Investigating and interpreting failure analysis of high strength nuts made from nickel-base superalloy
Investigating and interpreting failure analysis of high strength nuts made from nickel-base superalloy
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DOI：
10.1016/j.engfailanal.2016.12.018
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发表时间：
2017-04-01
影响因子：
4
通讯作者：
Pilarczyk, Robert T.
中科院分区：
文献类型：
--
作者：
Andrew, Dallen L.;Carlson, Scott S.;Pilarczyk, Robert T.
美国空军经历了安装在A-10飞机上的三个独立的零时、220 ksi Inconel 718螺母的故障。在调查过程中，另一个螺母断裂发生在一个业务喷气机。这种螺栓/螺母组合的使用时间非常少，远远低于预期的使用寿命。对采购数据的彻底审查显示，所有不合格的螺母都成功地通过了批量测试。这导致人们担心，目前的采购测试要求不足以识别可能在使用中意外失效的螺母。另一个令人费解的因素是，有证据表明，四个失败的螺母中有一个被卡住了。为了确定潜在的未来螺母断裂的风险，开发并执行了一种新的实验方法，以评估所有220 ksi Inconel 718螺母制造商和A-10飞机上使用的尺寸的强度和完整性。这些实验的目的是有一个组合的柄和预加载，并推动螺母到极端极限，目的是揭示低于标准的能力。失效时的扭矩量和螺母移动的距离是性能的两个度量。除了这些实验外，还进行了严格的冶金评估，以确定断裂和测试螺母内是否存在任何冶金异常。测量的扭矩值，然后用于相关的冶金评价和结果。这种新的测试方法提供了定量数据，以确定制造过程对螺栓/螺母组合性能的影响，并证明仅表征微观结构可能无法提供相应螺母性能的证据。(C)2017爱思唯尔有限公司版权所有。
The United States Air Force experienced failures of three separate zero-time, 220 ksi Inconel 718 nuts that were installed on A-10 aircraft. During the investigation, another nut fracture occurred on an operational jet. This bolt/nut combination had very few service hours on it and was well below the expected service life. A thorough review of the procurement data revealed that all the failed nuts had passed lot tests successfully. This led to concerns that the current procurement test requirements were insufficient to identify nuts that could unexpectedly fail in service. Another factor convoluting the situation was evidence of shanking on one of the four failed nuts. In order to determine the risk for potential future nut fractures, a novel experimental approach was developed and executed to evaluate the strength and integrity for all 220 ksi Inconel 718 nut manufacturers and sizes utilized on the A-10 aircraft. These experiments were designed to have a combination of shanking and pre-load and push the nuts to extreme limits with the intent of uncovering sub-par capability. The amount of torque at failure and the distance traveled by the nut were the two measures of performance. In addition to these experiments, a rigorous metallurgical evaluation was performed to determine if there were any metallurgical anomalies within the fractured and tested nuts. The measured torque values were then used to correlate to the metallurgical evaluations and the results are presented. This novel testing method provided quantitative data to determine the impact of the manufacturing process on the performance of the bolt/nut combination and demonstrated that a characterization of the microstructure alone may not provide evidence of corresponding nut performance. (C) 2017 Elsevier Ltd. All rights reserved.