Tool Material Design for Friction Stir Welding of High Strength Materials

Friction stir welding (FSW) has a distinct advantage over these other traditional fusion welding techniques as it involves no melting and solidification of weld plate. In addition, the economic advantage of using FSW has been established for welding of low melting point, Al and Mg alloys. However, tool material development has been the major limitation for the application of friction stir welding (FSW) or processing on high melting point alloys such as Ni-based alloys and titanium alloys over the past decade. During friction stir welding of these high melting point materials, weld temperatures can exceed 1000⁰C, so the tool material needs to be strong enough to sustain wear and deformation at elevated temperatures for long periods of time. The major drawbacks of currently available tool materials are insufficient high temperature strength, short tool life time and expensive tooling cost. Therefore, it is of great industrial interest to develop a new cost-effective tool material with the required high temperature strength and lasting tool life time.nbsp;In this SBIR program, QuesTek Innovations LLC and University of North Texas (UNT) propose to design a cermet-type tool material with high entropy alloys (HEAs) as the binder phase, by combining Integrated Computational Materials Engineering (ICME) and efficient experimental processing approaches. QuesTek will apply the ICME approach to computationally design and optimize the ceramic-binder tool material (composition and processing) and UNT will process and test the material with their expertise in Spark Plasma Sintering (SPS) techniques and processing FSW tool materials. The final goal of this program is to design a suitable tool material for FSW on high strength Ni-based superalloys such as Inconel 718 or Haynes 230 alloy of interest to NASA.