Bonding Characteristics of Additive Friction Stir Deposition

Additive friction stir deposition relies on local forging of solid feed stock to create a deposition that is bonded to a substrate. Layer by layer this solid-state, metal additive process can deposit higher volumes of metal than any fusion based processes currently available. While the process is near-net-shape rather than a net-shape process like some powder metal deposition methods, properties of additive friction stir deposition are deposited as fully consolidated forged product. Bonding of this solid-state additive process is dependent on temperature, pressure, and material properties; however, little has been reported of how temperature may influence the overall bonding characteristics of each layer. The focus of this work is to present the influence of temperature in additive friction stir deposition on bonding characteristics. Temperature for this study was monitored and controlled using a closed-loop temperature control system that could maintain deposition temperature to within +/- 5 degrees Celsius. Evaluating variation in layer temperatures provided a means for determining the bonding relationship of temperature to bonding characteristics of additive friction stir deposition.