Cold Rolling Steel

Overview of Cold Rolling

Cold rolling is a rolling process that is carried out at room temperature (or slightly above room temperature). It uses hot-rolled steel coils as raw materials and undergoes continuous cold deformation rolling after pickling to remove oxide scales. The finished products are called rolled hard coils. Due to the cold work hardening caused by continuous cold deformation, the strength and hardness of rolled hard coils increase, while the ductility and plasticity indicators decrease, making them less suitable for stamping applications but ideal for parts requiring simple deformations.

Definition

Cold rolling (Cold Rolling) refers to the re-processing of hot-rolled steel plates or strips under room temperature or slightly above room temperature conditions. This process does not change the chemical composition of the material but alters its physical properties, such as strength and hardness.

Applications

Cold-rolled products are widely used in various fields, including automobile manufacturing, electrical products, railway vehicles, aviation, precision instruments, food cans, and more. Their high hardness and strength characteristics make them ideal materials for manufacturing parts requiring high strength and hardness.

Classification

Cold-rolled products have multiple classifications based on different standards and processing methods. Here are some common classifications:

  1. By Processing Method:
    • Longitudinal rolling: Rolling along the length direction of the steel material.
    • Transverse rolling: Rolling along the width direction of the steel material.
  2. By Product Type:
    • Hot-rolled pickled coils: Raw materials for cold rolling, subject to pickling to remove oxide scales.
    • Rolled hard coils: The main product of cold rolling, exhibiting high hardness and strength.
    • Cold-rolled thin steel sheets (cold sheets): Cold-rolled steel sheets with a thickness of less than 4mm, featuring smooth surfaces and excellent quality.
    • High-quality cold-rolled thin steel sheets: For example, deep-drawn cold-rolled sheets made from low-carbon quality steel 08A1, possessing excellent processing properties.

Common Steel Grades

There are various steel grades for cold-rolled steel, and here are some common grades:

  • Q195: A commonly used grade for cold-rolled steel sheets, boasting good cold workability and weldability.
  • SPCC: A grade for cold-rolled low-carbon steel sheets, renowned for its excellent surface quality and processing performance, widely applied in home appliances, automobiles, electronics, and other industries.
  • Q235: Although primarily used for hot rolling, it is also employed for cold rolling in certain specific cases, owing to its good comprehensive mechanical properties.

Please note that the choice of steel grades depends on specific application scenarios and requirements. The grades listed above are only a fraction of the numerous cold-rolled steel grades available, and actual usage requires selection based on specific conditions.