Distortion prevention of axisymmetric parts during laser metal deposition

One of the main problem of large parts manufacturing using laser metal deposition (LMD) is the high residual distortion. Effects of layer-by-layer evolution of stresses and strains was studied by finite-element simulation. It was shown that distortion of axially symmetrical parts can be successfully predicted by the developed simulation procedure. Required dimensional accuracy of additively manufactured parts can be achieved by the optimization of deposited part size and shape in order to compensate volume shrinkage during layers solidification. The corresponding simulation procedure was developed and validated. Another major problem is prevention of distortion during deposition of thick flange on the surface of thin shell structures. In this case the following procedure was proposed and studied: on the first step spacer ring introduces in the shell, then deposition of the flange is carried out and on the last stage whole structure is heat treated in order to remove residual stresses.