Laser-based Additive Manufacturing of Lightweight Metal Alloys

Abstract

Additive manufacturing is becoming more popular in the aerospace industry due to its efficiency and relatively low cost. However, laser-based methods that are often used for metals cause phase transitions, which in turn lead to residual stresses, defects, and worsened material properties. This issue is problematic because aerospace components must have the mechanical and thermal properties required to survive launch and harsh space environments. Some of the main materials used in aerospace components are aluminum and titanium alloys, and the powders of these metals are more prone to oxidation than steel powders, which are more commonly used for additive manufacturing. Among aluminum alloys, those with increased silicon content are often easier to process, but this improvement comes at the expense of favorable mechanical properties. This senior thesis aims to create an additive manufacturing system for lightweight metal alloys, specifically aluminum alloys. The proposed design deposits the powder needed for each layer, uses a laser to fuse the powders in the required configuration, lowers the build plate in small increments, and repeats these steps until all the layers are manufactured. With this system, it will be possible to control different parameters, such as laser power and scan speed, to determine how the process can be modified to obtain desired material properties. These properties, including microstructure, porosity, and mechanical properties, can be analyzed using microscopy and tensile testing to find the optimal process parameters for different metal alloys. Circumstances caused by the COVID-19 pandemic halted manufacturing and testing of the system, however the design is complete and all parts and materials have been identified and purchased. The next steps required to complete the manufacturing, assembly, and testing of the system are reported to ensure that the project can continue smoothly next year.