Steel fibers refer to fibers produced by cutting fine steel wires, cold-rolling steel strip shearing, steel ingot milling, or rapid cooling of molten steel, with a length-to-diameter ratio (the ratio of fiber length to its diameter, or the diameter of an equivalent circular cross-sectional area when the fiber cross-section is not circular) ranging from 40 to 80.

Steel fiber performance varies with different production methods. Although steel fiber has been around for a short time, its applications are becoming more widespread and the variety is increasing.

Steel fibers are primarily used in the production of steel fiber reinforced concrete, and any steel fiber produced by any method can enhance the strength of concrete.

The reinforcing effect of fibers primarily depends on the matrix strength (fm), the length-to-diameter ratio of the fibers (the ratio of steel fiber length l to diameter d, i.e., l/d), the volume fraction of the fibers (the percentage of volume occupied by steel fibers in steel fiber concrete), the bond strength between the fibers and the matrix (τ), and the distribution and orientation of the fibers within the matrix (η). When steel fiber concrete fails, it is usually due to the fibers being pulled out rather than broken, thus improving the bond strength between the fibers and the matrix is one of the main controlling factors for enhancing the reinforcing effect.

Concrete reinforced with steel fibers exhibits significantly improved properties such as compressive strength, tensile strength, flexural strength, impact strength, toughness, and impact toughness.