Nickel-based superalloys show severe cracking tendency during laser powder bed fusion (LPBF), which hinders their widespread applications in aerospace. A two-step heat treatment, including hot isostatic pressing (HIP) and solid solution heat treatment (SSHT), was proposed to obtain crack-free LPBF nickel-based superalloy components with a supersaturated solid solution of alloying elements for desirable mechanical performance. The HIP process aimed to annihilate microcracks, and the subsequent SSHT focused on modifying the microstructure and improving the solid solution extent of alloying elements. The pore-and-microcrack-containing defects with a volume fraction of 0.96% in the LPBF samples were transformed to pore-dominated defects with a volume fraction of 0.08% after the HIP process. After the SSHT, it was not observed the reappearance of the previously coalesced microcracks, but the porosity volume fraction showed a slight rebound to 0.11% due to the coarsening or regrowth of the pores. The tensile strength and elongation at break of HIP + SSHT samples printed along the horizontal plane at room temperature were 3.6% and 113.5% higher than those of as-fabricated ones. An 11.9% and 410.0% improvement in tensile strength and ductility at 900 ℃ was achieved after the two-step treatment. The development of the microstructure after the HIP and SSHT, involving sub-grains, dislocation networks, carbide precipitates, and grains, was revealed systematically. The correlation between the microstructure and tensile properties was unveiled in depth. This work is anticipated to provide an efficient route with excellent industrial applicability for LPBF superalloy components to mitigate microcracks and acquire attractive mechanical properties.

镍基高温合金在激光粉末床融合（LPBF）过程中表现出严重的开裂倾向，阻碍了其在航空航天领域的广泛应用。提出了包括热等静压 (HIP) 和固溶体热处理 (SSHT) 的两步热处理，以获得无裂纹的 LPBF 镍基高温合金部件，其具有合金元素的过饱和固溶体，以获得所需的机械性能。HIP 工艺旨在消除微裂纹，随后的 SSHT 侧重于改变微观结构和提高合金元素的固溶程度。LPBF 样品中体积分数为 0.96% 的孔隙和微裂纹缺陷在 HIP 工艺后转化为体积分数为 0.08% 的孔隙主导缺陷。在 SSHT 之后，未观察到先前聚结的微裂纹重新出现，但由于孔隙粗化或再生长，孔隙率体积分数略有回升至 0.11%。室温下沿水平面打印的 HIP + SSHT 样品的拉伸强度和断裂伸长率比制造的样品高 3.6% 和 113.5%。经过两步处理后，900℃下的拉伸强度和延展性分别提高了11.9%和410.0%。系统地揭示了 HIP 和 SSHT 后微观结构的发展，包括亚晶粒、位错网络、碳化物沉淀和晶粒。微观结构和拉伸性能之间的相关性得到了深入揭示。