the defect signal is submerged in this noise making it difficult for detection, positioning and sizing. Several signal processing methods such as digital filtering, Split Spectrum Processing (SSP), Hilbert Transform and Correlation techniques have been developed in order to suppress unwanted noise and enhance the quality of the defect signal which can thus be used for characterization of defects and the material. Wavelet Transform based thresholding techniques have been applied largely for de-noising of ultrasonic signals. However in this paper, higher order wavelets are used for analyzing the de-noising performance for TOFD signals obtained from Austenitic Stainless Steel welds. It is observed that higher order wavelets give greater SNR improvement compared to the lower order wavelets.

Analysis of the Long-Distance Pipeline Failure Modes

The pipeline which is plugged after leaking will spend a lot of resources, therefore it is imperative to investigate safety analyzing method of pipeline. To reduce the production cost that timely test and evaluate the in-service pipeline, and take measures to extend the life span have been the key matter. To solve this problem, the article demonstrates the ultrasonic testing method. It is significant for the long-distance pipeline running safely.