Micro-Magnetic Evaluation of Micro-Residual Stresses of the IInd and IIIrd Orders

Micro-residual stresses (MRS) of the II nd and III rd orders play an important role in the fracture mechanical analysis of thermally-cycled materials and thus in lifetime analysis of such affected components. In multi-phase materials there can exist two kinds of MRS: thermally-induced MRS of the II nd order and coherent MRS of the III rd order. The first appear when individual material phases exhibit different thermal expansion coefficients and the second occur when the lattice parameter of the second phase particles which are embedded coherently in the matrix and the lattice parameter of the matrix are different. The main emphasis of the presented research work is the development of a micro-magnetic non-destructive technique for quantitative characterization of MRS of the II nd and III rd orders in iron-based materials. Forthat goal Fe-Cu-(Ni-Mn) samples were manufactured and characterized by means of a non-destructive procedure based on the tensile load dependence of the maximum Barkhausen noise amplitude.