Relaxation of residual stress in fused filament fabrication part with in- process laser heating

Fused filament fabrication (FFF) has become a preferred method for additive manufacturing due to its cost-effectiveness and flexibility. However, the parts built using FFF process suffer from lower mechanical strength compared to that fabricated using traditional method. In this work, an in-process laser heating method was presented to heal residual stress, therefore improve mechanical behavior along in-plane direction. The enhancement in tensile strength and elongation of fabricated samples with the utilization of laser heating have been demonstrated. In addition, models and hypothesis on the transformation of microstructure were proposed and verified by experimental data. With the utilization of laser predeposition heating, tensile strength of printed polyether ether keton (PEEK) part along in-plane direction increased by 11.4%, thus reached 93.5% that of the bulk material property. The fracture behavior was also altered from brittle to stretchable with visible necking effect, backed up with both tensile curve and scanning electron microscope images independently. (C) 2021 The Authors. Published by Elsevier B.V.