Red Seal Tool and Die Maker Practice Exam

What characteristic typically increases as a material is worked at higher temperatures during hot working?

1. Strength

2. Ductility

3. Hardness

4. Toughness

The correct answer is: Ductility

As a material is worked at higher temperatures during hot working, a key characteristic that typically increases is ductility. At elevated temperatures, the atoms in the material have more thermal energy, allowing them to move more freely. This increased mobility facilitates slip and dislocation movement, which are mechanisms that enable plastic deformation without fracture. Consequently, the material can undergo larger amounts of deformation before breaking, resulting in enhanced ductility. In contrast, other characteristics such as strength and hardness generally tend to decrease when a material is hot worked due to mechanisms like recrystallization, which reduces the dislocation density and strengthens the structure at lower temperatures. Toughness, defined as the ability of a material to absorb energy and plastically deform without fracturing, can be influenced by temperature, but it does not specifically indicate an increase in hot working conditions compared to ductility. Thus, the most accurate and relevant characteristic that increases during hot working is ductility.