Microstructural characteristics and mechanical properties of 304ss cross-structural parts fabricated via arc-directed energy deposition

Microstructural characteristics and mechanical properties in different regions of cross-structural parts fabricated by arc-directed energy deposition urgently need to be further clarified. This study focuses on the evolution of microstructure and mechanical properties in the intersection and non-intersection regions of 304 stainless steel cross-structural parts. The deposition height of the intersection region is higher than that of the non-intersection region, and the microhardness and ultimate tensile strength (UTS) of the intersection region are also significantly higher. As the intersection angle decreases, the deposition height and microhardness of the intersection region increase slightly, while the tensile properties show no obvious change. Compared with the non-intersection region, the intersection region benefits from superior heat dissipation conditions, which facilitates a higher solidification rate of the molten pool, leading to more uniform microstructure and refined grains. For the cross-structural part with a 90° intersection angle, the UTS values of the intersection region along the horizontal and vertical directions are 745.5 and 715.9 MPa, respectively, 11.5 % and 15.3 % higher than those of the non-intersection region. Additionally, the average size of grains larger than 50 μm decreases from 157.9 μm in the non-intersection region to 113.3 μm in the intersection region.