Effects of process time interval and heat treatment on the mechanical and microstructural properties of direct laser deposited 316L stainless steel
Effects of process time interval and heat treatment on the mechanical and microstructural properties of direct laser deposited 316L stainless steel
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DOI：
10.1016/j.msea.2015.07.056
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发表时间：
2015-09-17
期刊：
影响因子：
6.4
通讯作者：
Seely, Denver W.
中科院分区：
文献类型：
--
作者：
Yadollahi, Aref;Shamsaei, Nima;Seely, Denver W.
介绍了一种基于激光的附加制造方法--直接激光沉积(DLD)制备的316L不锈钢的力学性能和组织性能，并与传统制造方法的性能进行了比较。使用激光工程净成形(LENS(R))DLD系统，通过为每个构造板制造1个或9个样品来改变连续层沉积之间的时间间隔，或层间/空闲时间，以垂直向上制造圆柱形样品，从而增加每个构造板的总装配量。随后，研究了热历史和热处理对DLD零件的组织(即晶粒度和形貌)和力学性能(即拉伸、压缩和显微硬度)的影响。结果表明，与铸态和锻态相比，本文制备的DLD316L不锈钢试件具有较高的屈服和极限抗拉强度。此外，DLD 316L不锈钢的热历史、组织演变和力学性能与沉积之间的时间间隔有关。较长的局部时间间隔会导致更高的冷却速度，从而导致更细小的组织、更高/更均匀的强度和更低的断裂延伸率。此外，由于激光穿透深度的减少(例如，前一层重熔减少)，孔隙率和不太完整的冶金结合在离建板更高的位置更普遍。相反，时间间隔较短的零件被发现具有更粗糙的组织，较低的强度和较高的断裂伸长率，这是由于零件中整体温度升高导致的冷却速度较低所致。这些结果可能有助于未来设计和控制更高效、恒功率的DLD工艺，特别是在制造多个和/或更大部件方面；这是一种将中小批量生产时间降至最低的理想方法。(C)2015爱思唯尔B.V.保留所有权利。
The mechanical and microstructural properties of 316L stainless steel (SS) fabricated via Direct Laser Deposition (DLD), a laser-based additive manufacturing method, are presented and compared with those of conventionally-built counterparts. Using a Laser Engineered Net Shaping (LENS (R)) DLD system, the time interval between successive layer deposits, or inter-layer/idle time, for fabricating cylindrical specimens vertically-upward was varied by building either one or nine samples per build plate thus increasing total assembly volume per build. Subsequently, the effect of thermal history, as well as heat treatment, on microstructural (i.e. grain size and morphology) and mechanical (i.e. tensile, compression, and microhardness) properties of DLD parts were investigated. Results indicate that the DLD 316L SS samples produced herein have a higher yield and ultimate tensile strength relative to their cast and wrought forms. Furthermore, the thermal history, microstructural evolution, and mechanical properties of DLD 316L SS are shown to be dependent on the time interval between deposits. Longer local time intervals result in higher cooling rates, leading to finer microstructures, higher/uniform strength and lower elongation to failure. In addition, porosity and less integral metallurgical bonds are found to be more prevalent in locations further upward from the build plate due to reduced laser penetration depths (e.g. previous-layer remelting decreases). Conversely, parts manufactured with shorter time intervals were found to possess a coarser microstructure, lower strength and higher elongation to failure attributable to lower cooling rates caused by an increased bulk temperature in the part. These results may aid in future design and control of more efficient, constant-power DLD processes especially with regard i to building multiple and/or larger parts; an approach desirable for minimizing small-to-medium lot production times. (C) 2015 Elsevier B.V. All rights reserved.