seamless steel pipe On-line cold control technology - TMCP

On-line cold control technology for seamless steel pipe-TMCP

 

Control rolling and control cooling (for short, controlled rolling control cold, English abbreviation TMCP) technology in seamless steel pipe production has been more and more attention. As an effective means to reduce the consumption of alloy and reduce the cost of production, controlled rolling and controlled cooling technology is widely used in the industrial production of Hot rolled strip, plate, bar and H steel. Compared with strip controlled rolling and cooling technology, due to the limitation of steel pipe geometry, rolling process and rolling equipment, the controllable and variable factors in the production process of seamless steel pipe are relatively few; therefore, the application of controlled rolling and controlled cooling technology in seamless steel pipe production is restricted to some extent and is still in the stage of exploration and development. Although the seamless steel pipe controlled rolling and controlled cooling technology can not from deformation temperature, deformation, deformation path, deformation clearance time, finish rolling temperature and the cooling process after finishing to form a set of complete control rolling control cooling, but the current control of seamless steel pipe rolling control technology has formed including on-line constant, on-line quenching and on-line rapid cooling and other processes,

 

Diversified development. On-line normalizing is a heat treatment process, also known as on-line normalizing, which is the process of homogeneous metallographic microstructure after the process of rolling pipe in the hot rolling production line, so that the steel pipe is cooled or forced to cool in the austenite phase area. The process combines heat treatment process with rolling deformation process in continuous production of steel rolling, and its technological characteristics include both phase transformation and rolling deformation, thus belonging to a new rolling process.

 

Through the on-line constant process, it can not only make the steel structure uniformity, grain refinement, prepare for further heat treatment, but also improve the comprehensive mechanical properties of seamless steel pipes.

 

The application of on-line quenching process for seamless steel pipe includes on-line solution treatment of austenitic stainless steel and on-line quenching heat treatment of carbon steel and low alloy steel pipe. On-line rapid cooling process of seamless steel pipe is a new technology of control rolling and cooling technology based on super fast cooling technology in seamless steel pipe production. Ultra-fast cooling technology refers to the process of heat treatment directly after finishing mill by using residual heat of rolling, the control principle is to strengthen the cooling of the austenite after rolling, so that the metal cools quickly to the ferrite phase transition temperature in a very short time, thus inhibiting the austenite grain growth and keeping the austenite hardening state as far as possible.

 

At present, the seamless steel pipe cooling process on line is mainly limited by the uniformity of the cooling pipe along the length and the internal and external surface properties.

 

Improvement of controlled rolling and cooling device:

 

1) on-line technology: We should mainly pay attention to the rational selection of the length of the chain bed, the speed of the chain bed, the cooling mode, the increase of water gasifier and the setting of the technological parameters of reheating furnace.

 

2 on-line quenching (including on-line solution treatment) process: should focus on the choice of cooling mode, should try to choose "internal spray + outside, the steel pipe clamping rotation" or "steel pipe rotation at the same time immersed in the sink, the internal surface of the axial flow spray" quenching method, the latter can be converted to the pipe along the sink shaft or water-based liquid quenching.

 

3) on-line rapid cooling process: the main concern is to increase the temperature of water cooled ring control, the reasonable design of the length of the cooling device, the reasonable configuration of the rotating mechanism of seamless steel pipe and the reasonable improvement of cooler nozzle.