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Method of diagnosing pipeline welding crack using metal magnetic memory detecting signal

A technology of metal magnetic memory and welding cracks, applied in the direction of material magnetic variables, special data processing applications, instruments, etc., can solve the problems of limited promotion and application, distinction, etc., and achieve the effect of convenient on-line detection and fast non-destructive testing

Inactive Publication Date: 2006-06-28
TIANJIN UNIV
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Problems solved by technology

However, since the magnetic memory detection method cannot distinguish the stress concentration at the crack from the general stress concentration, this method can only provide a qualitative reference for crack detection, which limits this detection method to a large extent. promotion and application of

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  • Method of diagnosing pipeline welding crack using metal magnetic memory detecting signal
  • Method of diagnosing pipeline welding crack using metal magnetic memory detecting signal
  • Method of diagnosing pipeline welding crack using metal magnetic memory detecting signal

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Embodiment Construction

[0028] Use the TSC-1M-4 metal magnetic memory detector to detect the welded joint made of X70 pipeline steel. The geometric size of the steel pipe is Φ1016×21mm. The test results are as follows image 3 shown. Since the welding cracks have a certain length, in this example, the detection crack position accuracy is set to ±15mm, that is, the width of the window function is 30, so that it can be determined whether there is a welding crack within the detection range of 30mm. because K 0 It is related to the tensile strength of the tested material, for X70 pipeline steel, its tensile strength is σ b =656MPa, so K 0 The value is between 63.32 and 72.16. After the measured magnetic memory signal is processed in steps 1 to 4, the K values ​​at the two positions 137mm and 241mm away from the starting position are 95.15 and 87.47 respectively, all satisfying K≥K 0 According to the judgment conditions, it can be judged that there are cracks in the two window parts 137mm and 241mm aw...

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Abstract

A method of utilizing metal magnetic memory detection signal to diagnose welding crack of piping includes analyzing magnetic memory signal obtained by metal magnetic memory detector by applying Morlet wavelet function to decompose it to be detail part and large scale approximating part, carrying out discrete Fourier transform on detail part of said signal, carrying out delivery operation on transform amplitude value for obtaining K value and making decision scale be Ko, confirming that crack is on stress concentration position of detected section if K is not less than Ko, or otherwise not.

Description

technical field [0001] The invention relates to a method for diagnosing pipeline welding cracks by using metal magnetic memory detection signals, which belongs to the field of metal magnetic memory detection in nondestructive detection technology. technical background [0002] Welding cracks are the most dangerous welding defects, and the detection of welding cracks has always been a problem that must be paid attention to in the field of non-destructive testing. At present, commonly used non-destructive testing methods such as ultrasonic testing and radiographic testing can detect existing macroscopic cracks, but they are powerless for microscopic cracks. Under normal circumstances, the root cause of welding cracks is the effect of stress concentration. Under the induction of stress concentration, the crack tip first emits dislocations to form a dislocation-free region, and then nano-sized microcracks are in the dislocation-free region or have been ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/82G06F19/00
Inventor 李午申白世武邸新杰严春妍刘方明
Owner TIANJIN UNIV
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