Anisotropic Mechanical Properties of Ni-base Superalloy Compacts by Direct Laser Forming Technology
Anisotropic Mechanical Properties of Ni-base Superalloy Compacts by Direct Laser Forming Technology
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DOI：
10.2497/jjspm.63.427
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发表时间：
2016
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影响因子：
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通讯作者：
Naoto Yoshigai;K. Kudo;F. Tsumori;Toshiko Osada;H. Miura
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文献类型：
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作者：
Naoto Yoshigai;K. Kudo;F. Tsumori;Toshiko Osada;H. Miura
由于镍基高温合金的加工性能较差，激光直接成形（DLF）技术将成为制造复杂形状镍基高温合金零件的有力工具。重点研究了DLF成形件的微观组织，其晶粒沿成型方向沿着长大。这种各向异性的微观结构是由DLF生产的部件的主要特征之一，并且可能导致各向异性的机械性能。在这项工作中，最佳的激光成形条件，如激光功率，激光扫描速度，送粉速度，确定了通过评估所生产的零件的密度。在不同的施工方向上制作了三种拉伸试件和两种疲劳试件。它们在锻造材料中具有比JIS标准更高的极限拉伸强度。然而，它们的伸长率低于JIS标准的伸长率，并且伸长率的分散性也大。另一方面，疲劳极限略低于标准值。结果表明，采用DLF工艺生产的镍基高温合金零件，由于成形方向不同，其力学性能也不同。摘要金属部件的增材制造通常通过激光或电子束熔化进行，用于直接固结粉末，但也有其他可用的技术，例如Digital Metal ®使用的粉末床上的喷墨。Höganäs Digital Metal自2010年以来一直参与增材制造，其技术采用单独的成型和固结工艺。粉末床上的精密喷墨用于生产绿色部件，然后将这些部件烧结以获得最终密度和强度。该技术已成功用于生产316 L不锈钢部件，但基本上所有类型的金属或合金，以具有合适形态和粒度的粉末形式提供，都可用于打印部件。随后的烧结工艺可以针对每种合金进行优化，从而可以加工多种合金。在这项研究中，讨论了不同合金的可能性和挑战。
As Ni-based superalloy has poor workability, direct laser forming (DLF) would be a powerful tool for fabricating the complex shaped Ni-based superalloy parts. We focused on the microstructure of the parts produced by DLF, the crystal grains of which grow along the building direction. This anisotropic microstructure is one of the major features of the parts produced by DLF, and which may cause anisotropic mechanical properties. In this work, the optimum laser-forming conditions such as laser power, laser scan speed, and powder feeding rate were determined by evaluating the density of the produced parts. Three types of tensile test pieces and two types of fatigue test pieces were fabricated in different building direction. They had higher ultimate tensile strength than that of JIS standards in wrought materials. However, their elongation was lower than that of JIS standards, and also the dispersion of elongation was large. On the other hand, fatigue limit was a little lower than the standard value. It was confirmed that the mechanical properties of Ni-based superalloy parts produced by DLF were different by a difference in building direction. ABSTRACT Additive manufacturing of metal components is commonly performed by laser or electron beam melting for direct consolidation of powders, but there are also other techniques available, e.g. the ink-jet on powder bed used by Digital Metal ® . Höganäs Digital Metal has been involved in additive manufacturing since 2010, with a technology that utilizes separate forming and consolidation processes. Precision inkjet on powder bed is used for production of green components, and these components are then sintered to obtain final density and strength. The technique is successfully used to produce components in 316L stainless steel, but basically all types of metals or alloys, available as powders with suitable morphology and particle size can be used to print components. The following sintering process then can be optimized for each individual alloy, making processing of a wide selection of alloys possible. In this study, possibilities and challenges with different alloys are discussed.