Visual Testing (VT) Practice Exam

Which welding method would you typically use for joining metals at lower temperatures compared to melting them?

1. Fusion welding.

2. Brazing.

3. Soldering.

4. Arc welding.

The correct answer is: Brazing.

Brazing is the correct choice for joining metals at lower temperatures compared to melting them. This method involves using a filler metal that has a melting point above 450°C (842°F) but below that of the base metals being joined. During the brazing process, the base metals do not melt; instead, the filler metal flows into the joint by capillary action, bonding the metals together as it cools and solidifies. This is especially useful for joining dissimilar metals or when working with components that may be affected by the high heat of melting. Unlike fusion welding and arc welding, where the base metals are melted to form a joint, brazing allows for a lower-temperature operation, which helps to minimize warping and thermal stress in the workpieces. For context, fusion welding and arc welding both involve melting the base materials to create a joint, typically requiring significantly higher temperatures and resulting in a different metallurgical structure. Soldering, while also involving lower temperatures than welding, is generally used for electronics and plumbing, with a focus on softer filler metals than those used in brazing. Choosing brazing enables greater versatility and reduces thermal impact on the materials involved.