Caution to Apply Magnetic Barkhausen Noise Method to Nondestructive Evaluation of Plastic Deformation in Some Ferromagnetic Materials

Manru He,Zhenmao Chen,Takanori Matsumoto,Hongen Chen,Tetsuya Uchimoto,Shejuan Xie,Toshiyuki Takagi

doi:10.1186/s10033-019-0420-0

Abstract

Magnetic Barkhausen Noise (MBN) method is known as an effective nondestructive evaluation (NDE) method for evaluation of residual stress in ferromagnetic materials. Some studies on the feasibility of the MBN method for NDE of residual strains were also conducted and found applicable. However, these studies are mainly focused on the state of residual strains which were introduced through a one-cycle-loading process. In practice, however, structures may suffer from an unpredictable and complicated loading history, i.e., the final state of plastic strain may be induced by several times of large loads. Whether the loading history has influences on MBN signals or not is of great importance for the practical application of the MBN method. In this paper, several ferromagnetic specimens with the same final state of residual strain but of different loading history were fabricated and inspected by using a MBN testing system. The experimental results reveal that the loading history has a significant influence on the detected MBN signals especially for a residual strain in range less than 1%, which doubts the feasibility to apply the MBN method simply in the practical environment. In addition, micro-observations on the magnetic domain structures of the plastic damaged specimens were also carried out to clarify the influence mechanism of loading history on the MBN signals.

Highlights

Non-destructive evaluation (NDE) is an important and synthetical technology to ensure the integrity of modern critical structural systems [1,2,3]
The results reveal that if the first residual plastic strain is less than 1%, the deformation history has clear influence on the detected Magnetic Barkhausen Noise (MBN) signals even the final residual strain is of a relative large value
While if the first residual plastic strain is over 1%, the plastic deformation history only has limited effect on the MBN signals

Summary

Introduction

Non-destructive evaluation (NDE) is an important and synthetical technology to ensure the integrity of modern critical structural systems [1,2,3]. Magnetic Barkhausen Noise (MBN) method is one of the important NDE methods for evaluation of residual stress in ferromagnetic materials [4,5,6,7,8,9,10]. Stefanita et al [15] investigated the different effect of elastic and plastic deformation on the MBN. MBN measurements were conducted for specimens with plastic strains of different loading. The correlation of the loading history and the corresponding MBN signals was investigated via a MBN testing system developed by authors. Magnetic powderpattern observations were carried out to investigate the reason why MBN signals is influenced by the loading history. A discussion is given based on the observed magnetic domain structures to explain the influence mechanism from micro defect point of view

Methods

Results

Conclusion