Abstract
This article elucidates the need to consider the inherent spatial transfer function (blur), of any thermographic instrument used to measure thermal fields. Infrared thermographic data were acquired from a modified, commercial, laser-based powder bed fusion printer. A validated methodology was used to correct for spatial transfer function errors in the measured thermal fields. The methodology was found to make a difference of 40% to the measured signal levels and a 174 °C difference to the calculated effective temperature. The spatial gradients in the processed thermal fields were found to increase significantly. These corrections make a significant difference to the accuracy of validation data for process and microstructure modeling. We demonstrate the need for consideration of image blur when quantifying the thermal fields in laser-based powder bed fusion in this work.
Highlights
IntroductionThermal imaging, or thermography, is an important and widely used tool in many
Thermal imaging, or thermography, is an important and widely used tool in manyAdditive Manufacturing (AM) processes [1]
We have shown that it is possible to overcome the low measurement resolution of a typical thermographic instrument and produce a more accurate temperature map than the camera can natively produce due to the inherent defects introduced by optics quantitatively described by the PSF
Summary
Thermal imaging, or thermography, is an important and widely used tool in many. Additive Manufacturing (AM) processes [1]. Spatiotemporally resolved thermal field measurements of the melt pool and Heat Affected Zone (HAZ) would be accessible. Full quantization of the surface temperature would improve our understanding of the complex phenomena occurring during deposition. A more accurate measurement of temperature would assist in the understanding of vaporization and liquation during the process and their role upon the formation of defects. The cooling rate dictates the solidification structure, and impacts the mechanical properties, the extent and nature of the anisotropy in mechanical properties, residual stresses, and component distortion. High-fidelity measurements are needed to verify and validate process modeling because the calculated thermal fields strongly influence microstructure and property predictions [2]
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