Cold Deformation of Metals
Metals are typically heated to a high temperature in order to be pliable enough to be formed by various metalworking techniques. When metal is heated it is said to be annealed, so that it becomes softer and easier to work with. However, some metalworking techniques make use of cold deformation to shape and form the metal, instead of relying on high heat. Cold deformation describes any forming of a metal workpiece at a temperature that is below its recrystallization temperature. This means the metal will actually form without being heated up first.
Cold deformation is usually used when the advantages of a material’s properties at room temperature outweighs the advantage of working with the material at a higher temperature. Cold deformation can result from plastic deformation, which is when a material undergoes permanent deformation instead of regaining its original shape when it is no longer subjected to any kind of force. There are several different methods of cold deformation, each of which has its own advantages and drawbacks.
Forging is a method of metalworking that uses the hammering pressure to create a desired shape. Forging works well on materials with high levels of ductility and malleability—this includes most aluminum and steel alloys. The choice of forging technique depends on the desired product shape and size, as well as the material used. Closed die forging is the most common technique used for forging metals, as the dies used are designed to match the desired product shape. The disadvantage of using forging is that it is a labor intensive process, and it can be difficult to achieve complex geometries or intricate detail with this technique.
Rolling is a metalworking process where the workpiece is deformed through the use of two rotating cylindrical rolls. This is a “cold” process because the metal is rarely heated above room temperature. Rolled metals can have improved flatness and surface finish, as well as improved mechanical properties. That said, this process is limited on versatile to shape and form the metal, and it can be difficult to make complex geometries with this technique. However, rolled metals are often used when forming large plates or sheets, as this process increases the surface area which can help reduce the cost.
Extrusion is another metalworking process that relies on cold deformation. With this process, a metal rod, bar, or other material is put under pressure as it is forced through a die with a smaller cross-section. This reduces the cross-section of the material and can create complex geometries and intricate details. This process is often used for creating beams, pipes, and many other types of shapes. Even though extrusion is a cold process, it is important to note that the shape of the die used to extrude the material will greatly influence the shape and size of the finished product.
Finally, stamping is another type of metalworking process that relies on cold deformation. This process is used when complex shapes or detailed designs need to be created. As with extrusion, the shape of the die used will influence the shape of the finished product. Stamping can also be used to create parts with very thin walls or intricate details. However, this process is generally not used for parts with large surface areas, as this can negatively impact the structural integrity of the finished product.
These are just a few of the metalworking processes that can be used to shape and form metal without relying on high temperatures. Cold deformation can provide many advantages; it is a cost-effective process that can produce parts with higher quality and improved properties. Even though some of the processes mentioned require more specialized equipment and labor, cold deformation can still be a great solution for many applications.
