Deformed bars, also known as reinforcement bars or rebars, are steel bars with surface deformations that provide enhanced bonding with concrete. These bars are commonly used in construction projects to reinforce concrete structures and increase their strength and durability. The deformations on the surface of the bars, such as ribs or patterns, create a mechanical interlock between the steel and the surrounding concrete, preventing slippage and improving load transfer.

Deformed bars are typically made from carbon steel and undergo a process called hot rolling, which involves subjecting the steel to high temperatures and shaping it while it is malleable. This process imparts the deformations on the surface of the bars, improving their adhesion properties when embedded in concrete.