Reconstruction of the Distribution of Eigenstrains and Residual Stresses across the Cross-Section of the Beam by the Cutting Method

The application of the cutting method is demonstrated for assessing the through‑thickness distribution of residual stresses in a linear element cut from a metallic structure with continuously distributed eigenstrains in cases where etching, hole‑drilling, and X‑ray diffraction provide only limited information. The investigated specimens were: a 250 × 25 × 10-mm beam made of an aluminum–magnesium alloy, one narrow face of which was subjected to localized point pressure; a 150 × 25 × 10-mm rib of austenitic stainless steel built up by wire‑arc deposition; and a 14-mm-thick low‑alloy sheet steel with a bainite–pearlite microstructure subjected to gradient thermomechanical treatment. The method used was as follows. A beam was cut out from the workpiece and 1-mm‑thick strips were machined by electro‑discharge cutting normal to the coordinate along which the membrane (in‑plane) component of the residual stresses was nonuniformly distributed. The strips’ deflections were then measured and, from these data, the distribution of the target residual stress component and the incompatible part of the eigenstrains producing those residual stresses were reconstructed using relations previously derived by the authors. In all the investigated cases, the method showed a sufficiently good resolvability and revealed technologically important differences in the distributions of residual stresses along the height of the rib built up by wire-arc surfacing with layer-by-layer forging and without it as well as along the thickness of the sheet subjected to one-sided rapid cooling with plastic bending in one direction or another and without bending. The method does not require specialized laboratory equipment, and the cutting procedure minimally affects the material; internal strips were cut symmetrically from both sides. Surface residual stress values obtained by the hole‑drilling method were used as supplementary data.