Micro-magnetic evaluation of micro residual stresses of the Ilnd and IIIrd order

摘要

Micro residual stresses (MRS) of the IInd and IHrd order 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 IInd order and coherent MRS of IIIrd order. The thermally induced stresses of the IInd order appear when individual material phases exhibit different thermal expansion coefficients. The coherent MRS of the IIIrd order appear when the lattice parameter of the second phase particles 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 IInd and IIIrd order in iron-based materials.