How to ensure the performance homogenization of GBT 8162 Q345D seamless steel pipes

GBT 8162 Q345D seamless steel pipes are relatively easy to appear some problems in the production process. In order to ensure the performance homogenization of GBT 8162 Q345D seamless steel pipes, we need to strictly control the annealing temperature, heat preservation time and cooling speed of Q345D seamless steel pipes.

(1) Strictly control the annealing temperature of GBT 8162 Q345D seamless steel pipes. When the annealing temperature is too high, the carbides dissolve more, the austenite homogenization degree is large and the core of the spheroidizing will be reduced or lost. The sheet like pearlite is easily obtained after the annealing of the Q345D seamless steel pipe; the temperature is too low, the original lamellar pearlite is difficult to dissolve, and the spheroidizing object can not be reached.

(2) Proper holding time of heat preservation. The long heat preservation time will lead to the homogenization of GBT 8162 Q345D seamless steel pipe, which is not conducive to the spheroidization. When the time is too short, it is difficult to completely destroy the flake tissue in the original tissue, and can not achieve the effect of the spheroidization.

(3) Precise control of cooling speed. The cooling rate of spheroidizing annealing does not affect the shape of pearlite, but determines the dispersion of carbides, thus determining the hardness after annealing. When the cooling rate is too large and the carbide is not enough to gather and grow, the GBT 8162 Q345D seamless steel pipe will produce a new crystal nucleus in the cooling, thus the fine granular or dot like pearlite with large dispersion can be obtained, and the hardness will be high. On the contrary, the coarse granular pearlite with a small dispersion and a low hardness is often obtained.

Therefore, for the whole production process of GBT 8162 Q345D seamless steel pipe, the quality requirements are strictly controlled. At present, Q345D seamless steel pipe has a relatively good development potential in the whole market development process.