• Ritchie, David
• Nguyen, Vu

Abstract

In recent years there has been considerable progress in developing AM simulation capabilities aimed at process optimization, component qualification and process control. The amount of energy transferred to the part by the laser or electron beam is, of course, a critical factor. However, at least for selective laser melting (SLM), the published literature contains surprisingly little data on laser absorptivity that apply to the actual operating conditions.To address this gap, we report the results of a detailed investigation of the factors affecting laser absorption by Ti-6Al-4V during SLM. By calibrating melt pool CFD simulations against single track experiments conducted over a range of energy densities, we have been able to determine the intrinsic laser absorptivity of Ti-6Al-4V during SLM. Our simulations incorporate multiple laser reflections and cover the transition from conduction to keyhole mode. We also discuss physical mechanisms that may be responsible for an increase in the effective laser absorptivity at high energy density which is observed in this and other work.

Topics

• density
• impedance spectroscopy
• energy density
• experiment
• simulation
• melt
• selective laser melting