Location

Brunswick, ME

Start Date

1-1-1997 12:00 AM

Description

Micromagnetic Barkhausen signals from magnetic material originate from the discontinuous motion of domain walls in the presence of a changing applied magnetic field. Barkhausen emissions that are detected by a surface coil as a voltage signal and come predominantly from a surface layer. The Barkhausen signal is affected by changes in material microstructure and the presence of residual stress since these affect the dynamics of domain wall motion. The selective attenuation on high frequency components of the Barkhausen signal due to eddy currents in electrically conducting materials is used to evaluate changes in material condition at different depths inside the component. Barkhausen measurements have been made on specimens subjected to different thermal exposure during surface conditioning procedures. Comparison has been made with X-ray diffraction results for assessment of residual stress, and microhardness measurements which evaluate the surface condition. The results show that the Barkhausen emissions can be utilized to evaluate changes in the surface condition of materials.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

16B

Chapter

Chapter 6: Material Properties

Section

Materials Characterization

Pages

1459-1462

DOI

10.1007/978-1-4615-5947-4_189

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Micromagnetic Changes in Steel Due to Surface Modification

Brunswick, ME

Micromagnetic Barkhausen signals from magnetic material originate from the discontinuous motion of domain walls in the presence of a changing applied magnetic field. Barkhausen emissions that are detected by a surface coil as a voltage signal and come predominantly from a surface layer. The Barkhausen signal is affected by changes in material microstructure and the presence of residual stress since these affect the dynamics of domain wall motion. The selective attenuation on high frequency components of the Barkhausen signal due to eddy currents in electrically conducting materials is used to evaluate changes in material condition at different depths inside the component. Barkhausen measurements have been made on specimens subjected to different thermal exposure during surface conditioning procedures. Comparison has been made with X-ray diffraction results for assessment of residual stress, and microhardness measurements which evaluate the surface condition. The results show that the Barkhausen emissions can be utilized to evaluate changes in the surface condition of materials.