S45C Cold Drawn Steel Round Bar

Using standard-compliant S45C hot-rolled round steel as the raw material, the steel is first cut to a length suitable for subsequent processes using cutting equipment. Then, surface oxide scale, rust, and impurities are removed, laying the foundation for the cold drawing process.

The pretreated round steel is placed in a pickling tank to remove residual oxide scale. A dense phosphate film is then formed on its surface via phosphating treatment, which acts as a lubricant to minimize cold drawing resistance and protects the steel surface from damage.

The surface-treated round steel is fed into cold drawing equipment. With the extrusion and stretching action of the die, the steel undergoes plastic deformation at room temperature, achieving precise control over the outer diameter, roundness, and surface finish, thus improving product precision.

Due to plastic deformation, the cold-drawn steel develops internal stress and increased hardness. It is then heated to a specified temperature in an annealing furnace, held at that temperature for a set period, and slowly cooled to eliminate internal stress, reduce hardness, and restore the steel's toughness and processability.

The annealed round steel bars undergo finishing processes such as straightening, cutting, and grinding. Subsequently, they are subjected to dimensional measurement, surface inspection, and mechanical property testing to ensure compliance with standard requirements before being put into storage.

Cold drawing, performed at room temperature using a die, enables precise control over the diameter and roundness tolerances of the round bar, with a tolerance range far narrower than that of hot-rolled round bars. In most cases, no additional rough machining is required, directly meeting the dimensional requirements for assembly or finish machining and significantly shortening the production cycle.

Cold drawing avoids high-temperature oxidation, resulting in a smooth, clean surface free from defects commonly seen in hot-rolled counterparts, such as oxide scale, pitting, or cracks. It allows for direct surface treatments like electroplating, spraying, and carburizing, eliminating the need for pre-treatment processes such as grinding and rust removal, thereby reducing processing costs.

The work hardening effect of cold drawing significantly improves the material's yield strength and tensile strength while maintaining appropriate toughness and plasticity, avoiding issues of uneven microstructure caused by uneven cooling in hot-rolled round bars. Products from the same batch exhibit high performance consistency, making it suitable for components requiring high strength and stability.

The smooth surface and precise dimensions reduce tool wear during cutting operations, enhancing the efficiency of processes such as turning, drilling, and bending. Smaller cutting allowances also minimize material loss and improve material utilization.

Cold drawing is a room-temperature plastic working process, which prevents grain coarsening and microstructure segregation caused by uneven cooling in hot rolling. The uniform pearlite-ferrite microstructure ensures more balanced stress distribution in components under load, effectively reducing the risk of deformation and cracking due to local stress concentration during service.