A Review of Non-Destructive Testing (NDT) Techniques for Defect Detection: Application to Fusion Welding and Future...

Area of Science:

• Materials Science and Engineering
• Manufacturing Technology
• Quality Control

Background:

• Defects such as porosity, cracks, deformation, and lack of fusion commonly occur in Wire and Arc Additive Manufacturing (WAAM) and fusion welding processes.
• These defects significantly degrade mechanical properties and can lead to component failure during service.
• Non-destructive testing (NDT) methods are essential for identifying these defects without damaging the workpiece.

Purpose of the Study:

• To provide a comprehensive overview of various NDT techniques applicable to WAAM and fusion welding.
• To present novel research, operating principles, and required equipment for these NDT methods.
• To highlight the capability of NDT in detecting minimum defect sizes for quality assurance.

Main Methods:

• Review of established and novel NDT techniques including laser-ultrasonic, acoustic emission, optical emission spectroscopy, laser-induced breakdown spectroscopy, laser opto-ultrasonic dual detection, and thermography.
• In-process defect detection via weld current monitoring with an oscilloscope.
• Compilation of minimum detectable defect sizes from academic research and industry tests.

Main Results:

• Detailed presentation of multiple NDT techniques for defect detection in WAAM and fusion welding.
• Information on the operating principles and equipment necessary for each NDT method.
• Quantification of the minimum defect sizes identifiable by different NDT approaches.

Conclusions:

• NDT methods are vital for recognizing and characterizing defects in WAAM and fusion welding.
• The application of these NDT techniques facilitates the production of high-quality components.
• This overview serves as a guide to selecting appropriate NDT methods for additive manufacturing and welding quality assurance.