Advantages and Disadvantages of Cold-Drawn Steel and Hot-Rolled Steel

I. Differences in Processing Principles

• Hot-rolled steel: Steel billets are heated to above the recrystallization temperature (usually over 800°C) and rolled into shapes using rolling mills. The steel remains in a high-temperature plastic state during processing.

• Cold-drawn steel: Using hot-rolled steel as raw material, it is forced through dies at room temperature to reduce the cross-section and increase length, belonging to cold working processes.

II. Comparison of Advantages and Disadvantages

1. Dimensional Accuracy and Surface Quality

2. Mechanical Properties

• Hot-rolled steel:

  • Advantages: Good ductility, high toughness, low internal stress, and resistance to brittle fracture, making it suitable for withstanding impact loads (e.g., building steel structures).

  • Disadvantages: Lower strength (tensile strength around 300-500MPa) and hardness (HB100-150).

• Cold-drawn steel:

  • Advantages: High strength (tensile strength up to 600-1000MPa), high hardness (HB150-300), and good wear resistance, ideal for load-bearing components (e.g., automotive drive shafts).

  • Disadvantages: Poor toughness, increased brittleness, and susceptibility to fracture under impact; residual internal stress may cause later deformation.

3. Processing Cost and Efficiency

• Hot-rolled steel:

  • Advantages: High processing temperature improves steel plasticity, reducing rolling resistance. It has low energy consumption, high production efficiency, and lower overall costs.

  • Disadvantages: Requires subsequent processing (e.g., cutting, grinding), increasing additional costs.

• Cold-drawn steel:

  • Advantages: Can be used directly, reducing secondary processing costs.

  • Disadvantages: Cold working requires overcoming high deformation resistance, leading to high energy consumption, slow processing speed (long time per piece), and 30%-50% higher costs than hot-rolled steel.

4. Material Utilization and Shape Limitations

• Hot-rolled steel:

  • Advantages: Suitable for large-sized products (e.g., round steel with a diameter over 500mm) and thick-walled, large components.

  • Disadvantages: Oxide scale on the cross-section causes material loss, with a utilization rate of about 80%-85%.

• Cold-drawn steel:

  • Advantages: No oxidation loss, with a material utilization rate of over 95%; capable of processing complex cross-sections (e.g., hexagonal steel, special-shaped steel pipes).

  • Disadvantages: Limited by cold working deformation, it is usually small-sized (diameter ≤100mm) and difficult to process thick-walled parts.

5. Suitability for Application Scenarios

• Hot-rolled steel is preferred for:

  • Large-sized, high-toughness, low-cost needs, where subsequent processing is acceptable.

  • Examples: Building structures (I-beams, channel steels), pipeline engineering (seamless steel pipes), and large machinery bases.

• Cold-drawn steel is preferred for:

  • High precision, high strength, and smooth surface requirements, with tolerance for higher costs.

  • Examples: Precision mechanical parts (bolts, bearing shafts), automotive components (shock absorber piston rods), and slender rods in instruments.

III. Summary and Selection Recommendations

• Choose hot-rolled steel when large sizes, high toughness, low costs, and acceptance of post-processing are required.

• Choose cold-drawn steel when high precision, high strength, smooth surfaces, and higher costs are acceptable.