Additive manufacturing (AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backs-catter diffraction, and compression tests. After a solution heat treatment (SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′- and γ″-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ″ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.

镍基高温合金部件的增材制造（AM）可以显着降低航空航天应用的重量。通过快速的熔化过程，通过选择性激光熔化使IN718产生AM，可形成具有高位错密度的非常精细的树枝状微结构。这种合金的复杂相组成具有三种不同类型的析出物和高残余应力，因此有必要对AM零件的常规热处理进行调整。为了找到最佳的热处理方法，通过透射和扫描电子显微镜（包括电子背散射衍射和压缩测试）研究了不同固溶热处理样品的微观结构和力学性能。固溶热处理（SHT）后，富Nb的Laves相溶解，位错密度降低，消除了树突状的子结构。930或954°C的SHT导致δ相的析出，从而降低了在随后的两阶段时效处理过程中形成的强化γ'相和γ''相的体积分数。在1000℃的较高SHT温度下，没有δ相沉淀，可以获得更高的γ'和γ''体积分数，这导致了所有固溶热处理条件的最佳强度。