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Recently, binder jetting additive manufacturing (BJAM) was used to manufacture complex metal parts in an economical and large-scale way. However, the usage of resin to bond metal powder renders as-printed green parts with low strength, which is potential to cause the structural damages of final parts during post treatments. To overcome the intractable problem, a self-developed binder mainly consisting of A-stage phenolic resin was explored for BJAM to achieve relatively high-strength as-printed green parts. The binder can be cured as a C-stage phenolic resin with 190 ℃ and then provide a high strength for the green parts. The effect of layer thickness and binder saturation on the strength, dimensional accuracy, and surface roughness of the BJAM-printed 316 L stainless-steel green samples using the developed binder was investigated systematically. With the optimized parameters (a layer thickness of 100 μm and a binder saturation of 30.2 %), green samples can possess the ultimate bending strength (UBS) of 10.08 MPa and the ultimate compressive strength (UCS) of 25.56 MPa, which are beneficial for the structural stability of the printed samples during subsequent treatments. A reduction in strength and an increase in roughness are observed with increasing the layer thickness for the as-printed green samples. An increment in binder saturation results in the improvement in strength and surface roughness of the green samples. The relationships between the binder and the mechanical performance of the green samples were discussed from the viewpoint of the uneven distribution of binder in depth. This work explored a promising binder with a low saturation for BJAM to fabricate 316 L green parts with desirable mechanical strength and acceptable surface roughness.

In this work, the effect of the pouring temperature of magnesium melt, the preheating temperature of the barrel of the screw mixer and the shear rate, on the solidified microstructures of semi-solid slurry was investigated by the mechanical stirring method. The appropriate processing parameters of slurry preparation were obtained. The mold filling for a thin-walled casting was examined. The results indicated that the solid volume fraction of non-dendritic structure increased with decrease in the pouring temperature of the magnesium melt and in the barrel preheating temperature of the screw mixer. Also, the grain size of the primary α-phase was reduced. Furthermore, the solid volume fraction of semi-solid non-dendritic structure decreased with increase in the shear rate. At the same time, the grain size of the primary α-phase changed slightly. A fine round granular solidified structure of 30–50 μm of prepared AZ91D magnesium semi-solid slurry was obtained. Finally, it was possible to successfully fabricate a 1.0 mm extremely thin-walled casting with a clear contour and good soundness.