What occurs when a metal undergoes deformation in machining?

When a metal undergoes deformation in machining, it changes shape permanently. This is a fundamental characteristic of plastic deformation, which occurs when the applied stress on the material exceeds its yield strength. In this state, the atomic structure of the metal is altered in such a way that it does not return to its original shape once the external force is removed. This property is crucial in machining processes, where precision and specific shapes are desired after the cutting tool interacts with the material.

The permanent shape change can affect the material's properties, such as its microstructure, which may lead to enhanced performance characteristics in some cases, but the key outcome is the permanent alteration of form. For example, when metal is cut, bent, or otherwise shaped, the new configuration of its atoms will remain even after the machining forces are removed, which aligns with the definition of plastic deformation.