The plug is mainly composed of carbon, iron, chromium and molybdenum. The C is 0.13-0.3%, Cr is 1.0-2.2%, Ni is 1.0-4.5%, Si is 0.2-1.4%, Mn is 0.2-1.4%, Mo is 0.1-0.7%, W is ≤ 0.6%, s is ≤ 0.04%, P ≤ 0.04%, and the rest are Fe and other small elements (their contents are calculated by weight percentage). Due to the addition of alloy elements, the strength of the piercing plug has been greatly improved, which can not only meet the necessary stiffness for piercing, but also have good high temperature resistance. When threading seamless steel pipe, the service life is more than three times that of similar domestic and foreign products, thus greatly reducing its production cost.
Plug is the key tool in seamless steel pipe production. The quality and service life directly affect the output, quality and economic benefits of steel pipe production. In the process of threading seamless steel pipe, the solid pipe blank is made into hollow rough pipe, and the metal deformation is mainly carried out on the plug. The working conditions of the piercing plug are very bad. It should not only bear strong axial pressure, but also overcome the strong deformation and friction force with the inner wall. Therefore, it can be considered that the piercing plug works under the condition of low cycle fatigue, so its wear and scrapping is the main reason affecting its service life. In view of the use of plugs in China's steel pipe industry, the company continues to improve plug production and manufacturing technology, so as to gradually improve the quality of plug, such as cleanliness, toughness, wear resistance, thermal conductivity and oxygen resistance. We will serve users with excellent plugs. The main technical bidding material is H13 (4cr5movisi), and the material warranty is attached to the supply; The smooth connecting thread specification of each curve arc part shall be processed according to the user's requirements. After the molybdenum inlaid welding quality head is repaired, it shall pass the dye flaw detection. The special specification head shall be implemented according to the data provided by the user.
In view of the failure form of seamless pipe piercing plug, a new process of infiltrating Cr, Mo, Al, Ni and other alloy elements into the surface of low alloy steel plug by double glow discharge alloying technology and then ion nitriding treatment is proposed. The surface composite treatment is carried out on 20crnisi piercing plug, and preliminary results are obtained, It lays a good foundation for further research on plug.
