Heat Treatment of Metals

The students will learn the basics of heat treating metals. The terminology, process used in heat treatment and finally they will participate in properly heat treating low carbon with the “pack method”. Heat treating is a very critical aspect of the manufacturing process and very essential that a machinist has a basic understanding of the process.

Heat treatment one can alter the physical, and sometimes chemical, properties of a material. Heat treatment necessitates the use of heating or chilling, normally to extreme temperatures, to achieve the desired result such as hardening or softening of a material.

Heat treatment is defined as an operation or combination of heating and cooling of a metal or alloy in the solid state for the purpose of obtaining the desired changes in properties. The heat treatment includes. Heating the metal to a predetermined temperature. Holding the metal at that temp until the structure becomes uniform throughout the mass. Cooling at a predetermined rate to cause the formation of the desired change. Simple it is the process of heating (but never allowing the metal to reach the molten state) and cooling metal in a series of specific operations which changes or restores its mechanical properties.

Cutting, or even grinding on metal produces heat, which in turn has an effect on the structure of the metal. As a machinist, you need to understand the effect that heat treatment has on metals so you can attain the desired properties for a particular metal. You also need to know what methods can be used to restore a metal to its original
Condition.

Heat treatment makes a metal more useful by making it stronger and more resistant to
impact, or alternatively, making it more malleable and ductile. However, no heat-treating procedure can produce all of these characteristics in one operation; some properties are improved at the expense of others. For example, hardening a metal may make it brittle, or annealing it may make it too soft.

By the end of this lesson plan, the students will have learned and applied the concept of heat treating metals.