Advanced Friction Stir Processing for Ultra-refined Microstructure Development of Aluminum 7XXX Series Alloys

Friction Stir Processing (FSP) has been demonstrated to generate refined microstructures, resulting in improved material properties. This has several areas of application. First, FSP can enhance the formability of the particular alloy of interest. This is especially important for the superplastic forming process, where the use of FSP can be used to create superplastic behavior at high strain rates from standard alloys, that otherwise would not exhibit such behavior. This allows for significantly lower material cost. This can allow more standard alloys and thicker material to be used in the superplastic forming process. Furthermore, this can enable the superplastic forming process to be used in a larger range of applications, allowing its benefits (unitization or part count reduction, potential weight reduction, and lower cost) to be realized. Other areas where FSP can be used to modify properties and achieve significant benefit are the processing of castings and local addition of stiffening phases. Local processing can be performed to locally improve material properties to improve overall part performance (e.g. fatigue life, stiffness), reduce costs, and potentially reduce weight. This project will investigate commercial and technical feasibility to understand how FSP can be used in aerospace structures to reduce cost and weight.