An ultra-high strength martensitic steel fabricated using selective laser melting additive manufacturing: Densification, microstructure, and mechanical properties
An ultra-high strength martensitic steel fabricated using selective laser melting additive manufacturing: Densification, microstructure, and mechanical properties
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DOI：
10.1016/j.actamat.2019.12.037
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发表时间：
2020-03-01
期刊：
影响因子：
9.4
通讯作者：
Karaman, Ibrahim
中科院分区：
文献类型：
--
作者：
Seede, Raiyan;Shoukr, David;Karaman, Ibrahim
马氏体钢由于其超高的屈服强度和合理的延展性，最近在汽车、航空航天和国防应用中的应用重新引起了人们的兴趣。最近发现的低合金马氏体钢AF 9628由于e-碳化物相的形成而显示出大于1.5GPa的强度和大于10%的拉伸延展性。为了生产具有高度几何控制的高强度零件，本文的工作提出了选择性激光熔化（SLM）参数对这种新钢的微观结构和机械性能的影响。介绍了一种确定无气孔零件制造工艺参数的优化框架。该框架利用计算成本低廉的Tumar-Tsai模型，单轨道实验校准，预测熔池的几何形状。确定最大允许舱口间距的几何标准也被开发，以避免缺乏融合引起的多孔性的印刷零件。使用该框架，在广泛的工艺参数范围内成功制造了全致密样品，从而可以构建AF 9628的SLM加工图。打印的样品显示出高达1.4 GPa的拉伸强度，这是迄今为止报道的任何3D打印合金的最高强度，伸长率高达11%。工艺参数选择的灵活性，同时保持全密度，开辟了局部微观结构细化和参数优化的可能性，以改善印刷零件的机械性能。这里介绍的工艺优化框架预计将允许以加速的方式成功打印新材料。(C)2019 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Martensitic steels have gained renewed interest recently for their use in automotive, aerospace, and defense applications due to their ultra-high yield strengths and reasonable ductility. A recently discovered low alloy martensitic steel, AF9628, has been shown to exhibit strengths greater than 1.5 GPa with more than 10% tensile ductility, due to the formation of e-carbide phase. In an effort to produce high strength parts with a high degree of control over geometry, the work herein presents the effects of selective laser melting (SLM) parameters on the microstructure and mechanical properties of this new steel. An optimization framework to determine the process parameters for building porosity-free parts is introduced. This framework utilizes the computationally inexpensive Eagar-Tsai model, calibrated with single track experiments, to predict the melt pool geometry. A geometric criterion for determining maximum allowable hatch spacing is also developed in order to avoid lack of fusion induced porosity in the as-printed parts. Using this framework, fully dense samples were successfully fabricated over a wide range of process parameters, allowing the construction of an SLM processing map for AF9628. The as-printed samples displayed tensile strengths of up to 1.4 GPa, the highest reported to date for any 3D printed alloy, with up to 11% elongation. The demonstrated flexibility in process parameter selection, while maintaining full density, opens up the possibility of local microstructural refinement and parameter optimization for improved mechanical properties in as-printed parts. The process optimization framework introduced here is expected to allow successful printing of new materials in an accelerated fashion. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.