The oxidation behavior of the selective laser melting (SLM)–fabricated Inconel 718 was investigated through isothermal oxidation testing at 650 °C for 500 h and compared with that of the as-cast and as-forged specimens at the same testing conditions. The effect of microstructure and surface roughness on the oxidation behavior of the SLM-fabricated, as-cast, and as-forged Inconel 718 specimens was examined. The result shows that Inconel 718 fabricated by SLM with the unique layer structure exhibited a better resistance to the 500 h oxidation at 650 °C compared with as-cast and as-forged 718 with coarse dendritic structure and uniform equiaxed grain microstructure, respectively. The influence of the surface roughness on the long-time oxidation resistance of SLM specimens is not pronounced compared with that of as-cast and as-forged specimens. The tiny dendrites instead of grain boundaries are a major influencing factor for the oxidation process of SLM specimens. The surface roughness has more evident influence on the oxidation resistance of as-forged specimens than that of the as-cast ones subjected to the 500 h oxidation at 650 °C.

通过在650°C下进行等温氧化测试500 h，研究了选择性激光熔化（SLM）制造的Inconel 718的氧化行为，并将其与相同测试条件下的铸态和锻造试样进行了比较。检验了微观结构和表面粗糙度对SLM制造，铸态和锻造Inconel 718试样的氧化行为的影响。结果表明，与具有粗枝状组织和均匀等轴晶粒组织的铸态和锻造718相比，由SLM制造的具有独特层结构的Inconel 718分别在650°C下表现出更好的抗500 h氧化性能。与铸态和锻造试样相比，表面粗糙度对SLM试样的长期抗氧化性的影响并不明显。微小的树枝状晶体而不是晶界是SLM试样氧化过程的主要影响因素。与在650°C下进行500 h氧化的铸态试样相比，表面粗糙度对铸态试样的抗氧化性具有更明显的影响。