Soldering is performed at temperatures below 840 degrees Fahrenheit. Which process is described?

• A. Brazing
• B. Soldering
• C. Welding
• D. Annealing

Answer: (B)

Soldering uses a filler metal that melts at a temperature lower than the metals being joined, and the base metals stay solid while the molten filler flows into the joint by capillary action. Saying the process occurs at temperatures below 840°F fits soldering because the filler alloys used for soldering melt far below that threshold, while brazing and welding operate at higher temperatures and/or involve melting the base metals. Annealing is just a heat-treatment to soften or relieve stress, not a joining method. In practice, solders like tin-lead or tin-silver-copper melt in the 350–450°F range, well under 840°F, which is why this description points to soldering.