Deformation Effects on Metal Magnetic Memory in API 5L X70 Steel

2011 ◽  
Vol 415-417 ◽  
pp. 2101-2104
Author(s):  
Fang Bai ◽  
Bo Song
Keyword(s):  
Plastic Deformation ◽  
Pipeline Steel ◽  
Magnetic Method ◽  
Magnetic Memory ◽  
Stress Effect ◽  
Gradient Index ◽  
Metal Magnetic Memory ◽  
Destructive Testing ◽  
Elastic And Plastic Deformation ◽  
Api 5L X70 Steel

Metal magnetic memory technology is a passive magnetic method of non-destructive testing based on the residual magnetic field of a ferromagnetic component. The MMM measurements were performed on a series of X70 pipeline steel samples for various values of uniaxial elastic and plastic deformation from zero up to about 20% strain. The outcomes evidence that the metal magnetic memory gradient index m can be used to evaluate the stress-strain state of ferromagnetic materials under tensile stresses. The tensile stress effect on the gradient index m significantly in elastic stage, but the gradient index m remained unchanged in the plastic deformation stage.

A Review of the Metal Magnetic Memory Technique

2016 ◽  
Author(s):  
Sheng Bao ◽  
Meili Fu ◽  
Shengnan Hu ◽  
Yibin Gu ◽  
Huangjie Lou
Keyword(s):  
Experimental Investigations ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Non Destructive Testing ◽  
Early Failure ◽  
Destructive Testing ◽  
Damage State ◽  
Recent Developments ◽  
As Stress ◽  
Non Destructive

Metal magnetic memory (MMM) is a newly developed non-destructive testing (NDT) technique. It has potentials to detect early failure, such as stress concentration, micro-crack and fatigue damage of ferromagnetic components. This paper outlines the recent developments of the mechanism studies on the MMM technique. Several advances in experimental investigations on the MMM technique are also summarized, e.g. the factors which can influence the detection signals, the criteria for judging the damage state and the magnetic parameters which can be used to assess the testing results. Finally, some future development trends about this technique are suggested.

Quantitative research of defects for pipelines based on metal magnetic memory testing

2020 ◽  
Vol 62 (5) ◽  
pp. 292-299 ◽  
Author(s):  
Wei Zhou ◽  
Jianchun Fan ◽  
Xiangyuan Liu ◽  
Shujie Liu
Keyword(s):  
Quantitative Research ◽  
Three Dimensional ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Magnetic Signal ◽  
Destructive Testing ◽  
Gas Industry ◽  
Defect Profile ◽  
Comparison Results ◽  
Dimensional Distribution

Pipelines are widely used in the oil & gas industry but defects seriously affect their safe operation. Therefore, it is necessary to perform non-destructive testing (NDT) to quantify the defects. In this study, a magnetic dipole model was established to characterise the defects and magnetic flux leakage (MFL) of defects was simulated using the finite element method (FEM) to reveal the spatial distribution of the magnetic vector. Magnetic signals were measured using a tunnel magnetoresistance (TMR) sensor array and the results showed that defects with different sizes could be quantified using the metal magnetic memory (MMM) method. Three-dimensional distribution of the magnetic signal and its gradient reflected the defect profile well and the gradient of the magnetic signal was found to reduce the effect of non-uniform magnetisation. Furthermore, experimental results were verified by comparison with the simulation results and the comparison results showed a consistent variation trend. Quantitative analysis was conducted and the characteristic parameters of the gradients could be used to quantify the defects.

Non-Contact Measurement of Residual Magnetization Caused by Plastic Deformation of Steel

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Aroba Saleem ◽  
P. Ross Underhill ◽  
Thomas W. Krause
Keyword(s):  
Plastic Deformation ◽  
Stress Concentration ◽  
Oil And Gas ◽  
Magnetic Measurements ◽  
Magnetic Domain ◽  
Residual Magnetization ◽  
Magnetic Memory ◽  
Buried Pipe ◽  
Destructive Testing ◽  
Primary Means

Abstract Pipelines are the primary means of land transportation of oil and gas globally, and pipeline integrity is, therefore, of high importance. Failures in pipelines may occur due to internal and external stresses that produce stress concentration zones, which may cause failure by stress corrosion cracking. Early detection of stress concentration zones could facilitate the identification of potential failure sites. Conventional non-destructive testing (NDT) methods, such as magnetic flux leakage, have been used to detect defects in pipelines; however, these methods cannot be effectively used to detect zones of stress concentration. In addition, these methods require direct contact, with access to the buried pipe. Metal magnetic memory (MMM) is an emerging technology, which has the potential to characterize the stress state of underground pipelines from above ground. The present paper describes magnetic measurements performed on steel components, such as bars and tubes, which have undergone changing stress conditions. It was observed that plastic deformation resulted in the modification of measured residual magnetization in steels. In addition, an exponential decrease in signal with the distance of the sensor from the sample was observed. Results are attributed to changes in the local magnetic domain structure in the presence of stress but in the absence of an applied field.

scholarly journals Research on Internal Force Detection Method of Steel Bar in Elastic and Yielding Stage Based on Metal Magnetic Memory

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1167 ◽  
Author(s):  
Caoyuan Pang ◽  
Jianting Zhou ◽  
Ruiqiang Zhao ◽  
Hu Ma ◽  
Yi Zhou
Keyword(s):  
Tensile Force ◽  
Extreme Points ◽  
Internal Force ◽  
Axial Position ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Destructive Testing ◽  
Force Detection ◽  
Steel Bar ◽  
Tensile Forces

Based on the metal magnetic memory effect, this paper proposed a new non-destructive testing method for the internal tensile force detection of steel bars by analyzing the self-magnetic flux leakage (SMFL) signals. The variation of the SMFL signal of the steel bar with the tensile force indicates that the curve of the SMFL signal has a significant extreme point when the tensile force reaches about 65% of the yield tension, of which the first derivative curve has extreme points in the elastic and yielding stages, respectively. To study the variation of SMFL signal with the axial position of the steel bar under different tensile forces, a parameter reflecting the fluctuation of the SMFL signal along the steel bar is proposed. The linear relationship between this parameter and the tensile force can be used to quantitatively calculate the tensile force of steel bar. The method in this paper provides significant application prospects for the internal force detection of steel bar in the actual engineering.

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