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Manufacturing Process Of Cold-Rolled Stainless Steel Plate

Sep 19, 2024

Hot rolling is relative to cold rolling. Cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the crystallization temperature. In the previous article, we introduced hot-rolled stainless steel plates in detail. So, today, let's take a look at cold-rolled stainless steel plates!

What Is Cold-Rolled Stainless Steel Plate?

Cold-rolled stainless steel plate is a material produced by compressing and rolling stainless steel plates at room temperature. This processing technology can greatly improve the strength, surface quality and thickness accuracy of steel. Compared with hot-rolled stainless steel plates, cold-rolled stainless steel plates are thinner, smoother and have higher dimensional accuracy.

The cold rolling process can further process thicker hot-rolled stainless steel plates to thinner thicknesses while improving the structure and surface quality of the material. Usually, the thickness of cold-rolled stainless steel plates ranges from 0.5 mm to 3 mm, but there are also some ultra-thin materials with a thickness as low as 0.1 mm or less.

Basic Principle Of Cold Rolling:

The cold rolling process is carried out when the steel is not heated to the recrystallization temperature, so no obvious plastic deformation will occur during the cold rolling process. Cold-rolled plates are usually rolled multiple times to gradually reduce the thickness, so that the strength and hardness of the material can be improved.

In order to eliminate the internal stress generated during the cold rolling process, cold-rolled stainless steel plates usually need to be annealed to restore a certain toughness and ductility. At the same time, pickling treatment helps to remove impurities on the surface and improve the smoothness and corrosion resistance of the plate.

Characteristics Of Cold-Rolled Stainless Steel Plates:

High surface finish：

Cold-rolled stainless steel plates are rolled at room temperature and the production process is finely controlled, so the surface quality is very high. Cold-rolled stainless steel plates usually present a bright and smooth surface. After different surface treatment processes (such as 2B, BA, 8K, etc.), mirror effects or other decorative appearances can be achieved.

High dimensional accuracy：

The cold rolling process accurately controls the thickness and size of the plate through multiple rolling passes, so the thickness and width tolerances of cold-rolled stainless steel plates are very small and the dimensional accuracy is high.

Excellent mechanical properties：

After rolling at room temperature, the strength and hardness of cold-rolled stainless steel plates are improved compared to hot-rolled stainless steel plates. Cold processing optimizes the grain structure of the material and improves the tensile strength, yield strength and hardness of the material. Although cold rolling increases the strength of the material, it may also reduce its ductility, so it is necessary to balance the relationship between the two when using it.

Strong corrosion resistance：

Stainless steel itself has strong corrosion resistance. Cold-rolled stainless steel plate has a dense and smooth surface, which reduces the adhesion of pollutants and corrosive substances, further improving its corrosion resistance. Especially after surface treatment, its corrosion resistance is more significant in humid, acidic or alkaline environments.

Cold work hardening phenomenon：

Cold-rolled stainless steel plate undergoes hardening phenomenon due to the deformation of crystals during processing, which increases its strength but reduces its plasticity. Therefore, in some applications, cold-rolled plates need to be annealed to eliminate the work hardening effect and restore the plasticity and ductility of the material.

Manufacturing Process Of Cold-Rolled Stainless Steel Plate:

1.Raw material preparation:

Cold-rolled stainless steel plate is produced with hot-rolled stainless steel plate as the base material. The thickness of hot-rolled stainless steel plate is larger, and its thickness is further reduced through the cold rolling process.

2. Raw material cleaning:

Hot-rolled stainless steel plate will adhere to oxide scale and impurities during the rolling process, and the raw materials need to be cleaned before entering the cold rolling process. Common cleaning methods include pickling, alkaline washing, etc. to remove surface oxides, grease and other impurities to ensure a smooth surface of the plate during cold rolling.

For example: Pickling: Pickling is the use of acid (such as sulfuric acid, hydrochloric acid) to treat hot-rolled steel to remove the oxide scale on its surface. During the pickling process, the steel plate is immersed in acid, and the oxide scale is dissolved and removed. After the pickling is completed, the surface of the steel plate becomes bright and flat, ready for the subsequent cold rolling process.

3. Cold rolling process:

The cold rolling process is divided into multiple rolling passes, each of which thins the plate thickness and ensures uniform thickness by adjusting the roller pressure. Normally, cold-rolled stainless steel plates can be rolled to very thin thicknesses while maintaining high strength.

4. Intermediate annealing:

During the cold rolling process, the material will produce large internal stresses after multiple rolling passes. In order to reduce these internal stresses and prevent the material from breaking or deforming during further processing, intermediate annealing is usually performed. Intermediate annealing is usually carried out when rolling to the intermediate thickness, by heating the steel plate to the recrystallization temperature to restore the internal grain structure.

5. Continuous annealing or hood annealing:

The annealing process is divided into two types: continuous annealing and hood annealing. Continuous annealing is completed on the production line, through rapid heating and cooling, suitable for large-scale production. Hood annealing is to place the material in a closed hood furnace for a long time annealing. The annealing process can effectively eliminate work hardening and improve the plasticity and toughness of the material.

6. Surface treatment:

The cold-rolled stainless steel plate that has been annealed can be further surface treated. Common surface treatment methods include polishing, pickling, passivation, wire drawing, etc. to meet the needs of different application scenarios. Polishing can make the stainless steel surface brighter, and pickling can remove the oxide scale formed during the processing.

7. Final inspection and packaging:

After the production of the cold-rolled stainless steel plate is completed, we will conduct a strict quality inspection on it. The inspection items usually include thickness tolerance, surface quality, mechanical properties, etc. Qualified cold-rolled stainless steel sheets will be properly packaged to prevent damage during transportation. Our packaging methods include anti-rust paper, plastic film and wooden boxes.