Steel pipe knowledge: T91 steel pipe is a kind of steel pipe

T91 steel pipe is a kind of steel pipe, and T91 steel is a new type of martensitic heat-resistant steel developed by the United States National Laboratory like the Shuling Laboratory and the United States Combustion Engineering Corporation Metallurgical Materials Laboratory. It is based on the 9Cr1MoV steel to reduce the carbon content, strictly limit the sulfur, phosphorus content, add a small amount of vanadium, niobium elements for alloying.
1T91 steel alloying principle, especially adding a small amount of niobium, vanadium and other trace elements, high temperature strength, oxidation resistance than 12 Cr1MoV steel has been greatly improved, but its poor welding performance.
2 bolt test shows that T91 steel has a greater tendency to cold cracking, select the preheating 200 ~ 250 °C, the interlayer temperature of 200 ~ 300 °C, can effectively prevent the occurrence of cold cracks.
Before 3T91 heat treatment after welding, it must be cooled to 100 ~ 150 °C, heat 1 h; tempering temperature 730 ~ 780 °C, holding time is not less than 1 h.
4 or more welding processes have been applied to 200 MW and 300 MW boiler manufacturing practices with satisfactory results and greater economic benefits. Steel pipe is a long strip steel with a hollow section and no joints around it. The steel pipe has a hollow cross-section and is used in a large amount as a pipe for conveying fluids, such as pipes for transporting petroleum, natural gas, coal gas, water, and certain solid materials. Compared with solid steel such as round steel, steel pipes have a lighter weight when subjected to the same flexural and torsional strength, and are economical cross-section steels. They are widely used in the manufacture of structural and mechanical parts such as oil drill pipes, automobile transmission shafts, and bicycles. Frames and steel scaffolds used in construction. The manufacture of ring-shaped parts from steel tubes can increase material utilization, simplify the manufacturing process, save material and processing man-hours, such as rolling bearing rings, jack sleeves, etc. Currently, steel tubes have been widely used for manufacturing. The steel pipe is also an indispensable material for various conventional weapons. The barrels, barrels, etc. must be made of steel pipes. Steel tubes can be divided into round tubes and shaped tubes according to the shape of the cross-sectional area. Since the circle area is the largest under the condition of the same circumference, more fluid can be transported by the circular tube. In addition, when the ring section is subjected to internal or external radial pressure, the force is more uniform. Therefore, most steel pipes are round pipes.
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