Differences in Ultrasonic Testing Methods for Castings and Forgings

2022-05-26

Due to the differences in manufacturing processes between castings and forgings, the internal microstructures of these two types of workpieces differ significantly, resulting in markedly different inspection methods. Forgings are produced by applying an external compressive force to metal, causing plastic deformation to achieve the desired shape. This external force is typically applied using a hammer or a press. The forging process also refines the grain structure within the material and enhances its mechanical properties; key advantages of forgings include their ability to elongate along the longitudinal axis while reducing in cross-sectional area.

Advantages and Application Prospects of Phased-Array Ultrasonic Testing

2022-05-19

Ultrasonic phased arrays have garnered increasing attention due to their flexible beamforming capabilities and rapid imaging performance, making them a burgeoning research focus in the field of ultrasonic nondestructive testing. The concept of phased arrays originated in radar antenna electromagnetic wave technology, and ultrasonic phased arrays were initially used exclusively in the medical domain. In recent years, with the rapid advancement of new technologies such as microelectronics and computing, ultrasonic phased arrays have gradually been adopted in industrial nondestructive testing. By enabling the orderly superposition of acoustic beams emitted by individual array elements, ultrasonic phased arrays can flexibly generate steered and focused beams, without

Weld Quality Inspection of Tower Crane Lattice Columns

2022-04-27

With social development and the continuous improvement of construction technology, ultra-high-rise buildings and multi-level underground structures—which enable more efficient utilization of land resources—have become the primary direction of development. Tower cranes, as indispensable vertical transportation equipment in construction, play a crucial role in enhancing the efficiency of excavation support and basement construction. As the supporting strut system for tower crane foundations, the quality of lattice columns is of paramount importance. Lattice columns typically have cross-sections designed from angle steel or steel plates, configured as either bi-axially symmetric or uniaxially symmetric sections. The structural members of a lattice column system consist of web members and bracing elements; the web members primarily resist axial forces, while the bracing elements mainly counteract lateral forces. According to the lattice

Nondestructive Testing of Storage Tanks

2022-04-21

Storage tanks are the vessels used to store petroleum products and constitute one of the core facilities in the storage and transportation system of oil depots. For a long time, many in-service storage tanks in China have exhibited defects such as cracks and corrosion to varying degrees. Coupled with inadequate management during operation, this has led to frequent safety incidents, resulting in equipment damage and even casualties. Therefore, nondestructive testing of in-service storage tanks is of great significance. Currently, abroad, acoustic emission technology is primarily employed for online detection of active defects on the shell plates of atmospheric storage tanks and of corrosion and leakage signals on the tank bottom plates; magnetic flux leakage methods are used for periodic inspection of corrosion and leakage on the tank bottom plates; and ultrasonic techniques are utilized...

Classification, Functions, and Selection of Ultrasonic Testing Probes

2022-04-14

With the continuous emergence of new technologies and the ongoing upgrading of inspection equipment, ultrasonic testing has become one of the fastest-growing and most widely applied nondestructive testing methods, occupying a critically important position within the field. During the inspection process, in addition to the ultrasonic testing instrument itself, the transducer—responsible for both transmitting and receiving ultrasonic waves—plays an equally vital role. Consequently, the performance of the transducer and the appropriateness of its selection during flaw detection directly affect the accuracy and reliability of the inspection results. The following section will focus on the classification, functions, and selection criteria for piezoelectric ultrasonic transducers.

Tundish Trunnion Defects and Nondestructive Testing

2022-04-08

The ladle is a critical vessel in the metallurgical industry, primarily used in steelmaking and foundry shops to receive molten steel at the furnace front and to carry out refining and treatment of molten steel and hot metal. Among its components, the ladle trunnion plays an indispensable role: it must support the entire weight of the ladle and, in certain applications, also withstand the forces generated by gentle tilting of the ladle. Moreover, the trunnion is in constant friction with the hook lining, making it prone to scratching and the development of cracking defects. As a key load-bearing component of the vessel, the trunnion is vital for the safe operation of the ladle and directly affects the overall safety of the equipment. If defects in the trunnion are not detected in a timely manner, they can lead to serious accidents.

Principles and Application Scope of Eddy Current Testing

2022-04-02

Nondestructive testing refers to a method that, based on the principle of electromagnetic induction, evaluates certain properties of conductive materials and their components or detects defects by measuring changes in eddy currents induced within the test object. In industrial production, eddy current testing is one of the primary means for quality control of various metallic materials as well as a limited number of nonmetallic materials, such as graphite and carbon-fiber composites, and their products. Compared with other nondestructive testing methods, eddy current testing is easier to automate and delivers particularly high detection efficiency for tubular, bar, and wire-shaped products. Eddy Current Testing: Eddy currents arise when a conductor is placed in a time-varying magnetic field. The changing magnetic field induces a swirling electric field around it, which exerts a force on the free charges within the conductor, causing them to move and form eddy currents. Eddy current testing, abbreviated as ET, operates on the basis of Faraday’s law of electromagnetic induction: an alternating current is passed through a detection coil, generating an alternating magnetic field perpendicular to the test piece. As the detection coil approaches the test piece, eddy currents are induced on the surface of the workpiece, producing a secondary magnetic field that opposes the original field and partially cancels it out. This results in changes in the resistance and inductance of the detection coil. If the metal workpiece contains defects, the intensity and distribution of the eddy current field will be altered, leading to corresponding changes in the coil impedance; detecting these changes allows one to determine whether defects are present. With the advancement of microelectronics and computer technology, along with the adoption of various signal-processing techniques, significant progress has been made in eddy current transducers, signal-processing technologies, and instrumentation for eddy current testing. Characteristics of Eddy Current Testing: I. Advantages 1. During testing, the coil does not need to contact the workpiece, nor does it require any coupling medium, resulting in rapid inspection. 2. It exhibits very high sensitivity in detecting surface and near-surface defects, with good linear response over a certain range, making it suitable for quality management and control. 3. It can be used for inspections under high-temperature conditions, in narrow areas of the workpiece, and on the walls of deep holes, including pipe walls. 4. It can measure the thickness of metallic coatings or nonmetallic layers. 5. It can also inspect nonmetallic materials that are capable of inducing eddy currents, such as graphite. 6. The test signal is electrical, allowing for digital processing, which facilitates storage, reproduction, and comparative analysis of data. II. Disadvantages 1. The test object must be a conductive material, limiting its application to the detection of surface defects in metals. 2. There is an inherent trade-off between detection depth and sensitivity; when performing ET on a particular material, one must comprehensively consider the material properties, surface condition, and inspection standards before determining the testing plan and technical parameters. 3. When using through-type coils for ET, it is impossible to pinpoint the exact circumferential location of a defect. 4. Rotating-probe ET can provide localization, but the inspection speed is relatively slow. III. Applications of Eddy Current Testing in High-End Industries 1. Aviation and Aerospace Eddy current testing technology is widely used in the aerospace and aviation sectors for inspecting metallic components. To ensure flight safety, relevant parts must undergo regular in-service inspections. Eddy current techniques are typically employed to detect cracks in aircraft engine blades, bolts, internal cracks in bolt holes, defects in multi-layer structures, landing gear, wheel hubs, and subsurface defects beneath aluminum skin, as well as defects in wing attachment welds. During inspection, interference signals caused by probe vibration and material non-uniformity can be effectively suppressed. Metal magnetic memory testing can be used to diagnose stress concentrations or early damage in the aforementioned components. 2. Power and Petrochemical Industries Eddy current testing is utilized in power plants—both thermal and nuclear—as well as in the petrochemical industry—including oilfields, refineries, and chemical plants—for in-service and pre-service inspections of both ferrous and nonferrous metal pipelines, such as copper pipes, titanium pipes, stainless steel pipes, and boiler tubes. It can reliably detect intergranular corrosion, wall-thickness reduction, and external-wall wear, while effectively filtering out interference signals from support plates and tube sheets during inspection. In addition, eddy current methods are also applied to inspect the central bore of steam turbine spindles, engine blades, sucker rods, drill rods, bolts, and bolt holes; acoustic pulse testing can be used for rapid inspection of various metallic and nonmetallic pipelines, and metal magnetic memory technology can be employed to diagnose early damage in ferromagnetic components of in-service equipment. 3. Metallurgy and Machinery Eddy current testing is used for online and offline flaw detection of various metal pipes, bars, wires, and filaments. During flaw detection, it can simultaneously address both long, continuous defects and short, localized defects (such as through-holes), while effectively suppressing certain interference signals during online and offline pipeline inspections—such as material non-uniformity and vibration—and maintaining high sensitivity for detecting defects on both the inner and outer walls of metal pipelines. It can also be used for sorting mixed mechanical parts, evaluating carburizing depth and heat-treatment conditions, and measuring hardness. 4. Nuclear Energy and Defense Industry Eddy current testing is employed for inspecting metal pipelines such as nuclear fuel rods, titanium pipes, and threaded pipes; it is also used for pre-service and in-service inspections of military weaponry, including gun barrels, missile launchers, bomb bases, shell casings, as well as aircraft engine blades, wings, landing gear, and wheel hubs. Metal magnetic memory technology is utilized for early diagnosis of structural components in armored vehicles and naval vessels; low-frequency electromagnetic fields and leakage-flux techniques are applied to quality control of ferromagnetic materials and welds in decks and oil-storage tanks. Future research and development in eddy current testing include: refining transducer design theory and developing higher-performance eddy current transducers; researching eddy current localization techniques and three-dimensional imaging technologies for determining defect size, shape, location, and depth; exploring and promoting far-field eddy current testing; and further investigating eddy current detection techniques for surface fatigue cracks, cracking, machining-induced burn marks, and residual stresses in metallic materials. Conclusion: The application of this technology in nondestructive testing is bound to become increasingly widespread. This article was reprinted by the editors of our website for the purpose of disseminating additional information and does not necessarily reflect the views or endorse the authenticity of the content. If there are any issues related to the content, copyright, or other matters, please contact us within 30 days, and we will promptly remove the relevant content!

Classification and Characteristics of Leak Detection Technologies

2022-03-24

During the manufacturing or operation of process equipment, it is not only necessary to determine whether leaks are present, but also to quantify the leak rate. In leak detection technology, the concept of “leak” is inherently linked to the notion of the maximum allowable leak rate. A leak is an absolute condition, whereas “no leak” is a relative one. For vacuum systems, as long as the pressure within the system can be maintained below the specified vacuum level over a given time interval, the system can be considered leak-free even if leak holes do exist. For pressurized systems, as long as the pressure drop remains within the permissible limit and does not adversely affect the system…

< 1...3 4 5...9 > proceed page

Address: Room 104, Building 9, Futong Intelligent Manufacturing Industrial Park, Jinye 1st Road, Yiyang County, Luoyang City, Henan Province

Phone:+86-379-66915081 +86-379-66915005

Email:lywcjc@lywcjc.cn

Fax:+86-379-66919852

Website:www.lywcjc.cn

WeChat

Yu Public Security Bureau Filing No. 41030602000129

COOKIES

Our website uses cookies and similar technologies to personalize the advertising shown to you and to help you get the best experience on our website. For more information, see our Privacy & Cookie Policy

COOKIES

required

These cookies are necessary for basic functions such as payment. Standard cookies cannot be turned off and do not store any of your information.

analyze

These cookies collect information, such as how many people are using our site or which pages are popular, to help us improve the customer experience. Turning these cookies off will mean we can't collect information to improve your experience.

Feature

These cookies enable the website to provide enhanced functionality and personalization. They may be set by us or by third-party providers whose services we have added to our pages. If you do not allow these cookies, some or all of these services may not function properly.

advertise

These cookies help us understand what you are interested in so that we can show you relevant advertising on other websites. Turning these cookies off will mean we are unable to show you any personalized advertising.