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为了实现激光选区熔化成形(SLM)这项新工艺在液体火箭发动机高温合金结构上的推广应用,明晰其强化机理以及研究相应的热处理制度,对激光选区熔化快速凝固条件下组织形成及演化规律、第二相析出特点进行了分析和讨论。采用SLM成形K4202镍基高温合金试样,通过光学显微镜(OM)、扫描电镜(SEM)及X射线衍射(XRD)等理化分析手段,将基于ANSYS生死单元技术的温度场数值模拟结果和经典凝固理论相结合,揭示了其组织特征及演化规律:沉积态表现为外延生长柱状晶,层间可见层带组织,顶部出现转向枝晶和二次枝晶臂,γ’强化相和碳化物的析出受到抑制。
In order to realize the popularization and application of new laser melting process (SLM) on superalloy structure of liquid rocket engine, to clarify its strengthening mechanism and to study the corresponding heat treatment system, The second phase precipitation characteristics were analyzed and discussed. The K4202 nickel base superalloy samples were formed by SLM. The temperature field numerical simulation results based on the ANSYS technology were compared with the classical solidification by optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) The combination of theory and microstructure reveals its microstructure and evolution: the depositional state is epitaxial growth of columnar grains, and the layers of strata are visible between layers. The top and the dendrites are dendrites and secondary dendrites, and the precipitation of γ ’strengthening phase and carbides Suppressed.