Abstract

All welded parts undergo aging once operated at elevated temperatures. Exposures of structures on elevated temperatures adversely affect the material performance and deteriorate the structure’s toughness. The welded part also develops the high risk of brittle fracture. In order to establish the fracture toughness, it is not always possible to remove the specimen from the service. Therefore, it is desirable to develop an in situ non-destructive testing (NDT) based on ultrasonic testing (UT) method along with advanced signal processing techniques. Ultrasonic testing is an extensively used Non-destructive testing technique that offers improved damage detection capability. The objective of the study is to found a quantitative relation between UT and mechanical properties of welded joint heat treated specimens. The data was acquired from the testing of weld specimens at different levels of temperatures through ultrasonic testing. There is a trend observed between the variation in the UT signal’s characteristics i.e. attenuation and the variation in the mechanical properties. The possible categorization of UT signal in terms of different thermal aging levels has also been explored using Hilbert Huang transform (HHT) on acquired UT signals. The experimental relationships will enable welded specimen toughness prediction solely through in situ ultrasonic testing while the specimen will remain in service.

中文翻译：

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使用超声波测试和 Hilbert Huang 变换对焊接低碳钢 (E-6013) 进行评估和表征

摘要

一旦在高温下运行，所有焊接部件都会老化。将结构暴露在高温下会对材料性能产生不利影响并降低结构的韧性。焊接部分也产生脆性断裂的高风险。为了确定断裂韧性，并不总是可以从使用中取出试样。因此，需要开发一种基于超声波检测（UT）方法以及先进的信号处理技术的原位无损检测（NDT）。超声波检测是一种广泛使用的无损检测技术，可提供改进的损坏检测能力。该研究的目的是发现 UT 与焊接接头热处理试样的机械性能之间的定量关系。这些数据是通过超声波测试在不同温度水平下测试焊接试样获得的。在 UT 信号特性的变化（即衰减）和机械特性的变化之间观察到了一种趋势。还使用 Hilbert Huang 变换 (HHT) 对获取的 UT 信号进行了根据不同热老化水平对 UT 信号的可能分类进行了探索。实验关系将使焊接试样的韧性预测仅通过原位超声检测，而试样将继续使用。还使用 Hilbert Huang 变换 (HHT) 对获取的 UT 信号进行了根据不同热老化水平对 UT 信号的可能分类进行了探索。实验关系将使焊接试样的韧性预测仅通过原位超声检测，而试样将继续使用。还使用 Hilbert Huang 变换 (HHT) 对获取的 UT 信号进行了根据不同热老化水平对 UT 信号的可能分类进行了探索。实验关系将使焊接试样的韧性预测仅通过原位超声检测，而试样将继续使用。