Investigation of Short Pulse Nd:YAG Laser Interaction with Stainless Steel Powder Beds

Abstract

The development of metallic object construction has occurred at quite a pace over the last five years with provision of many commercial techniques such as indirect and direct sintering of metal powder beds. Although porosity is still a major problem for metal building a number of notable solutions have been proposed, these include infiltration with low melting point alloys or direct fusing with binary powder mixtures. Neither of these solutions allows one to build components without compromising part strength and functionality. A process route is required that will allow solid parts to be built from a single powder component without requiring time consuming downstream processes. To this end, the present work examines the feasibility of using low energy high peak power laser pulses from a Q-switched Nd: YAG laser to melt stainless steel powder fractions whilst examining the melt displacement through high recoil pressures induced by rapid partial vaporisation of the powder layer. The effect of laser pulse energy laser beam intensity, pulse frequency, and environmental gas control on the integrity of the fused powder layer is presented.