Particle Size Influence Upon Sintered Induced Strains Within 3DP� Stainless Steel Components

Johnston, Scott
Anderson, Rhonda
Storti, Duane
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Three-dimensional printing (3DP™ 1 ) is a layer-by-layer manufacturing process whereby a three-dimensional (3D) component is created by the distribution of a liquid binder onto a powder media. A 3DP™ process using stainless steel powder as its printing media requires post-printing thermal processing for debinding and sintering of the printed green component. To minimize dimensional distortion while increasing structural integrity of the green component, 3DP™ thermal post-processing is designed to produce only neck growth between particles, defined as initial stage sintering. The accepted theoretical model governing initial stage sintering strain for spherical powder particles provides a qualitative account of strain development with respect to time and temperature variance; however, the model does not produce an accurate quantitative account for the magnitude of the strain when compared to dimensional experimental results. The theoretical model indicates that powder particle size is the dominant parameter governing sintering strain. The purpose of this study is to introduce an effective particle size into the theoretical model, thus enabling the application of the theoretical model to estimate dimensional change for components produced by 3DP™. Dimensional sintering experimentation has been performed using 3DP™ test specimens with spherical powder particles having mean diameters of 20 Pm, 80 Pm, and 200 Pm. Experimental results and progress on the theoretical model are discussed.