Effect of dual-laser powder bed fusion on surface quality, internal defects and properties of 316L stainless steel

Abstract

Dual-laser powder bed fusion has excellent potential in the preparation of high-performance components due to its ability to suppress defects and control properties during the formation. This paper investigates the effects of various remelting intervals and remelting laser power on the mechanical properties, internal defects, and surface quality of dual-laser powder bed fusion 316L. Compared to increasing laser power, shortening melting intervals offers a more effective compensation for energy losses resulting from the rapid cooling effects of LPBF. Higher surface quality (Ra = 5.876, Str = 0.633) and higher relative density (99.28 %) can be attained with a shorter remelting interval. However, due to excessive energy that increases porosity and grain size, the improvement in mechanical properties (667.19 MPa, 49.3 %) is less than long-interval remelting (703.55 MPa, 50.4 %). In comparison to vary remelting time interval at the high laser power, the depth of the melting pool can be controlled more precisely within a shorter interval by varying the laser power. However, the semi-melting of the spatter caused by applying a medium remelting laser power introduces new lack of fusion voids. This study highlights the advantages of dual-laser powder bed fusion in ensuring consistent formation and demonstrates its potential for producing customized microstructures and high-quality surfaces. Furthermore, it presents a novel approach for the dual-laser powder bed fusion of high refractive materials and room temperature brittleness materials.

Keywords

• Surface roughness
• Density
• Melt pool morphology
• Spatter
• Grain
• SLM