Developing Cost-Effective Indirect Manufacturing of H13 Steel from Extrusion-Printing to Post-Processing

Material-extrusion additive manufacturing of composite parts consisting of solid metallic powder and molten polymer enables indirect fabricating metallic components through subsequent debinding and sintering. This multi-step process offers the advantages of low cost, high efficiency, and safety, which is flexible and friendly for small or medium size enterprises and individual studios. Here is an entire cost-effective route of fabricating H13 steel parts with highly-filled feedstocks consisting of 60 vol% powders. The printing defects of large tunneling were optimized to a small amount of weak bonding of interlayers. Two-step (solvent and thermal) debinding followed by sintering allows for producing high-quality H13 parts with a relative density of 96.8 %. In the optimal sample, the distributions of the micropores and duplex microstructure (ferrite and martensite) are isotropic with no elemental segregation. The ultimate tensile strength and elongation after fracture are 1388 ± 27 MPa and 1.94 ± 0.05 %, respectively. Incomplete or no solvent debinding in the workflow led to macro defects or even sample collapse. Particular focus was placed on the solvent-debinding behavior of different samples. For the as-built parts with different shapes and open porosities, the complete solvent debinding time varied from ∼ 96 h to ∼ 2 h, which is determined by the specific surface area. The classic kinetic model is applicable to estimate the solvent-debinding behavior of the samples with open porosity less than ∼ 0.5 %. These findings provide insights into critical processes for optimizing indirect additive manufacturing of metal parts, offering an alternative method for producing isotropic, low dislocation-density metallic parts by solid-state sintering.