Structure-property relationships of common aluminum weld alloys utilized as feedstock for GMAW-based 3-D metal printing

The relationship between microstructure and properties is not widely assessed in parts produced by additive manufacturing, particularly for aluminum. These relationships can be used by engineers to develop new materials, additive processes, and additively manufactured parts for a variety of applications. Thus, the tensile, compressive, and microstructural properties of common aluminum weld filler alloys (ER1100, ER4043, ER4943, ER4047, and ER5356) were evaluated following gas metal arc weld (GMAW)-based metal 3-D printing to identify optimal alloy systems for this type of additive manufacturing. The porosities in all test specimens were found to be less than 2%, with interdendritic shrinkage in 4000 series alloys vs. intergranular shrinkage in 5356. The 4000 series alloys performed better than 1100 and 5356 with respect to printed bead width, porosity, strength, and defect sensitivity. In comparison to standard wrought and weld alloys, the 3-D printed specimens exhibited similar or superior mechanical properties with only minor exceptions. Long print times allow for stress relieving and annealing that improved the print properties of the 4000 series and 5356 alloys. Overall the GMAW-based 3-D parts printed from aluminum alloys exhibited similar mechanical properties to those fabricated using more conventional processing techniques.