Effects of Inter-Layer Dwell Parameters on Hardness Profiles in Thin Wall Mild Steel WAAM
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Bernhardt, Lila J.
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Abstract
Wire arc additive manufacturing (WAAM) is an emerging technology, and as such the ideal parameter sets for various metals, structures, and applications are still in development. This study examines the inter-layer dwell parameter, which determines how long a deposited layer is left to solidify before the next layer is deposited. The solidification time, interpass temperature reached, and reheating cycles due to subsequent layer depositions directly impact the geometry and material properties of the final structure. A literature review has shown that both the dwell parameters of a constant inter-layer dwell time and of a constant interpass temperature are frequently used in WAAM applications throughout various structures and materials. This study directly compares the two methods of dwell by implementing an in-situ forward looking infrared camera to monitor the inter-layer temperature during depositions. Two sets of experiments were conducted: one set which varied the constant interlayer dwell time between 10 seconds to two minutes, and one set which varied the interpass temperature from 500 °C to 150 °C. Rockwell B Hardness tests were then taken on all wall samples, and geometry was measured. This allowed for direct comparison between the two dwell methods and the relationship between interlayer dwell parameter and resultant hardness, geometry, and total deposition time to be considered. The findings of this study indicate that there is a threshold in interpass parameter control where the improvements to final properties may not be justified by the increase to total deposition time. This is emblematic when comparing the one- and two-minute constant interlayer dwell time samples where the width decrease was 5.4%, average hardness value increase was 0.6 HRB, and increase in total deposition time was 70%.
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2024-04-29
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