Browsing by Subject "cooling rate"
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Item The Effect of Powder on Cooling Rate and Melt Pool Length Measurements Using In-Situ Thermographic Techniques(University of Texas at Austin, 2017) Heigel, J.C.; Lane, B.M.High-speed thermal cameras enable in situ measurement of the temperatures in and around melt pools generated during powder bed fusion processes. These measurements can be used to validate models, to monitor the process, and to understand the microstructure formed during the process. Unfortunately, pre-placed powder layers complicate the measurement due to spatter and irregular surfaces that impact emissivity. The objective of this work is to present high speed thermographic measurements of single and multiple scan tracks on substrates with and without pre-placed powder and to analyze and compare the impacts of powder on melt pool length and cooling rate measurements.Item Simulation of Cooling Rate Effects on Ti-48Al-2Cr-2Nb Crack Formation in Direct Laser Deposition(University of Texas at Austin, 2016) Yan, Lei; Li, Wei; Chen, Xueyang; Zhang, Yunlu; Newkirk, Joe; Liou, Frank; Dietrich, DavidTransient temperature history is vital in direct laser deposition (DLD) because it reveals the cooling rate at specific temperatures, which directly relates to phase transformation and types of microstructure formed in deposit. FEA simulation was employed to study the transient temperature history and cooling rate at different experimental setups in Ti-48Al-2Cr-2Nb DLD process. In this paper, an innovative model was described, which combines a moving Gaussian distribution heat source and element birth and death technology in ANSYS, help to analysis cooling rate control method and guide crack-free deposits build process.