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What Is the Essence of the Seamless Steel Pipe?
Apr 17, 2022
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The seamless steel pipe is perforated by the whole round steel pipe, and the surface of the steel pipe is seamless without welding. The seamless steel pipe is divided into the hot rolled seamless steel pipe, the cold rolled seamless steel pipe, the cold drawn seamless steel pipe, the extruded seamless steel pipe, the pipe jacking, etc. The seamless steel pipe can be divided into the round seamless steel pipe and the special-shaped seamless steel pipe. The special-shaped pipe can be divided into the square seamless steel pipe, the oval seamless steel pipe, the triangle seamless steel pipe, the hexagonal seamless steel pipe, the melon seed shape seamless steel pipe, the star seamless steel pipe, the wing pipe and other seamless steel pipes with complex shapes.
The hot rolled seamless steel pipe is divided into the ordinary steel pipe, the stainless steel pipe, the high-pressure boiler steel pipe, the medium pressure boiler steel pipe, the low pressure boiler steel pipe, the petroleum cracking pipe, the alloy steel pipe, the geological steel pipe and so on. In addition to alloy steel pipes, ordinary steel pipes, petroleum cracking pipes, middle and low-pressure boiler steel pipes, high-pressure boiler steel pipes, stainless steel pipes, there are also stainless steel thin-walled steel pipes, carbon thin-walled steel pipes, alloy thin-walled steel pipes and special-shaped steel pipes.
The outer diameter of hot rolled seamless pipes is generally greater than 32mm. The wall thickness is between 2.5-75mm. The outer diameter of cold rolled seamless pipes can be up to 6mm. The wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm. The wall thickness is less than 0.25mm. The highest yield in seamless steel pipes is made of carbon structural steel, low alloy structural steel and alloy structural steel. The seamless steel pipe is mainly used for conveying fluid pipes or structural parts.
Seamless steel pipes are carefully drawn or cold-rolled with high precision steel. The inner and outer walls of seamless steel pipes have no oxide layer to withstand the advantages of this high-pressure system. There are many advantages of seamless steel pipes, like no leakage, high precision, high finish, cold bending deformation, flaring, flattening and no crack. They can mainly be used in the production process of pneumatic or hydraulic components products, such as cylinders or oil cylinders.
Main applications: automobile, mechanical equipment accessories, and so on. The user only needs the precision of precision steel pipes, as well as the user's requirements for high finish. Due to the use of high-precision seamless steel pipes, lines 2-8 can maintain tolerances, many users have processing stations to save material losses. When the seamless steel pipe is used, the pipe or rod is slowly converted to the seamless steel pipe.
The influence of elements in seamless steel pipes on high temperature tempering brittleness can be divided into: impurity elements in the initiators of seamless steel pipes with high temperature tempering brittleness, such as phosphorus, tin, antimony, which exist in different forms and different degrees, or slow down the high temperature tempering brittleness of alloy elements. Chromium, manganese, nickel and silicon act as accelerators, and molybdenum, tungsten and titanium act as retarders, and carbon also plays an important role.
The seamless steel pipe with high temperature tempering brittle is usually considered as the characteristic of phosphorus, tin, antimony, arsenic and other impurities at austenite grain boundary segregation. It results in the grain boundary brittleness effect. On the contrary, molybdenum has strong interaction with phosphorus and other impurity elements, which can form precipitated phase in the crystal and hinder the grain boundary segregation of phosphorus. Titanium efficiently promotes the precipitation of impurity elements, such as phosphorus in crystals, which reduces grain boundary segregation of impurity elements and slows temper brittleness.
The measures to reduce the brittleness of seamless steel pipes at high temperatures are: after high temperature tempering, oil cooling or water cooling is improved quickly to inhibit the segregation of other impurities and main elements at grain boundaries. The tendency of high temperature tempering employment decreases significantly when the content of molybdenum in steel increases to 0.7% of seamless steel pipes. Beyond this limit, the special carbides form No. 20 precision steel pipes which are rich in molybdenum, and the molybdenum content decreases. However, the trend of seamless steel pipes increases.
Reduce the content of impurities and elements in 20 precision engineering steel pipes. For parts working in high temperature tempering empowerment zone for a long time, it is difficult to effectively prevent embrittle by adding molybdenum alone. The high temperature tempering brittleness can be prevented more effectively only by reducing the technical content of main impurity elements in No. 20 precision steel pipes, improving the purity of seamless steel pipes and combining with the composite alloying of aluminum and rare earth metal elements.
The hot rolled seamless steel pipe is divided into the ordinary steel pipe, the stainless steel pipe, the high-pressure boiler steel pipe, the medium pressure boiler steel pipe, the low pressure boiler steel pipe, the petroleum cracking pipe, the alloy steel pipe, the geological steel pipe and so on. In addition to alloy steel pipes, ordinary steel pipes, petroleum cracking pipes, middle and low-pressure boiler steel pipes, high-pressure boiler steel pipes, stainless steel pipes, there are also stainless steel thin-walled steel pipes, carbon thin-walled steel pipes, alloy thin-walled steel pipes and special-shaped steel pipes.
The outer diameter of hot rolled seamless pipes is generally greater than 32mm. The wall thickness is between 2.5-75mm. The outer diameter of cold rolled seamless pipes can be up to 6mm. The wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm. The wall thickness is less than 0.25mm. The highest yield in seamless steel pipes is made of carbon structural steel, low alloy structural steel and alloy structural steel. The seamless steel pipe is mainly used for conveying fluid pipes or structural parts.
Seamless steel pipes are carefully drawn or cold-rolled with high precision steel. The inner and outer walls of seamless steel pipes have no oxide layer to withstand the advantages of this high-pressure system. There are many advantages of seamless steel pipes, like no leakage, high precision, high finish, cold bending deformation, flaring, flattening and no crack. They can mainly be used in the production process of pneumatic or hydraulic components products, such as cylinders or oil cylinders.
Main applications: automobile, mechanical equipment accessories, and so on. The user only needs the precision of precision steel pipes, as well as the user's requirements for high finish. Due to the use of high-precision seamless steel pipes, lines 2-8 can maintain tolerances, many users have processing stations to save material losses. When the seamless steel pipe is used, the pipe or rod is slowly converted to the seamless steel pipe.
The influence of elements in seamless steel pipes on high temperature tempering brittleness can be divided into: impurity elements in the initiators of seamless steel pipes with high temperature tempering brittleness, such as phosphorus, tin, antimony, which exist in different forms and different degrees, or slow down the high temperature tempering brittleness of alloy elements. Chromium, manganese, nickel and silicon act as accelerators, and molybdenum, tungsten and titanium act as retarders, and carbon also plays an important role.
The seamless steel pipe with high temperature tempering brittle is usually considered as the characteristic of phosphorus, tin, antimony, arsenic and other impurities at austenite grain boundary segregation. It results in the grain boundary brittleness effect. On the contrary, molybdenum has strong interaction with phosphorus and other impurity elements, which can form precipitated phase in the crystal and hinder the grain boundary segregation of phosphorus. Titanium efficiently promotes the precipitation of impurity elements, such as phosphorus in crystals, which reduces grain boundary segregation of impurity elements and slows temper brittleness.
The measures to reduce the brittleness of seamless steel pipes at high temperatures are: after high temperature tempering, oil cooling or water cooling is improved quickly to inhibit the segregation of other impurities and main elements at grain boundaries. The tendency of high temperature tempering employment decreases significantly when the content of molybdenum in steel increases to 0.7% of seamless steel pipes. Beyond this limit, the special carbides form No. 20 precision steel pipes which are rich in molybdenum, and the molybdenum content decreases. However, the trend of seamless steel pipes increases.
Reduce the content of impurities and elements in 20 precision engineering steel pipes. For parts working in high temperature tempering empowerment zone for a long time, it is difficult to effectively prevent embrittle by adding molybdenum alone. The high temperature tempering brittleness can be prevented more effectively only by reducing the technical content of main impurity elements in No. 20 precision steel pipes, improving the purity of seamless steel pipes and combining with the composite alloying of aluminum and rare earth metal elements.
