Visual Testing (VT) Practice Exam

What process uses a filler metal with a liquidus state that does not exceed 449 °C (840 °F) and does not melt the base material?

1. SMAW

2. Brazing

3. Soldering

4. Resistance welding

The correct answer is: Soldering

The process that utilizes a filler metal with a liquidus temperature not exceeding 449 °C (840 °F) while ensuring that the base material does not melt is soldering. Soldering is a technique used to join electronic components and mechanical parts by melting a filler metal, known as solder, which is typically composed of tin and lead or lead-free alloys. The solder is melted and flows into the joint between components, creating a conductive and mechanical bond upon cooling. Importantly, the melting temperature of solder is specifically designed to be lower than that of most base materials, allowing for effective joining without damaging them. In contrast, brazing involves filler metals that have melting points above 450 °C (840 °F), which can potentially affect the properties of the base materials. Similarly, shielded metal arc welding (SMAW) and resistance welding involve higher temperatures to create welds, which can melt the base materials, unlike soldering where the base material remains intact.