Millwright Level 1 Practice Exam

When the grain structure opens up in braze welding, what phenomenon can occur?

1. Tinning

2. Hardening

3. Soaking

4. Fusing

The correct answer is: Tinning

In braze welding, when the grain structure opens up, it typically leads to a process known as tinning. Tinning occurs when molten filler metal is drawn into the base metal due to capillary action, which fills the gaps in the surface. This process is important because it enhances the adhesion and overall strength of the joint. As the grain structure opens, it allows for better penetration of the filler metal, which ultimately creates a more robust bond. The opening of the grain structure can facilitate a chemical reaction that helps the brazing material bond effectively with the base metal, thus promoting a strong, reliable connection. This understanding underscores the significance of the grain structure in the effectiveness of braze welding, particularly in applications where joint integrity is crucial.