Stainless steel is a relatively common material in real life. It is widely used in building materials, industry and food industry. So, do you know the classification of stainless steel? According to different production processes, stainless steel can be divided into cold-rolled stainless steel and hot-rolled stainless steel. Today we will first learn about cold-rolled stainless steel!
1. What Is Cold Rolled Stainless Steel?
Cold-rolled stainless steel is a hot-rolled stainless steel sheet processed into a thinner product through a multi-pass rolling process at room temperature. The cold rolling process can not only make the product thickness more precise, but also make the product surface quality better and have higher mechanical properties.
2. What Is The Production Process Of Cold Rolled Stainless Steel?
The production process of cold-rolled stainless steel includes pickling, cold rolling, annealing, leveling and dressing. Each step has its specific purpose and process requirements to ensure the quality and performance of the final product.
Pickling:
Pickling is an important step in removing oxide scale on the surface of hot-rolled stainless steel. Acid solutions such as sulfuric acid, hydrochloric acid or nitric acid are usually used to dissolve the oxide scale through chemical reactions to expose a smooth metal surface. The surface of the pickled stainless steel is clean and free of scale, ready for the subsequent cold rolling process.
Cold rolled:
The pickled stainless steel undergoes multiple rolling processes at room temperature to gradually reduce the thickness. Deformation hardening during cold rolling will increase the hardness and strength of the material, but reduce the plasticity. Therefore, cold-rolled stainless steel needs to be annealed to restore its plasticity and toughness.
Annealing:
Annealing is to heat cold-rolled stainless steel to a certain temperature (usually between 700°C and 800°C) and then slowly cool it to eliminate the internal stress and hardening phenomenon generated during the cold rolling process. Annealed stainless steel has good plasticity and toughness, making it easy for subsequent processing and use.
Leveling and trimming:
The annealed stainless steel undergoes leveling and trimming processes to ensure uniform thickness and smooth surface. Leveling is to stretch and flatten stainless steel plates through rolling equipment to eliminate waves and unevenness. Trimming is trimming the edges to ensure that the dimensional accuracy meets the requirements.
3. What Is The Appearance Color Of Cold Rolled Stainless Steel?
Cold-rolled stainless steel has a smooth surface and a silvery white luster due to processes such as pickling, cold rolling and annealing. Its surface quality is high and there are no obvious oxide scales and defects. The surface treatment processes of cold-rolled stainless steel include 2B, BA, No.4, HL and other types.
| Surface | Features | Application |
| 2B | The 2B surface is a smooth, slightly silvery matte surface obtained by annealing, pickling and leveling cold-rolled stainless steel. 2B surface has good corrosion resistance and processing performance. | food industry, medical equipment, building decoration |
| BA | The surface of BA is made of cold-rolled stainless steel and annealed in a bright annealing furnace. The surface is bright, flat and has a mirror effect. | architectural decoration, household appliances, kitchen equipment |
| No.4 | The surface of No.4 is cold-rolled stainless steel that has been mechanically polished and has uniform fine sand patterns on the surface. | architectural decoration, elevator panels, household appliances |
| HL | HL surface (Hairline) is cold-rolled stainless steel that has been mechanically polished in a long strip, with a uniform hairline pattern on the surface. | architectural decoration, automobile interiors, elevator panels |
4. Specifications Of Cold-Rolled Stainless Steel Plates:
The thickness of cold-rolled stainless steel plates usually ranges from 0.3mm to 3mm, the width ranges from 600mm to 1500mm, and the length can be customized according to customer needs. Due to its thin thickness, cold-rolled stainless steel plates are suitable for manufacturing precision parts and high-demand decorative materials.
- Common specifications:
Common specifications of cold-rolled stainless steel plates include thicknesses of 0.4mm, 0.5mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm and other types, and widths of 1000mm, 1219mm, 1500mm and other sizes. Cold-rolled stainless steel plates can also be customized in specific lengths and widths according to different application requirements.
- Surface quality requirements:
The surface quality requirements of cold-rolled stainless steel plates are relatively high, including surface finish, flatness, no scratches, no cracks, no oxide scale, etc.
5. Application Of Cold-Rolled Stainless Steel:
- Household appliances: shells and linings of refrigerators, washing machines, microwave ovens, etc.
- Auto parts: body panels, structural parts, exhaust systems, etc.
- Medical devices: surgical instruments, medical equipment, implants, etc.
- Architectural decoration: curtain walls, doors and windows, stair handrails, elevator panels, etc.
6. Physical Properties Of Cold Rolled Stainless Steel
Cold-rolled stainless steel has higher hardness and strength due to cold working, but its plasticity and toughness are reduced. Through annealing treatment, its plasticity and toughness can be restored, giving it good comprehensive mechanical properties.
- Hardness and Strength
Cold-rolled stainless steel has higher hardness and strength, especially cold-hardened stainless steel that has not been annealed. Its tensile strength can reach more than 600MPa, and its hardness can reach more than HV200. After annealing, the hardness and strength of cold-rolled stainless steel are reduced, but the plasticity and toughness are improved.
- Elongation
The elongation of cold-rolled stainless steel is low, especially that of chilled stainless steel, where the elongation is usually around 10%. After annealing, the elongation of cold-rolled stainless steel can be increased to more than 30%, and it has good formability and processing performance.
