Modelling of residual stresses and distortions of the wall on a substrate built by wire-arc surfacing

To study the arising of technological distortions and residual stresses in structures created by wire-arc surfacing, it is proposed to consider a wall consisting of ten layers deposited on a substrate. A wall is deposited with and without layer-by-layer forging on a fixed steel plate with AISI 308 LSi austenitic stainless steel wire and the deflection of a released wall on the substrate is measured. As for numerical modelling, the process was presented as successively solved problems: a) thermal — surfacing of ten layers of material, b) elastic-plastic — formation of eigenstrains and residual stresses due to cooling of the created structure with nonuniformly distributed temperature, c) thermo-elastic-plastic — forging of the workpiece with a pneumatic tool at elevated temperature (this stage may be excluded) and d) elastic-plastic — the structure distortion and changes in the field of residual stresses when the structure is released. Problems (a), (b), (d) were solved in the COMSOL Multiphysics software package, (c) — in LS-DYNA. It is established that tensile residual stresses are formed in the deposited wall near its upper face, and the forging of this face is accompanied by a decrease in longitudinal strains, distortion of the released specimen and inhomogeneity of the distribution of residual stresses by the wall height. The calculated deflection values correspond to our experimental data and the results of Cranfield University for the IN718 austenitic alloy. A rod-beam model of the built-up multilayer wall was developed, the results of the application of which correspond to numerical calculations.