Effects of process parameters, debinding and sintering on the microstructure of 316L stainless steel produced by binder jetting

Binder Jetting is becoming increasingly important in the scenario of metal Additive Manufacturing processes due to the absence of rapid melting and solidification steps that can induce defects in most sensitive alloys and lead to unwanted reactions. However, this technology requires to consider the effects of different factors such as powder packing, wettability with the binder and sinterability to define suitable process parameters and to achieve desirable material properties. Although several research works focus on individual aspects of Binder Jetting and sintering of parts, a comprehensive understanding of material evolution under different processing conditions has not been achieved yet. The present research explores the effects of different process and thermal parameters on the porosity and mechanical properties of binder jetted 316L samples. The effect of layer thickness and binder saturation, considering the powder bed features, and debinding and sintering atmospheres, referring to the post-processing stages, were investigated at the green and sintered stages via microstructural and compositional analysis and mechanical characterization. Thermal treatments simulations were employed to determine the microstructural evolution during sintering. The 316L steel produced in this work by Binder Jetting exhibited a fine equiaxed microstructure, tensile strength values comparable to those of cast products and superior ductility compared to other additive techniques.