| Abstract Scope |
Laser welding of aluminum under vacuum or an inert gas atmosphere requires an enclosed chamber with laser transparent windows. Such chambers enable both final seal welds for controlled atmosphere hardware and realistic space welding simulations. However, the altered pressure environment from vacuum pumping and pressure spikes from vaporization produces unexpected changes in weld physics that must be studied. To address these needs, we developed two scalable vacuum chamber laser welding rigs, a smaller one for spot wobble welds on purge tube seals, and a larger chamber for linear welds.
The smaller chamber was used to develop spot wobble laser welds on purge tubes, which are typically sealed using an arc weld. These final seals do an excellent job of containing a controlled atmosphere, but the high heat input, large weld size, and limited re-usability of traditional arc welds can be improved with laser welding. In our experiments, this chamber enabled laser welds that surpassed conventional arc welds in heat input, bead size, and potential for reuse. However, process control must be altered to address shock from laser welds.
The larger chamber utilizes a 125mm window for linear welds, and offers a versatile testbed for realistic space welding scenarios, specifically for aluminum welds in lunar conditions. Laser welding in space is an active research space, but the effect that lunar regolith has on aluminum weld quality is unknown. We used various simulated lunar and Martian regolith samples to emulate these environments and determine the effect of extraterrestrial soil on aluminum weld quality, morphology, and cracking behavior. The weld setup, experiments, and analysis will be discussed. Overall, this platform establishes a foundation for further investigations into laser welding under extraterrestrial environment constraints necessary for future lunar and Martian habitats. |