Visual Testing (VT) Practice Exam

What is defined as the portion of base metal that has been affected by the heat of welding but not melted?

1. The fusion zone

2. The heat-affected zone

3. Both a and b above

4. None of the above

The correct answer is: The heat-affected zone

The heat-affected zone is defined as the portion of base metal that has been impacted by the heat generated during the welding process without actually melting. This area experiences changes in its microstructure and physical properties due to the thermal cycles associated with welding. Understanding this concept is crucial, as the heat-affected zone can exhibit altered strength, hardness, and ductility compared to the unaffected base metal. The differences may affect the overall integrity and performance of the welded joint. The fusion zone refers specifically to the area where the base metal has melted and solidified, which is a distinct area compared to the heat-affected zone. As such, the heat-affected zone is the correct choice as it captures the portion of the base metal influenced by heat without undergoing melting. Recognizing these zones and their characteristics is essential for predicting the performance and structural integrity of welded components.