Extremely high-speed-rate laser directed energy deposition has attracted considerable attention for large-scale industrial component manufacturing owing to its outstanding fabrication efficiency. However, interlayer metallurgical defects and thickness fluctuation stacking caused by the previous non-uniform rough surface layer hinder the preparation of customized thicknesses of large-scale components with high performance. Herein, an integrated extremely high-speed-rate additive manufacturing technology, that is, extremely high-speed-rate laser-directed energy deposition accompanied by extremely high-speed-rate laser remelting, is proposed to eliminate porosity and reconstruct the microstructure of multilayer parts. The remelted specimens exhibited uniform roughness and ultrafine grains when defocusing amount was less than zero. The relatively lower temperature gradient G and morphology factor G/R in the remelting process led to more favorable subcooling, which further promoted more nucleation sites and contributed to grain refinement and columnar-to-equiaxed transition. A multilayer 316 L stainless steel material with an interlayer remelting treatment was further prepared, and a typical heterogeneous structure dominated by ultrafine equiaxed grains was obtained. The multilayer specimen characterized by such a special structure exhibited a higher yield strength of 546 MPa, along with a ductility of 49.1 %. This novel integrated manufacturing technology highlights a new strategy that can expand the extremely high-speed-rate additive manufacturing window and achieve simultaneous improvements in the manufacturing efficiency and performance of large-scale components.

中文翻译：

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通过集成极高速激光定向能量沉积和层间重熔制造高性能功能涂层


极高速激光定向能量沉积由于其出色的制造效率而在大规模工业部件制造中引起了广泛关注。然而，先前不均匀的粗糙表面层引起的层间冶金缺陷和厚度波动堆积阻碍了高性能大型部件的定制厚度的制备。本文提出了一种集成的极高速增材制造技术，即极高速激光定向能量沉积伴随极高速激光重熔，以消除孔隙并重建多层结构的微观结构。部分。当离焦量小于零时，重熔试样呈现出均匀的粗糙度和超细晶粒。重熔过程中相对较低的温度梯度G和形貌因子G/R导致更有利的过冷，进一步促进更多的形核位点，有助于晶粒细化和柱状到等轴的转变。进一步制备了经过层间重熔处理的多层316L不锈钢材料，获得了以超细等轴晶粒为主的典型异质组织。具有这种特殊结构的多层样品表现出高达 546 MPa 的屈服强度和 49.1% 的延展性。这种新颖的集成制造技术凸显了一种新策略，可以扩展极高速增材制造窗口，同时提高大型部件的制造效率和性能。