Cold drawn seamless steel pipe is one of the production processes of seamless pipes. The carbon content is between 0.24% and 0.32%. The reason that simn is listed separately is because of the five major elements (carbon C, silicon Si, manganese Mn, phosphorus P, sulfur S). ), the high content of silicomanganese is about 1.10-1.40%. Cold drawn seamless steel pipes are suitable for power plants, boiler plants, chemicals, vehicles, and ship accessories.
【Main Features】
The performance of cold drawn seamless steel pipe is better than that of 30Mn2 steel. It has higher hardenability, with a critical hardenability diameter of 8-22mm in water, good machinability, moderate cold deformation plasticity and weldability; in addition, the toughness of steel is not reduced during heat treatment. However, it has quite high strength and wear resistance, especially high toughness during water quenching; however, this steel is highly sensitive to white spots, and has a tendency to temper brittleness and overheat sensitivity during heat treatment.
【Application examples】
Cold drawn seamless steel pipes are mainly used in quenched and tempered state to manufacture hot stamping parts that require high toughness and wear resistance; they can also be used in normalized or hot rolled supply conditions, such as tractor track pins. Pickling is to soak the carrier with 6mol/L hydrochloric acid for 2 hours or heat and soak with concentrated hydrochloric acid for 30 minutes, filter, wash with water to neutrality, and dry. Pickling can remove iron, aluminum, calcium, magnesium and other impurities on the surface, but not silanol groups. The pickling carrier is suitable for analyzing acidic samples.
Degreasing and derusting the surface of cold drawn seamless steel pipes for preparation for the next process. In the production process, the pickling process is to remove the surface oxide scale, then go through lubrication treatment, and then carry out deep drawing processing.
If cold drawn seamless steel pipes are not pickled, there may be oxides and oil stains on the surface, and the nuclear energy of the phosphating solution cannot remove them, and the quality of phosphating will be reduced.
Heat treatment process of cold drawn seamless steel pipe:
Cold drawn seamless steel pipe vacuum quenching vacuum quenching furnace is divided into oil quenching and gas quenching according to the cooling method, and divided into single-chamber type and double-chamber type according to the number of stations.
Oil quenching can easily cause surface deterioration of the workpiece. Due to the high surface activity, significant thin-layer carburization can occur under the action of a short high-temperature oil film. In addition, the adhesion of carbon black and oil on the surface is not good for simplifying the heat treatment process.
The development of vacuum quenching technology for cold drawn seamless steel pipes mainly lies in the development of air-cooled quenching furnaces with excellent performance and single station. The aforementioned dual-chamber furnace can also be used for gas quenching, but the dual-station operation makes it difficult to produce large quantities of furnaces, and it is also easy to cause deformation of the workpiece during high-temperature movement or change the orientation of the workpiece to increase quenching deformation.
https://www.skivingtubelw.com
