Influence of laser power on the high-temperature creep rupture life of 304L stainless steel manufactured by selective laser melting

To study the influence of laser power on the high-temperature durability performance of 304L stainless steel, its effect on the porosity, hardness, relative density, and creep rupture life have been studied using a single-factor experiment. The relative optimal process parameters were obtained, and the microstructure and mechanical properties of the as-built samples were characterized. The results showed that the creep rupture life reached a peak at 55H for the following process parameters: scanning speed = 900 mm/s, layer thickness = 0.03 mm, hatch space = 0.1 mm, laser power = 280 W, room temperature hardness = 91.5 HRB, and relative density = 99.4%. Furthermore, the microcellular structure was uniform and dense with few pores, the orientation of the fine grains at the boundary of the molten pool was random, and the orientation of the larger columnar crystals in the molten pool had a specific preference along the <001> direction. After 55.1 h (maximum) duration at a temperature of 700 °C, the cellular substructure, that had been formed by a large number of dislocation clusters, had dissipated significantly. The dislocation lines were more evident, and a large number of dislocations had interacted with spherical nano-precipitates (enriched with O–Si–Mn nanoparticles).