Micro-magnetic evaluation of micro residual stresses of the 2nd and 3rd order

Micro residual stresses (MRS) of the 2nd and 3rd order play an important role in the fracture mechanical analysis of thermally-cycled materials and thus in lifetime analysis of such components. In multi-phase materials there can exist two kinds of MRS: Thermally-induced MRS of the 2nd order and coherent MRS of 3rd order. The first appear when individual material phases exhibit different thermal expansion coefficients and the second occur when the lattice parameters 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 and separation of MRS of 2nd and 3rd order in iron-based materials.