Tool Material Design for Friction Stir Welding of High Strength Materials

In the proposed Phase II SBIR program, QuesTek Innovations LLC will build off of the successful design framework developed in the Phase I effort to optimize, scale up, and commercialize a novel cermet tool material with enhanced high temperature properties to enable friction stir weld (FSW) processing of high melting point materials such as Ni-based alloys. Having demonstrated a robust proof-of-concept design in the Phase I, QuesTek will leverage its expertise in Integrated Computational Materials Engineering (ICME) and Materials by Designreg; approach to design and model binder phase properties, optimize processing pathways, and predict cermet performance to achieve longer tool life with more affordable tool materials. The development of such a tool material would significantly enhance NASArsquo;s efforts to implement fully friction stir-welded space exploration system elements (i.e. SLS, Orion and ground systems). The efforts here would be invaluable in advancing the solid-state welding technologies at NASA in conventional friction stir-welding (C-FSW), Hybrid-FSW, thermal stir welding (TSW) of high melting point materials.nbsp;nbsp;In the current proposed Phase II effort, QuesTek will further improve the designed cermet materials by focusing on aspects such as improving feedstock materials, optimizing ball-milling and sintering conditions, tuning the ratio of binder to ceramic phase in the cermet, and others which were not able to be evaluated in the short 6-month phase I program. Detailed microstructural characterization and mechanical properties evaluation and modeling will be carried out to validate achievement of all requisite performance objectives for the tool material.nbsp;The 2-year Phase II program will also aim at prototyping of larger sintered samples that would be utilized to fabricate actual FSW tool components. These fabricated tools will be used to perform initial FSW plunge tests on Ni-based superalloys to investigate the component fracture toughness.