What happens to metal tools when heat is applied?

When heat is applied to metal tools, they typically become softer. This phenomenon is known as thermal softening, which occurs because the introduction of heat increases the kinetic energy of the metal's atoms. As a result, the atomic structure of the metal becomes more malleable and ductile, making it easier to deform. This characteristic is especially important in processes like forging and machining, where metals are often heated to allow for shaping without breaking.

The process can also lead to a reduction in hardness due to the alteration of the metal's microstructure, particularly in heat-treated steels. Heat treatment can relieve internal stresses and promote dislocations, which are mechanisms that allow the metal to deform more easily under stress.

In contrast, some metals can become harder upon cooling after being heated, depending on the specific metal and the treatment it undergoes. However, in general terms, the immediate effect of applying heat is a decrease in hardness, leading to a softer state. This property is crucial for metallurgical applications, as it allows for processes such as welding or reshaping of tools.