Which test method is primarily used to test fillet welded joints?

The nick break test is specifically designed to evaluate the integrity of fillet welded joints. This method involves making a notch or nick in the weld area, which is then subjected to bending. During the process, it allows for the observation of the weld's internal structure and quality, providing insights on any defects or issues such as lack of fusion, inclusions, or porosity that may not be visible through visual inspection.

This testing method is particularly effective for fillet welds because it can assess the soundness of the joint by exposing the weld's cross-section, enabling evaluators to ascertain if the weld has been properly executed and can withstand the necessary load requirements. The nick break test is also relatively simple and provides immediate feedback on the weld quality.

The other methods, while useful in their own right, serve different purposes or apply to different types of welds. For instance, visual inspection is limited to surface defects and cannot assess internal integrity. Guided bend tests and tensile tests evaluate joint strength and ductility but do not specifically address the unique characteristics of fillet welds like the nick break test does. Thus, for fillet welded joints, the nick break test is the most appropriate method to confirm quality and reliability.