Additive Layer Manufacture of Tensile Tests Specimens in Stainless Steel 316L by Laser Consolidation

Laser Consolidation (LC) is an Additive Layer Manufacturing (ALM) process which produces net-shape fully dense metal parts. LC uses a synchronised pulsed Nd:YAG laser and a powder delivery unit to build parts which exhibit excellent mechanical properties and impact resistance. These properties may be tailored at build time by modifying build parameters but the non-coaxial nature of the LC head assembly causes direction dependant features. This paper investigates the mechanical properties and microstructure of AISI 316l parts built by LC. Tensile test specimens were constructed in different orientations and underwent tensile testing and SEM observation. All the specimens exhibited high elongation at break and Ultimate Tensile Strength (UTS) but parts properties were significantly affected by build direction. Parts built by relative head movement along the plane of LC head assembly (X direction) were more ductile and stronger compared with parts constructed orthogonally. SEM analysis revealed a higher presence of voids in the latter. It was speculated that the voids were the major factor in the reduction in strength and ductility of the parts.