Non-destructive evaluation of wire arc additively manufactured samples with surface roughness

• Main Author: Wee, Adwin Hong Shiun
• Other Authors: Fan Zheng, David
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Wire arc additive manufacturing; Non-destructive evaluation (NDE); Ultrasonic testing; Surface roughness
• Online Access: https://hdl.handle.net/10356/176722
• Institution: Nanyang Technological University

Wire Arc Additive Manufacturing (WAAM) is a type of Metal Additive Manufacturing (MAM) method that uses welding technology to fabricate 3D components. It is a cost-effective method to producing large metallic components due to its high deposition rate. During fabrication, defects such as delamination and cracks may be introduced on the surface or within the component. Such defects affect the performance of the components. As such, inspection of the fabricated components is necessary. Non-Destructive Evaluation (NDE) methods, namely Ultrasonic Testing (UT), can be used to detect the defects. However, there is a lack of inspection guidelines related to WAAM. Thus, there is a need to study UT on WAAM components to promote WAAM adoption in the industry. The wavy surface texture of WAAM components may pose a challenge for UT due to poor coupling and the interaction between the soundwaves and the wavy surface. Hence, the Immersion Ultrasonic Testing method was used for the project to reduce the difficulties caused by poor coupling. Thus, the focus of the project was to study the interaction between the soundwaves and the wavy surface so as to determine the defect detectability of the Immersion Ultrasonic Testing method on WAAM samples. Firstly, the most optimal frequency was determined for the given samples on a typical Immersion Ultrasonic Testing setup. Next, defects in the form of Flat Bottom Holes (FBH) were introduced into the samples. Afterwards, face milling was performed on the surface of the samples. Lastly, a comparison of the UT inspection before and after the milling. The results show that the Immersion Ultrasonic Testing method is a possible inspection method. However, postprocessing to the As-Fabricated surface should be done to significantly improve the defect detachability, as the defect echoes were more distinct after milling. With the results, the Immersion Ultrasonic Testing method with a suitable postprocessing technique on the As-Fabricated surface of the inspected component can be applied in an industrial setting to inspect for defects. However, more studies on UT and WAAM should be performed to develop a new specialized method that improves defect detachability and better complements WAAM technologies.