Effect of prestraining on Barkhausen noise vs. stress relation

Mild steel specimens were uniaxially strained in tension at strain levels v arying from 0.5 to 10% followed by X-ray diffraction residual stress and Ba rkhausen noise (BN) measurements. After this tension and compression loadin g was applied to the specimens. BN measurements were carried out during the whole reloading sequence. These measurements showed that prestrain increas ed the tensile stress value at which the BN saturated. The linear range of the stress vs. BN curve shifted towards the tensile stress range as a funct ion of prestrain. In the linear range the stress sensitivity remained uncha nged despite the prestrain. The obtained stress vs. BN relation was used in the residual stress measurements of a welded tube segment. The residual st ress values measured by the BN were compared to X-ray diffraction residual stress values. When the BN values were within the linear range of the stres s vs. BN curve, the BN residual stress values agreed quite well with the X- ray diffraction residual stress values. (C) 2001 Elsevier Science Ltd. All rights reserved.