Cold-rolled seamless steel tube, also known as precision seamless steel tube, is a high-precision steel tube produced using a cold-rolling process. Its outer diameter ranges from 4.0 to 450 mm, and its wall thickness from 0.04 to 60 mm, conforming to standard GB/T3639-2008.
Round tube billet → Heating → Piercing → Heading → Annealing → Pickling → Oiling (copper plating) → Multi-pass cold drawing (cold rolling) → Billet tube → Heat treatment → Straightening → Hydrostatic test (flaw detection) → Marking → Warehousing.
Their production processes are basically the same in the first three steps. The difference begins from the fourth step. After the round tube billet is hollowed out, it needs to be headed, annealed, and then acid-washed with a special acidic liquid. After acid washing, it is oiled, followed by multiple cold drawing (cold rolling) cycles to form a new billet tube, a special heat treatment, and then straightening.
After straightening, the steel pipe is conveyed to a metal flaw detector (or hydrostatic test) for internal flaw detection. If there are cracks, bubbles, or other problems inside the steel pipe, they will be detected. After quality inspection, the steel pipe undergoes strict manual selection. Finally, the steel pipe is painted with its serial number, specifications, production batch number, etc.
1. High dimensional accuracy; inner and outer diameter errors can be controlled within ±0.05mm;
2. Smooth surface, no oxide layer, suitable for direct machining;
3. Excellent mechanical properties; uniform and dense metal structure;
4. Facilitates automated processing and assembly, improving product efficiency.
Advantages of Cold-Rolled Precision Seamless Steel Pipes: The main advantage of cold-rolled steel pipes is their large section reduction rate, especially their strong wall reduction ability. For carbon steel, the section reduction rate in a single rolling can reach 80%–83%, and for alloy steel, it can reach 72%–75%. Its main disadvantage is the difficulty in tool replacement. Besides being used directly to produce some high-precision cold-rolled tubes, cold rolling is often combined with cold drawing for cold drawing billet preparation. This fully utilizes the wall-reduction capacity of cold rolling and cleverly takes advantage of the ease of changing cold drawing tools, which is beneficial for improving productivity, expanding the product range, and improving the surface quality of steel pipes.
The production process of cold-rolled precision seamless steel tube:
Raw material preparation: The base tube for cold-rolled precision seamless steel tubes is usually made of hot-rolled seamless steel. The material of the base tube is generally high-quality carbon structural steel or alloy structural steel such as 10#, 20#, 35#, 45#, 16Mn, 20CrMo, and 42CrMo. The surface of the raw material must be smooth and free of defects such as cracks, folds, and delamination to ensure the quality of subsequent processing.Round tube billet → Heating → Piercing → Heading → Annealing → Pickling → Oiling (copper plating) → Multi-pass cold drawing (cold rolling) → Billet tube → Heat treatment → Straightening → Hydrostatic test (flaw detection) → Marking → Warehousing.
Their production processes are basically the same in the first three steps. The difference begins from the fourth step. After the round tube billet is hollowed out, it needs to be headed, annealed, and then acid-washed with a special acidic liquid. After acid washing, it is oiled, followed by multiple cold drawing (cold rolling) cycles to form a new billet tube, a special heat treatment, and then straightening.
After straightening, the steel pipe is conveyed to a metal flaw detector (or hydrostatic test) for internal flaw detection. If there are cracks, bubbles, or other problems inside the steel pipe, they will be detected. After quality inspection, the steel pipe undergoes strict manual selection. Finally, the steel pipe is painted with its serial number, specifications, production batch number, etc.
Process Characteristics and Advantages of Cold-Rolled Precision Seamless Steel Tubes
Compared to ordinary seamless tubes, cold-rolled precision seamless steel tubes have the following significant advantages:1. High dimensional accuracy; inner and outer diameter errors can be controlled within ±0.05mm;
2. Smooth surface, no oxide layer, suitable for direct machining;
3. Excellent mechanical properties; uniform and dense metal structure;
4. Facilitates automated processing and assembly, improving product efficiency.
Advantages of Cold-Rolled Precision Seamless Steel Pipes: The main advantage of cold-rolled steel pipes is their large section reduction rate, especially their strong wall reduction ability. For carbon steel, the section reduction rate in a single rolling can reach 80%–83%, and for alloy steel, it can reach 72%–75%. Its main disadvantage is the difficulty in tool replacement. Besides being used directly to produce some high-precision cold-rolled tubes, cold rolling is often combined with cold drawing for cold drawing billet preparation. This fully utilizes the wall-reduction capacity of cold rolling and cleverly takes advantage of the ease of changing cold drawing tools, which is beneficial for improving productivity, expanding the product range, and improving the surface quality of steel pipes.
