Non-destructive evaluation of the micro residual stresses of IIIrd order by using micro magnetic methods

• A new method to detect of micro-residual stresses of IIIrd order is presented.
• That non-destructive method is based micro-magnetics.
• The micro-residual stresses of IIIrd order surround Cu nanoparticles.

Nanoscale coherent precipitates and the corresponding micro residual stresses play a dominant role in the strengthening process of materials. At present, there exists no experimental method for measuring micro residual stresses of IIIrd kind non-destructively. In the frame of the present work, it will be shown that micro-magnetic measurement techniques based on the tensile loading dependent maximum Barkhausen noise amplitude can be used for the analysis of micro residual stresses (MRS) of IIIrd kind (coherency residual stresses). For this purpose, Fe–Cu-alloys with well-defined contents of Cu-precipitates were produced and investigated.