45#Cooling method of seamless steel pipe

After the heat treatment of the 45# seamless steel pipe, it is necessary to wait for it to cool before proceeding to the next step. The cooling method of 45# seamless steel pipe changes with the change of its manufacturing materials. For most steels, natural cooling can be used. For some special 45# seamless steel pipes, to ensure its Organizational state, physical properties and mechanical properties are developing in the expected direction, and certain methods and systems must be adopted.
　　
　　For example, austenitic seamless steel tubes need to be rolled at a certain temperature, then quenched with water for solution treatment, and then sent to a cold bed for natural cooling; GCr15 bearing seamless steel tubes have a sheet-like pearlite structure and prevent The reticulated carbide is precipitated to facilitate the subsequent spheroidizing annealing process. It should be controlled to finish rolling at 850 degrees Celsius or higher, and then to be rapidly cooled at a rate of 50-70 degrees Celsius/minute. Therefore, it is necessary to use a blower or spray on a cold bed. Forced cooling.
　　
　　First, the shoddy thick-walled seamless steel pipe is prone to folding. GB5310 is mainly used for the manufacture of high-quality carbon structural steel, alloy structural steel and stainless steel heat-resistant steel seamless pipes for steam boiler pipes such as high pressure and above. Folding is a variety of fold lines formed on the surface of thick-walled seamless steel tubes, which often extend throughout the longitudinal direction of the product. The reason for the folding is that the fake and inferior manufacturers pursue high efficiency (ɡāo xiào) rate, the amount of pressing is too large, the ear is produced, and the next rolling is folded, and the folded product will be cracked after being bent (kāi liè), thick The strength of the wall seamless steel pipe is large.
　　
　　Second, the surface of the shoddy thick-walled seamless steel pipe often has a pockmark phenomenon. The pockmark is caused by the irregular wear and tear of the surface of the thick-walled seamless steel pipe due to the serious wear of the groove. Due to the pursuit of profit by shoddy thick-walled seamless steel pipe manufacturers, the most frequent rolling mill rolling is exceeded.
　　
　　Third, the surface of the shoddy thick-walled seamless steel pipe is prone to scarring. There are two reasons for this:
　　
　　1. The shoddy thick-walled seamless steel pipe is uneven in material and has many impurities.
　　
　　2. The fake inferior material manufacturer's guiding equipment is simple and easy to stick steel. These impurities are easy to produce crusting after biting the roller (gǔn). The 20G high pressure boiler tube has strict requirements on the steel grade used to manufacture the steel pipe. 20G high-pressure boiler tubes are often subjected to high temperature and high pressure conditions, and the tubes will oxidize and corrode under the action of high temperature flue gas and water vapor. Steel pipes are required to have high durability, high corrosion resistance and good structural stability. High-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, air ducts, main steam tubes, etc. for high-pressure and ultra-high pressure boilers.
　　
　　4. The surface of the fake inferior material is prone to cracks because the billet is adobe, the adobe has many pores, and the adobe is cracked due to thermal stress in the process of cooling, and there is crack after rolling. .
　　
　　Fifth, the shoddy thick-walled seamless steel pipe is easy to scratch, because the fake inferior material manufacturer equipment (shèbèi) is simple, easy to produce burrs, scratching the surface of thick-walled seamless steel pipe. The steel for the pressure component of the boiler used in the 20G high-pressure boiler tube is generally applied to boilers under 39 kg. In order to use it under higher pressure, the heated surface tube is often designed to be thick. In order to reduce the thermal resistance and save steel, to ensure the safety of steel for high or high pressure boilers, and also to reduce the amount of steel used, 16MnG is commonly used. At the same time, special steels with added metals such as rare earths and magnesium and non-metallic materials are also available. This will improve the performance of the boiler steel, reduce the steel consumption, and also reduce the thermal resistance. Deep scratches reduce the strength of thick-walled seamless steel tubes.