How do dislocations allow metals such as steel to be shaped?

In metallurgy, metals like steel are shaped through the process of plastic flow, which is fundamentally enabled by the generation and movement of line defects known as dislocations.12

These dislocations exist within the crystal structure of the metal. When external stress is applied—such as during forging, rolling, or drawing—these dislocations move along specific slip planes. This microscopic movement allows the atomic lattice to shift, enabling the material to deform plastically rather than fracturing.21

While the motion of these defects allows for shaping, it also dictates the material's strength. As a metal is deformed, the number of dislocations increases, and they begin to intersect and form tangles. These tangles act as obstacles that inhibit further slip, a phenomenon known as work hardening, which increases the metal's hardness and yield stress. Consequently, while dislocations are the mechanism that permits shaping, their interaction and accumulation are what ultimately strengthen the finished steel product.23