August 1, 2011.
Ferromagnetic metals, also known as ferrous metals, consist of small magnetic regions called domains that are separated from one another by boundaries called domain walls. Magnetic domain walls in ferrous metals are pinned by fatigue-induced microscopic defects. These pinned domain walls resist re-orientation due by imposed magnetic fields. When a magnetic field of sufficient magnitude is applied to the ferrous metal, the domain walls overcome pinning and spontaneously orient themselves with the magnetizing field. This release of potential energy produces Barkhausen noise that can be detected magnetically or acoustically. Attempts were made to develop a nondestructive method that applies Barkhausen noise analysis to predict the life expectancy of steel components in nuclear power plants. An instrument called the Rollscan 300 and Microscan 600 software were used to acquire Barkhausen noise data from fatigued steel samples. MATLAB software was used to evaluate results of the Microscan 600 software to better understand the signal processing algorithms. During this research internship staff in the Applied Physics Group produced MATLAB scripts to corroborate Microscan 600 data. PNNL-SA-82069.
Pacific Northwest National Laboratory (PNNL)
This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation.