Brazing involves heating materials in the presence of filler metal above which temperature?

Brazing is a joining process that requires heating the base metals to a temperature that exceeds 840 degrees Fahrenheit (450 degrees Celsius) while using a filler metal that has a melting point above this temperature and below that of the base metals. When the base metals reach this sufficient temperature, the filler metal can flow into the joint by capillary action, allowing for a strong bond to form as the material cools and solidifies.

This process is crucial because if the temperature remains below this threshold, the filler metal will not properly flow and adhere to the base materials, which could compromise the integrity of the joint. The choice of 840 degrees Fahrenheit as the critical temperature is widely recognized in the brazing standards and practices, thereby making it the correct answer.

Understanding this temperature threshold is essential for effective brazing, as it ensures the successful joining of materials without compromising their structural properties.