Material and Process Development for Metal 3D Printing Aerospace Structures and Parts

Abstract

Metal 3D printing technologies have been advancing rapidly in the past few decades. The advantage of creating complex geometry, once impossible, accelerated the development of this type of manufacturing. With the development of such technologies, Selective Laser Melting (SLM) technology has an advantage over other types of metal printing as it requires less post-processing, reduces costs, and has enhanced structural quality. This technology consists of depositing powdered material into a movable bed on its vertical axis and a scanning laser sinters this material layer by layer as it is deposited. The efficiency of this procedure depends on several factors, to name a few: laser power, printing direction, hatch distance, layer thickness, and scanning velocity.

This work brings a Design of Experiment (DOE) approach considering some of the parameters mentioned above. Once a DOE was developed the specimens were manufactured. With the specimens in hand, it was possible to test them using ASTM standards for Additive Manufacturing of powder metallurgy. The tensile test ASTM standard followed was B925 and procedures were followed from ASTM E8/E8M. Hardness tests utilizing the E18-20 standard also took place following recommendations of the B925 standard. The entire procedure from choosing the DOE parameters to discussing the test results is exposed in this thesis. With the results of the material properties in hand, it was possible to generate a printing procedure and estimate of mechanical properties for aerospace applications such as regenerative rocket engines.