Influence of Process Parameters on the Microstructure and Material Properties of Material Extruded (MEX) Three- Dimensional Steel Parts

Additive manufacturing of metal parts using the Material Extrusion (MEX) process is gaining popularity due to its better accessibility compared to powder bed fusion systems. During this process, a metal-polymer filament is extruded into a three-dimensional shape layer by layer, starting from a CAD model. This process implements traditional powder metallurgy manufacturing and applies it to additive manufacturing. In Metal MEX, a part is printed in the green state, washed to remove all of the polymer binder, and sintered to fuse the metal powder. Given the recent trends in the use of additively manufactured parts for end-use applications, more research needs to be done on the properties of the parts produced through the Metal MEX process, given its potential to print anisotropic parts. This study aimed to investigate the tensile strength and hardness of additive-manufactured steel with different infills and print orientations. Micro structure analysis was also performed to analyze the porosity and layer adhesion. To accomplish this, tensile bars were prepared, filled with a solid or triangular infill, and printed in the horizontal or vertical orientation. Tensile testing, hardness testing, and micro structure examination were performed on the specimens. The test results indicated that variations and porosities in the micro structure greatly impacted the tensile strength of the part. Still, the hardness of the material was not significantly affected by the porosity or print orientation.