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7240 |
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Friday, May 06, 2022, Hall K2 3:00 PM Process Diagnostics, Sensors & Controls |
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Investigation on laser cladding process using high-resolution in-line atomic emission spectroscopy |
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Malte Schmidt / Jade University of Applied Sciences, Germany Sven Gorny / Department of Engineering Sciences, Jade University of Applied Sciences, Germany Nick Rüssmeier/ Department of Engineering Sciences, Jade University of Applied Sciences, Germany M. Schmidt*/ Jade University of Applied Sciences, Germany |
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Process monitoring and control methods during direct metal deposition process (DMD) are used to ensure a consistent manufacturing quality of the process. Using spectrometers wavelength selective optical process emissions can be observed. Within these emission signals specific element lines can be detected and identified. However, DMD processes are in the heat conduction regime broad thermal spectral emissions dominate the signal. Object of our work is to investigate the temporal occurrence, incidence and peak intensity of specific element lines. Therefore, DMD experiments are observed using a high-resolution spectrograph with CCD-camera (resolution = approx. 50 pm FWHM @ 450 nm) and a medium resolution spectrometer (resolution = 0.73 nm FWHM) simultaneously with a bifurcated optical fibre. A parameter study varying laser power, scan velocity and powder feed rate has been made generating single tracks. This study was made using Co-Cr-based (MetcoClad21) and AISI Type 316L Stainless Steel powder on 1.1730 substrate material. Series of spectra have been detected for all sets of parameters with a rate of 100 Hz. Every individual spectrum has been analysed and sorted by an algorithm into two types. Type A spectra showed measurable element emission lines and Type B spectra showed only thermal radiation. The investigation showed that the relative number of Type A spectra with respect to the total amount of spectra is strongly correlated to the process parameters. Moreover, specific element lines contained in type A spectra could have been identified using an Atomic Spectra Database. Element identification was additionally verified by a more detailed spectra provided by the high-resolution spectrograph with CCD-camera. All detected and identified lines occurred to be non-ionised elements. Especially Cr I lines were frequently observed. This might be a suitable in-line monitoring technology in future for weld track quality control. |