Laser-based powder bed fusion additive manufacturing of pure copper

In this article, the laser-based powder bed fusion (L-PBF) processing behavior of pure copper powder is evaluated by employing a conventional infrared fiber laser with a wavelength of 1080 nm, a small focal spot diameter of 37.5 mu m, and power levels up to 500 W. It is shown that bulk solid copper parts with near full density (rho Archimedes = 99.3 +/- 0.2%, rho Optical = 99.8 +/- 0.1%) can be produced using a laser power of 500 W for the chosen combination of powder particle size, L-PBF settings, and pure copper baseplate. Moreover, at 500 W, parts with a relative density exceeding 99% are manufactured within a volumetric energy density window of 230-310 J/ mm3, while laser power levels below 500 W did not produce parts with a relative density above 99%. An analytical model is used to elucidate the L-PBF processing behavior, wherein both conduction and keyhole regimes corresponding to the employed L-PBF settings are identified. The analytical model-based results predict that the bulk solid copper parts with near full density are produced in a keyhole regime prior to the onset of keyhole-induced porosity, which is in accordance with the porosity types observed in the parts. The L-PBF fabricated copper parts exhibit an electrical conductivity of 94 +/- 1% compared to the international annealed copper standard (IACS) and demonstrate a tensile strength of 211 +/- 4 MPa, a yield strength of 122 +/- 1 MPa, and an elongation at break of 43 +/- 3% in the as-built condition.

Automated summary

This article evaluates the laser-based powder bed fusion (L-PBF) processing behavior of pure copper powder using a conventional infrared fiber laser, and identifies the key factors for producing solid copper parts with near full density.