The difference between cold drawn seamless steel tubes and hot-rolled seamless steel tubes

There are significant differences between cold drawn seamless steel tubes and hot-rolled seamless steel tubes in multiple aspects. The following are the main differences summarised from authoritative sources:

1. Different manufacturing processes

Cold drawn seamless steel tube: made through multiple drawing and annealing treatments. The specific process is to pass the steel billet through a circular hole of a certain specification, gradually reducing the tube diameter and increasing the tube wall thickness during multiple drawing processes.

Hot rolled seamless steel tube: made through high-temperature rolling process. The specific process is to heat the steel billet in a heating furnace to above the recrystallization temperature, and then continuously roll it through multiple sets of rollers, gradually deforming and thinning the steel ingot, and finally forming seamless steel tubes of the required specifications.

2. Different materials and characteristics

Cold drawn seamless steel tube: usually made of high carbon steel or alloy steel, with high strength, hardness, and fatigue resistance, but relatively poor toughness.

Hot rolled seamless steel tube: made of low carbon steel or low alloy steel, with lower strength and hardness, but better toughness, and easy processing and welding.

3. Different application fields

Cold drawn seamless steel tube: mainly used for manufacturing high-precision, high-pressure, high-temperature, and special medium transportation pipelines and mechanical parts, such as automotive transmission shafts, turbine engines, high-pressure vessels, etc.

Hot rolled seamless steel tube: It is more commonly used to manufacture structural components and fluid transport pipelines that do not require high strength but require good toughness, such as building structures, boilers, water and gas pipelines, etc.

4. Appearance and dimensional characteristics

Cold rolled seamless steel tube: usually has a smaller diameter, high precision outer diameter, shorter length than hot-rolled seamless steel tube, and more uniform wall thickness.

Hot rolled seamless steel tube: The outer diameter is usually greater than 32 millimetres, and the wall thickness ranges from 2.5 to 75 millimetres. Its outer diameter accuracy is relatively low, and the surface may be rough.

5. Manufacturing cost and difficulty

Cold drawn seamless steel tube: The manufacturing process is complex, requiring multiple drawing and annealing treatments, with a long production cycle and low output, resulting in high manufacturing costs.

Hot rolled seamless steel tube: The manufacturing process is relatively simple, the production cycle is short, and the output is high, so the manufacturing cost is relatively low.

In summary, there are significant differences between cold drawn seamless steel tubes and hot-rolled seamless steel tubes in terms of manufacturing processes, materials and properties, application areas, appearance and size characteristics, manufacturing costs and difficulties.