• Agiwal, Hemant

Abstract

<jats:title>Abstract</jats:title><jats:p>The objective of this work is to study friction surfacing process variability, hence future control requirements, when depositing multilayered coatings. This is motivated by the need to control deposition quality when depositing multiple friction surfacing layers, whether for repair, remanufacturing, or new part creation using this solid-state metal additive manufacturing process. In this study, 10-mm-diameter 304L stainless steel rods were used to create up to five layers of 40-mm-long deposits on 304L substrates using a constant set of processing parameters. In-process measurement of forces (X, Y, Z), flash temperature, flash geometry, layer temperature as well as post-process measurement of layer geometry, microhardness, and microstructure are used to characterize changes in the friction surfacing process as more layers are deposited. It was observed that with increasing layers: layer thickness and deposition efficiency decrease; process instabilities, offsetting of the deposition towards the retreating side, and temperature in the deposited layer increase; and flash temperature does not change. Frequency content in the force data contains information that can be used to monitor process stability. It is concluded that the friction stir process parameters need to be adjusted even after the second or third layer is deposited, corrections to the tool path are required after a couple of layers, and that frequency content in the measured process forces as well as deposited layer temperature may be useful to monitor and control the process.</jats:p>

Topics

• Deposition
• impedance spectroscopy
• microstructure
• stainless steel
• additive manufacturing