What types of expansion are encountered during welding?

What types of expansion are encountered during welding?

• A. Solid, transitional and fluid
• B. Thermal, magnetic, electrical
• C. Elastic, plastic, creep
• D. Gas, liquid, solid

Answer: (A)

When metal is heated in welding, expansion happens in three distinct ways that match its state. First, while the metal is still solid, it expands thermally as the atoms vibrate more and take up more space. Then, as it reaches the melting range, it goes through a solid-to-liquid transition, which involves a volume change due to the phase change. Finally, once molten, it expands as a fluid—the liquid metal occupies more volume than the solid did at the same temperature. So the three expansion types are solid-state expansion, expansion during the solid-to-liquid transition, and fluid expansion in the molten pool. (Other options describe different ideas like states of matter or other kinds of deformation, but they don’t capture these expansion modes.)

When metal is heated in welding, expansion happens in three distinct ways that match its state. First, while the metal is still solid, it expands thermally as the atoms vibrate more and take up more space. Then, as it reaches the melting range, it goes through a solid-to-liquid transition, which involves a volume change due to the phase change. Finally, once molten, it expands as a fluid—the liquid metal occupies more volume than the solid did at the same temperature. So the three expansion types are solid-state expansion, expansion during the solid-to-liquid transition, and fluid expansion in the molten pool. (Other options describe different ideas like states of matter or other kinds of deformation, but they don’t capture these expansion modes.)