Differences between Tensile Properties of WAAM SS304 Components in Different Directions

Wire arc additive manufacturing (WAAM) is particularly suitable for manufacturing large metal structure components. However, the anisotropy of mechanical properties of WAAM components cannot be avoided, which makes the mechanical properties of WAAM components unstable and seriously limits its engineering application. Herein, the tensile samples for 304 stainless-steel thin-walled structures along three directions (longitudinal, diagonal, and transverse) of the deposition layer are intercepted. The mechanical properties of the components are 9.3–54.6% higher than the standard values. The samples have obvious anisotropy characteristics. Samples with diagonal direction show the best mechanical properties, which are not affected by process parameters. The better the forming quality, the higher the mechanical properties of the samples. By correlating the mechanical properties results of the samples with the microstructures, it is found that very fine dendrites grow along the deposition direction in the samples, and this unique microstructure leads to the anisotropy of the mechanical properties. Under the action of uniaxial tensile load, the growth direction of precise dendrite in the sample with diagonal direction is almost the same as the slip direction of the maximum dislocation plane, which is the reason for the excellent mechanical properties of the sample with diagonal direction.