Ultrasonic testing of selectively laser melted parts

• Main Author: Teo, Zhi Jie
• Other Authors: Wong Chee How
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/71456
• Institution: Nanyang Technological University

Additive manufacturing (AM) has revolutionise the manufacturing industry in recent years. It minimises the time and cost as compared to conventional manufacturing procedures. AM also accommodates to consumer’s rapid changing of choices in products. The key concept of AM is the layer-by-layer of material addition process which differs from conventional methods of subtracting material. As AM emerges as an upcoming trend in current world technology, several procedures and process parameters are still lack in the area of standardisation. These limitations remained as a challenge for industries to overcome and produce parts that are free from defects. Porosity level of the end product is of the greatest importance to the manufacturers. It discloses the material properties and microstructure of the end product. Thus, all the industries have to make sure that the parts fabricated with AM are structurally safe for use in different types of operation. To address the issue, non-destructive testing (NDT) provides the best solution to detect the internal defects without destroying the product itself. NDT characterises the 3D printed stainless steel by providing information about the material properties. Location and sizing of defects can also be determined by various NDT methods. After comparing advantages and disadvantages of other NDT methods, ultrasonic testing (UT) is proved to be the most desirable method for detecting flaws. UT is also being used for quality control in the prevention of part failure. The part’s integrity and functionality must be ensured in order to achieve this. With more industries adopting AM technology, ASTM F42 is set up to develop standards for AM technology, in the areas of materials, operating procedure, processing parameters and testing methods. Thus, this project will investigate the use of NDT, specifically ultrasonic testing (UT), on additively manufactured metal parts for flaw detection. This project will also compare the microstructure and properties of the three-dimensional (3D) printed and conventional manufactured metal specimens by the use of a microscope. Specimens with various self-induced internal discontinuities will also be used for defect detection. It will then conclude the smallest detectable defect size that UT is able to detect in the 3D printed stainless steel specimens.