Which statement about brazing is true?

• A. The bond is created by capillary action.
• B. The joint is formed by melting the base metals.
• C. Brazing temperatures are below 600 degrees Fahrenheit.
• D. No filler metal is used.

Answer: (A)

In brazing, the joint is formed when a filler metal is melted and drawn into the gap between the base metals by capillary action, while the base metals themselves stay solid. The capillary flow wets the surfaces and fills the joint, creating a continuous bond as the filler metal cools and solidifies. This is why the statement about capillary action is the true description of how brazing bonds are made. The other ideas don’t fit: melting the base metals would be welding, not brazing; brazing temperatures are well above 600 °F—most filler metals melt in the higher range needed to flow into the joint; and brazing uses a filler metal, so no filler metal is not correct.