Laser welding of selective laser melted Ti6Al4V: Microstructure and mechanical properties
Laser welding of selective laser melted Ti6Al4V: Microstructure and mechanical properties
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DOI：
10.1016/j.matpr.2019.12.322
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
T. Rautio;A. Hamada;J. Mäkikangas;M. Jaskari;A. Järvenpää
中科院分区：
文献类型：
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作者：
T. Rautio;A. Hamada;J. Mäkikangas;M. Jaskari;A. Järvenpää
Ti6Al4V合金在生物力学应用以及结构工程应用，特别是在航空航天工业和海洋应用中表现出巨大的潜力。在这项研究中，报告了激光焊接 (LW) 对选择性激光熔化 (SLM) Ti6Al4V 晶粒结构和机械性能的影响。研究的材料以两种不同的最厚层（30 和 50μm）进行 SLMed，能量密度分别为 69.4 和 60.3J/mm3。进行940℃、4h的后退火处理，以消除应力，诱发β相，降低针状β马氏体含量，从而有助于提高其力学性能。随后，LW 使用以 60mm/s 行进的 2.4kW 激光来连接 SLMed Ti6Al4V 板。通过 SLM 和 LW 来研究建成时的微观结构，然后评估机械性能。应用 X 射线衍射 (XRD) 和光学显微镜进行物相分析，并进行单轴拉伸试验来研究接头强度。目前工作最相关的结果是层厚度对 SLMed Ti6Al4V 的拉伸性能起着关键作用。 t=50μm的SLMed材料表现出较高的强度，屈服强度为940 MP，极限强度为1130MPa，而t=30μm的相应性能分别为910MPa和1080MPa。然而，t=30μm 的竣工材料的断裂伸长率为 15%，而较高的材料的断裂伸长率为 9%。激光焊接材料的拉伸结果并未显示机械性能的损失。
Ti6Al4V alloy exhibits an excellent potential for biomechanical applications as well as structural engineering applications, especially in the aerospace industry and marine applications. In this study, the effect of laser welding (LW) on grain structure and the mechanical properties in a selective laser melted (SLM) Ti6Al4V is reported. The studied material was SLMed at two different layer thicknessest, 30 and 50 µm, and respective energy densities 69.4 and 60.3 J/mm3. Post-annealing treatment at 940 °C for 4 h was carried out to relieve stress, induce the β-phase and reduce the acicular ά martensite content, thereby helping to enhance its mechanical properties. Subsequently, LW was employed to join SLMed Ti6Al4V plates using a 2.4 kW laser travelling at 60 mm/s. The microstructures were studied as-built by SLM and after LW, followed by an evaluation of the mechanical properties. X-ray diffraction (XRD) and optical microscopy were applied for phase analysis and uniaxial tensile tests were conducted to study the joint strength. The most relevant results of the present work are that the layer thickness plays a key role on tensile properties of the SLMed Ti6Al4V. The SLMed material witht= 50 µm showed higher strength with yield strength 940 MP and ultimate strength 1130 MPa, while the corresponding properties oft= 30 µm were 910 MPa and 1080 MPa, respectively. However, the fracture elongation of the as-built materials witht= 30 µm was 15% as compared to 9% in the highert. The tensile results of the laser welded materials did not reveal loss in the mechanical properties at botht.