Is the welded pipe hot rolled or cold rolled?

Welded pipes, also known as welded steel pipes, are manufactured by rolling steel plates or strips into a tubular shape and then welding the edges together. This process typically involves flattening, crimping, welding, and leveling the material. There are two primary production methods for welded pipes: cold rolling and hot rolling.

Composition and Characteristics of Welded Pipes:

Welded pipes are predominantly made from black steel plates, with carbon and manganese as their main components. During the welding process, the composition of the welded joint changes, and chemical reactions occur between carbon and other elements. Consequently, the welded areas are generally more prone to corrosion compared to the non-welded sections.

Welded pipes are popular due to their lightweight, cost-effectiveness, high strength, and ease of processing. However, variations in the welding process and pipe composition can lead to some physical property deficiencies.

Differences Between Hot Rolling and Cold Rolling of Welded Pipes:

Hot Rolling:

Process: Hot rolling is conducted at high temperatures, which grants steel good plasticity and the ability to adapt to rapid deformations. This allows for the production of thick-walled welded pipes with a smooth surface.

Characteristics: The high-temperature process can alter the crystal structure of the material, potentially reducing fracture toughness and processing accuracy.

Cold Rolling:

Process: Cold rolling occurs at room temperature, maintaining high processing accuracy and preserving the material's toughness and ductility.

Characteristics: Although the production speed of cold-rolled pipes is slower and the cost is higher, these pipes exhibit excellent strength and toughness.

Application Differences Between Hot Rolling and Cold Rolling:

Hot Rolling: Due to its rapid production speed and smooth surface, hot-rolled welded pipes are widely used in construction, machinery, and the petroleum and chemical industries.

Cold Rolling: Cold-rolled welded pipes are preferred for manufacturing high-precision components such as those used in automobiles, electrical appliances, and precision instruments, owing to their superior strength and dimensional accuracy.

Summary:

This article provides an overview of the production processes and materials used in welded pipes, highlighting their characteristics and the distinctions between cold rolling and hot rolling methods. Understanding these factors helps in making informed decisions for selecting the appropriate type of welded pipe based on specific application needs and desired performance.