AWS Welding Inspection and Testing Certification Practice Test

In welding terminology, what does the term 'fusion' refer to?

1. The process of melting base metal and filler metal

2. The alignment of two parts before welding

3. The final cooling stage of the weld

4. The condition of a weld after post-weld heat treatment

The correct answer is: The process of melting base metal and filler metal

The term 'fusion' in welding terminology specifically refers to the process of melting both the base metal and the filler metal to create a weld joint. This melting occurs at the edges of the base material and involves the filler material as it is introduced into the molten area. Successful fusion is essential for creating a strong bond within the welded joint because it ensures that the materials bind together seamlessly at a molecular level. In welding, achieving adequate fusion is critical for the integrity of the weld. Insufficient fusion can lead to defects such as lack of fusion, which compromises the strength and performance of the weld. Therefore, understanding fusion is a foundational concept in welding practices, influencing techniques and inspection criteria for quality assurance.