Porous materials additively manufactured at low energy: Single-layer manufacturing and characterization

Abstract

This paper presents an appropriate method to significantly reduce the pore size of high porosity porous stainless steel 316L structures fabricated by laser powder-bed fusion (LPBF) utilizing pulse wave emission (PW). PW deliberately avoids full-melt and applies low energy conditions to achieve single layer sintered porous material with controlled characteristics. Experimental approaches on a lab-scale setup equipped with a pulsed fiber laser system were developed to investigate the effect of laser scan settings. Properties of low-energy laser single sintered layers are studied experimentally, and the influence of laser power and pulse duration is discussed. A layer of sintered porous material was characterized in terms of the pore size, layer thickness, porosity and thermal conductivity. The results show that sintered porous layers can be fabricated by effectively connecting metal powder in the powder bed similar to a sintering process or partial melting. The porosity of fabricated structures was 51%–61% and the average pore radius ranged between 22 and 29 μm. We found that the thermal conductivity of a single powder particle is 31.5% of the sintered layer value and the thermal conductivity of the sintered layer is 4.8% of its solid material.

Keywords

• Additive manufacturing
• Laser powder-bed fusion
• Pulsed laser
• Sintering/melting
• Porous structure
• Thermal conductivity