When a steel plate is severely bent, it may partially return to its original shape, but it remains permanently bent. This is called “plastic deformation” and the characteristic of not returning to the original shape is called “plasticity”.

Automotive body panels such as fenders, hood, roof panel and others are press formed into each required shape from large steel sheets. In this way, the characteristic that the shape of an object remains changed after a pressure is applied is plasticity. It is also possible to change the shape of an object by pulling (tension strength) or pressing it. The deformation caused by pulling is called “ductility” and the one by pressing is called “malleability”. The result of ductile deformation is an elongation and the one of pressing deformation is compression.