Tuning hatch distance to optimize microstructure and mechanical properties of 2205 duplex stainless steel produced by laser powder bed fusion

Abstract

Laser powder bed fusion (LPBF) of duplex stainless steel is a promising route to fabricate intricate parts with excellent mechanical properties. However, further understanding of build mechanisms is required to improve the process. This paper aims to better understand the influence of hatch distance on the densification behavior and figure out the correlation with microstructure and mechanical properties in LPBF of 2205 stainless steel. With the optimized laser power and scanning speed, the significant influence of hatch distance on the build quality is revealed. A hatch distance of 0.07 mm is selected for an even surface and dense part with a relative density of up to 99.13 %. The hatch distance has a crucial impact on the heat and mass transfer between tracks; hence, poor surface morphologies such as inter-track voids or swelling surfaces occur if an improper hatch distance is adopted. The optimal mechanical properties are also achieved. Specifically, the yield strength (0.2 YS), ultimate tensile strength (UTS), and elongation (EL) values are 896.8 MPa, 1035.13 MPa, and 15.34 %, respectively. The improvement in mechanical properties can be ascribed to the coordination between high dislocation density, fine grain size, high CSL boundaries and LAGBs, and high relative density with few pores. This work can help improve the build quality and expand the application horizon of duplex stainless steel for manufacturing intricate components.