The self-reacting friction stir welding (SR-FSW) method is extensively used in NASA’s current generation rocket, the Space Launch System (SLS). The initialization and termination of welds created by the SR-FSW process produce holes resulting from the removal of the weld tool assembly. These holes must subsequently be filled by the use of a separate process. These holes pose a mission-critical engineering challenge in the production of the SLS rocket. The current method for sealing the holes is the Friction Pull Plug Welding (FPPW) process, where a conical piece of material is spun and plunged into the remaining hole. The solid-state additive friction stir-deposition (AFS-D) process can create pull plugs with tailored microstructures that can increase the reliability of the current FPPW method.This work furthers the understanding of using AFS-D AA2219 material as a replacement for the material currently being used in the FPPW method. The impacts of this research are as follows:

1. The ability for NASA to predict the deformation response of AFS-D AA2219 material produced by any process parameter set intended for use in the SLS
2. An understanding of the effects of the AFS-D process on AFS-D AA2219, including deformation response, precipitation hardening effects, and cyclic material properties
3. An increased reliability in the plug/plate assembly because of more consistent properties between the base material and FPPW, enabling the SLS to fly. This is achieved through the creation and calibration of a micromechanical model that captures the effects of microstructure on the deformation response of AFS-D pull plugs as a function of the manufacturing process parameters. Ultimately, this work will provide the SLS engineering team with the necessary information to support a change in the FPPW process which will reduce the time of construction by mitigating the need for FPPW repairs.