Nickel-based superalloys have been widely used in manufacturing turbine blades, vanes, and discs of aircrafts and power generators that serve in challenging environment. In order to meet the requirements for rapid manufacturing of these large-scale and high-performance components, the extreme high-speed laser metal deposition (EHLMD) technology have attracted great attention in recent years. The EHLMD technology can significantly improve the efficiency compared with conventional laser metal deposition (LMD). Meanwhile, the solidification condition and the resultant microstructures and mechanical properties can also be dramatically changed. In this study, a high chromium superalloy (K648) has been additively manufacturing by using EHLMD for the first time. The key process parameters and the resulted microstructure and mechanical properties are investigated. The results have shown that the most important factors affecting the height, width, and depth of the single-track deposit of EHLMD K648 superalloy are powder feeding rate, laser power, and scanning speed, respectively. The height and the width of the deposits are the largest when the laser power, scanning speed, and the powder feeding rate are 1400 W, 25 m/min, and 30 g/min. There exist some incomplete fusions in the interlayer region and some pores in the interior region of the multi-track-multi-layer deposits. Columnar grains grow in the build direction within each layer, while equiaxed grains tend to form in the interlayer region. The average value of microhardness of EHLMD K648 superalloy is about 298.1 HV. The ultimate strength of EHLMD K648 superalloy is slightly lower than that of the forging GH648 superalloy but higher than that of the conventional LMD K648 superalloy.

镍基超级合金已被广泛用于制造在恶劣环境下工作的涡轮叶片，叶片，飞机圆盘和发电机。为了满足快速制造这些大型和高性能组件的要求，近年来，极高速激光金属沉积（EHLMD）技术引起了极大的关注。与传统的激光金属沉积（LMD）相比，EHLMD技术可以显着提高效率。同时，固化条件以及所得的显微组织和力学性能也可以显着改变。在这项研究中，高铬超合金（K648）首次通过EHLMD进行增材制造。研究了关键工艺参数以及所得的显微组织和力学性能。结果表明，影响EHLMD K648高温单道沉积物的高度，宽度和深度的最重要因素分别是送粉速度，激光功率和扫描速度。当激光功率，扫描速度和送粉速度分别为1400 W，25 m / min和30 g / min时，沉积物的高度和宽度最大。在多道多层沉积物中，层间区域存在一些不完全的熔合，内部区域存在一些孔隙。柱状晶粒在每一层内沿构造方向生长，而等轴晶粒倾向于在夹层区域中形成。EHLMD K648高温合金的显微硬度平均值约为298.1 HV。