Development of seamless steel tubes for TP960E ultra-high-strength crane jib

Seamless steel tubes are a type of large-diameter steel pipe that are used in many industries. They have been in use for many years due to their inherent advantages, such as their excellent strength-to-weight ratio and their ability to withstand extreme temperatures. The tubes have been used in the manufacturing of constructions cranes, petrol pipelines, and many other industrial applications.
    
Along with advancements in technology, new materials and higher strength steel grades have been developed. One of these new developments is the TP960E ultra-high-strength steel. This steel has impressive mechanical properties due to its high carbon and alloying elements (Ti, Nb, V, P, etc.). The combination of these elements make it ideal for applications such as a crane jib.
    
Seamless steel tubes made using the TP960E steel grade is the most suitable material for the construction of crane jibs due to the material’s excellent mechanical properties. To ensure their effectiveness, these tubes must be produced with excellent dimensional accuracy. This article reviews the development process of seamless steel tubes for use in a TP960E crane jib.
    
Materials & Manufacturing Process
The TP960E crane jib requires seamless steel tubes that are strong, lightweight and have superior corrosion-resistance. The most suitable material for such tubes is the TP960E ultra-high-strength steel. This steel grade has excellent mechanical properties, including high tensile strength and yield strength. It also has good fatigue resistance which makes it ideal for the rigorous repetitive operation commonly associated with crane jib applications.
    
To fabricate seamless tubes from TP960E, the material must first be subjected to hot-rolling. This process is done at high temperatures, typically between 1100-1300°C. During hot-rolling, the material is passed through a series of sets of rolls and emerges as thin strips. The strips are then cut into the desired size and shape of the seamless tube.
    
The hot-rolled strips are then cold-rolled. During this process, the strips are passed through a series of cold-rolling stands which change the material’s microstructure and increase its hardness. The material is reduced in thickness and width to the desired size, while the length of the tubes remains the same.
    
The next process is stress-relieving. This is done to reduce residual stresses present in the tubes due to the cold-rolling process. To achieve this, the tubes are heated in a controlled atmosphere and then cooled at a specific rate. The amount of time and temperature at which the tubes are heated depend on the size and other characteristics of the tubes.
    
The tubes are then heat treated. This helps to increase their strength and hardness, as well as help to reduce their susceptibility to cracking due to long-term loading and fatigue. Depending on the type of heat treatment required, the material is heated at specific temperatures, then rapidly cooled in different ways, either by air-cooling, water cooling or both.
    
The final process involves drawing the tubes. This process involves pulling the hot-rolled and cold-rolled strips through a die to achieve the desired wall thickness and size. In the case of the TP960E seamless steel tubes for the crane jib, cylindrical parabolas are drawn. The pipes are then heat treated again to increase their strength and corrosion-resistance.
    
Testing & Inspection
The finished seamless steel tubes for the crane jib are subjected to a range of inspections and tests before they are shipped and put into service. This helps to ensure that they have the desired levels of toughness and durability.
    
For the crane jib, one of the most important tests is the proof load test. This test is done to check the strength and load capacity of the tubes. A test load is applied to each tube and the load is increased until it reaches the desired load limit. The load is then monitored to ensure that no permanent deformation occurs.
    
Other inspections such as dimensional accuracy checks, surface finish inspections and ultrasonic testing are also done to check the metallurgical properties of the tubes. The inspections are done to ensure that the tubes meet the required specifications and that they are safe to use.
    
Conclusion
The TP960E ultra-high-strength steel is an excellent material for the construction of crane jibs due to its strong and durable properties. Seamless steel tubes fabricated from this material offer superior strength, light weight, and corrosion-resistance. To ensure their effectiveness, the tubes must be produced with excellent dimensional accuracy. This article has discussed the development process of seamless steel tubes for use in a TP960E crane jib. Through the implementation of hot-rolling, cold-rolling, stress-relieving, heat treatment and drawing processes, the seamless steel tubes for the crane jib are produced to the highest quality and safety standards.

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