Experimental and theoretical analysis of metal magnetic memory signals in the stress concentration area of 45# steel under tensile testing

2014 ◽  
Vol 46 (1) ◽  
pp. 271-280 ◽  
Author(s):  
Hao Su ◽  
Ming Chen
Keyword(s):  
Stress Concentration ◽  
Theoretical Analysis ◽  
Tensile Testing ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Memory Signals

Correlation between Magnetic Memory Signals and Mechanical Properties of 35CrMo Tempered and Quenched Steel

2015 ◽  
Vol 750 ◽  
pp. 186-191
Author(s):  
Peng Ju Guo ◽  
Xue Dong Chen ◽  
Wei He Guan ◽  
Hai Jiang Zhao
Keyword(s):  
Stress Concentration ◽  
Vickers Hardness ◽  
Tensile Testing ◽  
Magnetic Memory ◽  
Cross Point ◽  
35Crmo Steel ◽  
Quenched Steel ◽  
Memory Signals ◽  
Sudden Decrease ◽  
The Relationship

Magnetic memory signals and hardness of 35CrMo tempered and quenched steel were acquired during tensile testing. The magnetic signals of 35CrMo steel increased monotonously with the increase of tensile stress before yielding, followed by sudden decrease with further increase of stress after yielding. The zero-cross point ofHp(y) varied during tensile testing, indicating varied position of stress concentration zones with the process of tensile testing. Vickers hardness of the stress concentration zones of 35CrMo steel was lower than that around it, which may be attributed to the residual stress. The relationship between zero-cross point ofHp(y) and Vickers hardness was considered.

Effect of tensile stress on metal magnetic memory signals during on-line measurement in ferromagnetic steel

2021 ◽  
Vol 117 ◽  
pp. 102378
Author(s):  
Huipeng Wang ◽  
Lihong Dong ◽  
Haidou Wang ◽  
Guozheng Ma ◽  
Binshi Xu ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Line Measurement ◽  
On Line ◽  
Memory Signals ◽  
Ferromagnetic Steel

Metal Magnetic Memory Testing Technique for Typical Defects in Pressure Vessels and Pipelines

2015 ◽  
Author(s):  
Weihe Guan ◽  
Pengju Guo ◽  
Chen Xuedong
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Orientation Angle ◽  
High Sensitivity ◽  
Pressure Vessels ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Time Saving ◽  
Hydrogen Induced Cracking ◽  
Memory Signals

Metal magnetic memory technique has been extensively applied in different fields due to its unique advantages of time-saving, low cost, and high efficiency. However, very limited research has been carried out on studying the characteristics of metal magnetic memory signals of different defects except crack, and also the effect of orientation angle between testing direction and defect on magnetic memory signals. To promote study in this area, the magnetic memory signals of typical defects (such as crack, slag inclusion) are investigated as well as hydrogen-induced cracking. In addition, the characteristics of magnetic memory signals when measured with different angle between testing direction and defects were obtained. The results indicate that the metal magnetic memory technique is a promising method to detect typical defects of welding and also hydrogen-induced cracking. Moreover, the technique has high sensitivity on defects no matter the angle between testing direction and defect. However, further research is needed because it can only find the possible location of defects but cannot quantitatively describe the defect.

Eddy Current and Metal Magnetic Memory Testing Nondestructive Evaluation for Superficial Defects of Old Cylinder Barrel

2016 ◽  
Vol 850 ◽  
pp. 107-112
Author(s):  
Chang Liang Shi ◽  
Shi Yun Dong ◽  
Wei Xue Tang ◽  
Hao Zhan
Keyword(s):  
Stress Concentration ◽  
Eddy Current ◽  
Eddy Current Testing ◽  
Magnetic Memory ◽  
Memory Testing ◽  
Metal Magnetic Memory ◽  
Current Testing ◽  
Cylinder Barrel ◽  
Metal Magnetic Memory Testing

Eddy current testing and metal magnetic memory testing, cooperated with special testing devices, were applied to detect the superficial defects of old cylinder barrel. It was indicated that there were three types of the signals, which were non-defect signals, discontinuous peak signals and continuous peak signals. Non-defect signals indicated that there was no defect in cylinder barrel, and the discontinuous peak signals denoted that there was circumferential cracking, and the continuous peak signals showed that there was longitudinal cracking in the surface of cylinder barrel. The amplitude of eddy current testing signals characterizes the depth of cracking, and the gradient of magnetic signals descript the degree of stress concentration. The method mentioned above detects the cracking and stress concentration in the superficial coat of old cylinder barrel, which effectively guarantee the quality of automobile cylinder.

scholarly journals Diagnosis Model of Pipeline Cracks According to Metal Magnetic Memory Signals Based on Adaptive Genetic Algorithm and Support Vector Machine

2015 ◽  
Vol 9 (1) ◽  
pp. 1076-1080 ◽  
Author(s):  
Lihong Gong ◽  
Zhuxin Li ◽  
Zhen Zhang
Keyword(s):  
Support Vector Machine ◽  
Kernel Functions ◽  
Support Vector ◽  
Adaptive Genetic Algorithm ◽  
Magnetic Memory ◽  
Metal Magnetic Memory ◽  
Stress Concentrations ◽  
Rbf Kernel ◽  
Diagnosis Model ◽  
Memory Signals

Metal magnetic memory (MMM) signals can reflect stress concentration and cracks on the surface of ferromagnetic components, but the traditional criteria used to distinguish the locations of these stress concentrations and cracks are not sufficiently accurate. In this study, 22 indices were extracted from the original MMM signals, and the diagnosis results of 4 kernel functions of support vector machine (SVM) were compared. Of these 4, the radial basis function (RBF) kernel performed the best in the simulations, with a diagnostic accuracy of 94.03%. Using the principles of adaptive genetic algorithms (AGA), a combined AGA-SVM diagnosis model was created, resulting in an improvement in accuracy to 95.52%, using the same training and test sets as those used in the simulation of SVM with an RBF kernel. The results show that AGA-SVM can accurately distinguish stress concentrations and cracks from normal points, enabling them to be located more accurately.

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