Effect of post-printing annealing on the tensile behavior of stainless-steel wire mesh–reinforced PLA composites fabricated using material extrusion

This study investigates the optimization of annealing parameters to enhance the mechanical performance of stainless-steel wire mesh (SSWM)-reinforced polylactic acid (PLA) composite fabricated via material extrusion (MEX), commonly known as fused deposition modeling (FDM). The primary objective was to identify an optimal thermal post-processing window that can improve tensile properties while maintaining structural integrity of the metal–polymer composite. A full factorial design of experiment was employed to systematically evaluate the effects of annealing temperature (70°C–110°C) and holding time (20–60 min) on tensile strength, tensile modulus, and elongation at break. ANOVA was used to determine the most influential parameters affecting the tensile properties. The results indicated that post-printing annealing significantly influences the mechanical performance of the developed composites. The annealing temperature of 90°C and holding time of 40 min was identified as the best-performing condition within the investigated range of chosen parameters. Moderate annealing improved tensile strength and modulus, while excessive annealing temperature reduced ductility due to structural changes in the PLA matrix. The change in the properties of the composite observed after post-printing annealing is mainly attributed to residual stress relaxation, improved interlayer bonding, and thermally induced structural reorganization of the polymer matrix. The findings also demonstrated that controlled annealing could enhance load transfer in metal–polymer structures fabricated via MEX.