Residual stress on AISI 300 sintered materials

Selective Laser Melting (SLM) is one of t he most interesting technologies in the rapid prototyping processes because it allows to build complex 3D geometries. Moreover, full density can be reached and mechanical properties are comparable to those of bulk materials. However, the most important drawback is related to the thermal transient encountered during solidification which generates highly variable residual thermal stresses. Parameters such as laser scanner strategy, laser velocity and power should be optimized also in order to minimize residual stresses that are strictly dependent on the manufacturing process and cannot be completely avoided. Geometry of parts should be optimized in order to keep residual stresses and distortions low. This paper presents a study on residual stress distribution on SLM rectangular plates built by means of a new scanning strategy, implemented by dividing the fused zone in very small square sectors. Residual stresses measurement on SLM samples are performed by means of the hole drilling technique. Specimens made of AISI Maraging 300 steel are investigated and the residual stress profiles are compared with those related to previous measurements on SLM disks coming from the same process parameters.