Duplex stainless steel is an important alloy in various industrial settings such as, e.g., in water desalination. In this work, the standard duplex stainless steel UNS S32205 (EN 1.4462) was processed by Selective Laser Melting (SLM). Experiments were performed varying both laser power and focus position and resulting porosities were determined. A local optimum of parameters was found at a laser power of 304 W and a laser beam focus offset of 1.9 mm from the powder surface. For these parameters, an average porosity of 0.33 ± 0.30 percent was reached.
The SLM apparatus used operates with a pseudo-pulsed laser, meaning that, as in the application of a classical pulsed laser, in the present case the laser beam moves from spot to spot, thereby exposing successive small regions of the working surface to radiation. However, in the present case, the laser power remains constant between the successive spots (pulses), while in classical pulsed laser operation, the laser power is shut off between pulses. Motivation for the use of a pseudo-pulsed laser is the well-known fact that pulsed wave laser operation can distinctly improve performance of laser manufacturing methods when compared to operation without pulsing.