Investigations on residual stresses and deformations in selective laser melting

For establishing Selective Laser Melting (SLM) in production technology, an extensive knowledge about the transient physical effects during the manufacturing process is mandatory. In this regard, a high process stability for various alloys, e.g. tool steel 1.2709 (X3NiCoMoTi 18-9-5), is realisable, if approaches for the virtual qualification of adequate process parameters by means of a numerical simulation based on the finite element analysis (FEA) are developed. Furthermore, specific methods to evaluate and quantify the resulting residual stresses and deformations due to the temperature gradient mechanism (TGM) are required. Hence, the presented work contains particular approaches using the FEA for the simulation of transient physical effects within the additive layer manufacturing (ALM) process. The investigations focus on coupled thermo-mechanical models incorporating specific boundary conditions and temperature dependant material properties to identify the heat impact on residual stresses and deformations. In order to evaluate the structural effects and simultaneously validate the simulation, analysis on residual stresses based on the neutron diffractometry as well as considerations concerning part deformations are presented.