Absorptivity measurements during laser powder bed fusion of pure copper with a 1 kW cw green laser. (March 2022)

• Record Type: Journal Article
• Authors: Nordet, G.; Gorny, C.; Mayi, Y.; Daligault, J.; Dal, M.; Effernelli, A.; Blanchet, E.; Coste, F.; Peyre, P.
• Is Part Of: Optics & laser technology. Volume 147(2022)
• Publication Date: 2022-03
• Subjects: Green laser -- Pure copper -- Powder bed fusion -- Single beads -- Absorption rate measure; Optics -- Periodicals; Lasers -- Periodicals; Electronic journals; 621.366
• DOI: 10.1016/j.optlastec.2021.107612
• Languages: English
• ISSNs: 0030-3992

Abstract

Highlights: Copper absorptance A evaluated using time-resolved reflectivity measurements. Absorptance change at green wavelength with material state: powder, liquid, keyhole. Experimental A values (powder-bed and keyhole) goodly compared to analytical models. Scatters on A values during a 2D powder bed surface scan was attributed to spatters. Abstract: A 1 kW CW green laser source operating at 515 nm was used to investigate the absorptivity of pure copper powder beds and pure copper substrates. Various interaction regimes were considered, ranging from the solid and/or powder layers, to the liquid state and up to the deep penetration keyhole regime. Reflectance measurements were carried out using an Ulbricht integrating sphere during static tests and single L-PBF tracks. For each experiment, absorptivity values were discussed using the real penetration depth observed on cross-section. Absorptivity values were found to be in relatively good agreement with analytical models of the powder bed and the keyhole regime absorptivity. Such results provide useful insight on the use of green wavelengths for the optimization of the L-PBF process on highly reflective and conductive materials like copper.