【标题】Novel bulk triaxial residual stress mapping in an additive manufactured bridge sample by coupling energy dispersive X-ray diffraction and contour method measurements
【参考中译】通过耦合能量分散X射线散射和轮廓法测量，在增材制造桥梁样本中进行新型体三轴残余应力绘制
【类型】 期刊
【关键词】 Residual stress; Diffraction; Contour method; Additive manufacturing; Titanium
【参考中译】 残余应力;折射;轮廓法;增材制造;钛
【作者】 Nicholas A. Bachus; Maria Strantza; Bjorn Clausen; Christopher R. D'Elia; Michael R. Hill; J. Y. Peter Ko; Darren C. Pagan; Donald W. Brown
【摘要】 A novel approach for determining triaxial residual stress states by coupling energy dispersive X-ray diffraction and contour method measurements is provided and validated in a Ti-5Al-5V-5Mo-3Cr additive manufactured (AM) bridge sample. Synchrotron X-ray diffraction (SXRD) can provide relatively fine spatial resolution (on the order of 10-100 μm) for mapping 3D elastic strain fields within a sample. However, for samples with dimensions larger than one or two centimeters the path length can get prohibitive as both constant wavelength and energy dispersive SXRD are based upon transmission measurements. As an example, for a plate-like sample geometry where the thickness is limited (less than a centimeter) it is trivial to measure the longitudinal and height direction elastic strain components with excellent in-plane spatial resolution (～100 μm) and a somewhat lower through-thickness resolution (10-15 times larger) but obtaining the through thickness component is often not possible as the beam path must be parallel to one of the large dimensions of the plate. While small samples of low Z-number alloys (e.g., Ti or Al) allow determination of the three elastic strain components, this is often not the case for higher Z alloys (e.g., Fe or Ni) or large samples where some strain components can be indeterminable. To overcome these limitations, this work applies a combination of synchrotron X-ray diffraction and the contour method (a mechanical relaxation technique), to determine the triaxial stress state. This novel combination is demonstrated and validated in a relatively small additive manufactured sample where all three orthogonal strain components are accessible via X-ray diffraction for stress determination. The paper also explores methods for determining the strain-free lattice parameter, typically obtained from a small stress-free reference sample. This work shows that a small size AM sample is not stress free, producing unreliable magnitudes of strain and stress. Instead, a strain-free lattice parameter is determined using residual stress equilibrium conditions, which gives consistent strain and stress trends for both X-ray diffraction (alone) and the new diffraction-contour coupling technique. This demonstrates that the coupling technique can be confidently applied to samples to determine stress when path length (size or Z-number) prohibit determination of three orthogonal strain components via diffraction.
【参考中译】 提出了一种将能量色散X射线衍射法和轮廓法相结合来确定三轴残余应力状态的新方法，并在添加添加剂的Ti-5Al-5V-5Mo-3CR桥试件上进行了验证。同步辐射X射线衍射仪可以提供较高的空间分辨率(约10-100μm)来绘制样品内部的三维弹性应变场。然而，对于尺寸大于一到两厘米的样品，由于恒定波长和能量色散SXRD都基于透射率测量，因此路径长度可能会变得令人望而却步。为了克服这些限制，本工作应用同步加速器X射线衍射和轮廓法(一种机械松弛技术)相结合的方法来确定三轴应力状态。这种新颖的组合在一个相对较小的添加剂制造的样品中得到了演示和验证，其中所有三个正交应变分量都可以通过X射线衍射来确定应力。本文还探索了确定无应变晶格参数的方法，通常是从一个小的无应力参考样品获得的。这项工作表明，小尺寸的AM样品并不是无应力的，会产生不可靠的应变和应力大小。取而代之的是，利用残余应力平衡条件确定了无应变晶格参数，这为X射线衍射和新的衍射-轮廓耦合技术提供了一致的应变和应力趋势。这表明，当路径长度(尺寸或Z数)不允许通过衍射确定三个正交应变分量时，耦合技术可以可靠地应用于样品以确定应力。
【来源】 Additive Manufacturing 2024, vol.83
【入库时间】 2024/7/1
【标题】Crystallographic texture and multiscale boundaries mediated creep anisotropy in additively manufactured Ni-based Hastelloy C276 superalloy
【参考中译】增材制造的镍基哈氏合金C276超级合金的晶体结构和多尺度边界介导的蠕动各向异性
【关键词】 Wire and arc-based directed energy deposition; Hastelloy c276 superalloy; Microstructure; Creep anisotropy; Creep mechanism; Microstructure evolution
【参考中译】 线丝和弧基定向能沉积;哈氏合金c276高温合金;微观结构;蠕动各向异性;蠕动机制;微观结构演变
【作者】 Zhijun Qiu; Hanliang Zhu; Zhiyang Wang; Ondrej Muransky; Tao Wei; Elizabeth Budzakoska-Testone; Joel Davis; Andrew Studer; Qinfen Gu; Ulf Garbe; David Wexler; Huijun Li
【摘要】 The microstructure and high-temperature creep mechanisms of Ni-based Hastelloy C276 superalloy fabricated using wire and arc-based directed energy deposition were investigated systematically and innovatively. The microstructural investigation revealed that the as-fabricated samples comprise γ-Ni matrix and topologically close-packed (TCP) P phase precipitates. The γ matrix subgrains and grains are spread over multiple highly textured columnar dendrites, with a majority of γ <001> crystallographic orientations closely aligned along the deposition direction. Moreover, the interdendritic regions exhibit severe Mo segregation, P phase particles, and dislocation bands. Creep tests were conducted on miniature samples under various temperature and stress conditions, loaded either in the deposition direction (DD) or travel direction (TD). DD samples exhibit lower minimum strain rates, greater strains-to-failure, and longer creep rupture lifetimes than TD samples, indicating significant creep anisotropy. Dislocation creep was identified as the primary creep mechanism for both DD and TD conditions. During creep, dynamic precipitation of TCP phases occurred in the interdendritic regions, resulting in varying creep resistance between interdendritic and dendritic core regions. Isostress and isostrain models, considering both crystallographic texture and precipitation strengthening, reasonably predicted the observed creep anisotropy during the secondary creep stage. Additionally, variations in the Schmid factor led to significant deformation incompatibility among dendrites in TD samples. Dislocation accumulation in TD sample interdendritic regions promoted new grain nucleation, triggering dynamic recrystallisation, facilitating grain boundary sliding, and accelerating tertiary creep. Furthermore, TCP phase particles in the interdendritic regions contributed to microcrack development, further accelerating creep fracture, especially in the TD condition.
【参考中译】 系统地、创新性地研究了线基和弧基定向能沉积制备的镍基Hastelloy C276高温合金的组织和高温蠕变机制。显微组织研究表明，所制备的样品由γ-Ni基质和拓扑紧密堆积的(TcP)P相组成。γ基体亚晶和颗粒分布在多个高度织构的柱状树枝晶上，大部分γ<001>晶向沿沉积方向紧密排列。此外，枝晶间区域还存在严重的Mo偏析、P相颗粒和位错带。在不同的温度和应力条件下，进行了沿沉积方向(DD)或行进方向(TD)加载的微型试件的蠕变试验。与TD样品相比，DD样品表现出更低的最低应变率、更大的失效应变和更长的蠕变断裂寿命，这表明了显著的蠕变各向异性。位错蠕变是DD和TD条件下的主要蠕变机制。在蠕变过程中，在枝晶间动态析出了TCP相，导致枝晶与枝晶核心区的蠕变抗力不同。等应力和等应变模型综合考虑了晶体织构和析出强化，较好地预测了二次蠕变阶段的蠕变各向异性。此外，施密德因子的变化导致了TD样品中树枝晶之间的显著变形不相容。Td样品枝晶间位错的积累促进了新的晶核，触发了动态再结晶，促进了晶界滑移，加速了三次蠕变。此外，枝晶间的TCP相颗粒促进了微裂纹的发展，进一步加速了蠕变断裂，尤其是在Td条件下。
【标题】A novel magnetic field assisted powder arc additive manufacturing for Ti60 titanium alloy: Method, microstructure and mechanical properties
【参考中译】Ti60钛合金的新型磁场辅助粉末弧增材制造：方法、显微组织和力学性能
【关键词】 Magnetic field assisted powder arc additive; Manufacturing; Powder spattering problem; Powder melting behavior; Ti60 high-temperature titanium alloy; Microstructure; Mechanical properties
【参考中译】 磁场辅助粉末弧添加剂;制造;粉末飞溅问题;粉末熔化行为; Ti60高温钛合金;显微组织;机械性能
【作者】 Kexin Kang; Yibo Liu; Huisheng Ren; Qinghua Zhang; Shiqing Wang; Yina Kong; Wenyuan Li; Jianrong Liu; Qingjie Sun
【摘要】 Due to the rapid heating-cooling process and unstable keyhole, pore defects are easily formed during the high energy beam-powder additive manufacturing (AM) process, posing great challenges to the high-performance manufacturing of aerospace components. Using an arc with lower energy density as a heat source can effectively avoid these defects, but its matching raw materials are limited to wire. In this paper, a novel magnetic field assisted powder arc additive manufacturing (MFA-PAAM) method has been proposed, which combines arc heat source and powder raw material to achieve dense metal parts. A transverse magnetic field (TMF) was introduced to solve the powder spattering problem which impacts the stability of the PAAM process, by regulating the direction of the arc plasma flow and the arc pressure. The unique melting behavior of the powder under arc heating was captured by a high-speed camera, which can be summarized into two steps: balling and adsorption by the molten pool. And the well-formed and fully dense Ti60 high-temperature titanium alloy wall components were successfully manufactured using the self-developed equipment. The microstructure of the thin-wall component is dominated by basket-weave distributed α laths and few β sheets remaining at their boundaries. A layered periodic distribution along the building direction was observed, which is mainly distinguished from the content and morphology of the β phase. The average ultimate tensile strength (UTS) and elongation to failure in the travelling direction are 1003.2 MPa and 15.1%, while the average UTS and elongation along the building direction are 1009.3 MPa and 16.6%, respectively. The fracture morphologies in both directions are characterized by ductile fracture. The MFA-PAAM technique shows great potential for fabricating materials that are difficult to be drawn into wires with high efficiency and performance.
【参考中译】 高能束流-粉末添加剂制造(AM)过程中，由于加热冷却速度快，小孔不稳定，容易形成气孔缺陷，给航空零部件的高性能制造带来了巨大的挑战。采用能量密度较低的电弧作为热源可以有效地避免这些缺陷，但其匹配的原材料仅限于线材。本文提出了一种新型的磁场辅助粉末电弧添加剂制造方法(MFA-PAAM)，该方法将电弧热源和粉末原料相结合，以获得致密的金属零件。为了解决影响PAAM工艺稳定性的粉末飞溅问题，引入横向磁场(TMF)，通过调节电弧等离子体流动方向和电弧压力来解决粉末飞溅问题。用高速摄像机捕捉到了粉末在电弧加热下独特的熔化行为，其过程可概括为两个步骤：成球和熔池吸附。并利用自行研制的设备成功地制造出了成形良好、致密的Ti60高温钛合金壁件。薄壁构件的显微组织主要为篮状分布的α板条和少量残留在其边界的β片材。观察到了沿构筑方向的层状周期性分布，这主要与β相的含量和形貌不同。沿行进方向的平均极限抗拉强度和断裂延伸率分别为1003.2 Mpa和15.1%，而沿建筑方向的平均极限抗拉强度和延伸率分别为1009.3 Mpa和16.6%。两个方向的断裂形态均以韧性断裂为特征。MFA-PAAM技术在制造高效率和高性能的难以拉伸成线的材料方面显示出巨大的潜力。