Reverse Engineering - Properties to Parameters for Friction Stir Welding

The development paradigm for solid-state welding processes like friction stir welding has traditionally employed creative use of tool geometries and materials, variations in rotational and linear velocities, and regulation of either the vertical engagement of the tool or the down force on the tool. More recently, improvements in control methodologies have enabled additional variation in process parameters, such as temperature and torque control as a means of varying weld parameters. Whether changing the rotational velocity of the spindle motor, the linear velocity of the tool, or the temperature setpoint of a weld, all these approaches rely on first making a weld and then characterizing the properties. Building on the recognition that properties are a function of parameters, the approach shown herein demonstrates a pathway from prescribed properties back to parameters that enables a reverse approach to selecting friction stir welding parameters. The focus of this work is in both 2xxx and 7xxx series aluminum alloys and defines an integrated computational material engineering (ICME) methodology to selecting weld parameters that achieve weld properties.