The production process of
16MnDG seamless steel pipes mainly includes hot rolling and cold rolling (drawing). The following is a specific introduction:
First, the hot rolling process of 16MnDG seamless steel pipes
- Preparation and inspection of tube billets: Select steel billets that meet the chemical composition and quality requirements, strictly inspect their surface quality, dimensional accuracy, etc., remove surface defects such as cracks and scars, etc., to ensure that the quality of the tube billets is qualified.
- Heating of tube billets: Send the qualified tube billets into the heating furnace and heat them to a suitable temperature range, generally around 1200℃1250℃, so that the tube billets have good plasticity and machinability.
- Perforation: The heated tube billets are sent to the perforator for perforation. Through the mechanical force and thermal action of perforation, a cavity is formed in the center of the tube billet to make a rough tube. During the piercing process, the tube billet rotates and moves forward continuously, and the prototype of the seamless steel pipe is gradually formed under the action of the rollers and the mandrel.
- Pipe rolling: The rough tube is then sent to the tube rolling mill for rolling. Through multiple rolling passes, the wall thickness of the steel tube is further reduced, its dimensional accuracy and surface quality are improved, and the shape and size of the steel tube are gradually close to the requirements of the finished product.
- Steel pipe reheating: The steel pipe after tube rolling may increase its hardness and reduce its plasticity due to work hardening and other reasons. It needs to be heated again to improve its structure and performance and prepare for subsequent sizing and other processes.
- Sizing (reducing): The reheated steel pipe enters the sizing machine or reducing machine. Through the extrusion of the rollers, the outer diameter of the steel pipe is accurately controlled to reach the specified dimensional tolerance range and obtain the required outer diameter accuracy and surface finish.
- Heat treatment: The sizing steel pipe is heat treated, generally using normalizing treatment, to refine the grains, improve the uniformity of the structure, eliminate internal stress, and improve the comprehensive mechanical properties of the steel pipe, so that it meets the use requirements in low-temperature environments.
- Finished pipe straightening: After heat treatment, the steel pipe may bend and deform to a certain extent. It needs to be straightened by a straightening machine to make the straightness of the steel pipe meet the standard requirements and ensure the appearance quality and performance of the steel pipe.
- Finishing: Surface treatment of the straightened steel pipe, such as pickling and phosphating, is performed to remove impurities such as scale and rust on the surface of the steel pipe to improve the surface quality of the steel pipe. At the same time, the two ends of the steel pipe are cut and chamfered to make the end surface flat and smooth, which is convenient for subsequent installation and use.
- Inspection: Comprehensive quality inspection of finished steel pipes, including non-destructive testing, physical and chemical properties testing, dimensional accuracy testing, etc. Non-destructive testing mainly uses ultrasonic flaw detection, eddy current flaw detection, and other methods to check whether there are defects such as cracks and pores inside the steel pipe; physical and chemical properties testing analyzes and tests the chemical composition and mechanical properties of the steel pipe to ensure that it meets relevant standards and technical requirements; dimensional accuracy testing mainly checks whether the outer diameter, wall thickness, length and other dimensions of the steel pipe are within the specified tolerance range. Only steel pipes that have passed the inspection can be put into storage or delivered for use as finished products.
Second, the cold rolling (drawing) process of 16MnDG seamless steel pipe
- Billet preparation: Select suitable hot-rolled pipe billets or steel pipes that have been pre-treated by pickling, annealing, etc. as billets, and check the dimensional accuracy and surface quality of the billets to ensure that they meet the requirements of the cold rolling (drawing) process.
- Pickling and lubrication: To remove the oxide scale and oil stains on the surface of the billet, improve the surface quality of the steel pipe, and increase the service life of the cold rolling (drawing) mold, the billet needs to be pickled. After pickling, apply lubricant on the surface of the billet to reduce friction during the cold rolling (drawing) process and prevent scratches on the surface of the steel pipe and wear of the mold.
- Cold rolling (drawing): The pickled and lubricated billet enters the cold rolling mill or cold drawing machine for processing. Cold rolling is to make the steel pipe produce plastic deformation at room temperature through the extrusion of the roller, thereby reducing the wall thickness, and improving the dimensional accuracy and surface quality; cold drawing is to draw the steel pipe through the die to reduce its cross-sectional area and increase its length to achieve the required size specifications. In the cold rolling (drawing) process, it is necessary to reasonably select the process parameters such as the number of rolling or drawing passes and deformation amount according to the material, specifications, and finished product requirements of the steel pipe to ensure the performance and quality of the steel pipe.
- Heat treatment: After cold rolling (drawing), the steel pipe has higher strength and hardness due to work hardening, but lower plasticity and toughness, and needs heat treatment to improve its structure and performance. Annealing or tempering treatment is generally used. Annealing can eliminate work hardening and restore the plasticity and toughness of the steel pipe. Tempering can further improve the toughness and stability of the steel pipe while maintaining a certain strength.
- Straightening: Similar to the hot rolling process, the cold-rolled (drawn) steel pipe after heat treatment also needs to be straightened to ensure that its straightness meets the requirements.
- Finishing: Surface treatment of the straightened steel pipe, such as pickling, phosphating, shot blasting, etc., is performed to remove impurities such as oxide scale and oil stains on the surface to improve the surface finish of the steel pipe. At the same time, the two ends of the steel pipe are cut and chamfered to meet the requirements of dimensional accuracy and appearance quality.
- Inspection: Comprehensive quality inspection of the finished cold-rolled (drawn) steel pipe, including non-destructive testing, physical and chemical performance testing, dimensional accuracy testing, etc., to ensure that the quality of the steel pipe meets the relevant standards and user requirements before it can be put into storage or delivered for use.
Threeway Steel is known as a professional supplier engaged in manufacturing and distributing a wide range of steel pipe, and our headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
Threeway Steel is known as a professional supplier engaged in designing, manufacturing and distribution of a wide range of steel products with the headquarter located the central part of China – Hunan and six associated factories throughout China.
