Abstract
Control of the melt pool size is necessary to achieve more homogenous material properties in wire arc additive manufacturing (WAAM). The melt pool size can be measured by camera imaging or temperature field measurement. The paper aims to investigate the feasibility of using a high dynamic range two-colored pyrometric camera (Pyrocam) for melt pool size measurement in a gas metal arc welding–based WAAM process. A set of band-pass filters is identified using spectroscopy analysis to reduce the optical arc emission while the melt pool remains visible. The fusion line is identified in temperature field images, the melt pool size is measured by an automated algorithm, and the results are compared with high-speed camera images. A possible correlation between melt pool size and the grain size is examined.
Highlights
In recent years direct energy deposition (DED) processes have become more important in the industry
There seems to be no correlation between the melt pool dimension, that slowly grows over multiple oscillations, and the grain size that developed in homogenous size after one oscillation
It is shown that the evaluation of the melt pool dimension using both a high-speed camera and a high dynamic range two-colored pyrometric camera provide comparable results
Summary
In recent years direct energy deposition (DED) processes have become more important in the industry. A high dynamic range two-colored pyrometric camera shows promising potential as a comprehensive online monitoring tool. It measures a temperature field, and its vision channel enables the measurement of the bead geometry. It has been successfully applied in laser cladding [17] and laser gas metal arc hybrid welding [18]. The focus of this work is to prove the applicability of this camera as an online monitoring tool in a wire-based direct energy deposition process using GMAW as well as to investigate the influence of the melt pool size on the microstructure
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