Исследование выявляемости поверхностных объемных дефектов при ультразвуковом контроле с применением волн Рэлея, генерируемых электромагнитно-акустическим преобразователем

2021 ◽  
pp. 22-30
Author(s):  
Н.П. Алешин ◽  
Н.В. Крысько ◽  
А.Г. Кусый ◽  
С.В. Скрынников ◽  
Л.Ю. Могильнер
Keyword(s):  
Pitting Corrosion ◽  
Signal To Noise Ratio ◽  
Ultrasonic Method ◽  
Low Carbon Steel ◽  
Statistical Processing ◽  
Probability Of Detection ◽  
Low Carbon ◽  
Electromagnetic Acoustic Transducer ◽  
Destructive Testing ◽  
Acoustic Transducer

The paper presents the study of the "pitting corrosion" surface operational flaws detectability by the ultrasonic method of non-destructive testing. The possibility of using Rayleigh surface waves excited by an electromagnetic acoustic transducer (EMAT) for these purposes is considered. Blind vertical drills of various diameters and depths were used as artificial defects to simulate these flaws in low-carbon steel specimens. Based on the measurement results, the dependences of the amplitude of the received signals on the drilling parameters were plotted. During the statistical processing of the results, the signal-to-noise ratio was taken into account upon excitation of the Rayleigh wave using EMAT on defect-free areas of the samples. To construct curves of probability of detection (PoD), optimal models of the amplitudes distribution are determined. Under the conditions of the experiments carried out using the constructed PoD curves, conclusions were made about the minimum dimensions of a "pitting corrosion" type defect, detected with a probability of 90 %, taking into account the confidence interval of 95%, and about the possibility of adjusting the ultrasonic testing parameters using signals reflected from vertical drills.

Исследование выявляемости поверхностных плоскостных дефектов ультразвуковым методом с применением волн Рэлея

2021 ◽  
Vol 6 ◽  
pp. 26-34
Author(s):  
Н.П. Алешин ◽  
Н.В. Крысько ◽  
С.В. Скрынников ◽  
А.Г. Кусый
Keyword(s):  
Experimental Studies ◽  
Signal Amplitude ◽  
Probability Of Detection ◽  
Non Destructive Testing ◽  
Electromagnetic Acoustic Transducer ◽  
Destructive Testing ◽  
Testing Method ◽  
Acoustic Transducer ◽  
Non Destructive ◽  
Planar Flaw

The issues of detecting operational surface planar flaws by the ultrasonic non-destructive testing method with the use of Rayleigh surface waves generated by an electromagnetic-acoustic transducer are considered. The paper presents experimental studies of planar defects detection, simulated by an artificial reflector of the "notch" type with different width, depth and angle of inclination. The dependences of the signal amplitude on the listed parameters are constructed and their character was estimated. The optimal amplitude models for constructing the probability of detection curves (PoD) have been determined. A conclusion is made about the minimum dimensions of an operational planar flaw detected by the considering method with a probability of 90%, taking into account the confidence interval of 95%.

An electromagnetic acoustic transducer with electromagnetic pulse restraining

2021 ◽  
Vol 63 (2) ◽  
pp. 111-117
Author(s):  
Wu Dehui ◽  
Yang Jiaxin ◽  
Chen Wenxiong ◽  
Wang Teng
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Pulse ◽  
Design Method ◽  
Signal To Noise Ratio ◽  
Ultrasonic Waves ◽  
Alternating Magnetic Field ◽  
Electromagnetic Acoustic Transducer ◽  
Destructive Testing ◽  
Acoustic Transducer ◽  
Magnetic Field Model

Electromagnetic acoustic transducers (EMATs) are widely used in non-destructive testing (NDT). However, when ultrasonic waves are excited, the transmitting coil generates a strong alternating magnetic field, resulting in the generation of an electromagnetic pulse. To address this problem, an EMAT with electromagnetic pulse restraining is presented in this paper. First, the cause of the electromagnetic pulse is investigated. Second, the conditions for restraining the electromagnetic pulse using the new transmitting coil are analysed. Finally, the design method for the new transmitting coil is provided through evaluation of the magnetic field model of the new transmitting coil. The experimental results demonstrate that the new transmitting coil has a significant effect on the excitation of ultrasonic waves in the tested material and the restraining of electromagnetic pulses. Therefore, the method proposed in this study can self-compensate for the strong alternating magnetic field generated by the transmitting coil, reduce the interference of the electromagnetic pulse with the ultrasonic wave and improve the signal-to-noise ratio (SNR) of EMATs.

scholarly journals Microstructure Examinations in Corners of the Low-Carbon Steel Slabs from Continuos Caster Machine

2016 ◽  
Vol 61 (4) ◽  
pp. 2051-2056 ◽  
Author(s):  
G. Kwinta ◽  
S. Kara ◽  
B. Kalandyk ◽  
R. Zapała ◽  
P. Pałka
Keyword(s):  
Surface Defects ◽  
Cast Steel ◽  
Continuous Process ◽  
Low Carbon Steel ◽  
Casting Process ◽  
American Petroleum Institute ◽  
Test Material ◽  
Low Carbon ◽  
Destructive Testing ◽  
Gaseous Fuels

Abstract The exposed selvedge layers in slabs cast by the continuous process should be free from surface defects, which in most cases appear in the form of cracks on the casting surface and run to its interior. In addition to the parameters of the casting process, the occurrence of such defects depends on the chemical composition of cast steel, on the segregation of surface active elements and formation of the precipitates of carbides, nitrides and other phases. Due to the frequent occurrence of defects in corners of the slabs, non-destructive testing was performed on the mechanically cleaned surfaces of slabs. The test material was low-carbon API(American Petroleum Institute API 5L standard) steel micro alloyed with Nb and Ti designed for the production of pipes to handle gas, oil and other liquid and gaseous fuels. Despite the use of different methods of inspection, i.e. ultrasonic, magnetic particle and penetrant, cracks were not traced in the examined material. Then, from the corners of the examined slabs, specimens were cut out for metallographic examinations. The main purpose of these examinations was to disclose the presence of possible cracks and micro cracks on the surfaces transversal and longitudinal to the direction of casting. At the same time, studies were conducted to establish the number and morphology of non-metallic inclusions in selvedge layers of the slab corners and axis. Additionally, hardness of the slabs was measured. The conducted studies revealed only some minor differences in the slab hardness along its axis (130 ÷ 135 HB) and in selvedge layers (120 ÷ 123 HB).

Feature Extraction of the Acoustic Emission Signals of Low Carbon Steel Pitting Corrosion Based on Independent Component Analysis and Wavelet Transform

2013 ◽  
Vol 373-375 ◽  
pp. 677-680
Author(s):  
Wei Li ◽  
Yu Li Gong ◽  
Yang Yu
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Independent Component Analysis ◽  
Pitting Corrosion ◽  
Wavelet Transformation ◽  
Low Carbon Steel ◽  
Component Analysis ◽  
Independent Component ◽  
Low Carbon ◽  
Ae Signals

Based on the characteristics of the acoustic emission (AE) signals from low carbon steel pitting corrosion, a new extraction method was proposed with wavelet transformation and independent component analysis. The experiment result shows that the new method can overcome the influence induced by the uncertainty of the independent source of low carbon steel pitting corrosion and good extraction result can be achieved.

Effects of Stress on Pitting Corrosion Behavior of Low-Carbon Steel

2013 ◽  
Author(s):  
Huaixiang Cao ◽  
Hao Zhang ◽  
Xingqi Qiu
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
High Stress ◽  
Low Carbon Steel ◽  
Pressure Vessels ◽  
Structural Safety ◽  
Low Carbon ◽  
Corrosion Morphology ◽  
Accelerated Corrosion

Low-carbon steel Q235B was widely used in low or middle pressure equipments, which were not only withstanding the corrosive effect of the environment or medium, but also the high stress in service processes. In this paper, acetic acid accelerated corrosion test of low-carbon steel Q235B under the action of various stress levels was conducted, and its pitting corrosion behavior was studied by corrosion morphology, pitting corrosion parameters, scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). The results showed that, the degree of pitting corrosion of low carbon steel Q235B with stress was more serious than that of non-stress. And the corrosion started from grain boundary, which was corroded before grain itself, and then grains fell off or dissolved. Furthermore, it would have the tendency of deep hole corrosion with stress, which was more of a threat to the structural safety of pressure vessels.

scholarly journals Pengaruh Perlakuan Shot Peening Terhadap Korosi Retak Tegang Baja Karbon Rendah Pada Lingkungan Korosif

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
S. Sujita
Keyword(s):  
Carbon Steel ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pitting Corrosion ◽  
Shot Peening ◽  
Sea Water ◽  
Water Environment ◽  
Low Carbon Steel ◽  
Corrosion Cracking ◽  
Low Carbon

The aim of this study is to investigate the effect of shot peening on stress corrosion cracking of a low carbon steel in ocean water environment. The dimension of specimens were prepared in accordance with the ASTM G39. The hardness testing was carried out using microvickers with 0,25 kgf load in the longitudinal direction. The corrosion cracking test was immersed into artificial sea water for about 7 months. The test shows that the pitting corrosion is dominantly nucleated at the metal film interface. The biggest pitting corrosion was occurred under the static loading of 70 for the specimens unpeened. The presence of pitting corrosion promotes stress corrosion cracking. The cracking has a intergranular branched morphology which is typical for the chloride cracking of low carbon steel

scholarly journals Physic perspective fusion of electromagnetic acoustic transducer and pulsed eddy current testing in non-destructive testing system

2020 ◽  
Vol 378 (2182) ◽  
pp. 20190608
Author(s):  
Wei Guo ◽  
Bin Gao ◽  
Gui Yun Tian ◽  
Dan Si
Keyword(s):  
Eddy Current ◽  
Surface Defects ◽  
Eddy Current Testing ◽  
Non Destructive Testing ◽  
Electromagnetic Acoustic Transducer ◽  
Destructive Testing ◽  
Current Testing ◽  
Pulsed Eddy Current ◽  
Acoustic Transducer ◽  
Non Destructive

Comprehensive non-destructive testing (NDT) for pipelines is a critical and challenging task. This paper proposes a novel physic perspective fusion NDT method of electromagnetic acoustic transducer (EMAT) and pulsed Eddy current testing (PECT) for detecting hybrid defects. This transceiver-integrated fusion sensor structure can simultaneously excite ultrasound and pulsed eddy current. Therefore, the generated ultrasound is applied to detect deep defects, while the eddy current detects surface defects. The theoretical derivation of EMAT and PECT fusion mechanism has been developed for analysis and interpretation of the results. In addition, numerical simulation on the detection of hybrid defects including surface defects with different width, depth and multiple bottom-thinning defects has been conducted. Experiments on both ferromagnetic and non-ferromagnetic material verify the feasibility of composite detection. Finally, tests have been validated on pipeline with weld defects, and the results show that the composite inspection method is capable of monitoring thickness variations and inspecting surface defects. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

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